NON‐ENZYMATIC BROWNING OF HYGROSCOPIC WHEY POWDERS IN OPEN VERSUS SEALED POUCHES

The moisture sorption behavior and non‐enzymatic browning of hygroscopic whey powders stored in open and sealed conditions were examined. The water released from crystallization of the amorphous lactose in the whey powders was entrapped within sealed pouches, resulting in an increased local moisture content as well as a_w for products initially humidified in the 0.33 to 0.44 range before packaging. Thus, the rate of non‐enzymatic browning reaction during storage at 35° was greatly increased in the sealed samples compared to samples stored open to the environment. In fact, at 0.33 a_w a maximum was observed for the sealed storage samples, while a minimum was shown in the open stored samples. Because of this, precautions should be taken in using the results of storage studies of open systems to predict kinetics of deteriorative reactions during shelf‐life tests of sealed food systems, especially if amorphous to crystalline change can occur.