粉体食品の吸湿特性

抄録

For dehydrated powdered food, hygroscopicity should be considered important for preventing the powder from caking, the food from becoming insoluble or off-flavour and for deciding proper mode of packing. Measurements are made on sorption isotherm of many kinds of powered food by the spring balance method with the following results.
1. Sorption isotherm of most of the food is of sigmoid type. Water content per molecular layer calculated by B. E. T equation seems to be the limit for safe storage. But for those food for which B. E. T. plots are not linear, water content can be higher.
2. B. E. T. plot of dry skim milk of 35% protein, 53% lactose and others deviates from linearity above 35°C. From Harkins-Jura equation, it is found that, as the temperature rises, the water molecules, even when the water content is low, remain condensed state, probably because of particular hygroscopicity of lactose.