Food Technology
Elham Ghiami; Arash Koocheki; Elnaz Milani
Abstract
Introduction Quinoa, which is known as the mother grain,has higher protein content than common cereals and possesses a large lysine content. Quinoa is composed mainly of carbohydrates (60-75%), of which 10-13% is dietary fiber. Quinoa also has a slightly higher protein content (12-16%) compared ...
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Introduction Quinoa, which is known as the mother grain,has higher protein content than common cereals and possesses a large lysine content. Quinoa is composed mainly of carbohydrates (60-75%), of which 10-13% is dietary fiber. Quinoa also has a slightly higher protein content (12-16%) compared with cereal grains and fat content (5-9%) that is rich in unsaturated fatty acids. Quinoa seeds contain similar or slightly higheramounts of bioactive compounds such as polyphenols (2.7-3.8 g/kg). Moreover, quinoa is gluten-free, thus providing the ability to enhance the selection of gluten-free products forconsumers with celiac disease, but this type of characteristicis challenging to development of bakery products from quinoa with desirable physicochemical properties. Processing of cereal grains and pseudo-cereals into products that deliver a nutritive valueto consumers represents a considerable opportunity for large scale food processing. There havebeen some reported studies on roasting, extrusion, steam pre-conditioning and pearling of quinoafor further uses. Extrusion cooking is a promising technology for improvement of functional properties of quinoa flour. The Evaluation of physicochemical properties and microstructure of Expanded quinoa as affected by extrusion conditions was the main goal of this project. Material and Methods In this study, a parallel twin-screw extruder (Jinan Saxin, China) with die diameter of 3 mm was applied. The effects of extrusion process parameters including feed moisture content (14 and 16%) and die temperature (130, 150 and 170 °C) on final moisture content, bulk density, water absorption index (WAI), color parametersL* (lightness), a*(redness), b*(yellowness), hardness, and microstructure of Expanded quinoa were studied. Extrusion was carried out using a co-rotating twin screw extruder with L/D ratio of 10:1 and die diameter of 4 mm. The feed rate of flour and the screw speed were set at 40 kg/h and 200 rpm, respectively. The physicochemical properties were measured using standard methods. The hardness measurement was performed by a texture analyzer. The cylinder steel probe (2 mm diameter) was set to move at a speed of 1 mm/s The samples were punctured by the probe to a distance of 10 mm . The color parameters of the samples were determined by the Hunterlab machine. The morphology of samples was assessed using a scanning electron microscopy (SEM). Results and Discussion A comprehensive study on impacts of extrusion processing conditions on quinoa flour was conducted. The effect of process variables on the physicochemical attributes of the extrudates was observed. the expanded quinoa with higher feed moisture content had greater moisture and those extruded at higher die temperatures showed lower moisture content (p<0.05). Moisture can reduce the shear force as a plasticizer and increase the amount of moisture absorption of the product. While increasing the die temperature, the effect of shear force on starch dextrification increases and reduces moisture absorption (p<0.05). WAI was significantly influenced by extrusion variables. In fact, feed moisture content and die temperature both positively changed the WAI of quinoa flour so that all extruded samples had significantly higher WAI than the untreated sample (p<0.05). Moreover, the sample with the higher feed moisture content (24%) treated at the highest extrusion temperature (170 °C) showed the largest and lowest water absorption and Hardness respectively (p<0.05). Another important feature of expanded quinoa is the lightness index, the results revealed that extrusion cooking caused a reduction in L* and enhancements in a* and b*. While changes in color parameters were more pronounced at more severe die temperature, higher feed moisture content counteracted the effects of cooking temperature on the color of the products. As expected from changes in the abovementioned color parameters, the sample with lower feed moisture content (16%) treated at the highest extrusion temperature (170 °C) experienced the greatest color change (ΔE). The texture profile analysis (TPA) indicated that higher feed moisture content yielded extrudates with harder texture whereas, extrusion at higher temperature resulted in lower hardness. The scanning electron micrographs showed that the native quinoa flour encompassed both small- and large-sized starch granules while the extruded sample mainly consisted of disaggregated particles. Furthermore, extrusion cooking of samples with higher feed moisture content caused formation of more uniform starch aggregates with smoother surfaces.
Food Technology
Fatemeh Shokrollahi; Fakhri Shahidi; Mohammad Javad Varidi; Arash Koocheki; Farshad Sohbatzadeh
Abstract
IntroductionSorghum is a valuable source of starch for human use, being a drought-tolerant cereal grain that contains a large amount of starch (approximately 70%). However, native sorghum starch has limited application in the food industry due to its poor functional properties. Modification of sorghum ...
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IntroductionSorghum is a valuable source of starch for human use, being a drought-tolerant cereal grain that contains a large amount of starch (approximately 70%). However, native sorghum starch has limited application in the food industry due to its poor functional properties. Modification of sorghum starch would overcome its shortcomings and tailor it to the targeted application. Among physical methods, non-thermal plasma is a novel method for starch modifications. Plasma is an ionized gas including electrons, atoms, ions, radicals, and quanta of electromagnetic radiation that affects the functional properties of starch. The effect of plasma on starch is influenced by apparatus type, treatment conditions (feed gas, time, and power), and the source of starch. Two main mechanisms of starch modification are known as cross-linking and oxidation together with depolymerization. Although the effect of plasma on many types of starch has been investigated, no research has yet been found on sorghum starch modification by non-thermal plasma. So, this investigation determines the effects of non-thermal plasma on sorghum starch to overcome the deficiency of the native form and to explore wider applications for sorghum starch. Materials and Methods Sorghum starch was extracted by alkaline steeping and purified using toluene-salt-water treatment. Dielectric Barrier Discharge (DBD) plasma was performed to modify sorghum starch. The applied DBD plasma setup consisted of two flat rectangular aluminum electrodes with the dimension of 6.5×45 cm and 7×18 cm and an electrode distance of 3 and 6 mm for air and argon plasma, respectively. Each of the electrodes was covered with a mica sheet as a dielectric barrier. DBD reactor was supplied with alternating current (AC). The frequency was adjusted to 375 Hz. Starch samples were treated for 1, 10, and 20 min at 23 kV at atmospheric pressure. The amylose content of sorghum starch was determined by iodine binding colorimetry. Evaluation of other chemical parameters including protein, lipid, ash, and moisture was carried out according to AAC methods. The clarity was determined using a spectrophotometer at 650 nm. The swelling and solubility of 1.5% sorghum starch suspension (at 55, 65, 75, and 85 °C) were measured using the centrifuge method. The centrifuge-filtration method was performed to evaluate freeze-thaw stability of sorghum starches up to 4 cycles. Results and Discussion Chemical parameters showed that the extracted sorghum starch was purified. The amount of protein, lipid, ash, and amylose was 0.39, 0.15, 0.59, and 29.23%, respectively. Plasma caused significant altering in sorghum starch properties. Compared to the argon plasma, the air plasma was more effective at increasing the clarity, solubility, and freeze-thaw stability. Increasing the time of treatment also improved the above-mentioned functional properties. The clarity of native starch (14.02%) was increased to 56.10% for the sample treated with air plasma for 20 min, probably due to intense oxidation and depolymerization of starch molecules. While the lowest clarity (13.07%) belonged to the 1-min argon plasma treated sample, this value was improved with increasing time of treatment. Probably cross-linked bonds were predominantly formed during the first minute of argon plasma treatment, resulting in a reduction of paste clarity, while a competitive depolymerization and oxidation reaction could be a reason for the increase of paste clarity. Solubility was increased for all treatments (except for argon-1 min). The highest solubility in each of the temperatures was found for 20 min air plasma treated sample. Depolymerization of starch molecules under plasma treatment produces low molecular weight fragments which leach out easily and increase solubility. The swelling power of 20 min air plasma treated starch was lower than that of native starch, probably due to the structural disintegration. Other samples had higher swelling power. The lower freeze-thaw stability of 1 and 10 min argon plasma treated samples may be due to cross-linking which increase retrogradation. The 20 min air-plasma treated sample had higher stability than other samples in 3 and 4th cycles of freeze-thawing. The freeze-thawing stability of other samples was similar to that of the native starch. Conclusion Non-thermal plasma treatment improved the functional properties of sorghum starch. The best results were detected for the sample treated with air plasma for 20 min. Cross-linking may be the main reaction in the first minute of argon-plasma treatment. However, this mechanism was suppressed in a longer treatment time. It may also be stated that the effect of oxidation along with depolymerization was predominant in air-plasma treatment.
Food Engineering
Fateme Mousavi Baygi; Arash Koocheki; Behrooz Ghorani; Mohebbat Mohebbi
Abstract
Introduction Curcumin, as a natural polyphenolic nutraceutical has been shown many health-promoting effects, mainly associated with its chemical structure. In various studies, different properties of this compound, including anti-tumor and anti-cancer activity, reduction of blood and liver cholesterol ...
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Introduction Curcumin, as a natural polyphenolic nutraceutical has been shown many health-promoting effects, mainly associated with its chemical structure. In various studies, different properties of this compound, including anti-tumor and anti-cancer activity, reduction of blood and liver cholesterol levels, increase of immune function, prevention of cardiovascular diseases, prevention of damage to biological membranes against peroxidation and anti-inflammatory properties have been reported. Despite possessing a potential health benefits to humans, the susceptibility of this polyphenol towards environmental conditions and low chemical stability has restricted the direct usage of curcumin into aqueous-based food formulations. The encapsulation of curcumin in liposomes is a potentially effective way to protect them from degradation during passing the digestive system.Materials and MethodsCurcumin (powder, purity greater than 99%, 368.38 g/mol), lecithin, cholesterol (C3045-25G), pancreacin (extracted from porcine pancreas, P7545-25G), bile salts (B8756-10G) and calcium chloride (CaCl2) was obtained from Sigma Aldrich (USA). Consumable ethanol was purchased from Pars Ethanol Company (96%, Iran). Lipase enzyme (extracted from pig pancreas, L8070) and pepsin (activity 3500-3000 NFU/g, P8390) were obtained from Solarabio (China). Potassium chloride, dipotassium hydrogen phosphate (K2HPO4) and alpha-amylase enzyme with a purity of at least 99% were obtained from Merck, Germany, sodium chloride (NaCl), sodium bicarbonate (NaHCO3) and calcium chloride were obtained from Sigma. The effect of lecithin content (0.02- 0.08 g), lecithin cholesterol ratio (0.5- 4), curcumin level (1.5- 6mg) and ultrasound treatment time (1-5 minutes) on production of liposomes containing curcumin was evaluated. The particle size, particle size distribution, zeta potential and efficiency were determined by response surface methodology. Furthermore, physical nature, molecular structure, physical stability at 4ºC and 25ºC and release behavior of curcumin loaded-liposome in mouth, stomach and intestines were explored.Results and Discussion The results showed that all independent variables had a significant effect on liposome particle size and increasing the ratio of lecithin: cholesterol caused more uniform particle size. Lecithin was determined to be the only component affecting the zeta potential of liposome particles, and increasing the ultrasound time increased the efficiency of curcumin encapsulation in liposomes. The optimal point of liposome preparation conditions in the amount of 0.08 g lecithin, 4: 1 the ratio of lecithin: cholesterol, 4.16 mg curcumin and 5 minutes the ultrasound treatment was introduced by Design Expert software. In addition, curcumin was amorphous in optimal liposome spherical particles. Furthermore, the results of TEM showed that the liposomes are in the form of single-layer particles, spherical and without membrane rupture. This makes the bilayered nature of the vesicles clearly visible in this micrograph. The size of the particles obtained from this method was consistent with the data obtained from the dynamic light scattering method. From the results of infrared spectroscopy, it can be seen that curcumin is trapped in the liposome through hydrogen bonding in the double-layered vesicle of the liposome, the phenolic ring of curcumin with the phospholipid head group, as well as the hydrophobic interactions of the aromatic rings with the acyl phospholipid chains. Liposomes were more stable at refrigeration temperature. A very small amount of curcumin was released in the simulated oral phase, which is probably due to the short time and lack of specific enzymes to disrupt the phospholipid bilayers of the liposome. Although the pepsin enzyme is unable to penetrate the liposome membrane, acidic conditions change the angle of the head and tail groups of the lipids and lead to a change in the surface charge of the liposomes. The release of curcumin from liposome vesicles was greatly increased in the intestine. This sudden increase is due to the presence of bile salts as an emulsifying agent that can disrupt the phospholipid membrane and make the membrane more fluid. In addition, pancreatic lipase is adsorbed on the surface of lipids and then hydrolyzes the phospholipid into 2-acyl and 1-acyl lysophospholipids and free fatty acids. The release behavior of curcumin under gastrointestinal conditions was based on the Fick mechanism.
