Food Biotechnology
Dina Shahrampour; Morteza Khomeiri; Seyed Mohammad Ali Razavi; Mahboobeh Kashiri
Abstract
Introduction: Due to the low variety of probiotic food products, it is important to provide appropriate solutions for new products. Trapping probiotic bacteria in the polymers structure of edible films and coatings is a new approach that has been proposed to increase the survival of these microorganisms ...
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Introduction: Due to the low variety of probiotic food products, it is important to provide appropriate solutions for new products. Trapping probiotic bacteria in the polymers structure of edible films and coatings is a new approach that has been proposed to increase the survival of these microorganisms and to develop new probiotic products in the food industry.Materials and Methods: In this study, an alginate-based probiotic bioactive film containing L. plantarum was fabricated. The effect of bacterial addition on physical, mechanical and prevention properties of alginate film was evaluated. In addition, the effect of two temperatures 4 ° C and 25 ° C on the survival of embedded probiotic bacterium in the film structure during one month of storage was investigated by microbial count assay on MRS agar medium. Then, the model food was covered with probiotic film and the survival of probiotic bacterium during food storage was determined.Results and Discussion: The results showed that the population decline of probiotic bacterium after drying of alginate film solution was about 4.61%. Addition of probiotic bacterium to the alginate film increased the thickness, turbidity, and tensile strength of the film, While on solubility, water activity, Elongation(%) and microstructure of alginate film had no significant effect. In addition, the probiotic film containing bacteria had less luminosity, moisture content and water vapor permeability (WVP) than the control film. The survival percentage of L. plantarum in alginate film after one month of storage at 4 ° C was higher than 25 ° C and 96.84 and 47.29%, respectively. Also, the population of embedded bacteria in the film structure on the food model (sausage) surface after three weeks storage in refrigeration was in desired level of probiotic products (> 106 cfu / gr).Conclusion: Therefore, alginate film is recommended as a suitable carrier for probiotic microorganisms to produce new functional products.
Food Engineering
Mohammad Reza Salahi; Seyed Mohammad Ali Razavi; Mohebbat Mohebbi
Abstract
Introduction: Emulsion-filled gel is a sort of gel system that traps oil droplets as a filler and contains a wide range of semi-solid to solid food products. They can also be utilized as a dual system to distribute and control the release of both lipophilic and hydrophilic bioactive and micronutrient ...
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Introduction: Emulsion-filled gel is a sort of gel system that traps oil droplets as a filler and contains a wide range of semi-solid to solid food products. They can also be utilized as a dual system to distribute and control the release of both lipophilic and hydrophilic bioactive and micronutrient substances. The main polymers involved in gel formation in food products are proteins and polysaccharides. Using molecular interactions between biopolymers, a wide range of rheological and physicochemical properties of gels can be methodically created. As a result, the interaction between proteins and polysaccharides has received a lot of attention in order to generate novel products. Because of their functional qualities and high nutritional value, whey proteins are frequently used in the food industry. As a result, mixed gels based on whey protein have gained a lot of attention. k-Carrageenan is commonly utilized in the food industry as a gelling and firming agent. Because k-Carrageenan, like whey protein isolate, can form a gel independently, its interaction with whey protein isolate in emulsion gel systems appears appealing. Therefore, in this study, the effect of k-Carrageenan gum (0.0, 0.1, 0.3, 0.5, and 0.7%) on the textural (uniaxial compression test), rheological (steady shear, strain sweep, and frequency sweep tests), and water holding capacity of cold-set emulsion-filled gel based on whey protein isolate was investigated.Materials and Methods: Whey protein isolate (WPI) (98.9% protein, dry basis) was given as a gift by Agropur Ingredients Co. (Le Sueur, Minnesota, USA). k-Carrageenan and CaCl2 (m_w: 147.01 gr/mol) were purchased from Sigma Aldrich Co. (USA) and Merck Co. (Darmstadt, Germany), respectively. Sunflower oil was bought from a local supermarket. Stock dispersions of WPI and k-Carrageenan were made by dissolving sufficient amounts of their powders in deionized water. To prepare uniform oil in water emulsion, sunflower oil was added to the WPI dispersion and the obtained mixture homogenized first using a laboratory rotor-stator homogenizer (15000 rpm, 3 min), then by an ultrasonic homogenizer (20 kHz, 5 min). The prepared emulsion and k-Carrageenan dispersions were poured into Schott bottles and heated in a water bath (90 C, 40 min). WPI emulsion and AG dispersion were mixed in a cylindrical container on a stirring plate at a speed of 600 rpm for 6-8 min to obtain a homogeneous mixture. After decreasing the temperature to 60 C for the ion-induced gelation, the mixtures were charged with CaCl2 (10 mM). The prepared samples were incubated in a refrigerator overnight to stabilize the 3D network. The final mixed EFG samples contained 5.5% WPI, 20% oil, and 0, 0.1, 0.3, 0.5, and 0.7% (w/w) of k-carrageenan. The tests performed on emulsion-filled gel samples were: 1) steady shear (0.01-10 s-1), 2) strain sweep (strain: 0.1-1000%, frequency: 1 Hz), 3) frequency sweep (frequency: 0.1-100 Hz, strain: 0.5%), 4) uniaxial compression (target strain: 80%, deformation speed:1 mm/s), and 5) water holding capacity (by utilizing a microcentrifuge, 600×g for 10 min).Results and Discussion: According to the steady shear test, all samples had a shear thinning behavior, and based on the power-law model, this behavior was intensified in the presence of k-Carrageenan; and with increasing the gum concentration from 0 to 0.7%, the consistency coefficient increased from 339.9 to 545.7 Pa.s. In the strain sweep test, with the increase in the gum concentration, the values of the elastic and viscous modulus in the linear region and the modulus at the crossover point increased, and Tan LVE decreased from 0.17 to 0.13, which indicated an increase in the strength of the emulsion gel network structure. Based on the frequency sweep test, with the increase in k-Carrageenan concentration, the parameters K^' and K^'', network strength and network expansion, respectively, increased from 5311.8 Pa, 939.9 Pa, 1.5380 Pa.s1/z and 10.05 in the control sample to 25080 Pa, 3574.9 Pa, 16097.7 Pa.s1/z and 16.41 in the sample containing 0.7% k-Carrageenan, respectively. Moreover, the frequency dependency of elastic modulus decreased from 0.095 in the control sample to 0.050 in the 0.7% k-Carrageenan contained sample. According to the large deformation test, in general, in the composite emulsion-filled gels, the values of apparent modulus of elasticity and fracture stress were higher and fracture strain and fracture energy were lower than in the control sample. Also, the results showed that different k-Carrageenan concentrations had no significant effect on the water holding capacity.The obtained results showed that k-Carrageenan had considerable influence on the rheo-mechanical features of cold-set emulsion-filled gels based on whey protein which can add to the knowledge base for the production of new functional foods.
Food Engineering
Seyed Mohammad Ali Razavi; Morteza Kashaninejad
Abstract
Introduction Ultrafiltration is one of the most common membrane processes in the dairy industry, especially for condensing and separating milk components. Using this process, several products can be produced, including milk concentrate used for cheese production, low-lactose dairy products, milk ...
