Food Technology
Massoumeh Mehraban Sangatash; Maryam Dadras-Moghadam; Seyed Ali Mortazavi; Hanieh Yarabbi
Abstract
The increasing growth of cardiovascular diseases, high blood pressure, and hardening of the vessel walls as well as obesity in many countries has made low-fat and low sodium pizza cheese one of the subjects of study all over the world. The effects of four important independent variables including inulin ...
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The increasing growth of cardiovascular diseases, high blood pressure, and hardening of the vessel walls as well as obesity in many countries has made low-fat and low sodium pizza cheese one of the subjects of study all over the world. The effects of four important independent variables including inulin (0-0.025 %), pre-gelatinized starch (0-0.5 %), NaCl (0.35-1%), and KCl (0.35-1%) were studied. The fat content of imitation pizza cheese was significantly decreased to 11.91% with the increased levels of inulin and starch substitution (p<0.05). Also, its moisture and pH values were significantly different (p < 0.05). The increased levels of pre-gelatinized starch and inulin reduced hardness (from 5.04 to 3.55) and adhesiveness (from 4368.89% to 1640.54%), however, increased cohesiveness (from 0.365 to 0.43) and springiness (from 0.456 to 0.545). NaCl and KCl increased the hardness of the product. Inulin and starch led to decrease the a* value. The b* value decreases with the increase of inulin and increases with the increase of modified starch. The formulation containing 0.19% inulin, 0.4% pre-gelatinized starch, 0.35% NaCl, and 0.50% KCl was found as the optimal formulation for low-fat imitation cheese. Results of scanning electron microscope (SEM) images revealed that inulin crystals were accumulated in the continuous phase, which this can lead to important changes in the sensory and textural properties. The study concludes that inulin or starch can be used to replace up to 3.6% of fat in the imitation pizza cheese and 0.35% NaCl-0.50% KCl to lower the sodium content of the product.
Messiah Sarfarazi; Mohebbat Mohebbi; Mahdi Saadatmand-Tarzjan; Ali Mirshahi
Abstract
Introduction: Chocolate is a suspension of solid particles, including sugar, cocoa solids and milk powder (depending on the chocolate type) in a continuous fat phase, namely cocoa butter or its substitutes. The solid particles account for approximately 70% of chocolate with the fat constituting about ...
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Introduction: Chocolate is a suspension of solid particles, including sugar, cocoa solids and milk powder (depending on the chocolate type) in a continuous fat phase, namely cocoa butter or its substitutes. The solid particles account for approximately 70% of chocolate with the fat constituting about 30%. Sugar takes up nearly 40–50% of the total solid particles of chocolate, thus influencing its sweetness, particle size distribution, rheological and sensory properties. It is also considered to be a bulking agent and a source of energy which produces 394 kcal/100 g of refined sugar. Therefore, consumers are increasingly becoming concerned with chocolate sugar and calorie content nowadays. This issue can be resolved by replacing sugar with bulk (nutritive) sweeteners and/or dietary fibers. Bubbles are found in many food products, including cakes, chocolates and beverages. Although they do not increase the food nutritional value, they change its textural properties and mouthfeel. Bubbles are normally visible to the naked eye and their mean diameter ranges from 0.05 to 3 mm. X-ray computed tomography is a 3D imaging technique which captures the images of a sample cross-sections. It is used for the non-destructive visualization and characterization of food microstructure. In this method, a series of radiographs of a sample are captured from different angles to be utilized for the 3D reconstruction of the material microstructure. Materials and methods: sugar was replaced with inulin: maltodextrin mixture at ratios of 25:75 (CH2), 50:50 (CH3) and 75:25 (CH4). Carbon dioxide was injected into the samples at 6 bar to produce aerated chocolate. Using X-ray computed tomography, the images of the samples were captured and after processing, the obtained images were segmented using the Chan-Vese method. The properties of bubbles included total volume, diameter and surface to volume ratio. The crystallinity of the samples was determined through X-ray diffraction. The hardness of the chocolate bars