Food Chemistry
Ahmad Ehtiati; Massoumeh Mehraban Sangatash; Reza Karazhyan; Zahra Nazari; Farzad Sadeghi
Abstract
Introduction: Shortening is an important ingredient of bakery products, especially the ones with less developed gluten network like cakes and cookies . Shortening thermo-rheological properties are related to the presence of high levels of saturated fatty acids which have the capability of making ...
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Introduction: Shortening is an important ingredient of bakery products, especially the ones with less developed gluten network like cakes and cookies . Shortening thermo-rheological properties are related to the presence of high levels of saturated fatty acids which have the capability of making crystals at room temperature which melt during baking. Consumption of high saturated fatty acids increases the risk of coronary disease. Moreover, hydrogenation is a usual technique for elevating the saturated fatty acid content of vegetable oils. Lowering the saturated fatty acid content of a shortening results in the shortening with less functionality. Transition of an oil physical properties to those of a semi-solid structure can be done using low- or non-digestible oil gelators called oleogelation. Ethyl cellulose is a polymer with oil gelation capabilities at low concentrations. However, its oleogels are firm and brittle, so some low-molecular-weight gelators can improve its texture and increase its plasticity to mimmic commercial shortening functionality. In this study, the functionality of an oleogel based on ethyl cellulose, stearyl alcohol, stearic acid and sorbitan monostearate was evaluated as commercial shortening substitute in cake formulation. Materials and Methods: Based on previous studies and preliminary experiments, an optimized oleogel formulation was prepared as shortening, composed of ethyl cellulose (6.4%), stearyl alcohol:stearic acid (70:30) (7.5%), sorbitan monostearate (0.1%) and canola/soy mixture oil (75:25 ratio) (86%).The gel was formed by heating up the mixture to 150 °C for the complete solvation of the gelator compounds and gradual cooling to room temperature. In the next step, commercial shortening was substituted with the oleogel shortening at 0, 25,50, 75 and 100% in the cake formulation. Moisture content, water activity, specific volume, crust color, Lab color space indices based on image processing, porosity based on crumb image analysis, TPA parameters and sensory attributes were determined and compared using one-way analysis of variance and LSD mean comparison test. Results & Discussion: The results showed that there was no significant difference in the moisture content, water activity and specific volume of the cakes prepared with the oleogel shortening with the one prepared with commercial shortening. This reveals that the oleogel shortening functionality was acceptable compared with commercial shortening. In terms of crust color, there was no significant difference in the lightness index (L*) and red-green range (a*) indicators between different samples and only in the yellow-blue range (b*) index, the cake with 100% substitution showed a lower value than the control. For the porosity index, there was no significant difference between the five samples, proving the oleogel shortening can induce sufficient air bubbles generated during batter mixing and its preserving effect during baking. Examining the texture of the cake samples showed that the texture hardness and springiness indices decreased with a rise in the level of commercial shortening substitution, while the cohesiveness index did not differ significantly. The latter indicated that the oleogel shortening effectively shortened the gluten network; thus, it can be said that the same commercial shortening functionality is attainable using less oleogel shortening content. Furthermore, as the percentage of the commercial shortening substitutes increased, due to texture softening, the chewing energy of the samples decreased resulting in a better mouthfeel. Finally, sensory evaluation of the cake samples did not show a significant difference in taste, texture, appearance, color and overall acceptance based on scores obtained from ten untrained evaluators. In conclusion, the use of oleogel shortening instead of commercial shortening with high saturated fatty acid content in cake formulation not only can result in a cake with acceptable properties at 50% replacement level, but also can replace commercial shortening even up to 100%.The latter just lead to a softer texture. Optimization of the cake formulation based on the oleogel shortening would specifically result in a cake with better properties, while it has significantly lower saturated fatty acid content and nearly zero trans fatty acids.
Marzieh Salami; Massoumeh Mehraban Sangatash; Ahmad Ehtiati
Abstract
Introduction: Yogurt is one of the most popular dairy products, which has numerous health effects on human body. Dietary fiber consumption is highly recommended. Fibers are highly hydrophilic and absorb water into the digestive track, increase the volume of food and thereby facilitating excretion. These ...
