17C-14 |
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D. NILUFER, Food Engineering Department, Istanbul Technical University, Maslak, Istanbul, 34469, Turkey and Y. Vodovotz, Dept. of Food Science & Technology, Ohio State Univ., 2015 Fyffe Ct., 227 Parker Food Science Bldg., Columbus, OH 43210-1007. Soy bread with its high content of soy protein, isoflavones and dietary fiber is a potential functional food. Increasing the amount of soy proteins has become important in industrial application, principally because of their health promoting and functional characteristics. Functional characteristics of soy protein ingredients are generally dependent on the methods used for their manufacture, storage, handling and use. The objective of the study was to determine the functionality of partly denatured and undenatured soy protein isolates added into soy bread during storage as compared to control soy bread and soy bread with soymilk powder. Two pound loaves of soy breads containing undenatured and partly denatured soy protein isolates (approximately 12% replacement of wheat flour) were produced and stored for 7 days in polyethylene bags. Control soy bread were prepared for comparison. Protein denaturation in soymilk powder was evaluated by differential scanning calorimetry, DSC. Physical measurements (water activity, loaf volume and height, color), chemical analysis (soluble and insoluble dietary fiber, protein, ash contents), thermal analysis (thermal gravimetric analysis TGA, DSC and dynamic mechanical analysis DMA) and mechanical analysis (firmness with Instron testing machine) were performed. Increased soy protein content in soybread decreased loaf volume with undenatured soy protein isolate resulting in the smallest loaf height. Moisture retention of soybreads containing soy protein isolate and soymilk powder was greater when compared with control soybreads. “Freezable” water contents of soymilk powder added soybread and partly denatured soy protein isolate soybread were more stable during storage as compared to control soybread. ”Unfreezable” water decreased in all formulations during storage. Amylopectin recrystallization for undenatured soy protein isolate and control soybreads was similar, whereas partly denatured soy protein isolate soybread had similar behavior to that of soymilk powder added soybread. DMA results indicated that stiffness increased with storage. Lighter crumb color was observed for samples with increased soy protein content. Soy protein addition to soy bread formulation had different effects on the bread quality depending on the protein denaturation of the ingredients.
Session 17C, Food Chemistry: Cereals, grains, legumes and their products
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