Alireza Abbasi; Arash Koocheki; Elnaz Milani; Mohebbat Mohebbi
Abstract
[1]Introduction: Breakfast cereal products are considered as an important meal for athletes and children. By changing eating habits and increasing the consumption of these products, choosing healthy and nutritious raw materials such as whole grains to produce breakfast cereals with great impact ...
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[1]Introduction: Breakfast cereal products are considered as an important meal for athletes and children. By changing eating habits and increasing the consumption of these products, choosing healthy and nutritious raw materials such as whole grains to produce breakfast cereals with great impact on people's health. Rice grain as a technologically important source of starch causes the expansion of extruded products. Since in the production of breakfast cereal and baby food products, exclusively starch with low amylose is used, this indicates the suitability of this source for productionof such products. During the dehusking process, about 14% of the rice is broken to smaller grains, which is commercially classified as a low-value product. The broken rice can be converted to rice flour and used as a raw material in various types of food products. To maintain consumer demand for healthy diets, it is necessary to use high-fiber flours because these types of products will be able to modify the process of decomposition of starch. Although the integration of fiber in products has technological challenges, but by using rice grain as an important source of starch, the technological properties, expansion index, volumetric density and texture (texture hardness and brittleness) can be accepted. At present, modified starch derivatives are widely used in the food industry due to the increase in the quality of the final product. In the production of ready-to-use products for flaking, puffing, a process called extrusion is used. In this process, the product suddenly loses its moisture and leads to the creation of a dense structure containing pores. In this study, the effect of extrusion cooking process parameters on the desired characteristics of flax and rice meal breakfast cereal product with desirable physicochemical and sensory properties was investigated. Materials and Methods: Extrusion: In this study, a parallel twin-screw extruder (Jinan Saxin, China) was applied, die diameter of 3 mm, and extrusion temperature of 140 ℃. Central composite statistical design was used to study the effect of feed moisture (12, 15 and 18%), screw speed (140, 170 and 200 rpm) and Flaxseed oil cake addition (10, 20 and 30%) on technological and functional properties expanded extrudates. The chemical composition of flax meal and rice flour was measured by standard AACC (2000) methods. The expansion ratio was calculated by dividing the mean diameter (mm) by the diameter of the extruder die (4 mm) (Brennan et al, 2008). Textural measurement: The hardness of the extruded breakfast cereals was measured using Texture Analyzer (TA plus Ametek, UK). The cylinder steel probe (2 mm diameter) was set to move at a speed of 1 mm/s The samples were punctured by the probe to a distance of 10 mm. Bowl life hardness: Breakfast cereal samples were immersed in whole milk (3% fat) at 5 ° C for 3 minutes, Then rinsing was performed for 10 seconds and finally the samples were tested similar to the tissue hardness test procedure before immersion by a tissue analyzer (Oliveira et al, 2017). The color parameters L* (lightness), a*(redness), b*(yellowness) values of the samples were determined by the Hunterlab machine (Reston VA, US) (Rhee et al, 2004). Water absorption index in terms of grams of bonded water was calculated. The WSI of the dry solids regained through the evaporation of the supernatant obtained from the water absorption test was calculated (Alam et al, 2019). Sensory evaluation was performed using a 9-point hedonic test. Response surface methodology was applied for experimental data using a commercial statistical package, Design Expert (version 7.0) for the generation of response surface plot and statistical analysis of the experimental data. Results and Discussion: One of the most important parameters in the evaluation of breakfast cereal products is the amount of bowl-life hardness, which in this study, the highest amount was obtained at the level of 30% of flaxseed meal, 18% moisture and the lowest amount of screw rotation speed. After immersing breakfast cereal in milk, by increasing the percentage of flax meal due to the harder flow path, moisture absorption decreases and thus prevents the expansion of the product and increases the density of the mass and the hardness of the tissue. Due to the formation of a layer of lipids and micelles on the surface of the product prevents moisture transfer and absorption, so tissue hardness decreases and bowl-life hardness time increases. In fact, the amount of moisture absorption is a good model that shows the potential of bowl hardness-life of the samples. It is also compact and dense, which increases the retention time of breakfast cereal texture. Moisture can also reduce the shear force as a plasticizer and increase the amount of moisture absorption of the product. While increasing the speed of screw rotation, the effect of shear force on starch dextrinization increases and reduces moisture absorption. Another important feature of breakfast cereals is the lightness index, the highest value of which was obtained at the speed of screw rotation, humidity and low flax meal level. In the study of sensory properties of products produced at meal levels less than 20%, moisture content less than 15% and screw speed of 200 rpm showed the highest overall acceptance.
Seyed Amir Tavakoli Lahijani; Fakhri Shahidi; Mahmoud Habibian; Arash Koocheki
Abstract
[1]Introduction: Bread has a major role in the diet of people in Iran. One of the important factors affecting the quality of bread is the quality of wheat flour protein called gluten. Gluten is the principal structure forming elements of most baked products, contributing to the elasticity, cohesiveness ...
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[1]Introduction: Bread has a major role in the diet of people in Iran. One of the important factors affecting the quality of bread is the quality of wheat flour protein called gluten. Gluten is the principal structure forming elements of most baked products, contributing to the elasticity, cohesiveness and viscosity characteristics of the dough. Thus, gluten substantially control the quality of wheat flour based products. Due to the importance of the role of gluten and the requirement for improving the flour quality, providing a simple, economical, and efficient method to improve the technical quality of wheat and bread is also an important and controversial challenge. Oxidizing agents are generally added to the wheat flour to accelerate the natural maturing and the flour becomes paler and yields dough with improved baking properties. However, increasing concern about their adverse effects has highlighted the need for the development of alternative oxidants. Atmospheric cold plasma (ACP) is an emerging advanced oxidation process which has recently drawn considerable interest from food scientists. Therefore, the objective of this study was to investigate the effect of non-thermal plasma treatments on the properties of wheat flour.
Materials and Methods: For this purpose, medium wheat flour was prepared from local silages and treated with ACP at 25V for 0, 2, 4, 6, 8 and 10 min. Chemical composition of flour samples (moisture content, protein and ash) were determined using standard methods (AACC, 2002). Color properties, damaged starch water soluble index, wet gluten, gluten index, zeleny and falling number values, water and oil absorption capacities, swelling power and solubility of wheat flour samples were also measured.
Results and Discussion: The results obtained from the measurement of properties for the treated and untreated flour showed that the water and oil absorptions, swelling power, and solubility, wet gluten, gluten index, Zeleny number and whiteness increased significantly with increasing time, while the pH, moisture content, b * and a * indices, were decreased by plasma treatment. In addition, the results showed that ACP conditions have a significant effect on functional properties that can be created floursand products with various characteristics. The results showed that plasma treatment affected the gluten index and wet gluten and techno functional properties of wheat flour. Overall, this study demonstrated that non-thermal plasma is a quick, efficient way to improve the technological properties of wheat flour, as an alternative to chemical oxidants
Food Technology
Farinaz Saremnejad; Mohebbat Mohebbi; Arash Koocheki
Abstract
Introduction: Increasing diet-linked diseases and following that the consumers ongoing desire for healthier foods makes reduced-fat products of outstanding importance in the food industry. This study aims to reduce the fat content of sauces as a traditional condiment through the incorporation ...
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Introduction: Increasing diet-linked diseases and following that the consumers ongoing desire for healthier foods makes reduced-fat products of outstanding importance in the food industry. This study aims to reduce the fat content of sauces as a traditional condiment through the incorporation of air bubbles in the oil phase. Response surface methodology (RSM) was used for identifying the effect of aeration process variables on foam properties. However, the main challenge of reduced-fat foods is to ensure their acceptability. Recently fat taste has been introduced as a sixth basic taste. Fatty acids have been considered as the stimulus for this taste. So, linoleic acid as the stimulus for fat perception was added to the formulation to develop a product that tastes almost like full-fat versions but contains less fat. The advantages of aerated foods over conventional products are clear. Nonetheless, the determination of quality and sensory parameters during storage, marketing, and consuming is necessary. For this purpose, produced aerated sauces, along with commercial full- and reduced-fat sauces, were compared by measuring the acidity, pH, oxidative stability, and sensory properties. Materials and Methods: Required amounts of mono- and diglyceride (MDG) and oil were mixed. Then nonaqueous foams were generated by whipping the MDG-oil mixtures. In the optimization study, the effect of MDG concentrations (2, 6, and 10 wt. %), whipping speed (1100, 3250, and 5400 rpm) and time (5, 15, and 25 min) on foam properties (overrun and drainage) was analyzed using RSM. The foam obtained from the optimum process condition was used to produce an aerated reduced-fat sauce. Sauce preparation was performed according to a usual recipe with the difference that the fat content was replaced by nonaqueous foam. Furthermore, 3.00 mM of linoleic acid as a fat taste stimulus was added to the formulation. First, an aqueous phase containing ingredients was prepared. Then nonaqueous foam was progressively incorporated in the aqueous phase. For the purposes of comparison, aerated sauces (0 and 3.00 mM stimulus), along with commercial sauces (zero, low, and full-fat), were analyzed by measuring the pH, acidity, oxidative stability, and sensory properties. Results and Discussion: According to the results of the optimization study, the desired foam (overrun ≥ 60 %) achieved by oil containing 10 wt. % MDG at 3400 rpm for 10 min. Overrun increased progressively with MDG concentration but decreased slightly above 10 wt. % due to the difficulty of dispersing air bubbles in such a viscous gel. Considering the effect of whipping speed, and time, it was observed that mixtures reached their maximum volumes within 25 min. With a further increase in the whipping rate, the time required to achieve the maximum amount of foam was decreased. However, at high whipping speed (5400 rpm), foam volume decreased rapidly with time, and almost a lot of foam collapsed. The lowest and highest pH was related to zero and full-fat commercial sauces, respectively. There was no difference (p>0.05) between the pH of the control and the linoleic acid containing aerated, as well as low-fat sauces. Over time, as the pH decreases, the acidity of the aerated sauces increased and making the products with appropriate microbial stability. Due to the significant reduction of fat amount, oxidation of the aerated sauces was much slower than the full-fat one (p<0.05). Appearance, taste, and texture characteristics of aerated sauces provided a sensory profile similar to the full-fat sauce. The aerated sauce containing linoleic acid had higher sensory scores, indicating its general acceptance. Conclusions: In this study, nonaqueous foam as a new approach for fat replacement in emulsion-based foods such as sauces was practically applied. The optimum aeration process conditions were determined by the help of experimental design. Two types of aerated sauces were prepared based on the linoleic acid concentration, and their physicochemical and sensory characteristics were compared with commercial sauces. The acidity and pH of the sauces were in the standard range, and also their oxidative stability was acceptable during storage time. Generally, the aerated sauce containing linoleic acid had relatively similar sensory profiles to the full-fat sauce. Therefore, it seems that nonaqueous foam could be used successfully to develop reduced-fat alternative foods, which could also be meet the consumers' and marketing requirements.Materials and Methods: Required amounts of mono- and diglyceride (MDG) and oil were mixed. Then nonaqueous foams were obtained by whipping the MDG-oil mixtures. In the optimization study, the effect of MDG concentration (2, 6, and 10 wt. %), whipping speed (1100, 3250, and 5400 rpm) and time (5, 15, and 25 min) on foam properties (overrun and drainage) were analyzed using RSM. The foam obtained from the optimum process condition was used to produce an aerated reduced-fat sauce. Sauce preparation was performed according to a usual recipe with the difference that the fat content was replaced by nonaqueous foam. Furthermore, 3.00 mM of linoleic acid as a fat taste stimulus was added to the formulation. First, an aqueous phase containing ingredients was prepared. Then nonaqueous foam was progressively incorporated in the aqueous phase. For purposes of comparison, aerated sauces (0 and 3.00 mM stimulus), along with commercial sauces (zero and full-fat), were analyzed by measuring the pH, acidity, oxidative stability, and sensory properties. Results and Discussion: According to the results of the optimization study, the desired foam (overrun ≥ 60 %) achieved by oil containing 10 wt. % MDG at 3200 rpm for 10 min. Overrun increased progressively with MDG concentration but decreased slightly above 10 wt. % due to the difficulty of dispersing air bubbles in such a viscous gel. Considering the effect of whipping speed, and time, it was observed that mixtures reached their maximum volumes within 25 min. With a further increase in the whipping rate, the time required to achieve the maximum amount of foam was decreased. However, at high whipping speed (5400 rpm), foam volume decreased rapidly with time, and almost a lot of foam collapsed. The lowest and highest pH was related to zero and full-fat commercial sauces, respectively. There was no difference between the pH of the control and the linoleic acid containing aerated sauces. Over time, as the pH decreases, the acidity of the aerated sauces increased and making them products with appropriate microbial stability. Due to the significant reduction of fat amount, oxidation of the aerated sauces was much slower than the commercial ones. Appearance, taste, and texture characteristics of aerated sauces provided a sensory profile similar to the full-fat sauce. The aerated sauce containing linoleic acid had higher sensory scores, indicating its general acceptance. Conclusions: In this study, nonaqueous foam as a new approach for fat replacement in emulsion-based foods such as sauces was practically applied. The optimum aeration process conditions were determined by the help of experimental design. Two types of aerated sauces were prepared based on the linoleic acid concentration, and their physicochemical and sensory characteristics were compared with commercial sauces. The acidity and pH of the sauces were in the standard range, and also their oxidative stability was acceptable during storage time. Generally, the aerated sauce containing linoleic acid had relatively similar sensory profiles to the full-fat sauce. Therefore, it seems that nonaqueous foam could be used successfully to create reduced-fat alternative foods, which could also be meet consumers' and marketing requirements.
