Glass transition temperature of regular and lactose hydrolyzed milk powders

The glass transition temperatures (T-g) of lactose hydrolyzed milk powder (HMP) was determined and compared to that of regular milk powders (MP). Some physical and chemical changes (loss of flowing ability, browning development) were also evaluated during storage of the different milk powders. Sugars of HMP (glucose, galactose, lactose) influenced, but did not define, the T-g values of the product, on the contrary lactose governed the observed T-g values of NIP samples. Changes in the flowing characteristics of milk powder and color development, stored at different water activity values, were much more evident in HMP than in regular milk powder. Results suggested that the T-g value is not the unique parameter governing the flowability and color development in stored milk powders. (C) 2003 Swiss Society of Food Science and Technology. Published by Elsevier Science Ltd. All rights reserved.