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Introduction Ultrafiltration is one of the most common membrane processes in the dairy industry, especially for condensing and separating milk components. Using this process, several products can be produced, including milk concentrate used for cheese production, low-lactose dairy products, milk protein concentrate, and serum proteins for dietary supplements. The efficiency and cost of a membrane process depend on the percentage of rejection of the soluble components. Therefore, the use of concentrated milk made by ultrafiltration in the production of various dairy products depends on the efficiency of the membrane process and the changes in milk components during this process. On the one hand, the physicochemical properties of camel milk are different from those of cow milk, especially in terms of type and amount of protein. Because significant differences exist between the physicochemical properties of camel and cow milk, likely, the membrane processing conditions and the physicochemical properties of their products will be different completely. Although many studies have been conducted on the efficacy of the ultrafiltration processing of cow milk, there is no information about the efficacy of camel milk ultrafiltration, and most of the research done regarding optimizing is based on classical algorithms, Therefore, in this study, the effects of transmembrane pressure and temperature on the solutes rejection (protein, lactose, ash, and total solids) during camel milk ultrafiltration process were investigated, Then, these properties were optimized using particle swarm algorithm. Also, because the performance of the particle swarm algorithm is highly dependent on related parameters such as the number of iterations, the number of particles, accelerate constant, inertia weight, and velocity of the particles, so before optimization, the effect of these parameters on optimal responses were examined by partial least squares regression (PLS). Materials and Methods In this study, a pilot crossflow ultrafiltration system was used. A UF membrane (Model 3838 HFK-131, Koch membrane systems, Inc., USA) made of polysulfone amid (PSA) with MWCO of 20 kDa was applied. Camel milk was purchased from a local market in Mashhad and for camel skim milk production, its fat was separated by a pilot plant milk fat separator in the Food Research Complex, Ferdowsi University of Mashhad. The weight percentages of protein, fat, lactose, ash, and total solids of UF permeate samples were measured by ISO 8968-1:2014, ISO 1211: 2010, ISO 26462/IDF 214:2010, ISO 5544:2008, and ISO 6731:2010 at two replications, respectively. the process treatments were performed in the form of a central composite design (CCD) (5 replications at the central point) for two independent variables at three levels so that the total number of 13 treatments was obtained. The data were modeled using the statistical software of Design Expert (version 11) based on the response surface methodology and each of the response variables in the form of a regression model was presented as a function of independent variables. Results and Discussion The rejection of total solids and protein of the tested samples varied in the range of 45.4-51.03% and 94.09-97.51%, respectively. It means that in each TMP and T, more than 45% of the total solids and 94% of the protein of camel milk were kept by the membrane. The results also showed that none of the linear, quadratic and interactive effects of TMP and T on the total solids and protein rejections were not significant. According to the results, the RL reduced with increasing T. Increasing the TMP also led to a reduction at high T and an increase in RL rate of the samples at lover T. Also, the effect of TMP on RA showed a non-linear trend, so that TMP at high T led to an increase, and at low T, it led to a reduction in the RA of the samples. Conclusion The optimization results with the particle swarm algorithm showed that this algorithm has a high convergence speed and by recognizing and analyzing its parameters, the optimal conditions can be easily found. The optimum ultrafiltration conditions in this study with the lowest RL and RA were determined as 80 kPa TMP and 29.85 ͦ C T.
Food Technology
Shokohfeh Taziki; Seyed Mohammad Ali Razavi
Abstract
Introduction Wheat starch granules are composed of amylose and amylopectin, which are responsible for the functions of starch such as swelling, gelatinization, pasting, gel formation, and retrogradation. The retrogradation changes the functional properties, it is an undesirable phenomenon in some ...
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Introduction Wheat starch granules are composed of amylose and amylopectin, which are responsible for the functions of starch such as swelling, gelatinization, pasting, gel formation, and retrogradation. The retrogradation changes the functional properties, it is an undesirable phenomenon in some starch-based foods which reduces the acceptability of food, and shortens the shelf life. Delaying or preventing of starch retrogradation is a major challenge in the food industry. Various ingredients such as carbohydrates imply an important role in improving the functional properties, decreasing amylose leaching and retarding the retrogradation of starch gels. Cress seed gum (CSG), as an emerging galactomannan, has shown the ability to improve the textural and rheological features of food systems based on its unique properties. Addition of CSG to the composite wheat-rice bread increased dough stability and improved the staleness of bread compared to guar gum. Also, the addition of CSG and xanthan gum to gluten-free bread stabilized the texture of bread during storage. Sucrose (SUC) is a common additive in food formulations which is useful as a sweetening agent and textural modification. Sugars have been able to reduce amylose leaching and accelerate or delay starch gel formation. They also delay retrogradation of starch gels during storage. Therefore, the objectives of this study were to determine the impact of different substitution levels of CSG (0, 5, 10 and 15%), SUC (0, 5 and 10%), and their blend on the functional properties (swelling strength and solubility), microstructure features, retrogradation kinetics and synthesis of native wheat starch (NWS) gel (4% w/w).Materials and Methods Cress seeds were purchased from a local medicinal market. NWS and SUC were supplied from Sigma Aldrich (Spain) and Merck (Germany) respectively. Starch suspensions (0.6 gr powder/20 ml water) substituted with CSG (0, 5, 10, and 15% w/w) and SUC (0, 5, and 10% w/w) were prepared to estimate the swelling power and solubility index. To produce starch gel, the 4% w/w suspensions of NWS-CSG-SUC were prepared by dissolving the appropriate amount of CSG powder and SUC in deionized water. Then, each suspension was poured into a stainless-steel cylindrical container and was heated to 95 oC and held at 95 oC for 3 min and then cooled to 50 oC while stirring continuously at 160 rpm with a mechanical mixer. Finally, the pastes were kept at ambient temperature (25 oC) for 1 h. To assess gel structure, imaging of the gels was performed by scanning electron microscopy (SEM). The retrogradation kinetics and syneresis of gel samples were determined after storage at 4 oC for 0, 1, 7 and 14 days.Results and Discussions The swelling power and solubility index of NWS increased with increasing the replacement level of CSG. CSG promotes adhesive interactions among the gelatinized granules. This can enhance the forces applied to them, facilitating water entering (increasing swelling), amylose solubilization and its exudation. In contrast, SUC compete with starch molecules for water in the system and thus preventing gelatinization and mobility of starch molecules reduced the swelling power. The starch-gum-sugar mixtures had a higher swelling power compared to the starch and starch-sugar samples. The mixed samples had higher solubility values than each of them individually. SEM images showed that the pore size of starch gel decreased and increased from 33.01 to 29.44 µm and to 45.37 µm with increasing the substitution levels of CSG and SUC, respectively. NWS-15% CSG-5% SUC gel had 31.34 µm pore size. After storage for 14 days at 4 oC, the CSG substitution with NWS reduced the rate of retrogradation and syneresis from 0.101 to 0.52 (s-1) and from 50% to 23%, respectively. It could be related to creating a film around the granules by the leaked amylose and the CSG in the continuous phase, so inhibiting further swelling and polymers leaking out and related to high water holding capacity of CSG. The addition of SUC reduced the rate of the process to 0.096 (s-1) but because of its low water holding capacity, the value of syneresis enhanced to 57%. In the mixed gels, more reduction of the retrogradation rate and syneresis was observed which was clearly at high CSG replacement. The retrogradation rate of the NWS-15%CSG-5%SUC was 0.057 (s-1) and its syneresis was 45%. According to the results, it can be concluded that 15% CSG and 5% SUC replacement levels can effectively improve the functional properties and reduce the rate of retrogradation and syneresis of NWS during storage.