Seyed Hassan Jalili; Reza Farhoosh; Arash Koocheki; Abbas Ali Motallebi
Abstract
Introduction: Considerable amounts of essential fatty acids in fish oil makes it possible to use in the production of functional foods to meet nutritional needs and beneficial effects on health. One of the major problems is their high susceptibility to oxidative deterioration and consequent production ...
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Introduction: Considerable amounts of essential fatty acids in fish oil makes it possible to use in the production of functional foods to meet nutritional needs and beneficial effects on health. One of the major problems is their high susceptibility to oxidative deterioration and consequent production of undesirable flavor. At present, some synthetic compounds are used as antioxidants in food and biological systems, but the use of synthetic antioxidants is of concern due to their potential health hazards. Therefore, the use of natural antioxidants in foods is the first choice. Enzymatic protein hydrolysis has been applied to food industry by-products to produce foods with enhanced functional properties. Antioxidant and antiradical activity of protein hydrolysates from meat, skin, bone, viscera and roes of various aquatic species has been reported. Silver carp (Hypophthalmichthys molitrix) skin (SCS), as low price by-product from minced products processing plants is available in I.R. Iran. Amino acids composition and sequencing determines the functional properties of peptides, which depends on the source of protein, the method and conditions of preparation and molecular weight distribution of resulting hydrolysate. The enzyme type and hydrolysis conditions, including enzyme/substrate ratio, temperature, time and pH, can affect the peptides length and functional properties of protein hydrolysates. The effects of hydrolysate from SCS hydrolyzed by alcalase on some quality features and oxidative stability of microencapsulated Kilka (Clupeonella spp.) oil at pH 6.8 and 3.4 were investigated. Materials and methods: SCS was pre-treated with NaOH and acetic acid, washed and freeze dried. Proteolysis with alcalase (1% w/w) at 50 ºC, without pH adjustment, was performed for 4 hours with gentle stirring. Enzyme inactivated by placing the sample in a boiling water bath for 15 minutes. After centrifugation at 13000 g for 20 minutes, supernatant was removed as silver carp skin hydrolysate (SCSH) and freez dried. Emulsions were prepared with 31.25% dry material. 25% of wall materials (equal proportions of maltodextrin and Hi-Cap®100), fish oil 25% and SCSH (for preparing 1, 2, 3, 4 and 5 mg/mL treatments) in two adjusted pH 3.4 and 6.8, was used. Fish oil was refined using multi-layered column chromatography (alumina-silica gel), and fatty acid composition was determined. The emulsion pre-homogenized by the IKA Ultra-turrax at 15,000 rpm for 2 minutes and finally by a HSTO homogenizer at 350 bar for 5 circle, to produce microemulsion. Effects of treatments on the characteristics and oxidative stability of microencapsulated Kilka oil for 28 days in the dark at 45 ºC were compared by determination of surface oil, microencapsulation efficiency, free oil, emulsion stability (%separation), droplet size, optical microscopic observation of morphology and peroxidation stability. Results & discussion: Results showed significant differences between proximate composition of silver carp skin, before and after pre-treatment and revealed that applied method and conditions reduced the amounts of oil and ash to an acceptable level. No aggregation and cluster formation was observed in optical microscopic images of prepared emulsions. The effects of pH on the droplet size and microencapsulation efficiency were insignificant (p> 0.05), but the amount of free oil and emulsion stability were significant at ≥2 mg/mL concentrations of hydrolysate (p<0.05). Peptides effectively retarded the preoxidation of Kilka oil in the model system. Hydrolysate antioxidant power was dose dependent. Peroxidation trends were nonlinear for control and 1-4 mg/mL treatments. These trends continued linearly, with mild slope for 5 mg/mL, and was similar for 2 pH during 28 days. Hydrolysate of SCS may be used as a natural antioxidant for the production of stable microencapsulated fish oil for the enrichment of various kinds of beverages with a wide range of pH.
Soheila Ahmadian Mask; Farideh Tabatabaei Yazdi; Seyed Ali Mortazavi; Arash Koocheki
Abstract
Introduction: Kefir is a traditional beverage produced by fermented milk with kefir grains, which is becoming increasingly popular throughout the world due to its health benefits and disease prevention properties beyond its basic nutritional value. The grains contain a mixture of complex microflora such ...
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Introduction: Kefir is a traditional beverage produced by fermented milk with kefir grains, which is becoming increasingly popular throughout the world due to its health benefits and disease prevention properties beyond its basic nutritional value. The grains contain a mixture of complex microflora such as lactic acid bacteria, yeast and sometimes acetic acid bacteria which are lodged by a polysaccharide matrix calls “kefiran”. Kefir is a self-carbonated beverage that owes its distinctive flavor to a mixture of lactic acid, ethanol, carbon dioxide and other flavor products such as acetaldehyde and acetone. Kefir has been recommended for the treatment of several clinical conditions such as gastrointestinal problems, hypertension, allergies, and ischemic heart disease. Kefir grain fermentations from various substrates have been evaluated and a wide variety of bioactive compounds have been observed, such as organic acids, CO2, H2O2, ethanol, bioactive peptides, exopolysaccharides (kefiran), and bacteriocins. These compounds may act independently or together to produce the various health benefits attributed to kefir consumption. Nowadays, its popularity has been expanded worldwide and it is considered as a healthy product with high nutritional value in Europe, Asia, and South and North America. Wheat germ, corresponding to 2–3% of the total weight of wheat kernel, is almost systematically removed during milling since it adversely affects the keeping and processing quality of the flour. Wheat germ (WG) is widely recognized as a nutritious raw material for incorporation into food product formulations or as an independent food product. Wheat germ, containing about 8% - 14% oil (average 10%), is mainly used in food, medical and cosmetic industries as a source of oil. Unfortunately, the whole quantity of the germ produced in Iran is currently utilized in the production of animal fodder. According to chemical analyses, wheat germ contains magnesium, zinc, calcium, selenium, sodium, potassium, phosphorus, chromium, antioxidants including beta-carotene (for vitamin A), vitamin E, vitamin C, vitamin B12, vitamin B6, thiamin, riboflavin, niacin, folic acid, iron, amino acids, and enzymes, and has a high dietary and medicinal value. The purpose of this study was to investigate the effects of various concentrations of wheat germ powder on physicochemical, microbial and sensory properties of kefir beverage. Materials and methods: A commercial freeze-dried Kefir starter culture (ABT_2) was purchased from Chr. Hansen (Denmark) also Saccharomyces cerevisiae was supplied from Saf-Levure (France). Cow milk were obtained from the Department of Food Engineering, Ferdowsi University of Iran. Wheat germ was supplied from Isar Qaynat Co. All chemicals were from Merck Co.Steam stabilized wheat germ powder at 1, 2 and 3% levels with DVS starter and Saccharomyces cerevisiae at 25 ° C were transferred to full fat cow’s milk and the fermentation was ended at pH 4.6. Microbial, physicochemical and sensory tests were performed at 24, 48 and 72 hours after inoculation. The pH and acidity of kefir were determined according to National Iranian Standard Number 2852. The viscosity was also determined using a Brookfield viscometer (spindle 3, USA) at the temperature of 5°C and a shear rate of 80.0 1/s. Spectroscopic measurement of alcohol was performed according to Sayyad et al. (2015). Lactobacilli counts were performed on MRS medium at an incubation temperature of 37°C for 3 days. Yeasts counts were carried out on YGC at an incubation temperature of 25°C for 5 days. Total counts were performed on PCA at an incubation temperature of 30°C for 2 days. All statistical calculations were completed using the Minitab Version 16. Analysis of variance (ANOVA) was carried out using the general linear model (glm) procedure and Tukey test was used to determine the differences among means. Results and discussion: Wheat germ is a by-product derived from the wheat milling industry and is a rich source of vitamins, proteins, dietary fiber and minerals. Due to its antioxidant, sterol and essential amino acids contents, it has a lot of health effects and is known as a nutritious raw material for its composition in food formulations. Therefore, in this study it was used to produce kefir beverage to produce a high-nutritional product. Based on the obtained results, increasing the percentage of wheat germ powder concentration on the physicochemical, microbial and sensory properties of kefir beverage has a significant effect. The sample containing 3% wheat germ powder showed the highest acidity, ethanol, yeast and total microbial count, during the storage period, acidity, ethanol and yeasts increased in all samples, while pH, Lactobacilli, total microbial count and apparent viscosity had decreasing trend and samples of kefir containing wheat germ powder showed non-Newtonian flow behavior according to the power law model. On the other hand, the apparent viscosity of the samples significantly decreased with increasing wheat germ concentration. According to the sensory evaluation results, kefir produced with one percent wheat germ received the highest overall score within 72 hours after inoculation.
Nasim Hasanpoor; Mohebbat Mohebbi; Arash Koocheki; Elnaz Milani
Abstract
Introduction: Nowadays, frozen dough technology is used to produce bakery, pastry & cakes products. On the other hand, extrusion plays a role as a high-performance process in the food industry, which, given its unique characteristics, can replace many common methods of food processing. This study was ...
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Introduction: Nowadays, frozen dough technology is used to produce bakery, pastry & cakes products. On the other hand, extrusion plays a role as a high-performance process in the food industry, which, given its unique characteristics, can replace many common methods of food processing. This study was carried out aimed to investigate the effect of freezing methods (slow and rapid) and the storage time of frozen dough under freezing conditions on physicochemical and sensory properties of extruded and non-extruded sorghum flour for producing a gluten-free product suitable for Coeliac patients.
Materials and methods: In this study, extruded sorghum flour (an extruder with a temperature of 150-160°C, a moisture content of 14%, a speed of 150 rpm, feeding of 40 grams per minute and circular matrix with a diameter of 5 mm and, in the last step, using a grinding mill and 0.599 mm mesh, flouring is done), non-extruded sorghum flour (100%), Xanthan gum (1% w/w) were used in cookie dough formulation. Two types of slow and fast freezing were used to freeze the dough of cookie. Slow freezing according to the method provided by X.u et al. (2009) and Ke et al. (2013). In a fast freezing method, rapid cooling rooms were used at -40°C for 30 minutes. After freezing, the samples were placed in polyethylene bags and stored for 0, 2, 4, 6 and 8 weeks in a refrigerator at -18°C (X.u et al., 2009). For the thaw process, dough pieces were placed in a refrigerator at + 4°C for 16 hours (Maizani et al., 2012). Baking was performed in a microwave oven at 180°C for 14 minutes. The properties of the final product, such as the ratio of expandability (AACC 10-52), textural properties (cookie texture were carried out using a TA.XTplus Texture Analyzer (Walker et al, 2012)), total gelatinization and enthalpy temperature(Using the DSC device and temperature range 7-157°C and heating temperature 10°C/min), color, percentage of porosity, shell thickness (Image processing technique and ImageJ software) and sensory evaluation were investigated in a completely randomized factorial. Statistical analysis of the results was done using a factorial arrangement of completely randomized design and comparison of the meanings using Duncan's multiple range tests at 5% level. Data analysis was performed with three replications using SPSS 18 software.
