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Wheat starch is the most common type of starch in Iran as well as many other parts of the world with enormous applications in food and non-food products. To improve its physicochemical properties or create new functionalities, starch can be modified by changing its molecular structure. Amongst different methods for starch modification, physical methods have received more attention recently. Pre-gelatinization of starch is a physical method to modify the properties of native starch. The main aim of this research was to study the physicochemical properties of pre-gelatinized wheat starch produced using a small scale industrial twin drum drier. The results indicated that drum drying destroyed native starch granules, degraded molecular structure and reduced the degree of crystallinity of starch. Pre-gelatinized starch (PGS) showed cold water viscosity at 25 ºC, while native wheat starch was not able to increase the viscosity under this condition. It also increased water absorption and swelling of the starch compared to its native counterpart. Pre-gelatinized wheat starch can be used as a thickening agent in instant food products to eliminate heating stage in their production or in manufacturing of the products sensitive to high temperature.

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Production of part-baked bread is a successful method to postpone bread staling that has been applied widely for production of loaves. In this research, production and some physical characteristics of part-baked flat bread (Barbari) including hardness, volume, color, weight loss, and microstructure were studied during the storage of the samples at ambient (25ºC) and freezing (-18ºC) temperatures. The part-baked bread had higher moisture content than the control and full-baked breads. However, it had a shelf-life of 72 hours, which was shorter than the control at ambient temperature. Full-baking could level out the effects of staling and, hence, the quality of the full-baked bread was similar to that of the fresh bread. For the frozen samples, the optimum storage time was two months. The undesirable effects of frozen storage were more significant for the part-baked bread. Moreover, full-baking could compensate some of the adverse effects of freezing and the resultant bread had superior quality compared with the control.

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Wheat germ, a highly nutritive part of wheat kernels, is separated during milling as a by-product. In this study, wheat germ was used to supplement cakes. Different levels of the germ (0, 5, 10, 15 and 20%) at different particles sizes (280, 585, 890 and 1,195 µm) were added to a cake recipe. The results showed that with increasing the germ level and particle size, batter consistency and density of the cakes increased significantly, while the height of the cakes decreased. With increasing the germ level and its particle size, the crumb became slightly yellow while the crust color and the textural parameters (TPA test) remained unaffected. Determination of the sensory attributes of the samples showed that the particle size was negatively correlated with the crumb color and texture of the cakes, while other sensory parameters remained unaffected. In general, 15% of germ was the highest level and 280 µm was the most suitable particle size (as recognized by the panelists) for the production of an appropriate germ cake.

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 Increasing the nutritional value of bread is important since the enriched product can be used for special target groups such as developing countries or special diets. Wheat germ, a highly nutritive part of wheat kernel, is a by-product of milling factories and has the potential to be used for food supplementation. The main aim of this research was to supplement flat bread (Barbari) with wheat germ and to study the quality and staling of the resultant bread. Therefore, processed (heated at 150°C for 45 minutes) and raw wheat germs were added at the rates of 0, 5, 10 and 15% (w/w) in bread recipe, as separate treatments. Using a Farinograph, it was found that the dough made with raw germ had less water absorption, lower consistency, and shorter stability time. Modeling of the data showed that increasing the germ level had negative correlation with bread volume and softness. Such effects were enhanced when raw germ was used. It was found that addition of germ could not delay bread staling; however, it had positive effects on its taste and general acceptability, particularly when 15% processed germ was used.