Food Engineering
Morteza Kashaninejad; Seyed Mohammad Ali Razavi; Mohammad Reza Salahi
Abstract
Introduction: One of the products that its production has not been investigated well and is an imported product is cream powder. Foam mat drying is a widespread technique to dehydrate liquid or semi-liquid foods with high viscosity, adhesion and high sugar content, which are usually difficult to dry. ...
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Introduction: One of the products that its production has not been investigated well and is an imported product is cream powder. Foam mat drying is a widespread technique to dehydrate liquid or semi-liquid foods with high viscosity, adhesion and high sugar content, which are usually difficult to dry. Evaluating moisture content over time is the first indication of how the drying process is performed and can be used as a tool to compare the drying behavior of food. The rate of drying, which is expressed as a function of time or moisture content, is also a very important parameter that helps to understand drying properties of a material. Color can also indicate chemical changes in food during the thermal process such as browning and caramelization. Therefore, since in the drying industry, process time, product quality, optimization and equipment design are directly affected by the rate of drying of food, hence, in this study, in the process of drying the camel milk cream by the foam mat drying method, drying operation at temperatures of 45, 60 ,and 75 °C and thicknesses of 1, 3 and 5 mm was performed in a non-continuous cabinet dryer to evaluate the kinetics of drying , structure and color of the dried foam. Materials and Methods: Camel milk cream was mixed with carboxymethyl cellulose (0.1%), cress seed gum (0.1%) and 80% whey protein concentrate (5%) at 25 ° C. After pasteurization, the samples were stirred with a mixer at a maximum speed of 1500 rpm (5 minutes) for proper aeration. The foam samples were poured into a plate in a thin layer with thicknesses of 1, 3 and 5 mm and then dried in a dryer at temperatures of 45, 60 and 75 ° C until a constant moisture was reached. The process treatments were performed in a completely randomized central composite design (CCD) (5 replications at the center point) for 2 variables at three levels. The effective diffusion coefficient was calculated based on the second Fick's law of diffusion. Then, using Arrhenius equation, which shows the relationship between temperature and effective diffusion coefficient, activation energy was also calculated. After the drying stage, in order to investigate the changes in moisture during the drying, by determining MR, we have used some experimental models that were previously used for drying agricultural products, to fit the experimental data using the statistical software MATLAB 2016. Results and Discussion: The results showed that increasing the temperature from 45 to 75° C reduced the drying time of the samples by almost 50%. Reducing the thickness from 3 to 1 mm led to an 80% reduction in drying time of the samples. The overall effective diffusion coefficient of the tested samples varied between 7.09×10-10 and 8.11× 10-9 m2/s. The increase in the temperature led to an increase in the effective diffusion coefficient of the samples. The activation energy of the samples varied between 25.59 and 38.22 kJ /mol, and comparison of the means showed that the activation energy of the samples was also increased by increasing the foam thickness. Totally, 17 models were evaluated to investigate the drying kinetics of the samlses and in all cases of foam drying , page and Midilli models with R2 values above than 0.99 and the lowest values of RMSE indicate the best fit with the experimental data among the 17 fitted model. Examining the digital images of the samples also showed that at low temperatures, the structure of the dried foams was smooth and it became more uneven and porous as a result of increasing the temperature. Also, the trend of changes in the parameters of the gray level co-occurrence matrix (GLCM) (energy, correlation, and homogeneity) of the samples was almost the same with the changes in temperature and thickness so that, the increase in the drying temperature and a decrease in the thickness of the samples led to a decrease in these parameters. Increasing the foam thickness at high temperatures led to a decrease in the browning index and at low temperatures, led to an increase in the browning index of the samples.
Food Engineering
Aliakbar Gholamhosseinpour; Mostafa Mazaheri Tehrani; Seyed Mohammad Ali Razavi
Abstract
UF- Feta cheese is mostly produced from bovine milk and is usually consumed fresh or only after a short period of ripening (60 days). In this research, the influence of commercial starter cultures (SafeIT 2, FRC- 65 and R- 704) and ripening time (0- 60 days) on chemical (total solids, fat, protein, ash, ...
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UF- Feta cheese is mostly produced from bovine milk and is usually consumed fresh or only after a short period of ripening (60 days). In this research, the influence of commercial starter cultures (SafeIT 2, FRC- 65 and R- 704) and ripening time (0- 60 days) on chemical (total solids, fat, protein, ash, salt, acidity, pH), biochemical (pH 4.6, TCA, PTA-soluble nitrogen, acid degree value) and sensory (color and appearance, aroma, texture, flavor and total acceptance) characteristics of UF- Feta cheese analogues was investigated. According to our results, the starter culture types were known to have a significant effect (P≤ 0.05) on pH, %salt, %protein, and pH 4.6- soluble nitrogen of cheeses, whereas the other chemical properties were not affected by them. Ripening time only significantly (P≤ 0.05) influenced %acidity, pH, %salt, acid degree value (meq acid 100 g-1 fat), %protein and %proteolysis products of samples. Also, the starter culture and ripening time did not affect the sensory properties significantly, excluding color and appearance, however, the produced cheeses from SafeIT 2 had higher sensory scores compared with the others containing FRC- 65 and R- 704 cultures.
Food Technology
Zahra Kholoosi; Mostafa Mazaheri Tehrani; Seyed Mohammad Ali Razavi
Abstract
Introduction: Proteins and polysaccharides are natural biopolymers that consider among the most widely used hydrocolloids in the food industry (Gaonkar and McPherson 2006) Which are often used simultaneously to improve functional properties. In electrostatic interaction, positively charged proteins with ...
