Dynamic Mechanical Analysis for Glass Transitions in Long Shelf-Life Bread

Dynamic Mechanical Analysis (DMA) showed three thermal transitions in meal, ready-to-eat (MRE) bread, resulting in various degrees of change in the viscoelastic property. The moisture-dependent transition at an extremely low temperature (-90°C to – 50°C) was due to humcctants added, while that at a higher temperature T1 was possibly due to ice melting and the polymer components. T1 increased from ～?10°C at 29% moisture to ～ 150°C as moisture decreased to 2%. This correlated with hardening of the sample. A moisture independent transition at ～ 10-15°C by DMA was identified as a melting process of lipids (shortening). During storage, the magnitude of tan 8 peak decreased but its peak temperature did not change. No evidence of any network could be observed by DMA throughout 3 yr storage.