Results & discussion: The gelatinization temperature decreased with increasing times of storage; however, the total enthalpy of the process was increased. The results showed that with increasing freezing rate, the gelatinization temperature increased significantly (P≤0.05), and the total enthalpy of the process decreased and the cookie from frozen dough containing extruded sorghum flour has the highest gelatinization temperature and the minimum total enthalpy value. With increasing times of storage, the dough chewiness decreased significantly (P≤0.05) and the adhesion and stiffness of the dough texture increased. The dough chewiness increased with the increase in the freezing rate, however, the adhesion and stiffness of the dough texture decreased and cookie dough containing extruded sorghum flour resulted in a significantly higher chewiness and lower adhesion and stiffness (P≤0.05) of the texture compared to the non-extruded sorghum cookie flour in both methods of freezing. The extensibility ratio has significantly decreased (P≤0.05) with increasing the times of storage. The extensibility ratio of cookie was significantly increased with the increase in freezing rate (P≤0.05) and non-extruded sorghum flour samples showed a lower extensibility ratio relative to the extruded sorghum flour cookies. The dough freezing method also had a significant effect on the final cookie quality (P≤0.05). The stiffness of the cookie texture from the frozen dough decreased by increasing the dough freezing rate and its tissue was softer and cookie samples containing extruded sorghum flour have a significantly lower tissue stiffness compared to other samples. The stiffness of the cookie tissue increased significantly (P≤0.05) with increasing times of storage. L* parameter (lightness) significantly decreased (P≤0.05) with increasing the times of storage and decreased the yellowness factor (b*) and increased the redness factor (a*) significantly (P≤0.05) for the cookie made from frozen dough. The freezing rate had a significant effect (P≤0.05) on the lightness of the cookies. The parameters L* and b* decreased by increasing the freezing rate and the colors of these cookies were darker. Cookies containing extruded sorghum flour had the lowest level of L* and b* and highest level of a*. The porosity% and thickness of crust of cookie decreased significantly (P≤0.05) with increasing times of storage. These parameters increased significantly with increasing freezing rate (P≤0.05) and tissue porosity and thickness of crust of cookies obtained from the frozen dough containing extruded sorghum flour was significantly higher (P≤0.05). The results of the kinetics of cookie mass transfer from frozen dough showed that the effective moisture diffusivity of cookie was reduced by increasing times of storage. Overall, the results showed that the process of extruding sorghum flour has improved the physicochemical properties of the cookie, and the fast freezing process improves the quality of the cookie made from frozen dough, and in this condition extruded flour sorghum can be used as a suitable alternative to wheat. Also, the use of frozen dough for cookie production can be a good way to supply this product.
Sorour Lotfi Shirazi; Arash Koocheki; Elnaz Milani; Mohebbat Mohebbi
Abstract
Introduction: Snack foods have become an important part of the people’s diets. During last decade demands for utilization of fruit and vegetable waste in order to their dietary fibers in value added food products has been increased. Carrot pomace is rich in dietary fiber that contains important functional ...
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Introduction: Snack foods have become an important part of the people’s diets. During last decade demands for utilization of fruit and vegetable waste in order to their dietary fibers in value added food products has been increased. Carrot pomace is rich in dietary fiber that contains important functional and nutritional properties. Barley contains a high amount of dietary fiber, especially soluble fiber, which has essential role in reducing blood cholesterol level.
Materials and methods: In this project based on Central Composite Design, the effect of independent variables containing extrusion temperature (120-170 °C), moisture content (14-20%) and carrot pomace level (10-25%) were evaluated on expansion ratio, bulk density, WAI, WSI, hardness, color snacks were evaluated by panelists in terms of acceptance or non-acceptance.
Results and discussion: Results expressed that expansion ratio, lightness, total acceptability and WAI decreased by increasing the amount of carrot pomace. Reduction of expansion ratio and WSI and improvement of lightness and WAI were shown as increased in moisture levels. The hardness and bulk density decreased with an increase in temperature. When temperature increased up to 145°C, expansion ratio, lightness, WAI and WSI increased and decreased thereafter. The optimum conditions for barley flour-carrot pomace snack were determined at the maximum expansion ratio, L*, WAI and overall acceptability with minimum bulk density and hardness in a snack. The optimum condition provides the highest value of expansion ratio 296.1 (%), L* 65.087, WAI 4.931 (g/g) and overall acceptability 4.502 with lowest bulk density 1.22 (g/cm3) and hardness 6.756 (N). Accordingly, the optimum conditions for the snack are 10% carrot pomace, 148°C die temperature and 15.49% moisture. The approximate composition of the snack extruded and unextruded obtained under the optimal conditions. Extrusion did not affect the protein and ash contents but it decreased the fat content of snack. During the extrusion, the SDF increased from 7.63 to 9.27 g/100g while the IDF decreased from 5.24 to 3.71 g/100g. Extrusion cooking did not affect the TBG content in barley flour-carrot pomace snack. Extrusion cooking resulted in the conversion of insoluble to soluble fiber and well balance of both types of the fiber
Samira Abbaspour Monjezi; Mohammad Reza Edalatian Dovom; Mohammad Bagher Habibi Najafi; Arash Koocheki
Abstract
Introduction: Nowadays, consumers prefer foods produced without synthetic preservatives. These chemical preservatives have been gradually replaced by natural preservatives in formulation of edible films and coating. Since, edible films can be applied as carriers of antimicrobial agents, so, these aforementioned ...
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Introduction: Nowadays, consumers prefer foods produced without synthetic preservatives. These chemical preservatives have been gradually replaced by natural preservatives in formulation of edible films and coating. Since, edible films can be applied as carriers of antimicrobial agents, so, these aforementioned ingredients can be incorporated in such films. Among edible films, protein-based films such as whey protein concentrate (WPC)-based films are more attractive because they also supply valuable nutrients and introduce acceptable mechanical resistance. On the other hand, these films present moderate barriers to moisture due to the hydrophilic nature of whey proteins. Essential oils (Eos) can be incorporated in to edible films in order to compensate (overcome) this defect. Since no published research has been found on integrating mastic tree sap (Pistacia atlantica sub sp. kurdica) essential oil into whey protein edible films, this essential oil was applied for WPC-based film in this research. Some species belong to Penicillium have been known as contaminants of dairy and fruit products. Among Penicillium sp., P. expansum is more popular for causing post-harvest damage of apples. In this study, our objective was focused on mechanical and anti-fungal properties of WPC-based films incorporated with mastic gum essential oil.
Materials and methods: WPC, mastic tree sap and P. expansum were obtained from Multi Milk Company, Kurdistan mastic Gum Company and Persian Type Collection Culture, respectively. Extraction of EO from mastic gum was accomplished using water distillation or hydro distillation with the help of Clevenger-type apparatus for 5 hours to obtain a pale yellow oil. Solution (10%w/w) of WPC in distilled water was prepared. Glycerol (as plasticizer) was added to WPC solution at a ratio of 1:1 WPC: Glycerol. Then concentrations of EO (1000, 2000, 3000 and 4000 ppm) was added to solution and mixed for 2 min. In the next step, some characteristics of film were measured including: thickness and density, water solubility, stability in acidic and alkaline solutions, water vapor permeability and light transmission / film transparency. Some mechanical properties of films such as tensile strength (TS) and elongation at break (%E) of films were also determined.
Regarding microbial assays, following the activation and preparation of fungi spore, MIC was determined using Agar Dilution Method. Determination of antimicrobial activity of film was performed according to film disk agar diffusion assay
Results & Discussion: With increasing essential oil concentration, film thickness exhibited increasing trend which was due to entrapment of micro-droplets of essential oil in film. Along with increasing EO concentration in film samples, WVP declined significantly (P-value
Mohammad Ali Hesarinejad; Seyed Mohammad Ali Razavi; Arash Koocheki; Mohammad Amin Mohammadifar
Abstract
Nowadays, demands for hydrocolloids which improve the rheological properties of foods as well as retain their properties under the influence of food additives have increased. In this study, dilute solution properties were employed to understand the molecular and conformational properties of Alyssum homolocarpum ...
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Nowadays, demands for hydrocolloids which improve the rheological properties of foods as well as retain their properties under the influence of food additives have increased. In this study, dilute solution properties were employed to understand the molecular and conformational properties of Alyssum homolocarpum seed gum (AHSG), in presence of sucrose and lactose. The model of Tanglertpaibul & Rao was selected as the best model for the estimation of the intrinsic viscosity. It was shown that except for water, the solutions of sucrose and lactose are poor solvents for AHSG as indicated by a decrease in intrinsic viscosity, swollen specific volume, shape function, and coil dimensions. As the sucrose and lactose concentrations increased, the coil radius decreased. The reduction in the shape and swollen volume parameters in the presence of sucrose and lactose as compared to the sugar-free solution indicated the negative effect of the opted sugars on the molecular volume of the gum. Evaluations of the dilute solution properties of the gum in sucrose and lactose solutions revealed that the existence of a conformation tending to ellipsoidal shape and the probability of the conformation of random coil with no molecular entanglements in AHSG solutions.
Elham Ansarifar; Fakhri Shahidi; Mohebbat Mohebbi; Arash Koocheki; Navid Ramazanian
Abstract
Introduction: Microencapsulation has become an important technique in the food industry. One of the methods of producing microcapsules is to use layer-by-layer adsorption, in which oppositely charged polyelectrolytes are adsorbed consecutively onto a colloidal template. Creating multilayer films based ...
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Introduction: Microencapsulation has become an important technique in the food industry. One of the methods of producing microcapsules is to use layer-by-layer adsorption, in which oppositely charged polyelectrolytes are adsorbed consecutively onto a colloidal template. Creating multilayer films based on electrostatic interactions between oppositely charged components was introduced in 1991 by Decher et al. Layer-by-layer (LbL) polyelectrolyte deposition has become a popular technique for preparing polyelectrolyte capsules because of its ability to create highly tailored capsule shells through a simple, inexpensive and easily controllable adsorption process. It has been applied to produce capsules of various sizes, ranging from the nanometer to micrometer scale, with well-defined barrier properties. In this technique, assembly is driven by the electrostatic attraction of oppositely charged materials to form polyelectrolyte shells. The structure of the polyion layered capsule shell is determined mainly by the electrostatic interactions between the polyions used. The mechanical strength and permeability of the capsules can be controlled by varying the number of layers or by changing the characteristics of the encapsulating materials. The purpose of this study was to produce microcapsules using supramolecular assemblies consisting of common food ingredients such as soy protein isolate (SPI) and high methoxyl (HM) pectin. Moreover, some features of the developed microcapsulation were studied.
Materials and methods: SPI fibrils were prepared based on the method developed by Akkermans et al., (2008) and its morphology was studied using transmission electron microscopy (TEM) and atomic force microscopy (AFM). 0.5% (w/w) SPI fibril and pectin solutions were prepared by mixing at pH 3.5 were left stirring overnight. The LbL process for the production of microcapsules with protein fibril-reinforced nanocomposite shells has been described in Humblet-Hua et al., 2012. It starts with the production of A 2% w/w emulsion of (0.05 gr diacetyl in 1.95gr sun flower oil) in fibril SPI solution is produced using a homogenizer with a rotor-stator dispersion tool using a setting of 13500 rpm for 90 S. Because the proteins are below their isoelectic point, the emulsion droplets have a positive charge. To avoid interactions between the nonadsorbed SPI and the biopolymer of the next layer, the droplets are separated from the serum by means of centrifugation. After the isolation, the droplets are dispersed into a solution of HMP. The HMP is negatively charged at the chosen pH of 3.5. The bilayered droplets can be isolated again and dispersed in a fibril solution to deposit a third layer of a positively charged mixture of SPI fibrils. Subsequently, additional layers of HMP and SPI fibrils can be deposited by repeating the same procedures. Some features of the microcapsulation, including size, zeta potential, and morphology and release kinetics were studied.