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Introduction: Yogurt is one of the most popular dairy products, which has numerous health effects on human body. Dietary fiber consumption is highly recommended. Fibers are highly hydrophilic and absorb water into the digestive track, increase the volume of food and thereby facilitating excretion. These are some health benefits of these compounds. Consumption of fiber-containing yogurt can be helpful for people who suffer from cardiovascular diseases, hypertension, diabetes and obesity. Zucchini, as a vegetable, is a source of fibers and due to its health-promoting effects, can be used in dairy products. The aim of this study is to evaluate the effects of different levels of dried zucchini on stirred yogurt during storage. Materials and Methods: The raw materials for the production of the functional yogurt were zucchini, milk, skim milk powder, whey powder, hydrocolloids stabilizer compound and starter culture. Fresh zucchini was hot-air dried at 70 °C for 7 hours. Two forms of the dried zucchini (powder and granule) were added to fresh yogurt at levels of 0.7, 1.4, and 2%. The samples were then tested on days 1, 5, 10 and 15 for acidity (titration method), pH, texture stiffness (back extrusion), syneresis, color (using image processing) and sensory properties, including color, taste, aroma, consistency, mouthfeel and overall acceptance. The experiments were triplicated and analysis of variance was performed using Minitab software at 95% confidence interval. For the significant variables, the means were compared using LSD method. Graphs were drawn using MS-Excel. Results and Discussion: The effects of zucchini form and level of addition, storage time and interaction of these variables were significant (P<0.05) on the titratable acidity, pH and firmness. Over time, pH decreased and acidity increased, which was related to the starter activity and acid production. Due to the use of stabilizer and whey protein, all samples showed no syneresis. The firmness of the samples containing zucchini powder was higher than that of the granule- (P<0.05). This might be related to the homogeneous structure of zucchini fiber, which increased water absorption regarding its lower particle size. Firmness increased from day one to day five, due to the high water absorption of hydrocolloids that bind to free water present in the yogurt structure. The presence of milk proteins and whey protein concentrate in the yogurt formula enhanced crosslinking in the particle gel network, which resulted in a stronger gel structure. During longer storage, firmness decreased from day 5 to day 10, probably was due to the increased pH, which affects the proteins and polysaccharides interaction. The effects of the form and level of zucchini and the interaction between these variables were significant (p <0.05) on the changes in L*, a*, and b*. The L* and a* values which were higher in the samples containing zucchini granules than in the zucchini powder, most probably due to the smaller particle sizes of the powder compared with the granules, causing the number of the powder particles per unit volume to be larger and the powder-containing samples to become darker. In terms of the level of addition, L* increased as the zucchini level rose to 1.4% and then declined to 2%. The sensory properties of all samples were significantly affected by the storage time (P<0.05). With increase in the storage time, all the sensory scores increased. The highest overall acceptance score belonged to the yogurt sample containing 1.4% granule on the 10th day of storage. Overall, zucchini is a good candidate for yogurt fortification. This incorporation results in a greenish yogurt with more health functionalities. The highest overall acceptance score was obtained for the yogurt containing 1.4% zucchini granule on the 10th day of storage (best consumption date) and the results showed acceptable firmness for this sample.
Raza Bataghva; Massoumeh Mehraban Sangatash; Ahmad Ehtiati
Abstract
Introduction: Hypertension is the result of angiotensin converting enzyme (ACE) activity in the vessel wall membrane. This enzyme converts angiotensin I to angiotensin II which results in vessel wall stiffness and an increase in blood pressure. Inhibition of ACE activity is a therapy for hypertension. ...
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Introduction: Hypertension is the result of angiotensin converting enzyme (ACE) activity in the vessel wall membrane. This enzyme converts angiotensin I to angiotensin II which results in vessel wall stiffness and an increase in blood pressure. Inhibition of ACE activity is a therapy for hypertension. In addition to synthetic inhibitors, some bioactive peptides (which are the products of protein proteolysis) have been identified as ACE inhibitors. Bread is a widely consumed bakery product all over the world. During dough fermentation, yeast proteases hydrolyze wheat flour proteins to prepare amino acid for cell growth. Natural cereal proteases are considered to be the other sources of protease. Proteolysis produces peptides in dough, which are bake-stable and have physiological effects on human body. Soy protein is a valuable plant protein, reported to be a source of peptides with ACE inhibitory activity and can be used to induce diversity in peptide species during dough fermentation. In this study, a completely randomized factorial design was created to evaluate the effect of the type of soy protein derivative, wheat flour substitution level and fermentation time on the ACE inhibitory activity of dough bioactive peptides. Materials and Methods: Wheat flour was substituted with 3 soy protein derivatives, including soy protein isolate, extruded soy protein and soy protein hydrolysate at 5 and 10%. Moreover, fermentation time was adjusted at 30, 60 and 90 min. Dough aqueous extract was evaluated in terms of molecular weight distribution using SDS-PAGE technique. The extract was then filtered through 3KDa membrane to separate short-chain peptides (theoretically <30 amino acids). Peptide concentration was determined using UV absorbance difference. The peptide solution was tested for the degree of hydrolysis based on OPA complexation reaction and ACE inhibition activity using FAPGG as the reaction substrate at two peptide concentrations. The experiments were triplicated and data were analyzed by ANOVA and Fisher`s mean comparison test using MINITAB software. Results and Discussion: Based on the SDS-PAGE pattern, it was observed that samples had a high level of low molecular weight peptides fraction were those enhanced with extruded soy proteins and soy protein hydrolysate. This results indicated that the addition of soy protein derivatives led to a higher content of short-chain peptides compared with wheat dough. The results also showed that all the examined variables, i.e. the type of protein, substitution degree and fermentation time, significantly affected the degree of hydrolysis and ACE inhibition activity of the separated peptides. The maximum degree of hydrolysis was observed in samples with soy protein hydrolysate- which was expected to have greater peptides diversity. This might be the reason for the higher ACE inhibition activity observed for these samples. Addition of Soy protein extrudate resulted in a higher degree of hydrolysis compared with soy protein isolate revealing that the extrusion technique caused to increase the protein susceptibility to proteolysis during fermentation along with the higher content of broken amino acid chains. The higher wheat flour substitution level resulted in a higher degree of hydrolysis, while in the case of ACE inhibitory activity, it was not significant. Overall, longer fermentation time increase the degree of hydrolysis, but led to lower ACE inhibition activity, probably due to active peptides hydrolysis. Wheat flour itself had a high level of ACE inhibition activity at the shortest fermentation time, compared with composite flours, while this activity was reduced at extended fermentation time. IC50 was the highest for the samples containing soy protein hydrolysate, surely a benefit from the initial proteolysis. In conclusion, the wheat flour substitution with 5% soy protein hydrolysate substitution,would lead to reasonable ACE inhibition activity and is suggested for bread formulation with hypertension lowering effect. It also needs more research to be done in order to evaluate substitution degrees lower than 5%, because it was observed that peptides diversity was more important than high hydrolysis degree. Overall, soy protein extrusion enhanced proteolysis and short-chain peptides production during fermentation which is a better option compared with isolated soy protein.
