Rennet-whey cream

Reported values for the interfacial tension between milk and air vary from 40 to 60 Nm-1, with an average of about 52 Nm-1 at 20°C (Singh, McCarthy and Lucey, 1997). At 20-40°C, the interfacial tension between milk serum and air is about 48Nm-1 while that between sweet cream, buttermilk and air is about 40Nm-1 (Walstra and Jenness, 1984). Surface tension values for rennet whey, skim milk and 25% fat cream are reported to be 51-52, 52-52.5 and 42-45Nm-1, respectively (Jenness and Patton, 1959). 

Although the gelation properties of whey proteins are of great importance in many foods (Mulvihill, 1992) and it is possible to form a weak gel in creams by the formation of a continuous network of fat globules, most important milk gels are those involving casein micelles which can be made to form a gel matrix either by isoelectric precipitation (acid-induced gel) or by the action of a proteolytic enzyme (rennet-induced gel). Both gel types... 

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