The effects of heating rate, storage temperature and water activity on surface caking (Tsc) and advanced caking (Tac) of several dairy‐based infant formula powders were determined by the modified ampule and sealed glass test tube methods, respectively. The glass transition temperature, Tg, was determined by differential scanning calorimetry. Observed Tsc and Tac values were higher at faster scan rates (5 and 10°C/min) compared to a slower heating rate (1°C/3 min). In addition, because of the sample size and the difference in viscous flow time constants, Tac≥ Tsc≥ Tg. As expected, stability towards collapse and sticking decreased with Increasing amounts of low‐molecular‐weight carbohydrate. The predicted stable storage water activities at room temperature based on Tsc were higher than those observed during storage; however, the water activity at which Tstarage= Tg gave a good prediction of the %RH when collapse begins.
|Original language||English (US)|
|Number of pages||4|
|Journal||Journal of food science|
|State||Published - Jan 1994|
- glass transition
- infant formula