PHYSICAL AND MICROSCOPIC CHARACTERIZATION OF DRY WHOLE MILK WITH ALTERED LACTOSE CONTENT .2. EFFECT OF LACTOSE CRYSTALLIZATION

The purpose of this study was to investigate the effect of lactose crystallization on the structural characteristics of spray-dried whole milk powders with altered lactose concentration. Two methods of powder preparation (conventional spray drying and postdrying crystallization) and four nominal lactose concentrations (0, 30, 50, and 70%) were considered. Postdrying crystallization of lactose by exposure to high relative humidity increased free fat content and particle density, reduced surface area and vacuole volume, formed new pores, and caused particle accretion.