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Introduction: Proteins and polysaccharides are natural biopolymers that consider among the most widely used hydrocolloids in the food industry (Gaonkar and McPherson 2006) Which are often used simultaneously to improve functional properties. In electrostatic interaction, positively charged proteins with polysaccharides containing negative groups below the protein isoelectric point (PI) (LEE, MORR, and HA 1992), Leads to the formation of macromolecular particles by creating molecular aggregates rich in biopolymers suspended in the aqueous phase, called complex coacervate, which cause the coagulation and spontaneous separation of the phase. The ratio of protein-polysaccharide biopolymers and the pH of the mixture are important factors influencing the adsorption and compatibility of protein- polysaccharides as well as the characteristics of their aggregates (Shu et al. 1996). For this purpose, the optical density (turbidity) of protein-polysaccharide mixtures and the yield of dried sediments in this study as a basis for optimizing the complex coacervate process as in previous studies (Wang, Adhikari, and Barrow 2014; Huang et al. 2012) were used. In the present study, the optimization of complex coacervate formation conditions of whey protein concentrate-cress seed gum as well as the foaming properties of complex coacervate were studied for the first time. Whey proteins, as amphiphilic macromolecules, can adsorb at the interface (Scheer, Kruppke, and Heib 2001; Tamm et al. 2012; Wierenga and Gruppen, 2010) and form a viscoelastic adsorbent layer (Wilde 2000). Also, whey protein acts as a foaming agent with the ability to be adsorbed at the joint water-oil and water-air interface through hydrophobic interactions or disulfide bridges, and intermolecular bonds (Nicorescu et al. 2008; Nicorescu et al., 2008; Dickinson, 1992; Forschen, 2017). Cress seed gum has rheological, emulsifying, favorable foaming properties and is stable in a wide range of heat, cold, salt, and pH with synergistic effects in the presence of sugars (sucrose, lactose). These properties are important in stabilizing emulsions and foams. The general purpose of this study was to achieve the optimal point of electrostatic interaction of different ratios of whey protein concentrate with cress seed gum in the pH range of 2 to 7 using response surface methodology and to investigate the foaming properties of the coacervate complex at the optimal point in comparison with Pure control protein in the same ratio. Materials and Methods: The raw materials of this study included cress seed, whey protein concentrate with 80% purity (from Milli com., Germany), and hydrochloric acid with 37% purity (from Merck Com.). Different protein-polysaccharide mixtures were prepared to optimize the electrostatic interaction with the ratio of biopolymers (1: 5 to 5: 1 w / w) and pH of interaction (2 to 7). Mixtures, in the ratio determined by the software and the total concentration of biopolymer (0.3%), were prepared, and after 15 minutes of stirring and equilibration with the environment, were adjusted by hydrochloric acid of 0.1, 0.5, and 1 (n) to the desired pH, and stirred for 5 minutes at each pH with a magnetic stirrer at 400 rpm. Optical Density (OD) of protein: polysaccharide mixtures was evaluated by visible-ultraviolet optical spectrophotometry (Unico, Model S-2150, USA). To optimize the electrostatic complex coacervation process, the coacervation yield was determined. The result of the interaction of whey protein concentrate and cress seed gum as a function of pH and protein to gum ratio was investigated by measuring the sediment phase. For investigation of the foaming properties, the dispersions were homogenized using a homogenizer (Ultra Turrax T25 Digital) for 5 minutes at a speed of 10,000 rpm. After recording the sample volume in the dimension and before homogeneity, the foaming capacity was calculated. To determine the stability of the foam, changes in the volume of the samples were recorded and calculated after 30 minutes of foaming. In this study, the effect of two independent variables including the ratio of biopolymers in the range of 0.2-5 (w/w) and the pH within the range of 2 to 7 were analyzed using Design-Expert software based on two responses including turbidity and yield by the combined central design (CCD) with 5 replications to optimize the electrostatic interaction of whey protein concentrate with cress seed gum.Results and Discussion: The results obtained by using response surface methodology showed that the independent variables (ratio of whey protein to cress seed gum and pH) in this study affected the studied responses (turbidity and sediment percentage), although pH had the greatest effect. Optimal conditions for the formation of the maximum protein-polysaccharide coacervate complex were obtained in the ratio of protein to polysaccharide 5: 1 (w / w) and pH 4.24. The results of foaming properties at the optimal point showed an increase in foaming capacity and foam stability compared to pure protein (control sample). This increase in foaming properties is probably due to the presence of cress seed gum and its effect on the formation of a thick viscoelastic film, improved protein adsorption at the interface, and increased bulk phase viscosity.
Somayeh Niknia; Seyed Mohammad Ali Razavi; Mehdi Varidi
Abstract
In this study, sodium caseinate was hydrolyzed with Withania coagulans extract and the response surface methodology (RSM) was applied to optimize the effects of hydrolysis conditions including hydrolysis temperature, enzyme concentration and hydrolysis time on the degree of hydrolysis, solubility, and ...
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In this study, sodium caseinate was hydrolyzed with Withania coagulans extract and the response surface methodology (RSM) was applied to optimize the effects of hydrolysis conditions including hydrolysis temperature, enzyme concentration and hydrolysis time on the degree of hydrolysis, solubility, and foaming properties. The analysis of variance in RSM showed that the linear effects of enzyme level and hydrolysis time and quadratic effects of hydrolysis temperature were important factors affecting the hydrolysis process remarkably (P<0.0001). Results were indicative of the fact that the increase in responses was obtained by an increase in hydrolysis time and enzyme level. The generated quadratic model showed that the optimum conditions for maximizing the responses were when enzyme concentration of 1.75 (%w/w), temperature of 55.43°C and hydrolysis time of 490 min.
Makan Delfanian; Mohammad Hossein Hadad Khodaparast; Seyed Mohammad Ali Razavi; Reza Esmaeilzadeh kenari
Abstract
The central composite rotatable design by response surface methodology was applied for optimization of ultrasonic extraction conditions of Bene hull (Pistacia atlantica subsp. Mutica) polyphenols. The sonication time, temperature and ethanol-water ratio were independent parameters studied for the extraction ...
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The central composite rotatable design by response surface methodology was applied for optimization of ultrasonic extraction conditions of Bene hull (Pistacia atlantica subsp. Mutica) polyphenols. The sonication time, temperature and ethanol-water ratio were independent parameters studied for the extraction optimization. Total polyphenols and antioxidant potentials of extracts in terms of ferric reducing antioxidant potential (FRAP), DPPH scavenging activity and oxidative stability index (OSI) were determined. The obtained data were well consistent with the polynomial equations by significant variation in linear, quadratic and interaction impacts of the process factors. The optimized extraction conditions were sonication time, 26.91 min, temperature, 50.42 °C and ethanol concentration, 55.84%. The total polyphenols, DPPH, FRAP an OSI of optimal extract were 304.47 mg GAE/g, 72.47%, 54.04 mmol/100g and 8.55 h, respectively. High performance liquid chromatography (HPLC) analysis of optimal extract detected presence of epicatechin, chlorogenic, sinapic, caffeic and gallic acids.
Aliakbar Gholamhosseinpour; Mostafa Mazaheri Tehrani; Seyed Mohammad Ali Razavi
Abstract
In this study, a mixture of milk protein concentrate, whey protein concentrate, skim milk powder, soymilk, margarine, butter and water was used for production of recombined UF-Feta cheese analogue. Variables were milk protein concentrate (8%, 9%, 10%), whey protein concentrate (0%, 1.5%, 3%), soymilk ...
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In this study, a mixture of milk protein concentrate, whey protein concentrate, skim milk powder, soymilk, margarine, butter and water was used for production of recombined UF-Feta cheese analogue. Variables were milk protein concentrate (8%, 9%, 10%), whey protein concentrate (0%, 1.5%, 3%), soymilk (5%, 10%, 15%) and margarine (0%, 5%, 10%). Textural properties of Samples were analyzed 3 days post-manufacture. The central composite design was employed and the results were modeled and analyzed using response surface methodology. Coefficients of determination, R2, of fitted regression models for different variables were varied in the range of 89.59-97.80 and the lack-of-fit was not significant for all responses at 95%. Hence, the models for all the response variables were highly adequate. The results showed that the optimum processing conditions for producing cheese with suitable hardness and cohesiveness and lowest adhesiveness were: 9.13% milk protein concentrate, 3% whey protein concentrate, 15% soymilk and 7.65% margarine.
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.
Sajad Ghaderi; Mostafa Mazaheri Tehrani; Seyed Mohammad Ali Razavi
Abstract
Introduction: In the food industry, it is preferred to alter the formulations rather than modifying the legislations, so as to reduce the risk of facing consumer health. For instance, animal fats and oils could be replaced with vegetable oils to manufacture products with low cholesterol and saturated ...