was measured using the puncture test. The density of the aerated chocolates was also compared with that of the nonaerated ones. Introduction: Chocolate is a suspension of solid particles, including sugar, cocoa solids and milk powder (depending on the chocolate type) in a continuous fat phase, namely cocoa butter or its substitutes. The solid particles account for approximately 70% of chocolate with the fat constituting about 30%. Sugar takes up nearly 40–50% of the total solid particles of chocolate, thus influencing its sweetness, particle size distribution, rheological and sensory properties. It is also considered to be a bulking agent and a source of energy which produces 394 kcal/100 g of refined sugar. Therefore, consumers are increasingly becoming concerned with chocolate sugar and calorie content nowadays. This issue can be resolved by replacing sugar with bulk (nutritive) sweeteners and/or dietary fibers. Bubbles are found in many food products, including cakes, chocolates and beverages. Although they do not increase the food nutritional value, they change its textural properties and mouthfeel. Bubbles are normally visible to the naked eye and their mean diameter ranges from 0.05 to 3 mm. X-ray computed tomography is a 3D imaging technique which captures the images of a sample cross-sections. It is used for the non-destructive visualization and characterization of food microstructure. In this method, a series of radiographs of a sample are captured from different angles to be utilized for the 3D reconstruction of the material microstructure. Materials and methods: sugar was replaced with inulin: maltodextrin mixture at ratios of 25:75 (CH2), 50:50 (CH3) and 75:25 (CH4). Carbon dioxide was injected into the samples at 6 bar to produce aerated chocolate. Using X-ray computed tomography, the images of the samples were captured and after processing, the obtained images were segmented using the Chan-Vese method. The properties of bubbles included total volume, diameter and surface to volume ratio. The crystallinity of the samples was determined through X-ray diffraction. The hardness of the chocolate bars was measured using the puncture test. The density of the aerated chocolates was also compared with that of the nonaerated ones. Results and discussion: X-ray diffraction revealed that there were many strong peaks in the diffractogram of CH1, which can be ascribed to the high degree of sugar crystallinity in addition to the impurities present in the commercial sugar utilized in this study. In the case of the sugar-free samples, namely CH2, CH3 and CH4, two distinct peaks could be seen at 2θ of about 21° and 23.5°, both of which were much stronger and more defined in the scattering pattern of CH3, demonstrating the more crystalline structure of this sample. It seems that inulin and maltodextrin have physically interacted with each other or with the other ingredients of the chocolate, in particular CBS, which has been more pronounced at the ratio of 50:50. The results of image segmentation showed that the Chan-Vese method, compared with the adaptive thresholding one, was more able to segment the images, because this method does not depend on the image gradient and is especially suitable for the objects with vague edges. The mean bubble diameter of CH1 was bigger than that of the other samples, which could be due to its higher degree of crystallinity, because the crystalline structure of CH1 prevented the gas from being lost leading to the coalescence of smaller bubbles and the formation of bigger ones. In addition, it was observed that the density of the aerated chocolate was higher than that of the unaerated one in all the formulas as a portion of solid particles and fat was replaced with the gas. The results also demonstrated that the sugar-free aerated samples were softer than the corresponding nonaerated ones. However, it was reversed in the case of CH1 which could be ascribed to the presence of sugar in this sample, because in aerated products, solid particles, particularly sugar, form a continuous skeleton and play the same role as fat does in nonaerated products.
Fakhri Shahidi; Farideh Tabatabaei Yazdi; Majid Nooshkam; Zahra Zareie; Fereshte Fallah
Abstract
Introduction: Lipid oxidation leads to the generation of off-flavors and potential toxic compounds. Synthetic antioxidants are frequently applied for inhibiting this reaction, however; there is a concern regarding to the potent toxic effects of synthetic antioxidants on human health. The non-enzymatic ...
