Dehydration, freezing, extrusion, baking, confectionary and numerous other food industries benefit from materials science characterization as it gives a fundamental advantage to understanding processing and product requirements. Noncrystalline components in final products often provide structural support and associated textural and other sensory properties. Glass transition of many food components is known to result in dramatic changes in structural relaxation times leading to failures for example in drying, freezing, and extrusion processes. On the other hand, relaxation times variation as controlled by water plastizisation may determine product shelf life, sensory experience, digestibility and nutrients release. Glass transition temperatures, Tg, as measured by differential scanning calorimetry of food components at various water contents with resultant state diagrams are useful for locating critical processing and storage conditions. More detailed description of structural relaxation times around glass transition with effects of water and product formulation, however, are needed in translating structural relaxation times data for understanding critical kinetic phenomena and acceptable processing and storage conditions. We have developed tertiary state diagrams and also adopted the Williams-Landel-Ferry (WLF) relationship [log τ/τg= -C1(T-Tg)/C2+(T-Tg)] with material specific constants (C1 and C2; Figure 1) as derived from experimental dynamic mechanical analysis and dielectric analysis to determine strength, S, values as acceptable temperature difference to Tg. Data for miscible and immiscible components in formulations show significant differences in S. S values and modified WLF plots as well as tertiary state diagrams provide new tools for understanding water relationsips in foods, and processing and product characteristics.

Approaches for stucture-properties-performance translation of relaxation times data around glass transition

255th National Meeting (2018)

The official archive and repository for all ACS Meetings & Expositions abstracts and select posters or presentations.