Physical Factors Influencing the Formation and Fat Content of Gravit Cream

Abstract

The rate of creaming of milk, the depth of the cream layer, and the fat content of the cream and skim milk in gravity creaming have been the subjects for a large number of investigations. It has been shown that various treatments markedly affect the creaming of milk and since many of these treatments also produced other accompanying changes in the milk the conclusion, frequently, has been drawn that a causal relation existed between the creaming of milk and some of the accompanying phenomenon, when actually this was not the case. Arnold (1) believed that as the milk cooled rapidly the fat did not cool as fast as the plasma, and that therefore cooling produced a great difference in density and caused the cream to rise. Babcock (2) was the first to call attention to the clumped condition of the fat globules in normal raw milk but he then concluded that clumping tended to prevent cream from rising, Woll, Babcock and Russell (40) and Hammer (15) however associated the clumping of fat globules with creaming. The clumping of fat globules as it influences creaming was specifically studied by Rahn (28) van Dam and Sirks (33) Hekma and Sirks (19) Sirks (31) Brouwer (6) and Hekma (18) who came to the conclusion that normal gravity cream was obtained only when the fat globules were clumped. On the other hand Palmer and Anderson (26) and Palmer, Hening and Anderson (27) have presented the results of experiments which they interpret as