LAUSR

Abstract Heat treatments are used extensively in the dairy industry, primarily to inactivate bacteria but also to inactivate enzymes that can cause detrimental effects. In addition, some enzymes have attracted attention as markers of particular heat processes. The current knowledge of the effects of different heat treatments on the various enzymes in milk, both indigenous and endogenous (bacterial), has been gained from extensive investigations over many years. This review collates the published information on the heat stability of 23 indigenous and two bacterial enzymes of significance in the dairy industry. The indigenous enzymes show a wide range of heat stabilities with most being totally inactivated in the range 70–100 °C and the remainder requiring higher-temperature treatments for total inactivation. Many of the bacterial enzymes show higher heat stability than all the indigenous enzymes and are not inactivated by even the most intense heat treatments used in the dairy industry.