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 w ere prepared by ultrafiltration and diafiltration, and the lactose con centration in the powders was adjusted by addition of lactose to the s pray-dried feed. Milk powder particles with 0% lactose had a more poro us matrix with deep dents and wrinkles; lower true and apparent partic le 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 apparen t particle densities; and smaller median diameter, vacuole volume, sur face area, and free fat content. Whole milk powder with modified lacto se content may have potential in the manufacture of milk chocolate.