The kinetics of Maillard reaction in lactose-hydrolysed milk powder and related systems containing carbohydrate mixtures.

The kinetics of Maillard reaction in lactose-hydrolysed skim milk powder and related systems containing carbohydrate mixtures were analysed. The effect of the increase of water activity and temperature during storage of the commercial product was also evaluated. In systems with two and three carbohydrates, a marked decrease of the reaction rate was observed when monosaccharides were partially replaced by lactose, notwithstanding the fact that the former still remained in a higher proportion than lysine. The rate of available lysine loss in lactose-hydrolysed milk was mostly affected by the presence of galactose. The reaction rate constants at aw 0.52 and at 37 and 50 °C were higher than at aw 0.33. However, no significant differences were observed at 60 °C. Temperature is the most important factor to be controlled in order to minimise nutritional deterioration during storage.