Evaluation of Freeze-Drying, Pasteurization, High-Temperature Heating and Storage on Selected Enzymes, B-Vitamins and Lipids of Mature Human Milk

Abstract

The effects of freeze-drying, pasteurization, high-temperature heating and storage on key enzymes, B-vitamins and lipids of pooled mature human milk were determined. Freeze-drying significantly decreased (P<0.05) the activity of lactoperoxidase and lysozyme but had no effect on the lipase or protease of pooled human milk. Storage after freeze-drying destroyed lactoperoxidase activity but had no apparent effect on the other enzymes. Heating at 62.5°C for 30 min or 75°C for 15 min significantly decreased (P<0.05) the activities of lactoperoxidase, lipase and protease. Lysozyme was inactivated significantly only by heating at 75°C. Storage at −25°C following pasteurization had no significant effect on enzyme activity. Biotin, niacin and pantothenic acid appeared to be quite stable and were not significantly altered by freeze-drying, heating and/or storage. Similarly, there were no significant differences in lipid components following processing and storage.