Results & discussion: TEM and AFM micrographs showed that SPI fibrils obtained had a contour length of a few hundred nanometers, thickness of between 1 and 10 nm and its structure is highly branched. One of the most common problems reported in previous studies using the LbL technique to produce multilayer particles, is the tendency for flocculation. In the present system, this problem was not observed. The size distribution of isolated emulsion droplets (templates) did not change significantly from 1-layer droplets to 5-layer droplets. In other words, the emulsion droplets were stable against flocculation after applying more layers of polyelectrolytes. The Sauter mean diameters D (3, 2) of these droplets fluctuated between 5 and 7 µm and slightly increased as the number of layers increased; noting that the emulsion droplets were poly-dispersed. Another possible problem that may occur using the LbL technique is the complex formation between non-adsorbed protein and the pectin molecules. These complexes with a typical diameter smaller than 1 mm were not detected here. Result showed that the zeta potential distribution of emulsion droplets reverses from about plus (+) 30 mV (odd number of layers with SPI fibrils as outer layers) to about negative (-) 20 mV (even number of layers with HMP as outer layers) confirming the layer-by-layer adsorption based on electrostatic attraction. Comparing SEM of microcapsules with various numbers of layers, an improvement in shell strength can be seen. Indentation is observed on 1-layer microcapsules showing that there are defects on the shell. They could be formed during the drying process or they are shell defects due to incomplete coverage of materials, meaning more layers are needed to fully cover the microcapsule shell. These defects are seen less on 5-layer microcapsules. These observations indicate that the more layers the more consistent the shells and the more resistant. It is against the physical drying process. Results showed that the time of the maximum in release shifts to higher values as the number of layers of the capsules increased. We clearly see that increasing the number of layers in the shell of the capsules leads to a delay of the release of diacetyl and maximum release time as a function of the number of layers is increasing steadily which show the release can be delayed even more by adding additional layers. These results prove that the release properties of the multilayer capsules can be tuned by controlling the number of layers in the shell of the capsules. The modeling results of four different kinetic models are indicated that the Rigter–Peppas was an appropriate model for diacetyl release prediction from multilayer microcapsulation. It could be attributed that the release mechanism is mostly governed by the Swelling–Fickian mechanism.
Conclusion: In this study, the microcapsules were produced using the LbL technique and food-grade SPI fibrils and HMP. The microcapsules had a poly-disperse size distribution. No flocculation of microcapsules during applying of additional layers was observed. It was found that increasing the number of layers, decreases the release rate of diacetyl. The diacetyl release data were kinetically evaluated by zero-order, first-order, Higuchi, and Rigter–Peppas models and the results showed that the release phenomena is mostly governed by the Fickian mechanism. Since the materials are food-grade, the applications of these microcapsules can include food products or pharmaceutical purposes.
Maryam Mahfoozy; Arash Koocheki; Seyed Mohammad Ali Razavi
Abstract
Introduction: Freezing is one of the ways to extend the shelf life and improve the chemical and microbiological stability of food products. Food products are exposed to different processes and the functional properties of the products change during these processing. Hydrocolloids are used to stabilize ...
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Introduction: Freezing is one of the ways to extend the shelf life and improve the chemical and microbiological stability of food products. Food products are exposed to different processes and the functional properties of the products change during these processing. Hydrocolloids are used to stabilize the products undergoing different food processing. However the addition of hydrocolloids to food products shifts the foods characters. On the other hand, hydrocolloids decrease the growing rate of ice crystals in dispersions. Lipidium perfoliatum locally called Qodume shahri. The study on the functional properties of Lipidium perfoliatum seed gum (LPSG) proved that this gum was able to bind with a large amount of water and increase the product consistency. The main purpose of this study was to understand the effect of freezing condition on functional properties including the rheological properties (steady shear rate), emulsion particle size distribution and foaming stability at different gum concentration of LPSG.
Materials and methods: The materials were purchased from a local detailer. LPSG was extracted in optimum condition (T: 48±1 ºC, pH=8, proportion water to seed 30 to 1, t: 1.5 h) according to method previously described by koocheki et al. (2009). After the preparation of the freeze-dried gum powder, dispersions of LPSG were prepared in distilled water at different concentrations (0.5, 0.75 and 1% w/v). In order to study the effects of freezing condition on the functional properties of LPSG, the samples were freezed at slow and fast conditions. The flow behavior was described by fitting the shear stress (τ) to shear rate (γ) data with the models to determine the best model to describe the flow behavior of LPSG. For the Emulsion preparation, the aqueous phase was prepared by mixing 2 g WPC into 30 g distilled water and an appropriate amount of LPSG (0.1 and 0.2 g) into 50 g distilled water on a magnetic stirrer for 10 min at room temperature. The dispersions were then left overnight at 4 ºC prior to emulsion preparation. The emulsion was prepared by mixing 20 g sunflower oil with WPC using a magnetic stirrer for 10 min. The mixture was subsequently pre-homogenized with a laboratory homogenizer at a rate of 20,000 rpm for 2 min at room temperature. After that, the gum solution was added to the emulsion and homogenized for 4 min at the same rate. The particle size analyzer was used to measure the mean diameter. For the foaming stability, the gum dispersions were prepared at 0.5% gum concentration and left overnight in a refrigerator to ensure a complete hydration. Afterwards, they were treated with different temperatures. 2% of egg white powder was added to the solutions and mixed by a homogenizer for 2 min at 20000 rpm. The foam stability was calculated as the foam volume after 30 minutes. A completely randomized design with the factorial arrangement was used for statistical analysis. All experiments were statistically analysed by Analysis of Variance (ANOVA) in Minitab R14. The p-values of < 0.05 were considered significant. All measurements were triplicated and the average values were reported.
Results and discussion: Results showed that the LPSG apparent viscosity increased insignificantly after the fast freezing condition. All samples illustrated non-Newtonian shear thinning behavior. Herschel- bulkley model was the best model to describe the flow behavior of the LPSG solution with the high determination coefficients. Among the selected rheological models, the flow behavior indices and consistency coefficients were unchanged. However freezing condition had no significant effect on the emulsion particle size. After 30 min foam stabilized by LPSG was constant. Therefore, LPSG can be considered as an appropriate stabilizer and thickening agent during freezing condition.
Ahmad Ehtiati; Fakhri Shahidi; Arash Koocheki; Seyed Mohammad Ali Razavi; Mahsa Majzoobi
Abstract
Introduction: Sorghum (Sorghum bicolor) is a tropical plant and has the fifth ranking of world cereals production. One of the important aspects of sorghum is drought tolerance and little input need during growth which has made that suitable for cultivation in semiarid regions. Due to the presence of ...
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Introduction: Sorghum (Sorghum bicolor) is a tropical plant and has the fifth ranking of world cereals production. One of the important aspects of sorghum is drought tolerance and little input need during growth which has made that suitable for cultivation in semiarid regions. Due to the presence of tannin compounds in internal part of sorghum grains and low digestion of cooked protein, sorghum flour consumption is limited. Sorghum grain contains more than 70% starch which is an important tasteless ingredient in food formulas, as the main source of energy and thickening and gelling agent. Extraction of starch from sorghum in regarding to its nutritional problems is a good solution for extension of sorghum uses in food industry. Starch is a semi crystalline structure consisted on linear amylose and branched amylopectin molecules packed in granules. Ratio of these two molecules and their molecular short order and macrostructure and size and shape of granules determine functional properties of starch in the final product. Starch properties is depended on genetic residues so that starches from tubers have distinct differences with cereal starches even obvious differences exists between cereal starches and varieties. In this study we have investigated chemical, morphological, structural and thermal properties of starches four white sorghum line.
Material and methods: White sorghum grains were prepared from local farms with line numbers KDFGS1, KDFGS6, KDFGS9 and KDFGS20. Starches were extracted sorghum lines using alkaline steeping method and further purified using toluene-water-salt solution. Chemical parameters were determined including protein by Kjeldahl digestion method, lipid by soxhlet extractor, ash by burning in furnace, moisture by oven drying and amylose content by iodine binding colorimitry,. Light microscopy coupled with digital camera was used for granules shape and size determination moreover surface properties and morphology of granules was observed using scanning electron microscopy technique. Color of starches were determined with hunterlab colorimeter. To evaluate crystalline structure of sample i.e. type of crystals and degree of crystallinity, starches first were conditioned in desiccator containing saturated aqueous sodium chloride solution at 25°C for a week then X-ray diffraction of sample in diffraction angels from 4-40° was determined. Thermal properties of crystals melting or gelatinization were measured using differential scanning calorimetry of starch in deionized water in temperatures from 20-120°C with heating rate of 10°C/min .From heat flow changes over temperature, temperature of onset, peak and conclusion points of crystalline structure melting and its required enthalpy were calculated. Functional groups of starches were investigated using FTIR technique to observe.
Results & Discussion: Isolated starches had appropriate quality due to low amount of protein (
Fatemeh Rahmati; Arash Koocheki; Mehdi Varidi; Rassoul Kadkhodaee
Abstract
Introduction: Proteins are food ingredients with critical functional properties and participation in developing food products. So far, functional properties of several plant proteins such as pea, chickpea and lentil, groundnut, beach pea and bayberry have been investigated. Nowadays, there is an increasing ...
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Introduction: Proteins are food ingredients with critical functional properties and participation in developing food products. So far, functional properties of several plant proteins such as pea, chickpea and lentil, groundnut, beach pea and bayberry have been investigated. Nowadays, there is an increasing demand for plant proteins because they are available and inexpensive. Legume proteins are important plant protein sources. However, except for soy, due to the inadequate information about their structural and functional properties, they do not have appropriate application as functional ingredients in food products. Beans are a great source of nutrients such as protein, carbohydrate, dietary fiber, minerals and vitamins. Based on the several research reports, different dry beans have 15-25% protein and they are the second group of legume seeds, after soy, cultivated throughout the world. As mentioned earlier, insufficient information about structure of legume proteins is the main reason why they are unexploited in food industry. Therefore, the goal of this research was to evaluate the functional properties of proteins from three types of common bean (Speckled Sugar, Red Mexican and Great Northern bean). We also have attempted to evaluate the structure-function relation of these three sources of bean proteins because it is known that there is a direct relation between chemical conformation and the function of a protein which must be considered in food processing. Materials and methods: Protein of three types of common bean (Speckled Sugar, Red Mexican, and Great Northern) was extracted (pH 9, water flour 10:1). Afterwards, their physicochemical (including protein electrophoresis pattern, solubility, hydrophobicity), and functional properties (including emulsifying capacity, heat stability, gelation and foaming capacity) were evaluated to understand how bean protein structure influences its structure. Electrophoresis pattern was obtained based on 2 dimensions (pH and molecular weight). Protein solubility was evaluated by biuret method at pH range 3-9. ANS (8-anilino-1-naphthalenesulfonic acid) was used to measure surface hydrophobicity (pH 3-7).Emulsion samples (1% protein, 25% sunflower oil, pH 3-7) were produced, then emulsion capacity and emulsion heat stability (80°C for 30 min) were evaluated. Gelation of proteins was evaluated at protein concentration of 4-12% at different pH values (3-7). Foaming capacity (%) was measured as the difference between volume after and before whipping. Foam stability (%) was recorded during 90 minutes. Results and Discussion: Results showed that all proteins were rich in Phaseolin. In fact, this fraction was the major building fraction of all three bean proteins. Evaluation of solubility indicated that isoelectric point of three proteins was located at acidic pH range (pH 4.5). Results confirmed an indirect relation between protein solubility and hydrophobicity. All three protein isolates, similar to the other legumes protein, were more soluble at alkaline pH, while the highest surface hydrophobicity was observed at pH 3. Generally, Speckled Sugar bean protein had the most solubility, while Great Northern bean protein showed the highest surface hydrophobicity. Among three bean protein isolates, Speckled Sugar bean protein performed better as an emulsifier, whereas Great Northern bean protein formed gel at the lowest concentration (6% at pHs 3 and 7). In addition, foaming was higher at acidic pH (pH 3). Therefore, it was concluded that emulsifying capacity is mostly influenced by protein solubility, while gelation and foaming properties are affected by protein hydrophobicity. As the main consequence, the results achieved in this research confirmed that there is a direct relation between structure and the function of a protein. In fact, special structural properties are responsible for special functions.