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Introduction: Lipid oxidation leads to the generation of off-flavors and potential toxic compounds. Synthetic antioxidants are frequently applied for inhibiting this reaction, however; there is a concern regarding to the potent toxic effects of synthetic antioxidants on human health. The non-enzymatic glycosylation reaction (Maillard reaction) has been broadly used to ameliorate the biological and functional features of proteins and polysaccharides. The Maillard reaction produces products with versatile functions such as antioxidant, antimicrobial, antihypertensive, anti-browning, and prebiotic properties. In this regard, the Maillard reaction products (MRPs) can be used in the food industry to inhibit the oxidation reaction due to their superb antioxidant effect. In this study, chitosan was glycosylated with inulin, fructose, and glucose. Chitosan is a chitin derivative with cationic nature having antimicrobial, antioxidant, metal chelation, and film-forming features. Inulin is recognized as a prebiotic sugar with vast applications in food and pharmaceutical sciences. The purpose of this study was to chemically modify chitosan through the Maillard reaction in order to boost its antioxidant and antimicrobial properties. Materials and methods: Chitosan (0.5% w/v) was dissolved in 1.0% v/v acetic acid solution followed by stirring for 1.0 h at room temperature. Afterwards, sugars inulin, glucose, and fructose were separately added to the chitosan solution at final concentration of 1.0% w/v. The obtained solutions were then stirred until complete sugar dissolution. The pH of solution was adjusted to 6.07 by adding 2.0 M sodium hydroxide and then the chitosan-sugar Maillard conjugates were fabricated through autoclaving the solutions at 121 °C. Changes in pH after the reaction were measured using a pH meter. The extent of the Maillard reaction was estimated via measuring the absorbance of the conjugated solutions at 294 nm (the intermediate products) and 420 nm (final products). Fourier transform infrared (FTIR) spectroscopy at transmission mode and 400-4000 cm-1 was employed to evaluate the structural changes of chitosan upon conjugation. Antioxidant activity of the conjugates was evaluated based on the reducing power assay. One mL of the samples was charged with 1.0 mL of distilled water and 1.0 mL of potassium ferricyanide (1.0% w/v). The solution was mixed and incubated at 50 °C for 20 min. After adding 2.5 mL of tri-chloroacetic solution (10% w/v), the obtained solution was centrifuged at 5000 g for 5.0 min. Afterwards, 2.0 mL of the supernatant was mixed with 2.0 mL of distilled water and 1.0 mL of ferric chloride (0.1% w/v). The solution was stand for 10 min at ambient temperature and then its absorbance was recorded at 700 nm. Antimicrobial effect of the conjugates against pathogenic microorganisms (E. coli, S. aureus, B. subtilis, P. aeruginosa, A. niger, and C. albicans) was measured according to the minimum inhibitory (MIC) and microbiocidal (MBC) concentrations. SPSS software (version 21) and one-way ANOVA were applied for data analysis. Duncan’s multiple range test was employed to determine the differences between means. Results & discussion: The Maillard reaction led to a significant decrement in pH value of chitosan-saccharide systems, mainly due to the covalent coupling of amino groups of chitosan to carbonyl groups of reducing sugars in conjugation with the production of acetic and formic acids. The highest intermediate compounds (A 294nm) and lowest browning intensity (A 420nm) observed in chitosan-fructose conjugate, which was likely attributed to the lower reactivity of fructose. Chitosan-inulin conjugate presented the highest A 420nm and lowest intermediate-to-final ratio (A 294nm/A 420nm), probably due to the lower inulin molecules and subsequently carbonyl groups compared to fructose and glucose. These groups may react with amino groups of chitosan at initial reaction times, leading more conversion rate of the intermediate compounds to the final ones. FTIR spectra of the chitosan and conjugates revealed that absorbance peak at 1661 cm-1 in chitosan spectrum decreased and shifted to 1578 cm-1 (in chitosan-fructose conjugate), 1579 cm-1 (in chitosan-glucose conjugate), and 1580 cm-1 (in chitosan-inulin conjugate), indicating the stretching C-N group and -C=N group and the formation of Schiff base (-C=N) between reducing end of the saccharides and amino groups of chitosan. Reducing power of the chitosan-saccharide systems improved after the thermal process. Although, chitosan-glucose and chitosan-fructose conjugates had significantly higher reducing power than unconjugated counterparts, but chitosan-inulin conjugate showed non-significantly improved antioxidant activity compared to its non-heated mixture. Antioxidant activity of the Maillard conjugates was ascribed from the electron donating ability of their hydroxyl and pyrrole groups. The conjugates had lower MIC and MBC in comparison to their unconjugated pairs, except for chitosan-glucose conjugate, which showed no differences in MIC and MBC compared with its non-heated mixture. Antimicrobial property of the Maillard products, especially melanoidins has been attributed to their metal chelating features; melanoidins exert a bacteriostatic effect at low concentration and bactericidal effect at high levels through sequestering ionic iron from medium and magnesium from outer membrane, leading to the cell membranes destabilization. Additionally, antioxidant capacity, high surface activity, and inhibiting effect towards catabolic enzymes have been reported as another antimicrobial mechanisms of the Maillard products. In general, it can be concluded that chitosan-saccharide Maillard-based conjugates, particularly inulin-chitosan one could be used in the food sector as a novel prebiotic-based active bio-compound with antioxidant and antimicrobial features.
