Chemistry of High Pressure Processing of Milk

Abstract

High Pressure Processing (HPP) is a novel non-thermal food processing technology in which the product is subjected to very high pressure (100-1000MPa) at or near room temperature. The process serves as an alternative to conventional thermal processing as the former eliminates the adverse effects of heat and keeps the sensory and nutritional attributes of the food fresh like. A myriad of chemical changes occurs when milk is subjected to HPP. The water content get compressed with a depression in freezing point, which allows sub-zero processing of the product without ice crystal formation. The fat globule membrane remains unaltered at lower pressures which increases in size with increasing pressures due to the adsorption of denatured and disrupted proteins. High pressure causes better crystallization of fat which improves the whipping quality and melting rate of cream and ice cream respectively. The casein micelles get disrupted due to solubilization of colloidal calcium phosphate (CCP) and denaturation of whey proteins occurs with maximum susceptibility to β lactoglobulin. Mineral balance of milk get affected due to pressurization with effect on both distribution between colloidal and soluble phase. Most of the indigenous milk enzymes are barotolerant[DB1]  exhibiting different degrees of resistance to pressure. Little or no significant changes are observed in the lactose content. The varied physico-chemical and sensory properties obtained using the HPP offer exciting opportunities for the dairy industry

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