Arash Koocheki; Abdollah Hematian Sourki; Mohammad Elahi; Seyed Mohammad Ali Razavi
Abstract
Introduction: β-glucan is the most important water soluble fiber found in cell wall of some cereals such as barley, oat, wheat and rye, that are composed of β-D-glucoseunits with (1→4) (70%) and (1→3) (30%)anomericbonds(Benito-Román, Alonso, & Cocero, 2013).β-glucan ...
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Introduction: β-glucan is the most important water soluble fiber found in cell wall of some cereals such as barley, oat, wheat and rye, that are composed of β-D-glucoseunits with (1→4) (70%) and (1→3) (30%)anomericbonds(Benito-Román, Alonso, & Cocero, 2013).β-glucan is regarded as a dietary fiber in functional foods. It can act as a hydrocolloid due to its thickening characteristic in aqueous phase and can be used as a stabilizer in some foods such as sauces, salad dressing and ice cream (Dawkins & Nnanna, 1995; Kontogiorgos, Biliaderis, Kiosseoglou, & Doxastakis, 2004; Temelli, 1997; Wood & Webster, 1986). Hull-less barley is a barley variety that has no hard coat around its’ seeds. The content of soluble fiber e.g. β-glucan in hull-less barley is higher than of ordinary barley varieties. Hull-lessbarley cv. Lut is the first commercial hull-less barley in Iran registered in 2013 by SPII(Seed and Plant Improvement Institute). Lut is a kind of spring barley cultivar which is precocious and resistant to lodging. It’s average yield is 6.425 t/ha and it is suitable to cultivation in temperate regions of Iran (SPII, 2013).This type of barley contains about 6% β-glucan and thus is a good source for β-glucan extraction.To date no research has been conducted on properties of β-glucan from this cultivar of barley.Considering high technological properties of β-glucan, the present study was carried out to determine the optimal condition for extraction of β-glucan from hull-lessbarley using hot watermethod to achieve the highest qualitative and best functional properties.Materials and methods: Barley flour was obtained by grinding whole kernels of cv. Lut in a laboratory mill and sieved through a 0.50 mm screen. Prior to the extraction procedure, 50 g of barley flour was suspended in 200 ml of aqueous ethanol (80%, v/v) and stirred under reflux for 3 h to remove most of the lipids and inactivate the endogenous β-glucanases. The liquid phase was separated by vacuum filtration and dried at 40 °C for 12 h. 50 g of dried defatted barley flour was suspended in specified amounts of distilled water (solven:flour ratio = 6:1, 8:1 and 10:1) in a 1000 ml beaker. pH was adjusted to the designed levels (5, 7, and 9) by 0.1 N HCl and 0.1 N NaOH solutions. Extraction procedure carried out at 50±1°C for 30, 60 and 90 minutes. Total β-glucan content was determined by the specific enzymatic method of McClear and Glennie-Holmes (1985) using the mixed linkage β-glucan assay kit (K-BGLU 07/11) supplied by Megazyme International (Wicklow, Ireland). The colour of β-glucan gums was measuredusing a Hunter-Lab Colour Flex 45 spectrophotometer (Hunter Associates Laboratory, Inc., Reston, VA, USA). The L*a*b* (CIELAB space) colour space measurement was used for colour analysis of β-glucan samples. Emulsion stability (ES) against high temperature was determined by heating emulsions in a water bath at 80 °C for 30 min followed by centrifuging at 1200 g for 10 min. For foam stability, ovalbumin was dissolved in distilled water and added to β-glucan solution and then whipped vigorously with a laboratory rotor-stator homogenizer at room temperature. Flow behaviour measurements were done by a Brookfield viscometer. The flow behavior index (n) and consistency coefficient (k) values were obtained by fitting the power law model. All chemicals, reagents and solvents were of analytical grade and obtained either from Sigma-Aldrich Co (Deisenhofen, Germany) or from Merck (Darmstadt, Germany).Results &Discussion: Results showed that the extraction time, solvent: flour ratio and pH had significant effect on extraction yield, purity, foam and emulsion stability, consistency coefficient (k), flow behavior index (n) and colour. Increasing the extraction time had significant effects on β-glucan’s yield and purity and improved the emulsion and foam stabilizing effect of β-glucan. Increasing the pH from 5 to 9 significantly enhanced the purity, consistency coefficient (k), foam and emulsion stability. At higher pH levels, extraction yield, flow behavior index (n) and L* decreased. With increasing solvent:flour ratio, extraction yield, purity, consistency coefficient (k), foam and emulsion stability significantly increased. In contrast, the flow behavior index (n) decreased as a result of increase in solvent: flour ratio. However, solvent: flour ratio had no significant effect on L*, a* and b*. Models presented in this study were highly significant and the correlation coefficients could be used for optimization of ß-glucan extraction from hull-less barley. Considering the importance and desirability of the response variables, the best results were obtained when the extraction time, solvent: flour ratio and pH were 90 min, 10:1 and 7.33 respectively. At the optimal condition, extraction yield, purity, foam stability, emulsion stability, consistency coefficient (k), flow behavior index (n), L*, a* and b* were 4.12%, 69.11%, 86.95%, 88.77%, 1.51 Pa.sn, 0.62, 73.42, 0.81 and 8.72 respectively.
Leila Monjazeb Marvdashti; Masoud Yavarmanesh; Arash Koocheki
Abstract
Introduction:Packaging is an important factor in food industry and is dominated by petroleum-derived polymers. Therefore, the amount of research involving the production and characterization of biodegradable films has increased substantially, mainly due to interest in minimizing the ecological impact ...
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Introduction:Packaging is an important factor in food industry and is dominated by petroleum-derived polymers. Therefore, the amount of research involving the production and characterization of biodegradable films has increased substantially, mainly due to interest in minimizing the ecological impact caused by the use of synthetic packaging materials. Several biopolymers have been exploited to develop eco-friendly food packaging materials. Usually, films based on biopolymers are highly sensitive to environmental conditions and generally present low mechanical resistance. As a result, several researchers have developed films based on mixtures of biopolymers and synthetic polymers. In order to increase the workability and flexibility of biodegradable films, various plasticizers, usually poly-ols, have been widely used, glycerol being one of the most preferred and most studied. Plasticizers reduce intermolecular forces, increase the mobility of the biopolymer chains and thereby improve the mechanical properties of the films. Therefore, the aim of the present study were to investigate the effect of different proportions (20e100% w/w) of plasticizer (glycerol) on physicochemical, mechanical, permeability, surface and thermal properties of biodegradable PVA-AHSG blend films.Polymer blending is one of the most effective methods to have new material with desired properties. Films formed by blending of polymers usually results in modified physical and mechanical properties compared to films made of individual components. Since synthetic polymers are easily obtained and have low production cost, blending of natural and synthetic polymers improves the cost performance ratio of the resulting films. Since Alyssum homolocarpumseed gum (AHSG) is environmentally friendly due to its biodegradability and has good film forming properties, it is considered as a very promising biopolymer. Some synthetic polymers from non-renewable sources are also biodegradable, such as polyvinyl alcohol (PVA). PVA is a synthetic, water soluble polymer with excellent film forming, emulsifying, and adhesive properties. It also imparts good tensile strength (TS) and biodegradability and hence has been used in many biomaterial applications. PVA has also been approved for use in packaging meat and poultry products by the USDA (DeMerlis&Schonek, 2003). AHSG contains free hydroxyl and amine groups, and is therefore miscible with PVA due to the formation of hydrogen bonds.Materials and methods: The aim of this study was to investigate the possibility of producing a novel biodegradable blend film from PVA-AHSG with glycerol as plasticizer in the different concentrations. Films were prepared by the casting method using PVA and AHSG (60:40 ratio). Glycerol was used ac plasticizer because it is compatible with PVA-AHSG blend improving film flexibility, facilitating its handling and preventing cracks. The PVA–AHSG blend film was prepared with different glycerol concentration (20–70%, w/w).The optical properties such as opacity and color were measured. Water vapor permeability, moisture content, water solubility and density of the films were also investigated. Films were evaluated for mechanical and antitoxin properties. The PVA–AHSG blend films were characterized using DSC, FTIR and scanning electron microscopy.Results and Discussion: The results of this study showed that blend of PVA and AHSG could be used as a new film-forming material. However, it was not possible to make PVA-AHSG blend films without addition of glycerol as a plasticizer to the formula. Glycerols in 20-70% (w/w) concentration were used to prepare the blend films. At the level of 20% (W/W) of glycerol, PVA-AHSG blend films had the lowest thickness (0.065 mm), moisture sorption (118.76%), water vapor permeability (WVP) values (4.9 g mm m-2 kPa−1 d-1), elongation at break (EB)(2.1%), moisture content (22.5%) and water solubility (16.6%) and the highest values for tensile strength (TS)(64.6 MPa), young modulus (YM) (892 MPa),density (0.109 g cm-3),opacity (0.069 A/mm) and water contact angle (74.52◦). Increasing of glycerol concentration in PVA-AHSG blend films resulted in increase in water vapor permeability and percent of elongation while, decreased tensile strength and surface hydrophobicity. Increasing the glycerol concentration significantly (p < 0.05) diminished initial water contact angle of films from 74.52◦ to 37.80◦. It has been shown that the addition of plasticizers diminished the films’ water contact angle, which in turn, decreased hydrophobicity of the films. The higher hydro-philicity of the samples is attributable to the hygro-scopicity (water-binding capacity) of the plasticizer. Plasticizer can diminish interactions between biopolymer molecules and increase solubility due to its hydrophilic nature, giving the polymer molecules higher affinity to attract water. The moisture content increased significantly from 22.5% to 40.9% as the plasticizer content increased (p < 0.05). Because of glycerol acts as a water-holding agent, with the higher number of water molecules in glycerol-plasticized films increasing plasticizing activity.WVP increases as plasticizer content of the film increases due to its hydrophilic nature. WVP can be directly related to the quantity of OH group on the molecule. Also, environmental conditions can significantly affect the WVP. Increasing plasticizer concentration decreased the intermolecular forces between polymer chains and increased free volume and segmental motions, allowing water molecules to diffuse more easily and giving a higher WVP. Mechanical strength of films decreases due to plasticizer addition resulting in decreased tensile strength and increased elongation. The measurement of color values showed that by the increasing of the glycerol concentration in polymers blend matrix, the b and L values increased while a value decreased. Furthermore, the addition of glycerol promoted the interactions among PVA, AHSG and glycerol through hydrogen bonding as reflected on the shifting of main peaks of the glycerol-free film to higher wavenumbers as shown by FTIR spectra. Microscopic views indicated smooth and uniform surface morphology without obvious cracks, breaks, or openings on the surfaces after the incorporation of glycerol as a plasticizer. Scanning electron microscopy showed that the microstructure of PVA-AHSG blend films have a critical effect on their physical and mechanical properties that is important in food packaging applications.
Hamed Mahdavian Mehr; Arash Koocheki; Mohebbat Mohebbi
Abstract
Introduction:Deep fat frying is a cooking method where oil is used as the heat transfer medium, in direct contact with food at a temperature above boiling point of water. The aim of this process is to combine short cooking times with unique characteristics. It also involves heat and mass transfer simultaneously. ...