Ryhaneh Moghaddasi; Sara Movahhed; Hossein Ahmadi Chenarbon
Abstract
Introduction: The rheological properties of a bread dough describe its behavior under different process conditions. They are also central to its formulation, optimization, quality control, and better process capacity. A number of additives can improve the rheological properties of dough and breads. Fiber-based ...
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Introduction: The rheological properties of a bread dough describe its behavior under different process conditions. They are also central to its formulation, optimization, quality control, and better process capacity. A number of additives can improve the rheological properties of dough and breads. Fiber-based compounds and prebiotics in addition to gluten and starch, which have a large tendency to absorb the flour water, can affect the moisture distribution across the dough structure. Inulin and resistant starch are two types of prebiotics. Inulin is a water-soluble dietary fiber that is not absorbed by the enzymes at the upper section of he the digestive system and is partially fermented and metabolized by the microbial flora of the colon. Digestion-resistant starch is another prebiotic that acts as a food fiber and adds to the nutritional value. It can also improve the structure of the final product. In recent years, the rise in consumer awareness about health benefits of prebiotics has increased interests in functional foods particularly in bakery products. The present study qualitatively analyzed the effect of the prebiotics (i.e. inulin and resistant starch) on rheological properties of baguette bread doughs.
Materials and Methods: The study treatments are: Baking dough w/o inulin and resistant starch (Control); baking dough w 2.5% inulin (based on flour weight); baking dough w 5% inulin (based on flour weight); baking dough w 2.5% resistant starch (based on flour weight); baking dough w 5% inulin (based on flour weight); baking dough w 2.5% inulin + 2.5% resistant starch (based on flour weight); baking dough w 2.5% inulin + 5% resistant starch (based on flour weight); baking dough w 5% inulin + 2.5% resistant starch (based on flour weight); baking dough w 5% inulin + 5% resistant starch (based on flour weight). The treatments were rheologically tested by farinograph and extensograph after preparation. Study data were then analyzed using the completely randomized design. Means of data were also compared by Duncan's multiple-range test (α = 5%) in SPSS 16.
Results and Discussion: According to the results, the different levels of prebiotics (inulin and resistant starch) significantly improved dough water absorption compared to the control samples. This can be due to the presence of hydroxyl groups in the structure of the prebiotics, which increased the number of hydrogen bonds and thus water absorption in all treatments compared to the control. Moreover, these additives led to significantly higher dough development time than the control. This can be due to the hydroxyl groups in the structure of inulin and resistant starch, which increased the number of hydrogen bonds and thus cross-bonding with water. These additives also significantly increased the dough stability time compared to the control.This is a result of hydrogen attachments and hydroxyl bonding between gluten proteins (made up of glutenin and gliadin) and the prebiotics (inulin and resistant starch) that in turn improved the stability and strength of the doughs. As the dough stability increased, the dough softening degree after 10 and 12 minutes was also reduced, which was due to the hydrogen bonds resulting from hydroxyl cross-links of gluten with inulin and resistant starch. Note that the quality index increased when the stability and strength were improved compared to the control dough. According to the results, by adding different levels of inulin and resistant starch, the dough energy rised higher than the control sample after 45, 90 and 135 minutes. This is again due to (OH) hydroxyl bonds with hydrogen attachments between glutens and the prebiotics. In this regard, the highest resistance to extension after 45, 90 and 135 min was recorded for the treatments containing inulin and resistant starch whereas its lowest value was recorded for the control. This is due to the stable continuous lattice made by amylose in resistant starch granules, which led to the higher strength of other treatments than the control. Additionally, the increased dough resistance to extension can be due to the interaction of inulin and resistant starch with flour proteins. Regarding extensibility, significant differences were observed between the treatments and the control within all three time intervals. Accordingly, after 45, 90 and 135 min, the control treatment had the highest extensibility whereas the treatment with 5% inulin + 5% resistant starch (based on flour weight) had the lowest level of this parameter within these times. The increases in strength and stability of the doughs were caused by strong links between glutens and these prebiotics, which reduced the dough extensibility. The results showed that the highest dough ratio number after 45, 90 and 135 min belonged to the treatment with 5% inulin + 5% resistant starch (based on flour weight). The lowest ratio number was recorded for the control in these time periods. The gluten was the main factor behind dough stability. The large amount of hydroxyl groups in the structure of inulin and resistant starch led to formation of a better structured three-dimensional gluten lattice. In general, by taking all parameters into account, the treatment with 5% inulin + 5% resistant starch was selected as the best treatment.
