The effect of freeze-drying and storage on lysozyme activity, lactoferrin content, superoxide dismutase activity, total antioxidant capacity and fatty acid profile of freeze-dried human milk
Dorota Martysiak‐Żurowska, Patrycja Rożek, Małgorzata Puta
Abstract
Pooled human milk samples were freeze-dried and stored for 6 weeks at a temperature of 5 °C and 25 °C. Freeze-drying decreased the water content of milk by 86.5%, and the obtained lyophilizate was readily soluble in water. The freeze-drying process did not affect superoxide dismutase (SOD) activity, fatty acid (FA) profile or lactoferrin (LF) content, but it decreased total antioxidant capacity (TAC) of human milk by 22.1% and induced a minor increase in lysozyme (LZ) activity, by approximately 9.8%. Storage of freeze-dried milk did not show significant influence on TAC, LF, FA and LZ levels, while after six weeks of storage SOD activity decreased by around 27% relative to the level noted immediately after lyophilization. These findings and the remaining state of knowledge imply, that freeze-drying can be a useful method of human milk storage.HighlightsLyophilization does not significantly affect the level of SOD and LF of human milk.In freeze-dried milk, bioactive substances: TAC level, LF, FA and LZ, remain stable even at room temperature.During storage of freeze-dried milk SOD activity decreases significantly.