61A-49 |
Effect of soy on bread’s physico-chemical properties during storage |
Y. C. ZHANG1, J. R. Sachleben1, and Y. Vodovotz. (1) Dept. of Food Science & Technology, Ohio State Univ., 110 Parker FS&T Bldg., 2015 Fyffe Rd., Columbus, OH 43210 The addition of soy ingredients to bread can improve protein quality of the product. More recently, research has shown that soy contains isoflavones which may act against human cancer development. Few of these products are on the market since soy causes a significant decrease in loaf volume and acceptability. A better understanding of the physico-chemical changes in such breads, especially during storage, may lead to acceptable formulations. The objective of this work was to compare the physical states of whole wheat and soy breads and their components during storage. Wheat and soy breads were stored in polyethylene bags at room temperature for up to 10 days. The state of bread and its components was analyzed by Dynamic Mechanical Analysis (DMA) and Differential Scanning Calorimetry (DSC). Additionally, solid state 13C NMR spin lattice relaxation time (T1) was analyzed for changes in the carbon-chain motion. Both soy and wheat breads showed a major transition around 0 °C (DMA) attributed largely to ice melting (DSC). Additionally, a transition around 60 °C (DSC) was attributed to amylopectin recrystallization and was seen to increase at a much greater rate for wheat bread than for soy bread upon storage. DMA tan delta and storage modulus results showed an additional small transition for soy bread around –30 °C spanning 20 °C attributed partially to glassy to rubbery transition. For fresh soy bread the T1 (Carbon 6) was 0.53 sec and showed a single-phase relaxation while aged bread T1 (Carbon 6) was found to best fit a two-phase relaxation (7.9 sec and 0.18 sec), indicating a greater homogeneity after storage. Wheat bread showed the opposite trend with similar T1 values. A similar trend was observed by DMA. Addition of soy to bread changed the physical state of the bread polymers and seemed to decrease the deleterious effects of storage.
Session 61A, Carbohydrate
|