Heat Stability Characteristics of Porcine milk and mixed Porcine-bovine milk systems

Abstract

Abstract Porcine milk was much more heat labile than bovine milk and did not exhibit the Type A or Type B heat coagulation time (HCT)-pH profiles typical of bovine milk. Porcine milk had a higher buffering index than bovine milk, which was attributed to the higher level of colloidal calcium phosphate (CCP). The buffering maximum of bovine milk shifted from ∼pH 5.1 to ∼pH 4.4 upon heating, probably due to the precipitation of soluble calcium phosphate (SCP). In contrast, the buffering maximum of porcine milk did not shift upon heating, as the milk contained insufficient SCP to increase the buffering peak at ∼pH 4.4 to greater than that at pH 5.1. Removal of greater than 85% of the CCP from porcine milk converted the HCT-pH curve to that of a Type A bovine milk. Non-micellar porcine casein was relatively heat stable, but porcine casein micelles per se were very heat sensitive, due to their high levels of CCP and/or due to their high sensitivity to heat precipitated calcium phosphate. Redispersion of porcine casein micelles in porcine or bovine permeate, or dialysis of porcine milk against water or its dilution with water, did not increase heat stability. A slight maximum appeared in the HCT-pH curve of porcine casein micelles dispersed in bovine serum, although the system was still very heat labile.