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Gelatin has many applications in the food, pharmaceutical and cosmetic industries due to its technological and functional properties. By-products from fish cleaning are rich sources of collagen. The physical, chemical and rheological properties of gelatin or collagen depend on their sources as well as the extraction conditions. Response surface methodology (RSM) with three parameters was conducted to determine the optimum extraction conditions of gelatin from Caspian whitefish scale. A Box-Behnken design was used to study the combined effects of sodium hydroxide concentration (0.075-0.225 M), soaking time in sodium hydroxide solution (60-180 minute), and extraction temperature (30-50 ^oC) were determined. Viscosity (cp), gel strength (g), L*, a*, and b* were chosen as responses. The results showed the optimum conditions were sodium hydroxide concentration 0.109 M, soaking time in sodium hydroxide solution of 115.735 minutes, and Extraction temperature of 37.585^oC. The predicted responses including viscosity, gel strength, L*, a*, and b* were 2.17 cP, 145 g, 6.039, 6.801, and 38.859 respectively. The response surface method was able to estimate the optimal conditions of extraction gelatin with high desirability (0.99).
 

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Now a day antioxidants are widely used in foods to reduce the rate of oil oxidation reaction and researchers looking for potent antioxidants by less toxicity and greater efficacy. Plants are one of the best sources of natural antioxidants. Therefore, the aim of this study was to investigated the effect of adding different levels of alcoholic extract of Salvia leriifolia (0, 1, 2 and 3%) as a natural preservative to improvement storage time of fermented doughnut compared to TBHQ as commercial antioxidant on the physicochemical, textural and sensory properties of the final product in a completely randomized design (P˂0.05). The results showed that increasing the level of Salvia leriifolia extract from 0 to 3% had no effect on moisture content, specific volume, porosity and firmness of the final product (evaluated in three times of 2 h, 4 and 7 days after baking). However, by increasing the amount of this extract in fermented doughnut formulation, the peroxide index compared to other sample and the amount of total phenolic content, the antioxidant activity by DPPH method and the oxidative stability index at 2h, 4 and 7 days after baking were decreased and increased, respectively. On the other hand, the results showed that addition of Salvia leriifolia extract at different levels had no effect on the sensory properties of the final product. The results also indicated that the antioxidant activity of the sample containing 3% of Salvia leriifolia extract had the ability to compete with fried doughnut in oil containing synthetic antioxidant TBHQ. Therefore, the sample containing 3% of Salvia leriifolia extract was selected as the best sample because it had high antioxidant resistance, secondly, the addition of this extract had no adverse effect on physicochemical and sensory properties of the final product.
 

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The aim of this study was to produce a suitable cake with reduced fat with the help of apple pomace fiber as a fat substitute. After preparing fiber from apple pomace by water extraction method, first some properties of this fiber were evaluated. Due to the low amount of fat and energy and the amount of crude fiber, the extracted apple fiber was able to replace carbohydrate-based fat for flour products. In this study, optimization of the cake production process by three factors, including apple fiber with a ratio of (0.5, 10%) and oil (16.38, 15.47, 14.57%) with a shelf life of 0, 15 and 30 days. Response method was performed. The result showed that with increasing the amount of fiber moisture, fat, firmness and adhesion, the springiness of the cakes increased and the volume decreased. With increasing shelf life, moisture, fat, aw increased and the firmness and stickiness of cake spring decreased.  The results of this study show that the cake containing 5.163% fiber and 14.9% oil in 8 days was the best sample. The results showed that the use of apple pomace in the cake reduced the fat content by 9.3% compared to the control sample. According to the optimization results, the optimum sample moisture content is 22.847%, water activity 0.850%, fat 15.018%, specific gravity 82.737 cm3/g, hardness 10809 (N), spring content 0.747 cm and the amount of adhesion was determined to be 0.392.