Heat inactivation of superoxide dismutase in bovine milk.

Superoxide dismutase, and enzyme normal to bovine milk, may be inactivated partially by heat during processing of milk and milk products. A minimal pasteurization temperature (71.7 C for 15 s) does not cause heat inactivation of superoxide dismutase. Higher temperature of pasteurization or systems including a 'vac-heat process' will inactivate a substantial portion of the enzyme. Heat treatments greater than 75 C inactivated more than 20% of the superoxide dismutase. Purified superoxide dismutase fractionated from bovine milk was more sensitive to thermal processing than the superoxide dismutase in bovine milk serum.