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Introduction:Deep fat frying is a cooking method where oil is used as the heat transfer medium, in direct contact with food at a temperature above boiling point of water. The aim of this process is to combine short cooking times with unique characteristics. It also involves heat and mass transfer simultaneously. During frying time, the mass transfer is characterized by the dynamics moisture loss from the food and the fat uptake into the food. There is some experimental evidence showing that water loss and oil absorption are correlated and progress with specific kinetic. In the meantime, oil uptake of product is an important issue, affecting the nutritional and organoleptic qualities of fried foods. However, one problem associated with fried foods is the considerable amount of oil absorbed during the deep frying process. It is affected by oil temperature, frying time, initial water content of food ingredients, product surface area, the ratios of product weight to frying oil volume, pretreatments and many other factors. So far, several approaches have been suggested for decreasing oil uptake during deep frying of fried foods. One way to decrease oil absorption in foods is referred to batter coating. In this regard, the ingredients and flow behavior's properties of batter are the most important parameters to determine the performance of batter coating and reduction of oil uptake in the final product. In the batter formulations, proteins and gums can be used as important and effective components, because they have great water bonding and barrier properties, which has strong impact on reduction of oil uptake during frying. Therefore, the objective of the present study was to assess the effects of replacement of Godume shahri seed gum (0.5 and 1%) or soy protein isolates (2 and 4 %), as part of the wheat flour in batter formulation, on rheology of batter, batter pickup and mass transfer kinetic parameters during deep frying of chicken nuggets.Materials and method:Raw materials including fresh chicken breasts, onion, salt, hot pepper, wheat flour, baking powder, and 100% pure sunflower oil were purchased from local markets. SPI (92% protein. w/w, db) were obtained from FSL Co. The batter formulations consisted of wheat flour, salt (1.5% w/w, db), baking powder (0.5% w/w, db), SPI (2 and 4% w/v, db) and Godume shahri seed gum (0.5 and 1%). For all samples, water/dry mix proportion had always been 5:3.Rheological properties of the batters were carried out using a Bohlin rotational Viscometer. For each test, shear rate increased from 0 to 300 s−1. The flow behavior index (n) and consistency coefficient (k) values were computed by fitting the power law model.The chicken nuggets, containing a mixture of chicken breast meat (88%), onions (10 %), Pepper (0.5%) and salt (1.5 %) were prepared in slab shapes using a manually operated cutting device. The dimensions of the chicken nuggets were about 4.5 cm (length) × 2.6 cm (width) ×1.1 cm (thickness) (±0.2 cm). Batter pickups (%) were calculated by the weight difference between the chicken nuggets after coating to the weight of chicken nuggets before coating. Deep frying was performed in programmable deep fat fryer contained 1.5 L refined sunflower oil. Samples were placed in a wire basket and then submerged for the required times of zero, 1, 2, 3, 4 and 5 minutes at 150 ◦C, 170 ◦C, and 190 ◦C. Oil and moisture content of the chicken nuggets were determined by standard techniques. For modeling moisture and oil transfer phenomena in fried chicken nuggets, Fick’s law of diffusion and a first order kinetic model were used respectively.Results and Discussion:Results showed that Godume shahri seedgum had more effect on apparent viscosity compared with soy protein isolates. Polysaccharidic structure of Godume shahri seed gum prepares high number of hydroxyl groups. Hydrodynamic interactions between polar and hydrophobic groups trap most of the free water and consequently increase batter viscosity. All batters showed shear thinning behaviour (n≥0.529). The power law model was adequately suitable to describe the flow behavior of the batters (R2≥0.994). Coating uptake at the surface of nuggets was significantly affected by the batter consistency. The consistency index for batter containing gum was high and therefore the coating uptake was higher for these samples. The maximum moisture loss rate and the effective diffusion coefficient obtained for chicken nuggets coated with only batter. Addition of soy protein isolates and Godume shahri seed gum to batter formulation, decreased the Deff to 3.55-5.46×10-8 m2/s and 3.38-5.32×10-8m2/s, respectively. This can be attributed to the effect of different batter formulations and special functions of gum and protein. The activation energy to remove moisture and oil absorptionwere 10.79 (kJ/mol) and -7.91(kJ/mol) for the control sample, 13.37-17.64 (kJ/mol) and -5.90 to -9.18 (kJ/mol) for soy protein isolates and 11.9-14.7 (kJ/mol) and -7.56 to-10.30 (kJ/mol) for Godume shahri seed gum, respectively.
Saeed Mirarab Razi; Mohebbat Mohebbi; Mohammad Hossein Hadad Khodaparast; Arash Koocheki
Abstract
Introduction: Proteins are widely used in food industry because it has functional properties such as formation and stabilization of foam systems. These molecules had surface-active properties. They rapidly adsorb at interface during the foaming processes and form a film around gas bubbles. The bulk properties ...
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Introduction: Proteins are widely used in food industry because it has functional properties such as formation and stabilization of foam systems. These molecules had surface-active properties. They rapidly adsorb at interface during the foaming processes and form a film around gas bubbles. The bulk properties has important role in the stabilization foam system. It has been shown that protein adsorption is influenced by molecular properties, such as size, shape, surface hydrophobicity, conformation, and charge and conditions in the bulk solution, such as bulk concentration, pH and ionic strength. The foaming properties depend on many intrinsic factors (size, structure of protein, hydrophobicity, surface potential, charge, etc.); and environmental and processing factors (protein concentration, pH, temperature, addition of other ingredients, etc.) Foams are colloidal systems in which gas phase dispersed in an aqueous continuous phase. Foaming operation is usually devoted to produce lighter products, modify the appearance and the texture of food products, therefore, it be used to production new products adapted to consumer choice and needs, using air as a zero-cost component. Microstructure has fundamental role in foam properties. At foam based products, bubble size is of most importance at the foam properties, because it influences on texture, the mouth-feel and the stability of the aerated product. Many food products have aerated structure. In these foods, the gas phases, forms small bubbles that modify microstructure and mouth feel properties of product. Aerated desserts have shown a great market potential, which is dependent on consumer behavior, interested in lighter and healthier products. Food products based on foam structure such as chocolate mousse have good marketing; therefore deep knowledge about their properties is important. Mousse is an aerated dessert with stabilized foamy structure which little attention has been paid to industrial production. Although, the most popular mousse flavor is chocolate, orange, lemon and strawberry have good marketability.Materials and method: This study follows two important objectives; first, the effect of different amount of gelatin concentration and sodium caseinate on rheological, physical and sensory properties of chocolate mousse is investigated. Then, the relationship this parameters was discussed on the basis of laboratory results using PCA method. Chocolate mousse was include of, Gelatin(Bangladesh, type B, bloom 160-180), Cacao powder(Cargill Co., Netherlands), Whipped cream(Mahrang sahar shargh CO., Iran 27% fat), Sugar(Fariman, Iran) and Sodium caseinate (Milad, Iran). Chocolate mousse samples were prepared with different amount of gelatin (1, 2 and 3 gr) and sodium caseinate (1, 2 and 3 gr) concentrations. Gelatin was first dissolved in hot water. Next, cacao powder and sugar were stirred in hot water and added to whipped cream agitated by Gosonic home mixer with speed 5400 RPM for 3 minutes. Then, Sodium caseinate was mixed in distilled water for 2 minutes and added to mixture prepared. Finally, mousse was placed in refrigerator after stirring with gelatin solution. The samples were stored in a refrigerator for 24 hours.Results and Discussion: In this work, physical, sensorial and rheological properties of chocolate mousse were investigated. Rheological measurements were carried out using a rotational viscometer (Bohlin Model Visco 88, Bohlin Instruments, UK) equipped with a heating circulator (Julabo, Model F12-MCand, Julabo Labortechnik, Germany) and C30 spindle. All the experiments were performed at 25°C±0.2. A pre shearing of 10-15 s at 14.1 s was applied to all samples. Sample flow was measured by registering the shear stress/ shear rate data at an increasing trend from 14.1 to 300 s. To describe the time independent flow behavior, the experimental data (shear stress-shear rate) were fitted by Herschel- Bulkley, Bingham, power law, and Casson models. Sensorial properties were tested at the same optical condition and environmental temperature. Chocolate mousses were evaluated using hedonic analysis procedures by a sensory panel of ten assessors, who had been selected and trained. Sensorial properties were evaluated based on 1 to 9 scores. The gas hold-up was calculated by comparing the density of the aerated chocolate with the gas-free density of solid chocolate. PCA method was used for determination of the relation of sensory attributes and main component.Conclusion: Results showed that chocolate mousse incorporating 2 gr gelatin and 3 gr sodium caseinate had the best sensory properties. According to the R2 (R2>0/99) and RMSE values, it is obvious that the Power-law models can properly describe non-newtonian flow behavior of samples. Behavior index (n) and consistency coefficient (k) were obtained from fitting power-law model. Consistency coefficient was high in the sample containing 3 gr gelatin and 3 gr sodium caseinate. Density values decreased with increase in protein content and decrease in gelatin content. Based on PCA results, total acceptance of samples was severely related to the smoothness, jelly and melting rate attributes.
Atefeh Farahmand; Mehdi Varidi; Arash Koocheki
Abstract
Introduction: Exploiting natural substances with dual or multiple functionalities is getting more attention in food industry due to the requirement from the health- conscious consumers and the trends for sustainable environment. Hydrocolloids are high molecular weight macromolecules that can be easily ...
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Introduction: Exploiting natural substances with dual or multiple functionalities is getting more attention in food industry due to the requirement from the health- conscious consumers and the trends for sustainable environment. Hydrocolloids are high molecular weight macromolecules that can be easily dissolved and dispersed in water under appropriate conditions. They can modulate rheological properties of foods, and are generally used as food thickeners, texture modifier, stabilizers and emulsifiers for various applications. Mucilage is a high molecular weight polyuronides consisting of sugar and uronic acid units. It is partially soluble in water and can form highly viscous solution. It exhibits hampering effect on the diffusion of glucose, help to postpone the absorption and digestion of carbohydrates. The mucilage extracted from the seeds of the quince fruit contained cellulose micro-fibrils strongly associated whit a glucuronoxylan possessing a very high proportion of glucuronic acid residues. Analysis of quince seed mucilage (QSM) has shown the presence of more cellulosic fraction and hydrolysable polysaccharide.Quince seed mucilage is one of the endemic hydrocolloids, which due to high viscosity, its extraction needs a method to reduce the extraction time, energy consumption and especially raise the extraction efficiency. The traditional extraction method of polysaccharide from plant tissues are maceration, mechanical rabbling and heat reflux. Theses extraction methods depend largely on energy input and agitation to improve the solubility and mass transfer efficiency of polysaccharides. Usually, the convention extraction method requires long extraction time and high extraction temperature with low extraction yield, but high energy consumption. Ultrasound in combination with conventional extraction is a potential technique, which is a fully reproducible food process, completed in shorter time with high reproducibility, reduced processing cost, simplified manipulation and work-up. To achieve this goal, in this study ultrasound- assisted extraction (UAE) as a novel extraction method was used.Materials andMethods:Quince seed used in this study was purchased from a local market (KhorasanRazavi, Mashhad). They were cleaned manually by removing the foreign matter such as stones, dirt and broken seeds. They were packed in hermetic plastic vessels and stored at 5ºC until further use. For mucilage extraction, first conventional extraction was optimized to select the best hydration conditions and after that UAE (24 KHz probe and 400 W power) was performed at three different levels of intensity (20, 60 and 100%) and times (5, 15 and 30 min).All chemicals used were analytical grades. Yield value of hydrocolloid was calculated by dividing the weight of dried hydrocolloid by the weight of initial dry seeds. Emulsion heat stability was determines by the method described in previous studies. In order to measuring the water absorption capacity (WAC), 0.05 g of mucilage was added to deionized water until QSM was completely wet (~ 10ml). The tubes were then centrifuged at 1600×g for 10 min. Excess water was discarded and residue was weighted. Apparent viscosity of QSM solution with 0.1% (w/v) concentration was measured using a rotational viscometer (Brookfield, DV- ІІІ, USA). Shear rate increased linearly from 2.5 - 35 s-1 at 25˚C.For measuring the foam stability and emulsion heat stability, the mucilage dispersions were prepared at 0.25 and 0.5 (w/v) respectively, and kept overnight at 4˚C. After complete hydration, 2% (w/v) egg white powder was added and then foamed by whipping at 8600 rpm for 2 min using adisperser.Results and Discussion: Optimized conditions of conventional extraction were 45 min, 47˚C and 32.5: 1 water to seed ratio. The results showed that extraction at 30 min with 100% intensity raised the extraction yield to 42.7% in comparison with control sample.Improvement in hydrocolloid extraction by ultrasound is attributed to ultrasound pressure wave diffusion which results in cavitation phenomenon.Amplitude level and exposure time had a significant (p
Nasser Sedaghat; Ghodsieh Moradi; Sara Khoshnoudi; Arash Koocheki
Abstract
Introduction:Pistachio (Pistaciavera L.) is a tasty nuts and a good source of nutrients. During the last decade, the worldwide trades of pistachio have increasing trend, likely reflecting on the increase in consumers demand for this nuts. The high oil and essential fatty acid contents of the pistachio ...
