Influence of lactose pre-crystallization on the storage stability of infant formula powder containing lactose and maltodextrin

The effect of different proportions of pre-crystallized lactose (PCL; 0-31%) on the physico-chemical properties of fresh and aged infant formula (IF) containing lactose and maltodextrin was investigated. Fresh powders with a higher proportion of PCL had a larger particle size and higher surface free fat and water activity (a(w)). Powders with 7-24% PCL showed a lower rate of increase in a(w) and lactose crystallinity during storage at RH 54% compared to the control. A(w) correlated linearly with the glass transition temperature (T-g) and the relative effect of storage temperature on T-g was lower in samples with 7-24% PCL at RH 33%. Significantly (p < 0.05) lower surface free fat, particle size and color changes were observed in samples with 18-24% PCL under all ageing conditions (RH 11-54% and 25-45 degrees C). The presence of maltodextrin was found to work in conjunction with PCL to improve physicochemical properties and storage stability of IF powders.