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Due to the positive effects of fiber on human health, production and distribution of high fiber containing foods is on the increase. Amongst different foods, bread is a suitable option to convey fiber in human diets. Flat breads which are very common in Asian countries, are mainly produced from white flour and hence are low in fiber. The main objectives followed in this study were to produce high fiber Barbari bread (a popular flat bread) using wheat bran, while minimizing the adverse effects of inclusion of bran in the bread recipe. To achieve this, wheat bran of different levels (0-20%, w/w flour basis) and particle sizes (170, 280, 425 and 750 mm) were added to Barbari bread recipe. Using Brabender Farinograph, it was found that with increase in bran level and its particle size, the water absorption of the dough increased. Color determination results showed that the bread crust color became darker as the level of the bran and its particle size increased. The results of determination of the bread texture using Texture Profile Analyser, showed that the bread became harder and less cohesive with increase of the fiber in the dough and for each bran particle size. According to the panelists, barbari breads constituted the most appropriate breads with up to 15% bran with particle sizes of shorter than 280 mm. In total, it was concluded that by a control of the level and particle size of the bran, it is possible to increase the fiber content of the bread without any significant adverse effects on the quality.

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In this study, the effects of moisture content and corn variety on the physicochemical properties of popcorn were investigated and modeled using response surface methodology. Each of the two corn varieties (Hybrid corn KSC 600 PC and American) was prepared with a range of moisture (six moisture levels ranging from 10 to 20%) and popped by a hot air popper. Variety and moisture content affected the density, air bubble diameter as determined from electron micrographs, textural hardness and color parameters. The lowest densities for American and hybrid corns were obtained at moisture contents of 14 and 18%, respectively. As water content deviated from the optimum levels the popcorn density significantly decreased. For both corn varieties, with increasing water content, the lightness of the samples increased while b (yellowness-blueness) values decreased. For American popcorn no significant impact of the moisture content on the hardness was observed, however in hybrid corn, hardness of popcorns significantly decreased with increasing water content, and the lowest density and hardness were observed at moisture content of 18%. Experimental models are presented for the prediction of density, color parameters, air bubble diameter and hardness of popcorns at different moisture contents for American and hybrid corns.

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Rice bran is a major by-product of the rice milling process that contains high amounts of fiber, proteins, fats, vitamins, minerals as well as antioxidants and hence can be utilized in enriching food products. The main aim followed in this study was to determine the effects of rice bran of variable particle sizes (53, 125 and 210 µm) and its quantity (0, 5, 10, 15 and 20%) on the quality of batter and on sponge cake. Increasing bran quantity and particle size increased batter density and consistency. Using a higher quantity of bran with larger particle sizes increased cake density and weight of the cakes (after being baked) while decreasing the cake volume. Textural properties of the samples as determined instrumentally showed that maximum compressive force and the firmness increased, while cohesiveness and springiness decreased with increase in the contents of bran and increase in its particle size. Cake crust color became darker, more reddish and less yellowish with inclusion of rice bran. Increasing the levels of rice bran, negatively affected taste, crust and crumb color as confirmed by the sensory panel. Overall, it was found that addition of 10% rice bran with particle size of 125 µm resulted in the most desirable cake quality.

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In this research, seeds of Iranian carob trees grown wild in Kazeroon city (Fars Province) were used to extract Iranian locust bean gum as a seed galactomannan. Chemical composition, solubility, and rheological properties of crude and purified gums were investigated and compared with a commercial (Sigma) locust bean gum (LBG) sample. Chemical composition of the purified Iranian LBG was similar to the commercial LBG, however, the protein content of Iranian crude LBG was higher. Solubility data showed that the Iranian crude LBG was partially cold-water soluble (~ 55% at 25°C) and needed heating to reach a higher solubility value (~ 71% at 80 °C). Rheological properties of the solutions of the three LBG samples were investigated as a function of concentration and temperature (5-60 °C) at shear rate range of 0.5-200 s^-1. All three samples showed shear thinning behavior and Power law model was used to fit the experimental data. The Iranian LBG (crude and pure) was able to thicken aqueous solutions; however, its viscosity level was lower than that of the commercial LBG. Study of rheological properties of the three LBG samples at different pH levels (2.5-10) showed that they were significantly affected by pH. The intrinsic viscosities of the Iranian crude and purified LBG and commercial LBG were 3.95, 9.05, and 9.48 dL g^-1, respectively.

