Effects of glycerol and moisture gradient on thermomechanical properties of white bread
2001
Baik, M.Y. | Chinachoti, P.
The thermomechanical properties of breadcrumb were investigated using dynamic mechanical analysis (DMA) and differential scanning calorimetry (DSC). The main transition (T1, near 0 degrees C) shifted to lower temperature with added glycerol due to freezing point depression. The low-temperature transition (T3, approximately -50 degrees C), found only in high-glycerol (8.8%) bread, suggested that of excess or phase-separated glycerol. The high-temperature transition (T2, 60-85 degrees C) appeared only in aged breadcrumbs; its temperature range was correlated well with the amylopectin melting transition (DSC) but its tan delta amplitude did not correlate well with the amylopectin melting enthalpy (r2 = 0.72). On the other hand, the change of E" (viscous behavior) suggested that T2 might be related to the change in the amorphous region. Domain-to-domain (amorphous) and crumb-to-crust moisture migrations are two critical phenomenological changes associated with aging and could lead to significant local dehydration of some amorphous regions contributing to mechanical firming during storage.
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