33A-15 |
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D. NILUFER, Food Engineering Dept., Istanbul Technical Univ., 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. Increasing the dietary fiber content in bakery products has been shown to improve the water holding capacity and shelf-life properties yet some detrimental effects on bread quality may result. It is known that soluble and insoluble fiber have different characteristics, so their effects on the soy bread quality may vary. The objective of this study was to evaluate the effects of soluble and insoluble soy dietary fibers on the physical, chemical, mechanical and thermal properties of soy bread. Two pound loaf soy breads with 1% and 2% replacement of wheat flour with soluble soyfiber and insoluble soyfiber respectively, were produced and stored for 7 days in polyethylene bags. Also a control soy bread sample was prepared to compare the effects of the soyfiber ingredients. 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, differential scanning calorimetry DSC and dynamic mechanical analysis DMA) and mechanical analysis (firmness with Instron universal testing machine) were carried out. Highest loaf volume and peak height were obtained for breads made with added soluble fiber, whereas, insoluble fiber breads resulted in the smallest loaf volume and loaf height values. Water activity were similar for all formulations. “Freezable” water content was lowest in control soy bread but all formulations showed a decrease in “freezable” water content during storage. Insoluble fiber increased whereas soluble fiber decreased amylopectin crystallization during storage when compared to control soybread. From DMA results, it was observed that stiffness increased during storage. Firmness measured by Instron increased during storage in all formulations with the smallest increase observed for the soluble fiber added soybread. Lighter crumb color was obtained with dietary fiber ingredients when compared to control soybread. Enrichment of soy bread with soluble dietary fiber results in more acceptable soy bread with better keeping quality when compared to insoluble fiber added soy bread and control soy bread.
Session 33A, Carbohydrate: General
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