PHYSICAL AND MICROSCOPIC CHARACTERIZATION OF DRY WHOLE MILK WITH ALTERED LACTOSE CONTENT .1. EFFECT OF LACTOSE CONCENTRATION

The microstructures of spray-dried whole milk powders with 0, 27, 38, 48, 58, and 67% lactose were evaluated. Delactosed milk concentrates were prepared by ultrafiltration and diafiltration, and the lactose concentration in the powders was adjusted by addition of lactose to the spray-dried feed. Milk powder particles with 0% lactose had a more porous matrix with deep dents and wrinkles; lower true and apparent particle densities; and larger median diameter, vacuole volume, surface area, and free fat content. Higher lactose concentrations produced nearly spherical particles with a less porous matrix; higher true and apparent particle densities; and smaller median diameter, vacuole volume, surface area, and free fat content. Whole milk powder with modified lactose content may have potential in the manufacture of milk chocolate.