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Introduction: In the food industry, it is preferred to alter the formulations rather than modifying the legislations, so as to reduce the risk of facing consumer health. For instance, animal fats and oils could be replaced with vegetable oils to manufacture products with low cholesterol and saturated fatty acids. Application of vegetable-based products like vegetable-based milks as the sources which provide vegetable proteins and lipids in ice cream not only incorporates the nutritional values and health-promoting effects of vegetable compounds into ice cream, but also leads to the production of a novel product with specific properties such as lactose-free products, which could be attractive and useful for consumers. Soymilk is avegetable-based milk with a suitable lipid and protein content. The main objective of this study was to investigate the aging time on physicochemical, rheological and textural changes of vegetable-based ice cream of soy and sesame, compared with the typical ice cream.
Materials and methods: Optimization of the vegetable-based ice cream was carried out by the textural parameters related to each other using RSM and the D-optimal design. The best soymilk: sesame milk ratio was found to be 55:45. Subsequently, all parameters including overrun, melting resistance, rheological properties and the textural variables during the aging times of 0, 2, 4, 6, 8 and 24 hours were examined for the evaluation of aging. The textural variables were measured in this method that after the 50-g samples of vegetable-based and typical ice creams were kept at ambient temperature for 5 min. A texture analyzer (Brookfield CT3-10kg,US) was employed to analyze their texture. To that end, a probe of 6 mm in diameter was selected to penetrate 15 mm into the sample at a rate of 2 mm/s. Rheological analysis was measured in this method that after 24 h of aging, the apparent viscosity of the ice cream mix samples was determined using a rotational viscometer (Bohlin Model Visco 88, Bohlin instruments, UK) equipped with a thermal circulator (Julabo, Model F12-MC, Julabo Labortechnik, Germany) with the shear rat of 51.8 1/s at 5±0.5°C.
Results and discussion: Investigation of the rheological and textural behavior of the samples showed that aging was significantly (p
Younes Zahedi; Hadi Mahdavian Mehr; Seyed Mohammad Ali Razavi
Abstract
Identification of a new source of hydrocolloids is of interest due to their important effects on the textural attributes of food products. The objective of this study was to investigate the extraction conditions of Plantago major L. seed mucilage using a central composite rotatable design of response ...
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Identification of a new source of hydrocolloids is of interest due to their important effects on the textural attributes of food products. The objective of this study was to investigate the extraction conditions of Plantago major L. seed mucilage using a central composite rotatable design of response surface methodology. Temperature (25–85°C), pH (3–9) and water to seed ratio (50:1-50:4) were the factors investigated. Results showed that temperature was major factor in the extraction yield, whereas water to seed ratio and pH had minor effects on the yield. The maximum and minimum yields were 18.95% (conditions: temperature= 85 °C, water to seed ratio = 31.3 and pH= 6) and 6.35% (conditions: temperature = 25 °C, water to seed ratio= 31.3 and pH= 6), respectively. The optimal conditions were obtained at the temperature of 60 °C, water to seed ratio of 48.9 and pH of 3 in which predicted value for the extraction yield was 11.84%. The rheological properties of the mucilage, extracted at the optimal conditions, were investigated as a function of concentration at three levels of 3, 4 and 5% w/v, and shear rate ranged from 14 to 300s-1. Mucilage dispersions showed non-Newtonian shear-thinning behavior at all studied concentrations. The Power law model well described the rheological behavior of the mucilage solutions with high determination coefficients (R2>0.99). The flow behavior index (n) varied in the range of 0.30 to 0.36. The consistency coefficient (k) was in the range 6.13-17.81 Pa.sn. Overall, Plantago major L. seed mucilage could be attended as a new beneficial source for use as a food thickening agent.
Morteza Kashaninejad; Seyed Mohammad Ali Razavi; Mostafa Mazaheri Tehrani; Mahdi Kashani-Nejad
Abstract
In this study, the compositional, rheological, thermal and textural properties of omega-3 cow's butter (OCB), conventional cow's butter (CCB) and sheep’s butter (SB) were evaluated. The fatty acid composition of SB showed a relatively high content of the short chain fatty acids (SCFA) compared ...
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In this study, the compositional, rheological, thermal and textural properties of omega-3 cow's butter (OCB), conventional cow's butter (CCB) and sheep’s butter (SB) were evaluated. The fatty acid composition of SB showed a relatively high content of the short chain fatty acids (SCFA) compared with that of cow's butters and higher levels of CLA and omega 3 fatty acids in OCB were observed. Regarding to the firmness, at refrigeration temperature (5 °C), SB was much firmer than CCB and OCB, but as a function of temperature, it was softened much quicker. However, at temperatures around 18°C it was already softer than the latter. From dynamic rheological data, it was found that butter samples display solid-like viscoelastic behavior since the values of G׳ were much higher than those of G″ with a low dependence on frequency. The values of G׳ and G″ also decreased in butters containing more percentage of unsaturated fatty acids. The temperature effect on the viscosity followed an Arrhenius-type relationship and OCB had a less activation energy than others, indicating that the butter containing high SCFA was more sensitive to temperature changes. Through differential scanning calorimetery, the thermal behavior of the butters during melting was analyzed.
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 (
Sima Shamsaei; Seyed Mohammad Ali Razavi; Bahareh Emadzadeh; Esmaeil Atayesalehi
Abstract
Introduction: An emulsion is made of dispersed particles through the continuous phase, while not dissolving happens between two phases. Mayonnaise is oil-in- water emulsion (James and Dakin, 1962), as one of the most sauces used in the world. It has a mild odor and taste, creamy to pale yellow color ...
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Introduction: An emulsion is made of dispersed particles through the continuous phase, while not dissolving happens between two phases. Mayonnaise is oil-in- water emulsion (James and Dakin, 1962), as one of the most sauces used in the world. It has a mild odor and taste, creamy to pale yellow color and a pH in the range of 3.6- 4.0, which does not exceed 4.1 (Iranian National Standard, No 2454). Emulsion products are naturally instable. Different factors such as temperature, particles size, stirring, mechanical movements, constituents’ concentration, presence or absence of stabilizers and thickeners may affect the emulsion stability (David, 1999). Ocimum basilicum L., known as basil (or ‘‘Reyhan” in Iran), is a common herb plant grown in Iran. Soaking in water, basil seeds become gelatinous. The high mucilage content of basil seeds can make it a novel source of edible gum (Razavi et al., 2008). The objective of this paper was to investigate the effect of basil seed gum as well as xanthan as fat replacers on some physical and rheological properties of low fat mayonnaise. Materials and methods: Emulsion stability determination: Mayonnaise samples were centrifuged at 5000 rpm for 30 minutes. Emulsion stability (ES) was then determined using the following relation (Worrasinchai S et al., 2006): Stability index= (Total volume/ Volume of emulsion remaining)100. Particle size measurement: Particle size distribution of low-fat mayonnaise samples was determined using laser light diffraction technique (Fritsch Analysette 22, Germany). Rheological measurements: A rotational viscometer (Visco 88, Malvern, UK) equipped with a thermal circulator was used to measure the steady shear rheological properties of samples at the shear range of 14-300 s-1 and constant temperature of 25 oC. Power law, Bingham, Casson, and Herschel-Bulkley models were fitted on the experimental data and the rheological parameters of these models were determined using Slidewrite plus-bar Graph software (1983, Advanced Graphics Software, Inc, USA). Image processing: A scanner was used to capture the samples’ image and the scanner resolution was set to 300 dpi. 7g sample was placed onto a plate and then 152×210 Pixel parts was cut from the obtained image. All images were stored in JPEG format for further analysis. The Clemex image processing software (Clemex Vision Professional, PE4, Canada) was used to determine the color parameters (L*, a* and b*). Results and Discussion: Steady shear flow behavior: The results showed that all samples are classified rheologically as non-Newtonian shear thinning fluids. According to R2 values, Power law was considered as the best rheological model to describe the flow behavior of samples. The maximum and the minimum consistency coefficients of Power law model were observed for the formulation containing 0.75% xanthan gum and 0.45% basil seed gum, respectively. In this study, the apparent viscosity of mayonnaise (in shear rate 42 s-1) raised with increasing gum concentration that this increase in samples 4 and 5 were not significant (P>0.01). The highest apparent viscosity was observed in sample 3 that was prepared with a concentration 0.75% of xanthan gum, while the lowest viscosity was related to sample 4 that was contained of 0.45% basil seed gum. With increasing gum concentration, Bingham viscosity of the samples increased, but this increase in the samples (1, 7, 8) and (2, 6, 9) was not significant (P> 0.01). Yield stress values of Herschel-Bulkley (τH), Bingham (τB) and Casson (τC) models raised with the increasing of gum concentration. Highest yield stress value was related to mayonnaise containing 0.45% xanthan gum and the lowest yield stress value related to mayonnaise prepared with 0.45% basil seed gum. Particle size distribution: Particle size distribution of mayonnaise at concentration of 0.6 % xanthan gum, basil seed gum and mixture of xanthan- basil seed gum had mono-modal particle size distribution. Emulsion stability: Among samples, formulations of 1, 2, 3, 8, and 9 were quite stable and there was no instability (two-phase state). Higher stability in emulsions containing xanthan gum was probably due to higher viscosity of this gum compared to basil seed gum. Color: The best color was observed in sample 6. In this study, with increasing concentration of gum in three samples (1, 2, 3), the amount of L* decreased, it means that the brightness of the product was reduced while in samples containing a mixture of gums (xanthan- basil seed gum), increasing the gum concentration resulted in an increase in L* parameter.
