491. The effect of pre-heating milk at 230° F. (110° C) on the keeping quality of spray-dried whole milk

Abstract

1. Three samples of spray-dried whole milk were made from milk pre-heated at 190, 230° and 230° F. with regenerative cooling to 190° F., in an A.P.V. H.M. Paraflow Heat Exchanger and dried in a Kestner plant. The powders were packed in plain tin-plate cans and stored at 17, 37 and 47° C. The keeping quality of the powders was determined by examination at intervals for palatability, absorption of oxygen and peroxide value of the fat. The biological value and true digestibility of the protein of the powders were estimated in rat-feeding experiments initially and after 6 months' storage. The breadmaking properties of the powders were also examined.2. The keeping quality, biological and baking tests showed that the three milk powders were very much alike, and that no advantage was gained by raising the preheating temperature of the liquid milk from 190 to 230° F.