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There is some evidence on the effects of organic acids on the functional properties of native starches. However, there is little information on such effects on modified starches. The main objective of this study was to determine the effects of L-ascorbic acid (150 mg kg^-1, as the permitted level in bakery products) on functional properties of cross-linked wheat starch. Once the starch was treated with L-ascorbic acid, some spots and cracks appeared on the surface of the starch granules, as observed under a scanning electron microscope. Besides, the water solubility increased while water absorption decreased, but intrinsic viscosity of the samples, as determined by a U-tube viscometer, remained unchanged. Also, gelatinization temperature and enthalpy of gelatinization, measured by differential scanning calorimetery, as well as the hardness and elasticity of the starch gels decreased, while adhesiveness and cohesiveness of the gels remained unaffected. In general, it was concluded that the ascorbic acid had some degradation effect on cross-linked wheat starch molecules that could further affect its functional properties.

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Promotion of the dietary fiber of foods can enhance human health by reducing the risk of many serious diseases. Cakes are among the highly consumed foods but sadly of low fiber content. Therefore, increasing the fiber content in them is of great importance, and this was the aim followed in this study. Wheat flour was partially replaced at 0, 10, 20 and 30% (w/w) with corn Resistant Starch (RS), as a source of dietary fiber, and used in the production of sponge cake. Obtained results indicated that batter consistency increased while its density reduced with an increase in the level of RS. Increasing the level of RS caused an increase in cake density but a decrease in volume. Cakes became softer but their cohesiveness, springiness and chewiness reduced. They also became whiter, less reddish and less yellowish. Addition of less than 30% RS had no significant effect on the sensory attributes of the cakes. In total, it was concluded that a maximum level of RS in the sponge cake recipe to produce an acceptable product amounted to 20%.

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In this research, rehydration behavior of dried figs was studied at different temperatures (25, 60, 70, 80, and 90°C). The rehydration kinetic was examined using the four most frequently used empirical models, namely, Weibull, Peleg, first-order, and exponential association models. The Weibull model gave the highest coefficient of determination (R²) and the lowest values of root mean square error (RMSE), sum of squared error (SEE), and chi-square (χ²) was considered the best. In all models examined, the equilibrium moisture content showed statistically significant differences as compared to the rehydration temperature. The temperature dependence of kinetic constants was described in terms of Arrhenius relationship. The average activation energy for the four models was 24.362 kJ mol^-1. During the rehydration process hardness of dried figs decreased, which was further confirmed by microscopic evaluation. Scanning electron microscopy (SEM) images of rehydrated figs indicated porous structure proposing the presence of free water.

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 Despite the numerous health effects of the dietary fibers, the amount of the fiber in the diet is generally lower than the recommended value. Therefore, increasing the fiber content of the foods particularly those of high consumption can compensate for the shortage of the fiber in the diet. However, it seems a difficult task since increasing the fiber content can have adverse effects on product acceptability. The main objective of this study was to include oat fiber in the cake recipe and to determine the physical and sensory properties of the resultant product. Therefore, oat fiber at different levels of 0, 5, 10, 15, 20, and 30% (w/w, flour basis) were added in the cake recipe. Increasing the level of oat fiber resulted in the increase in batter density and consistency and cake volume. In addition, cake crust and crumb became darker. Cake hardness and gumminess increased, while cohesiveness and springiness decreased as determined using a texture analyzer. Cakes containing no more than 20% oat fiber had acceptable sensory characteristics. In total, it was concluded that addition of maximum 20% oat fiber to cake can result in a product of acceptable sensory characteristics.

