Heat stability of forewarmed milks: influence of κ-casein, serum proteins and divalent cations

Summary Addition of isolated κ-casein to milk reduced the destabilizing influence of forewarming, while the addition of isolated β-lactoglobulin (β-lg) to the κ-casein-enriched systems resulted in a loss in stability on forewarming. This effect was ascribed mainly to a β-lg:κ-casein interaction. Some individual milks were unaffected by forewarming while others were markedly destabilized by the same treatment. Addition of Ca2++ Mg2+and interchanging of milk sera by dialysis influenced stability. It is concluded that milks which are destabilized by forewarming generally give a type A response (minimum in the pH–heat stability curves) and that preheat-stable milks generally give a type B curve (no minimum).