Narges Samanian; Seyed Mohammad Ali Razavi
Abstract
Sensory evaluation of food materials is an important factor to choose and even produce new formulations. Being time consuming, results in being difficult to interpret and the necessity to educate specialists make these methods kind of impractical. In this study, we have made an effort to introduce physical ...
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Sensory evaluation of food materials is an important factor to choose and even produce new formulations. Being time consuming, results in being difficult to interpret and the necessity to educate specialists make these methods kind of impractical. In this study, we have made an effort to introduce physical properties as a substitute for sensory evaluations in a semi solid food such as chocolate pudding. Higher reliability, reproducibility and higher pace are among some of the advantages of instrumental measurements. Thus, if sensory evaluation can be predicted based on physical properties solely, besides increasing the inspection pace, they would be available to be used online. The obtained results can also be used in designing new products for special consumers such as the dysphasia patients. The results showed that parameters such as shear viscosity, plastic viscosity, yield stress, extensional viscosity, apparent modulus and adhesive force can be used to design and produce new materials; they make sense beside each other though. In this way, the products which have been designed for the patients with swallowing difficulties should have suitable texture in mouth and also good swallow ease.
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.
Fatemeh Heidari Dalfard; Masoud Taghizadeh; Seyed Mohammad Ali Razavi
Abstract
Introduction: Malt extract is one of the malt products obtainedfrom concentrations of water soluble extract of grains such as barley and is a proper alternative to white sugar. It has a high diastasis properties andcontainshigh amount of different vitamins specially the group of vitamin B as well as ...
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Introduction: Malt extract is one of the malt products obtainedfrom concentrations of water soluble extract of grains such as barley and is a proper alternative to white sugar. It has a high diastasis properties andcontainshigh amount of different vitamins specially the group of vitamin B as well as high amount of fermentable sugars. Therefore, malt extract has high nutritional value and is recommended by nutritionist for children and people who are having growth problems. In addition, it has a high potential to be used as sweetening agent in different food products such as cookies, biscuits, ice cream, chocolates etc. Knowledge on the thermo-physical properties of malt extract such as density, specific heat, thermal conductivity as well as thermal diffusivity is highly necessary for the designing of processing equipments, formulation of derived products, heating and chilling processes, and other unit operations such as pasteurization, concentration, dehydration as well as final safety and quality of formulated products. Since, no research work has been reported on thermo-physical properties of malt extract, the aim of this study was to determine different thermal properties of malt extract as well as investigation of the effect of temperature and soluble solid contents (SSC) of the studied properties.Materials and methods: Barley malt was purchased from local market. 150 gr of malt was first grounded and added to 600ml water at 46°C and stored for 30 minutes. Then, its temperature was increased using a heater to reach 70°C. 300 ml water was then added to the mixture and stored at 70°C for 60 minutes. Then, the mixture was cooled at room temperature and filtered to gain a sweet solution. The obtained solution was concentrated to 60, 70 and 80 degree of Brix for further experiments.Specific heat and thermal conductivity of samples were determined using a differential scanning calorimeter (DSC). DSC is a powerful tool which is able to spontaneously measure different thermal propertiesof samples such as specific heat, thermal conductivity, glass transition temperature, melting point, crystallization point etc. as a function of time and temperature at the desired temperature levels. Density of samples was also measured using a 50ccvolumetric pycnometer. 25 grams of samples were first solved in hot water and then were placed in an isothermal bath to measure the density. Thermal diffusivity of samples was determined using the following equation:∝=k/〖pC〗_p Results and discussion: The obtained results on specific heat measurement showed that decreasing SSC from 80 to 60% and increasing the temperature from 25 to 90°C would increase cp from 2.074 to 3.063 kJ/kg°C in a linear manner. Following equations were obtained to predict specific heat as a function of temperature:C_p=2.756+0.004T R^2=0.893 ، X_s=60C_p =2.245 +0.005T 〖 R〗^2=0.868، X_s=70C_p=2.066 +0.001T R^2=0.75، X_s =80Thermal conductivity measurements were also showed that decreasing SSC from 80 to 60% and increasing temperature from 25 to 90°C would increase the K values from 0.1196 to 0.347 W/m°C in a linear manner. Increasing temperature would increase molecular movements and therefore it elevates the heat transfer velocity and K increases. Following equations were obtained to predict thermal conductivity as a function of temperature:K=0.152 +0.003T R^2=0.761، X_s=60K =0.097+0.002T R^2=0.851، X_s=70K=0.114+0.001T R^2=0.706،X_s =80In order to develop a model to predict thermal conductivity of malt extract based on its soluble solid content and temperature, multiple regressions was used. The obtained model was a two-parameter linear model with R2 of 0.858. The results showed that 1% increase in soluble solid content percentage would cause an increase of 6% in K, while 1% increase in temperature would cause only 49% increase in thermal conductivity value.Density measurements were also showed that increasing density from 60 to 80% and temperature from 25 to 90°C would increase density of malt extract. Following equations were obtained to predict density as a function of temperature:P=1328.699-0.402T R^2=0.999، X_s=60 P=1375.451-0.290T R^2=0.999، X_s=70 P=1426.201-0.286T R^2=0.998،X_s =80Thermal diffusivity of samples was also determined using indirect method for soluble solid content of 60 to 80 and in the temperature range of 25 to 90°C. It was found that thermal diffusivity would increase linearly by decreasing soluble solid content and increasing temperature. Following equations were obtained to predict thermal diffusivity as a function of temperature:∝=5.176〖×10〗^(-8)+0.049×〖10〗^(-8) T R^2=0.783، X_s=60∝=2.993×〖10〗^(-8)+0.050×〖10〗^(-8) T R^2=0.929، X_s=70∝=3.125×〖10〗^(-8)+0.036×〖10〗^(-8) T R^2=0.94،X_s =80The results of the present work were in agreement with the results reported by other researchers confirming that both SSC and temperature have significant effect on thermo-physical properties of malt extract.