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The date fruit is of high nutritional value and its chemical composition is unique in providing energy, minerals, and vitamins for human. Date syrup, date concentrate and liquid date sugar are among semi-finished liquid products produced from low quality dates at industrial scale. In this research, some physicochemical properties of date syrup, concentrate, and liquid sugar in comparison with sucrose solutions were studied and the possibility of replacing sucrose with date liquid products was investigated. The results showed that the main chemical component of all three date products was simple sugars of fructose and glucose. Ash and protein contents of date liquid sugar were much lower than date syrup. pH values of date liquid products were also significantly different. Concentration of total phenolic and flavonoid compounds in date syrup was much greater than date liquid sugar. Overall, processing of date syrup to date liquid sugar reduced its nutritional quality while improving technological properties. It can be concluded that in choosing date liquid products as raw materials in food formulation, for the products that brown color of date liquid products does not affect the appearance of the final products, usage of date syrup or date concentrate is proposed. However, in other foods where brownish color of date syrup or date concentrate deteriorates sensory attributes of the final products, date liquid sugar is suggested. Date liquid products are also good candidates for high sugar products with sugar crystallization problem.

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To reduce sucrose consumption in biscuits, Date Syrup (DS) and Date Liquid Sugar (DLS) were replaced with sucrose at different levels (0, 20, 40, 60, 80, and 100%) and physicochemical properties of dough and the resultant biscuits were compared. Dough pH and cohesiveness decreased while softness and adhesiveness increased with addition of DS and DLS. The pH, softness and adhesiveness of the DS dough were higher than the DLS samples. The DS and DLS biscuits had lower pH, higher ash and moisture contents than the sucrose biscuits. The DS biscuits had more ash content than the DLS sample. Addition of DS and DLS resulted in biscuits with higher density, spread ratio, harder texture, and darker color. These changes were more pronounced when DS was used. Sucrose replacement with less than 40% DS or 60% DLS resulted in biscuits with sensory characteristics similar to the control, and higher antioxidant and mineral contents.

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Starch and Soy Protein Isolate (SPI) have numerous applications in food products mostly as gelling and texturizing agents. The main purpose of this research was to investigate the pasting and gelling properties of the mixtures of starch and various levels of SPI (0, 5, 10, 15, 20 and 25%). To determine the effects of starch sources on the results, wheat and corn starches were tested in this study. It was found that with increasing the quantity of SPI, the viscosities obtained from Rapid Visco Analyser (RVA) including final, holding, and setback decreased while pasting temperature remained unchanged. Increasing the SPI concentrations enhanced the peak viscosity of the wheat starch-SPI samples, while it had opposite effects on corn starch-SPI samples. The colour of both starch-SPI gels became darker and more yellowish with increasing the SPI concentration. Although gel hardness increased during storage for 1 and 3 days at 4˚C, the addition of SPI reduced the hardness of the gels. The residual modulus of the Maxwell model from stress relaxation data showed that gels became softer and less elastic with increasing the SPI concentration. The corn starch-SPI gels exhibited darker color, higher firmness, cohesiveness, springiness, gumminess and chewiness compared to the wheat starch-SPI gels. The results may be useful to obtain the desired quality in food products containing starch and SPI.
 

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Date Press Cake (DPC) is a by-product of date fruit juicing, which has remained mostly underutilized in food products. The main objective of this research was to investigate the viability of adding DPC in cake formulation. Thus, different levels (0, 10, 20, 30, and 40%) and particle sizes (210 µm= DPC₂₁₀ and 500 µm= DPC₅₀₀) of DPC were used in cake formulation. The results showed that DPC had higher fiber, ash, and fat content than cake flour. Increasing the level and reducing the particle size of DPC increased batter consistency, firmness, stickiness, cohesiveness and viscosity. Inclusion of DPC increased cake density, reduced pH and crust moisture content, but these were not affected by DPC particle size. The samples became harder and less cohesive as the level of DPC increased. DPC₂₁₀ resulted in softer and less cohesive cakes compared to the DPC₅₀₀. Addition of DPC improved the antioxidant content of the cakes, particularly when DPC₂₁₀ was added. Overall, the sample produced with 10% DPC₂₁₀ had acceptable sensory characteristics.