Mina Kargozari; Leila Bagheri; Alireza Mohammadi
Abstract
Introduction: In recent years, sugar-free or reduced-sugar foods and beverages are becoming very popular among the consumers. At the same time, consumers are increasingly concerned about the quality and safety of many products present in the diet, in particular, low-calorie synthetic or natural sweeteners. ...
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Introduction: In recent years, sugar-free or reduced-sugar foods and beverages are becoming very popular among the consumers. At the same time, consumers are increasingly concerned about the quality and safety of many products present in the diet, in particular, low-calorie synthetic or natural sweeteners. Sugar adds viscosity and provides body in drinks and semi-liquid foods like syrups and fruit juices. In order to achieve the same quality, taste and texture profile, reducing or removing sugar from a product often requires replacement with a number of alternative ingredients such as hydrocolloids. Hydrocolloids are widely used in many food formulations to improve quality attributes as thickening and gelling agents. Xanthan gum is a polysaccharide used as a food additive and rheology modifier, commonly used as a food thickening agent and a stabilizer, to prevent ingredients from separating. Stevia is an attractive natural sweetener and sugar substitute extracted from the leaves of the plant species Stevia rebaudiana. Inulin is a starchy substance found in a wide variety of fruits, vegetables, and herbs, which improves the technological properties and enhance the nutritional value of food and also has synergistic sweetening effect with sweeteners including stevia. Dietitians suggest that inulin belong to a class of water-soluble dietary fibers known as fructans, but research suggests prebiotic and bifidogenic properties of this compound that has caused it to be also regarded as a functional compound.
Materials and methods: Lemon drink with different formulations containing sugar (0, 6, 12 %), stevia (0, 0.02, 0.04 %) and xanthan (0, 0.18. 0.26 %) were prepared. To mask the bitter taste of stevia, inulin which has functional properties, was added to the formulation at the level of 0.5 %. In this study, liquid-gel method was used to suspend the solid particles of pulp and reach the desired consistency. Liquid gel structure was built by adding hot xanthan solution to the half diluted lemon drink while being stirred. Flow behavior and particle size distribution were examined. The dynamic yield stress of the samples was calculated and the stability of pulp particles in lemon drink was predicted by determination of the forces acting on the particle. Specific gravity measurement of lemon beverage was performed after removing the pulp using 50 ml pycnometer at 20°C according to the Iranian National Standard No. 2685. Mean diameter and size distribution of cloud-forming substances in pulp-free beverages were measured with a static light scattering laser diffraction-based particle size analyzer Malvern Master Sizer. Physicochemical (pH, acidity, ash, brix and density), sensory (taste and appearance) and microbial properties of lemon diet drinks were also examined.