Milad Fathi; Seyed Mohammad Ali Razavi
Abstract
In this study, potential application of image texture analysis as a non-destructive method for automation and prediction of mechanical properties of carrot chips was investigated. Samples were fried at different processing conditions and moisture content, colour parameters (i.e. L*, a*, b* and E) ...
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In this study, potential application of image texture analysis as a non-destructive method for automation and prediction of mechanical properties of carrot chips was investigated. Samples were fried at different processing conditions and moisture content, colour parameters (i.e. L*, a*, b* and E) and mechanical properties (i.e. hardness and apparent modulus) were determined. Hardness and apparent modulus increased by increasing frying temperature and time. Four image texture features namely contrast, correlation, energy and homogeneity were calculated using gray level co-occurrence matrix. The results showed contrast and energy of gray level images were well correlated with hardness of fried samples in compression and puncture tests. Correlation coefficients of 0.97 and 0.98 between four image texture features and hardness were obtained in compression and puncture tests, respectively. Results indicate that image texture analysis can be successfully applied as a non-destructive method for estimation of mechanical properties of carrot.
Behzad Nasehi; Seyed Mohammad Ali Razavi; Seyed Ali Mortazavi; Mostafa Mazaheri Tehrani
Abstract
The influence of 0-27 g/100g of full-fat soy flour (FFSF), 31-35g/100g of water content and extrusion conditions on the textural characteristics of spaghetti were evaluated. Process was performed with screw speed of 10-40 rpm and water circulating temperature of 35-70°C. This enrichment resulted ...
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The influence of 0-27 g/100g of full-fat soy flour (FFSF), 31-35g/100g of water content and extrusion conditions on the textural characteristics of spaghetti were evaluated. Process was performed with screw speed of 10-40 rpm and water circulating temperature of 35-70°C. This enrichment resulted in significant differences in mechanical strength and cutting parameter. Based on the mixture surface and contour plots, it was found that the optimum textural characteristic of spaghetti could be obtained by addition of 20.6 g/100g FFSF and 35.0 g/100g water and process in screw speed of 40 rpm and temperature of 35oC.
Seyed Mohammad Ali Razavi; Mostafa Mazaheri Tehrani; Bahareh Emadzadeh
Abstract
Introduction: Recently, consumers have directed their interest towards low fat products as they associated them with a reduced risk of well-known health problems such as obesity and coronary heart diseases. Fat is a multifunctional ingredient in ice cream system. Thus, in attempts to provide desirable ...
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Introduction: Recently, consumers have directed their interest towards low fat products as they associated them with a reduced risk of well-known health problems such as obesity and coronary heart diseases. Fat is a multifunctional ingredient in ice cream system. Thus, in attempts to provide desirable flavor and physical characteristics of full fat ice cream, manufactures looking for fat replacers (Drake et al. 1999). Hydrocolloids have functionalities such as thickening, gelling, fat replacing, which allow them to use in different industries (Roller and Jones, 1996; Williams and Phillips, 2000). Guar gum is used as a stabilizer in ice cream and provides smoothness in texture, retards ice crystal growth, and increases freeze-thaw stability (Wielinga, 2000). The rheological properties and potential of basil seed gum (Rayhan) as a novel stabilizer for structure formation and reducer for ice recrystallization in regular ice cream have been recently investigated (Hosseini-Parvar, 1388; Bahram-Parvar, 1391). In this research, the physicalproperties of light (5% fat) and low fat (2.5% fat) ice creams as a result of replacement of milk fat by guar gum (as a commercial hydrocolloid), basil seed gum (as a novel hydrocolloid) and their blend (50:50) at different concentrations were investigated and compared to those of control sample (10% fat). Materials and methods:The ice cream formulations were prepared based on the following composition: 2.5% (L), or 5% (R) or 10% (B) milk fat, 11% MSNF, 15% sugar, 0.1% vanilla, 0.15% emulsifierand 0.35%, 0.45%, 0.50% or 0.55% selected gums (guar gum, basil seed gum or blend (50:50) of them). Liquid materials including milk and cream were mixed together and warmed up to 50˚C. After that, the pre-weighed and mixed dry ingredients were dispersed into them, under agitation. The mixes were pasteurized at 80˚C for 25 s, homogenized at 23000 rpm for 2 min, cooled rapidly to 5˚C and then aged at constant temperature overnight (12 h) at 5˚C. The freezing was carried out in a batch soft ice cream maker. Apparent viscosity of ice cream mixes were evaluated using a rotational viscometer at 5˚C and 51.8 s-1. Before melting rate determination, samples were tempered at –18°C overnight, Ice cream samples (30 g) were put on a wire screen mesh and allowed to melt at ambient temperature. Melting rates were measured from the slop of linear portion of drained mass vs.time graphs. The pH values for mix samples were measured with a pH meter. After the mix was frozen in a batch freezer, Draw temperature of ice creams was obtained using a digital thermometer.Mix and ice cream samples (3 g) were diluted 1: 500 in two steps with deionized water and absorbance was measured by a spectrophotometer at 540 nm. Turbidity (%) was calculated as (absorbance in mix - absorbance in ice cream)/absorbance in mix 100%. A known volume of ice cream and mix were weight and overrun was determined as (weight of the mix - weight of the ice cream)/ weight of the mix 100%. Results & discussion: Reducing fat in any food formulation will cause a decrease in viscosity (Cody et al., 2007). Fat reduction decreased apparent viscosity (P0.05), ranging from 6.31 to 6.34. Draw temperature as a measure of freezing point of ice cream is dependent on the type and concentration of the soluble constituents and varies with the composition. Addition of some ingredients such as sweeteners, lactose and salts decrease the freezing point. Fat is immiscible with the aqueous phase and carbohydrate polymers are very large molecules, depression of the freezing point is caused indirectly by using of these materials, as a result of decreasing the water content (Marshall and Arbuckle, 1996). In this study, a reduction of fat content of full fat ice cream resulted in higher draw temperature. However, there was not a specific trend in the temperature values of samples with same fat content and different fat replacer levels. There was no significant difference between turbidity of samples with same kind of gum. Similar results were obtained by Schmidt et al. (1993), which related to sufficient amount of milk fat (2.1 and 4.8 %), milk proteins and emulsifiers in ice cream formulations. Conclution: Decreasing the fat content generally caused an increase in the value of overrun. But, very high viscosity of mix may prevent vigorous agitation and air incorporation that seems the reason of why increasing fat replacer concentration resulted in overrun reduction
Reza Farhoosh; Seyed Mohammad Ali Razavi
Abstract
Introduction: In this research, the effects of coating by Basil seed gum (BSG) (0.5 and 1%, w/w) compared to that by common gums such as xanthan and methylcellulose (MC) on the oil uptake, moisture removal, color, and texture in deep-fat fried potato strips were investigated. Today, numerous processed ...