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 (
Ahmad Ehtiati; Fakhri Shahidi; Mohebbat Mohebbi; Masoud Yavarmanesh
Abstract
SMP was substituted by WPC in four levels for preparing reconstituted milk. Two ropy and one nonropy starter cultures was used for Doogh preparation. Yield stress, viscosity, consistency index and pseudoplastic behavior of Doogh increased by increasing WPC content. Results showed that WPC increased colloidal ...
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SMP was substituted by WPC in four levels for preparing reconstituted milk. Two ropy and one nonropy starter cultures was used for Doogh preparation. Yield stress, viscosity, consistency index and pseudoplastic behavior of Doogh increased by increasing WPC content. Results showed that WPC increased colloidal particles dimension and constructed a network which led to a decrease in Doogh phase separation (%32 at the highest level of WPC) during storage. Starter type had no effect on the Doogh stabilization. It does not have any effect on the studied physical properties in the presence of WPC, as well. Adding WPC to milk leads to improve of physical properties and stability of Doogh but using EPS producing starter cultures requires further studies in this field.
Fakhri Shahidi; Mohebbat Mohebbi; Mohammad Noshad; Ahmad Ehtiati; Milad Fathi
Abstract
Banana is one of the most important tropical fruit from commercial and industrial point of view. This fruit is an extremely perishable fruit which can not be preserved using freezing process. Therefore, drying is the most promising method. Conventional air drying is energy intensive and consequently ...
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Banana is one of the most important tropical fruit from commercial and industrial point of view. This fruit is an extremely perishable fruit which can not be preserved using freezing process. Therefore, drying is the most promising method. Conventional air drying is energy intensive and consequently expensive method. Pre-treatments can be used to reduce the initial water content or to modify the fruit tissue which will result in higher yield with lower costs. In this research, the effect of osmotic dehydration and ultrasonic pre-treatment variables prior to air drying of bananas, including the type of solution (Glucose, Sucrose), time of immersion in osmotic solution (30, 45, 60 min), solution concentration (Brix 30 and 50), ultrasonication time (10, 20, 30 min) on water loss, solid gain, shrinkage, effective diffusivities and color in the process were studied. Results showed that the highest rate of water loss and solid gain and also the lowest rate of shrinkage were obtained in both pre-treatments when 50% glucose concentration was applied. The results indicated that unlike ultrasonication, osmotic pretreatment had a significant effect on color parameters of dried bananas.
Keywords: Banana, Drying, Image processing, Osmotic dehydration, Qualitative characteristics, Ultrasound
Atena Pasban; Mohebbat Mohebbi; Ahmad Ehtiati
Abstract
Nowadays, quality control of bread, especially in large scale production, requires application of novel methods. In this research, image analysis of digital images of Barbary bread enriched with soy flour was carried out at two storage intervals. Using Imagej software, crumb features (mean cell area ...
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Nowadays, quality control of bread, especially in large scale production, requires application of novel methods. In this research, image analysis of digital images of Barbary bread enriched with soy flour was carried out at two storage intervals. Using Imagej software, crumb features (mean cell area and void fraction) were computed for each image. Fractal dimensions of bread crumb images were measured using Fourier transform method with a code written in Matlab. Contrast, energy, correlation and homogeneity of images also were measured and statistically analyzed. Storage time had significant effect on fractal dimension and void fraction, also resulted changes in textural parameters of bread images. The deduction of this work could be regarded as rapid, non-destructive, objective and inexpensive method for quality evaluation of bread crumb.
Keywords: Barbary Bread, Fractal dimension, Image analysis, Soy Flour
