Lipase exposed to CO(2) (under atmospheric pressure) treatment at different pH and temperature conditions showed a decrease in enzyme activity. Inactivation was found to be highest as the temperature increased from 20 to 50 degreesC at initial pH 7.15. About 84% of the initial activity of the enzyme is lost at initial pH 7.15 and 50 degreesC. The faster drop in pH and enzyme activity occurred within 5 min. Without CO(2), no significant change (P > 0.05) was observed in activity at the highest temperature (50 degreesC). The pH drop and loss in enzyme activity were higher at initial pH 8.20. No changes in enzyme activity and pH were observed when nitrogen gas was applied instead Of CO(2). Studies using gel electrophoresis showed no differences in protein patterns between CO(2)-treated and non-treated control. After 6 weeks of frozen storage, no changes in pH and activity were observed for CO(2)-treated lipase solution. (C) 2002 Elsevier Science Ltd. All rights reserved.