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Introduction: In this research, the effects of coating by Basil seed gum (BSG) (0.5 and 1%, w/w) compared to that by common gums such as xanthan and methylcellulose (MC) on the oil uptake, moisture removal, color, and texture in deep-fat fried potato strips were investigated. Today, numerous processed foods are prepared by deep-fat frying all over the world, since in addition to cooking, frying provides unique flavours and textures that improve the overall palatability. In fact, the desirable characteristics of most fried foods are derived from the formation of a composite structure: a crispy, porous, and oily outer layer or crust, and a moist cooked interior or core, whose microstructures have been formed during the process. In addition, the high oil content is costly to the processor and results in an oily and tasteless product . Also, Excess consumption of fat is considered as the key dietary contributor to coronary heart disease and perhaps cancer of the breast, colon, and prostate . The concern to develop healthier products that contain less fat, absorbed during industrial pre-frying and frying processes, is one of the prevailing factors in the latest research trends in this area, prompting studies of ways to lower the oil content of fried food. An edible coating (EC) is a thin layer of edible material formed as a coating on a food product, the EC are applied in liquid form on the food, usually by immersing the product in a solution generating substance formed by the structural matrix (carbohydrate, protein, lipid or multicomponent mixture), When frying coated food pieces, the film hinders absorption of the oil, improving its nutritional qualities and reducing the fat content and calories of the final product. Basil (Ocimum basilicum L.) is one of the domestic plants in Iran that is produced and used as a pharmaceutical plant in high quantity. When the seed of the O. basilicum L. is soaked in water, the outer pericarp swells into a gelatinous mass due to the presence of a polysaccharide layer. the present study aimed to expands the scope of previous works and focus on the effect of basil seed gum (as a novel hydrocolloid) on oil uptake and product quality (texture and color) during deep-fat frying of potato strips. In the first part of the study, investigate and compare the effects of endemic hydrocolloid, basil seed gum with xanthan(xan) gum and methyl cellulose(MC) for use as commercial hydrocolloids for coating edible.Materials and methods: Aqueous suspensions of 0.5 and 1% (w/w) were provided and used for coating formulations. blanched samples of potato were dipped in the coating suspensions for 2 min and rinsed to removal excessive gum then dipped samples dryed in oven 150 ºC for 3 minute. Frying was carried out in a controlled temperature deep fat fryer (Moulinex, Toucan Automatic). For each stage, nine samples were fried in 3 L of blended oil of canola: palm olein: olive oil (75:15:10, respectively). The uncoated and coated potato strips were fried 6 min at three temperatures (160 °C, 180 °C, and 190 °C).Rheological characterization of gum dispersions were measured using a rotational viscometer (Bohlin Model Visco 88; Bohlin Instruments, Worcestershire, UK) equipped with a heating circulator (Julabo, Model F12-MC; Julabo Labortechnik, GmbH D-77960, Seelbach, Germany). According to the viscosity of dispersions, appropriate measuring spindles (C25 and C30) were selected during viscosity measurements. Moisture and fat contents were determined according to the method of AOAC (1996). The color Color of crust models was measured using an image processing technique . Crispiness of potato strips was evaluated in term of hardness by a penetration test performed in a Texture Analyser (QTS25 CNS Farnell, UK). The Conical prob diameter and the cross-head speed was 3 mm and 60 mm/min, respectively. Statistical analysis was performed using factor completely randomized design in Mstat version 1.42 software. The level of statistical significance was determined at 95%. If significant difference was found, the treatments were compared by using Duncan’s multiple comparison test.Results and discussion: Solutions of BSG and XAN exhibited interesting pseudoplastic behavior with the viscosity decreasing with increasing shear rate( from 10 – 1001/s). No Newtonian region was detected at low shear rates suggesting that the zero-shear viscosity could exist at very low shear rates. The presence of high yield stress in BSG solution was comparable to xanthan gum. The apparent viscosity of Xanthan was markedly higher but methylcellose at both concentrations had Newtonian behaivear during shear rate. with regard to the controlling role of water in oil uptake, the oil content in all coated samples was less than that of the control (uncoated potato strips). The potato strips treated with BSG 1% and 0.5% had the lowest oil uptake (0.14 and 0.16 % d.b., respectively). The highest amounts of the oil uptake were found for the control and potatoes coated with methylcellulose 0.5%, respectively. The potatoes treated with the hydrocolloids experimented showed that the moisture content in all coated samples was higher than that of the control. The samples treated with the BSG 1% and 0.5% had the highest amounts of the reduced moisture loss. Also, the samples treated with xanthan and BSG 1% had the highest total color change (∆E) and hardness. Conclusion: Results of this study showed that basil seed gum (as a novel hydrocolloid) can be suggested for coating and usage in industrial French fries production.
Mahdi Kashani-Nejad; Alireza Sadeghi Mahoonak; Seyed Mohammad Ali Razavi
Abstract
Introduction: Honey is a natural food product having a high nutritional and medicinal value. It is a sweet, viscous substance produced by the honeybees from the nectar of plants. Sensory and physical properties and chemical composition of honey depend on the botanical origin and the regional and climatic ...
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Introduction: Honey is a natural food product having a high nutritional and medicinal value. It is a sweet, viscous substance produced by the honeybees from the nectar of plants. Sensory and physical properties and chemical composition of honey depend on the botanical origin and the regional and climatic conditions of the area in which it is produced.The knowledge of honey rheology is very important for its processing, quality control, process control, and selection of proper process equipment, storage, handling, and transportation and plays an important role in fluid heat transfer. Rheological properties of honeys depend on many factors including composition, temperature, and amount and size of crystals. Different kinds of honeys with various floral origins (such as Rosa, Thyme, Astragalus, Trifolium, sunflower, Medicago, alfalfa and etc.) are produced in different regions of Iran. In this study, some physicochemical and rheological properties of four Iranian honeys from Golestanprovienceobtained from various floral sources, two poly floral (Mountain, Forest) and two mono floral (Sunflower, Ivy) were compared with adulteratedand sugar honeys.Materials and methods: Sixhoney samples were collected directly from beekeepers in Golestan Province,two monofloral (Sunflower, Ivy) and two polyfloral(Mountain, Forest), adulterated and sugar honeys. Some physico–chemical characteristics of samples including water content, Hydroxymethylfurfural content (HMF), diastase activity, pH, ash, free acidity, reducing sugars (fructose and glucose), sucrose contentand electrical conductivity were determined by the harmonized methods of the International Honey Commission. The rheological measurements were also carried out on the honey samples at eighteen rotations, ranging from 5-200 rpm and at five temperatures, ranging from 10-30ºC, using a viscosimeter Brookfield.Results and discussion: The samples were found to be different from each other in terms of physico-chemical properties. In the natural honey samples, this discrepancy can be due to diversity in original plant and harvesting season. All the values obtained in the natural honey samples were agreement with those reported by Codex Alimentarius and ISIRI. The values of sucrose and fructose/glucose ratio the sugar honey sample and sucrose, fructose/glucose ratio, pH, HMF, diastase activity of adulterated honey were not in the range suggested by Codex Alimentarius and ISIRI. Conclusion: Rheological characteristics of honeys were evaluated at different temperatures (10, 15, 20, 25 and 30ºC). All the honeys exhibited Newtonian behavior for shear rate in range of 1.045- 41.8 s-1.The temperature dependence of viscosity was described using the Arrhenius and the Vogel–Taumman–Fulcher (VTF) equations.Two models (Power Law and Exponential models) were also investigated to describe the concentration (ºBrix) dependence of viscosity
