Glass Transition Properties and Quality Control of Food

Abstract

Low-moisture food products commonly show glass to rubber transition (glass transition) at the glass transition temperature (T_g), and their physical properties are changed drastically. Since the T_g of hydrophilic materials decreases with increasing water content because of water plasticizing effect. Consequently, it is of practical importance to understand effect of water content on the T_g of food products. In this article, glass transition properties and quality control of food products are explained. Effects of water and maltodextrin on the T_g of freeze-dried mango puree were investigated systematically using differential scanning calorimetry (DSC). The T_g of mango puree increased with an decrease in water content and an increase in maltodextrin content. This result will be useful for the physical stability control (e.g., collapse, caking, and sugar crystallization) of freeze-dried mango puree. Although cookie sample showed indistinct glass transition behavior in DSC thermosgram, thermal rheological analysis revealed a clear glass transition, and thus mechanical T_g of cookie sample was evaluated. The mechanical T_g of cookie increased and decreased by the addition of trehalose and sorbitol, respectively. This result will be useful for the texture control of cookie.