Relation of the Temperature of Separation and the Heat Treatment Given the Skim Milk to the Keeping Quality of Spray Dried Ice Cream Mix

Abstract

Summary Twelve batches of dried ice cream mix were made from the same lot of milk. The milk was separated at various temperatures to secure cream and skim milk containing various amounts of agglutinin. The skim milk was forewarmed at both low and high temperatures and condensed in a stainless steel vacuum pan. Some of the cream was made into butter and butter oil. Dried ice cream mixes were made from these ingredients so that the relation of the heat treatment given the serum solids to the keeping quality could be studied. The carbon dioxide content of the headspace gas varied throughout the storage period. Oxygen concentration gradually became lower as the storage period advanced. There was a tendency toward more rapid oxygen absorption, more carbon dioxide evolved, and more oxidized flavor development in mixes that had the condensed skim milk forewarmed to 150° F. for 20 minutes than in those mixes that had the condensed skim milk forewarmed at 180° F. for 5 minutes. There seemed to be no significant differences in oxidized flavor development when the mixes were prepared from concentrated skim milk made from skim milk separated at 55° or 130° F. Whether the fat used was in the form of cream, butter or butter oil was not a factor influencing the keeping quality of the dried ice cream mix. All the batches became oxidized which contained butter oil, butter or cream which were made with skim milk forewarmed at 150° F. for 20 minutes. After one year dried mixes made from skim milk forewarmed. at 180° F. for 5 minutes had not developed an oxidized flavor and were still highly palatable. High forewarming temperature, on the skim milk before condensing is beneficial in prolonging the keeping qualities of dried, ice cream mixes and the retardation of oxidized flavor development.