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.

• Highlights

• Lyophilization 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.

摘要

将合并的母乳样品冷冻干燥并在 5°C 和 25°C 的温度下储存 6 周。冷冻干燥使牛奶的含水量降低了86.5%，得到的冻干物易溶于水。冷冻干燥过程不影响超氧化物歧化酶 (SOD) 活性、脂肪酸 (FA) 谱或乳铁蛋白 (LF) 含量，但它使母乳的总抗氧化能力 (TAC) 降低了 22.1%，并导致溶菌酶略有增加(LZ) 活动，减少约 9.8%。冻干奶的储存对 TAC、LF、FA 和 LZ 水平没有显着影响，而在储存六周后，SOD 活性相对于冻干后立即注意到的水平下降了约 27%。这些发现和剩余的知识状态表明，冷冻干燥可能是一种有用的母乳储存方法。

• 强调

• 冻干不会显着影响人乳中的 SOD 和 LF 水平。

• 在冻干乳中，生物活性物质：TAC 水平、LF、FA 和 LZ 即使在室温下也保持稳定。

• 在冻干牛奶的储存过程中，SOD 活性显着降低。