ABSTRACT
Introduction ........................................................................................................ 655
Materials and Methods ..................................................................................... 656
Results and Discussion ..................................................................................... 656
Water Sorption............................................................................................ 656
Glass-Transition Temperature.................................................................. 659
Nonenzymatic Browning.......................................................................... 659
Conclusions......................................................................................................... 661
References ........................................................................................................... 661
Maillard reaction can cause deterioration of dehydrated foods (Friedman,
1996). Stability of food and other biological systems containing sugars and/or
polymers is often related to their physical state (O’Brien, 1996). Studies ofNEB
kinetics have considered temperature, moisture content, water activity, pH,
concentration of reactants, etc., as controlling factors, and recently related to
crystallization and viscosity (Labuza and Braisier, 1992; Buera and Karel,
1995). The glass transition together with viscosity, material composition,
water activity, temperature, and other factors affect the rate of the reaction
through changes in molecular mobility. Crystallization of component sugars
may enhance the rate of an enzymatic reaction as a result of release of sorbed
water during the crystallization process (Cardona et al., 1997; Kouassi and
Roos, 2000). The crystallization of amorphous lactose in dehydrated milk
products has also been observed to result in acceleration of nonenzymatic
browning reactions, loss of lysine, as well as other deteriorative changes and
caking (Roos, 2001). The rate of crystallization depends on the composition of
food materials. Crystallization of lactose has been reported to be delayed by
trehalose (Mazzobre et al., 2001). The objective of the present work was to
study the nonenzymatic browning kinetics in lactose, trehalose, and lactose/
trehalose matrices, and to evaluate the effects of matrix composition and
component crystallization on NEB kinetics.
