Effect of heating on the distribution of transforming growth factor-β2 in bovine milk

The objective of this study was to characterize the impact of heat treatments on the distribution of transforming growth factor-beta (TGF-beta 2) between cream and skim milk and between the casein and whey fractions of skim milk. Skimming removed 45% and 62% of the TGF-beta 2 from raw and pasteurized milks and only 8% of the total TGF-beta 2 in skimmed pasteurized milk was found in whey, compared to 37% in whey from raw skimmed milk. The TGF-beta 2 content of whey decreased as the heat treatment of the milk increased in intensity (thermization > pasteurization > UHT sterilization). Using milk held for 1 or 2 min at temperatures ranging from 57 to 84 degrees C, it was shown that TGF-beta 2 in the whey portion decreases at temperatures above 66 degrees C and becomes undetectable at temperatures higher than 76 degrees C. Altogether, these data on the heat-induced changes in TGF-beta 2 content of cream, skim milk, casein and whey reveal a potentially negative impact of certain heat treatments in developing TGF-beta 2-enriched fractions from milk. (C) 2010 Elsevier Ltd. All rights reserved.