Results and discussion: Xanthan, having considerable effect on flow behavior of lemon drink samples, created high amounts of apparent viscosity at low shear rates. In samples containing xanthan, yield stress was observed and its value was measured by extrapolation based on the Herschel-Bulkley model. The calculations of pulp suspension were conducted based on the yield stress, which were consistent with the results of stability observed. The results of the particle size distribution test showed that xanthan significantly increases the particle size of the lemon beverage. This means that the anionic hydrocolloid xanthan also react with lemon drink colloids and broader range of particle size was created. Higher xanthan concentration had led to increased particle size range. Lower sugar and stevia concentration in combination with xanthan reduced the particle size. Based on the results obtained, pH of samples ranged from 2.85 – 2.90 and acidity expressed as citric acid ranged from 0.47 – 0.52 that was in accordance with the standard related to the physicochemical properties of non-carbonated drinks and beverages (Iranian National Standard No. 2837). Other properties such as water-soluble solids value and density were not discussed due to the lack of standards for low-sugar beverages and the need for a national standard in this field was felt. The results concerned to the physical and chemical characteristics of different treatments indicated that lemon beverage acidity and pH values did not show significant differences among the samples and the samples containing higher amounts of sugar, xanthan and stevia had higher brix, ash and density values (P
Nasrin Faraji; Mohammad Alizadeh khaled abad; Asghar Khosrowshahi; Soheila Faraji
Abstract
Heart disease - cardiovascular, cancer and obesity are the main causes of death and there are direct relationship between the consumption of high-fat foods and the incidence of these diseases. Therefore the demand for low-fat food products and probiotics has been dramatically increased. In this study, ...
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Heart disease - cardiovascular, cancer and obesity are the main causes of death and there are direct relationship between the consumption of high-fat foods and the incidence of these diseases. Therefore the demand for low-fat food products and probiotics has been dramatically increased. In this study, the effect of different levels of three hydrocolloids (inulin, chitosan and xanthan) at three levels (1, 2 and 3%) on survival of Lactobacillus acidophilus, physicochemical and sensory properties of yogurt during 15 days of storage was explored using a combined design. Increased levels of inulin and chitosan positively affected La-5 count, apparent viscosity, acidity and sensory scores during storage. Using graphical method of optimizing (overlaid contour plots), optimum ratios were: inulin 93.4%, xanthan 0.6% and chitosan 6%.
Elnaz Milani; Hajar Naeemi; Seyed Ali Mortazavi; Arash Koocheki
Abstract
In this study, symbiotic yog-ice (rozen yogurt) was produced that was inoculated with different levels of inulin(0,2.5 amd 5%)as prebiotic compound and Lactobacillus Casei as probiotic bacteria in two types; free and encapsulated with Sodium Algint-Whey Protein Concentration for low fat yog-ice cream.The ...
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In this study, symbiotic yog-ice (rozen yogurt) was produced that was inoculated with different levels of inulin(0,2.5 amd 5%)as prebiotic compound and Lactobacillus Casei as probiotic bacteria in two types; free and encapsulated with Sodium Algint-Whey Protein Concentration for low fat yog-ice cream.The survivability of this probiotic bacteria was evaluated under simulated gastro-intestinal conditions ,during 30 days storage at -18oC. In the samples with free state of probiotic bacteria, the number of viable cells ,after 1h exposuring simulated gastric juice(pH=2,pepcine) decreased from 9.78-9.81 log cfu/ml to 6.97-7.26 log cfu/ml,at the end of 30 days storage at -18oC,while, the viable number of encapsulated state of probiotic bacteria, after 1h exposuring simulated gastric juice, decreased from 8.15-8.66 log cfu/ml to 6.80-7.09 log cfu/ml at the end of 30 days storage at -18oc.After exposuring simulated gastric juice, samples was ezposured 2.5h under simulated intestinal juice(pH=7.4,panceratin), and the results that was gained showed that, the samples containing free probiotic bacteria after 2.5h exposuring simulated intestinal juice decreased from 8.808-9.355 log cfu/ml to 5.159-5.9 log cfu/ml at the end of 30 days storage at -18oC.While, in the samples containing sodium alginate-whey protein concentration capsules, the viable number of cells decreased from 7.38-8.201 log cfu/ml to 6.151-6.672 log cfu/ml, at the end of 30 days storage at -18oC. The results indicate that there are significant differences (p
