Heat induced changes in casein

Payal Karmakar

Abstract

In current times, dairy sectors involve milk being always subjected to heat treatment; main examples are: high temperature-short time (72 ˚C × 15 sec) pasteurization, low temperature-long time pasteurization (65 ˚C × 30 min), ultra-high temperature sterilization (140 ˚C × 5 sec), thermization (65 ˚C × 15 sec), in-container sterilization (112 ˚C × 15 min). Calcium chelators are, however, capable of increasing the heat stability of milk. Milk is considered to be quite a heat – stable system but, on heating, some chemical and physicochemical changes do occur in milk. These modifications include: denaturation of whey proteins, non-enzymatic (Maillard) browning, damage to the creaming properties, degradation of lactose to lactulose and acids, and after severe heat treatment, hydrolysis of the caseins, dephosphorylation and eventually heat-induced coagulation. In this article, the effect of heating on casein (when subjected to different temperature ranges) has been discussed. The changes in structures and functionalities of casein are also covered here.

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