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Introduction:Pistachio (Pistaciavera L.) is a tasty nuts and a good source of nutrients. During the last decade, the worldwide trades of pistachio have increasing trend, likely reflecting on the increase in consumers demand for this nuts. The high oil and essential fatty acid contents of the pistachio kernel is important from a nutritional point of view. However, high unsaturated fatty acids content makes pistachio nuts susceptible to oxidation and consequently off-flavors and off-aromas during storage.Mold growth and the production of aflatoxins is another food-safety concern about pistachio nuts. Lipid oxidation and fungal growth can be controlledby using an appropriateatmosphere in packaging.Therefore, the main objectives of this study were to determine the effect of Modified Atmosphere(MA) compared with Vacuum and Air condition packaging on physicochemical, microbialandsensory properties of raw dried Pistachio nuts (ohadi variety) in an accelerated storage conditions at 30±2°C and 50°C for 12 weeks. Material and methods: The pistachio nuts were treated with 3 different system packaging, these treatment includes modified atmosphere packaging (MAP at 88% N2; 10% CO2 and 2% O2), vacuum packaging and air condition packaging. The pistachio nuts were packed in five-layerpouches (2 PE+ 2 PA+1 glue :80 microns)and stored in triplicate at 30°C and 50°C for12 weeksand they were sampled every four weeks. Oil from pistachio kernels for peroxide, and fatty acid assay were extracted by cold extraction and n-hexane was used as extraction solvent. Peroxide value (Meq.kg-1) of the extracted oil was determined by spectroscopic absorbance reading at 500 nm. Free fatty acids (%), as oleic acid percentages in oil samples, were determined using the titration method. Moisture content (%) was determined by drying 5 g of ground kernels at 103±2 °C until constant weight. The mouldcontent (log CFU/g) of pistachios were performed according to the Iran standard method. The textural analysis of the pistachio nuts were performed using cylinderprobe (diameter: 20 mm) at test speed 50 mm/min and deformation of 4 mm for samples. Fracture force (N) and hardness (N) parameters were measured to evaluate textural properties ofpistachio nuts samples.Sensory evaluation was carried out by a 20 member trained panel (10 females and 10 males). Sensory attributes evaluated included color, firmness, rancidity and overall acceptability on 5 point hedonic scale, whit 5 for excellent and 1 for very dislike. Analysis of variance (ANOVA) was carried out using the least significance difference(LSD) test (p
Hamed Mahdavian Mehr; Arash Koocheki; Mohebbat Mohebbi
Abstract
Introduction: Batter coating is a new technology to reduce fat content of fried foods. The ingredients and flowproperties of batter are the most important parameters to determine the performance of batter coating and quality of the final product. Among batter additives, proteins can be used as an important ...
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Introduction: Batter coating is a new technology to reduce fat content of fried foods. The ingredients and flowproperties of batter are the most important parameters to determine the performance of batter coating and quality of the final product. Among batter additives, proteins can be used as an important and effective component, because of their emulsifying properties, water absorption, and barrier properties. Previous studies have shown that soya protein isolate (SPI) is a very good hydrophilic protein which could be used to control the viscosity of batter. The batter temperature has direct effect on its flow behavior's properties and has a major impact on the quality of final coated product. Therefore, the aim of the present study was to evaluate the effects of temperature (5, 25 and Cº45) and SPI content (2 and 4%), on flow properties of the batter and quality of deep-fried chicken nuggets. Materials and methods:Raw materials such as fresh chicken breasts, onion, salt, hot pepper, wheat flour, baking powder, and 100% pure sunflower oil were purchased from local markets. SPI (92% protein) were obtained from GolharKhorasanRazavi Company. The batter formulations consisted of wheat flour, salt (1.5% w/w, db), baking powder (0.5% w/w, db) and SPI (2 and 4% w/v, db). For all samples, water/dry mix proportion had always been 5:3. Rheological properties of the batters were carried out using a Bohlin rotational viscometer. For each test, shear rate increased from 0 to 300 s−1, followed by a logarithmically decrease from 300 to 0 s−1. The flow behavior index (n) and consistency coefficient (k) values were computed by fitting the power law model, and time dependency properties of the batters were obtained from the area between the upward and downward curves. Temperature dependency of consistency coefficients were assessed by fitting the Arrhenius model. The batter coating on the chicken substrate was appliedat three temperatures (5, 25 and 45 Cº), and batter pickups (%) were calculated by the weight difference between the chicken nuggets after coating to the weight of chicken nuggets before coating. Coated samples were stored at -18 Cº for two weeks. After thawing, chicken nuggets were fried at 180°C for 3 min in sunflower oil using a programmable deep fat fryer. The influence of SPI concentrations and batter temperature on color and crust adhesion of deep-fat fried chicken nuggets was measured with image processing. In brief, images were taken by a digital camera under controlled conditions, and then analyzed by Image J software. The Percentage of adhesion (CRA), obtained by calculating the ratio of the pixels corresponding to the perimeter of the substrate where coating is adhered to the pixels corresponding to the total perimeter of the substrate. The color of deep-fat fried chicken nuggets were examined in terms of L*, a* and b*values. Oil and moisture content of the chicken nuggets was determined by standard techniques. Results & Discussion: Results showed thatall samples had a shear-thinning behaviour at all batter temperatures (n≥0.539). Power law model was adequately suitable to describe the flow behavior of the batters (R2≥0. 994). The activation energy was between 5.106 to 5.630 (kj/mol).Addition of soy protein isolates into the batter, enhanced the time dependency, whereas, the increase of temperature decreased the hysteresis area. The relative increase in apparent viscosity with increasing SPI might be attributed to the high capacity of SPI to absorb free water. However, decrease in apparent viscosity and time dependency of batters with increasing the temperature could be due to the intermolecular interactions in batter system. An increase in temperature weakens the intermolecular interactions and increases the mobility of macromolecules which reduces the batter resistance to shear force. The batter temperature and formulation had significant effect on the batter pickup. This effect was mainly due to the changes occur on flow properties of batter. Using SPI increased the a* and decreased the L* of the final product. This could be due to the active participation of SPI in the Millard reaction. The data obtained for crust adhesion revealed that the increase in SPI concentration lead to a decrease in batter adhesion to the crust. In other words, the ability of soya proteins to form film during early time of frying reduces the moisture migration from the substrate to oil, which creates a positive pressure in the inner layer of crust and reduces the adhesion. Conclusion: Chicken nuggets coated with batter containing SPI had higher moisture and lower oil content than the control sample. Finally, the change in batter temperature had no significant effect on the crust adhesion and oil and water content in the final product.
Habib Jahandideh; Masoud Taghizadeh; Mohammad Hossein Hadad Khodaparast; Arash Koocheki
Abstract
Introduction: Nowadays, one of the most important nutritional problems in different societies is the protein mal-nutrition. Since bread is the main food material being consumed in all over the world, bread enrichment using the grains rich in protein such as sesame seeds would be an appropriate alternative. ...
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Introduction: Nowadays, one of the most important nutritional problems in different societies is the protein mal-nutrition. Since bread is the main food material being consumed in all over the world, bread enrichment using the grains rich in protein such as sesame seeds would be an appropriate alternative. However, addition of sesame products such as Tahini meal would cause some technical difficulties such as dough stability, water absorption, dough extension time, etc. in bread manufacturing processes.In this study the effect of addition of xanthan gum to on physical and textural properties of Baguette bread containing tahini meal was investigated.Materials and methods: Wheat flour and tahini meal were supplied from Damghan and Ardakan cities, respectively. They were then refrigerated prior to baking process and different chemical tests were carried out according to standard methods. Protein was measured based on Kejeldahl method. Moisture content as well as ash content were determined using oven method.Raw fat was calculated according to AACC-No. 30-10 and raw fiber was measured using appropriate instrument (Scientific velp-FIWE6 F30530201). Starch determination was carried out using Small universal polarimeter (SUP-Germany). Xanthan gum was purchased from Provisco Ltd. (Switzerland) in food grade quality. Bread yeast (Saccharomyces cerevisiae) was also supplied in dried form. All other chemical enhancers were purchased from Merck Ltd. (Germany). Baguette dough was produced from mixture of wheat and Tahini meal flour based on protein content and the amount of protein in final dough was increased from 10.28% in flour free of tahini meal to 12, 14 and 16% in different treatments. The rest time for all flour samples was fixed at 15 min and the baking process was carried out for 15 min at 300°C. Baked breads were exposed to room temperature for two hours and then were packed using poly-ethylene (PE) film for further tests. Specific volume of bread samples was measured using rapeseed displacement method (AACC, No. 54-30, 2000). Samples porosity was determined using image processing techniques. Samples were cut to 2cm×2cmcubes and an appropriate scanner (Canoscan 8800F, Japan) with 300 pixel resolution was used to acquire the images for further process using Image J(1.6r, 2010). Apparent color for the baguette samples (in terms of CIE ‘L*’- lightness,“a*” - redness and greenness, and “b*”- yellowness and blueness) were also measured using image processing techniques (Image J, 1.6r, 2010).Texture profile analysis (TPA) test was carried out using a texture analyzer (QTS Texture Analyzer, CNS Farnell, Hertfordshire, UK) to study the effect of xanthan gum and tahini meal on parameters such as hardness, gumminess and cohesiveness in all baguette samples.Results and discussion: ANOVA test showed the significant effect of xanthan gum and tahini meal on the porosity of samples. The porosity of samples containing less than 0.5% xanthan gum at all tahini meal levels, was significantly less than control sample.Similar results were obtained in the case of specific volume meaning that the employed treatments have significant effect on bread’s specific volume. Increasing tahini meal from 9.45% to 14.53% caused significant decrease in specific volume. This could be due to the weakness of dough gluten matrix. These results are in agreement with other works reported by other researchers (Paraskevopoulouet al., 2010; Mohammad Idrisset al., 2012; and Guardaet al., 2004). The results obtained for apparent color of bread core also showed the effect of xanthan and tahini meal. The only exception was found in case of a* value when studying the effect of xanthan gum, meaning that xanthan gum has no significant effect of this parameter. In the case of apparent color in bread crust, the studied treatments (xanthan gum and tahini meal) showed significant effect on all color parameters. Different textural properties of baguette samples including hardness, gumminess and cohesiveness were also measured. Conclusion: The results indicated obvious effect of xanthan gum and tahini meal levels on these mentioned parameters. Increasing tahini meal and xanthan gum levels would increase hardness as well as gumminess. However, addition of xanthan gum and tahini meal cause significant decrease in cohesiveness. This could be due to dilution effect of these substances which decrease the concentration of protein matrix existed in flour’s gluten.
Mohammad Ali Hesarinejad; Seyed Mohammad Ali Razavi; Arash Koocheki
Abstract
In this study, dynamic rheological, structural and thermal properties of Alyssum homolocarpum seed gum (AHSG) were investigated as a function of concentration (1.5, 2, 2.5 and 3% w/v) and temperature (5–85 °C). The effects of heating/cooling rate on the rheology of AHSGs were studied using ...
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In this study, dynamic rheological, structural and thermal properties of Alyssum homolocarpum seed gum (AHSG) were investigated as a function of concentration (1.5, 2, 2.5 and 3% w/v) and temperature (5–85 °C). The effects of heating/cooling rate on the rheology of AHSGs were studied using small amplitude dynamic oscillatory shear (SAOS). The LVE of this gum were observed at more than 1% strain. The elastic component was always higher than the viscous one. Mechanical spectra of these gum solutions were obtained by frequency sweep measurement classified into that of weak gels because G’ was larger than G” throughout the tested frequency range. The complex modulus has linear relationship with the frequency. The gums showed dependency behaviour as a function of temperature in the range of 5-85oC. The moduli were dependent on gum concentration. They were shown that strength of AHSG at cooling step was more than heating step. AHSG at concentrations above 2.5% was formed gel and its gel was irreversible. Gel formation temperature increased with increasing concentration. FT-IR spectra to understanding their functional groups were recorded in the transmittance mode.
