Human milk is the most suitable food for newborns,and is greatly beneficial to the health and growth of infants.In some circumstances,human milk need cold storage,but freezing/cooling storage will inevitably cause the loss of components in human milk.The most reasonable storage condition of human milk has not reached an agreement.This article focuses on the change of macronutrients,immune substance and microbial indicators of human milk which had been cold storaged,and summarizes the related researchs of home and abroad in recent years.

Objective To explore the optimal storage standard of fresh human milk, and to observe the influence of different cold storage condition (time-temperature) on macronutrients (fat, protein, carbohydrates, TS and energy), immune sub-stances (sIgA, lactoferrin, IL-6, 8, 10 and TNF-α) and bacteria indicators of fresh human milk.Methods Fresh milk samples (n=30) were divided and stored at three temperature and nine time points, which are 4℃ (24 h, 48 h, 72 h), -18℃(72 h, 7 d, 14 d, 4 w, 8 w, 12 w), and -80℃ (12 w, 24 w). At each time point, the macronutrients , immune substance, and bacteria colony counts of each milk sample were measured and compared with fresh milk. Results Compared with fresh milk, all indicators with the exception of lactoferrin in stored human milk showed signiifcant difference (P<0.05). Under 4℃ refrigeration condition, fat, IL-6, and TNF-α decreased, bacteria colony counts and Gram-positive colony counts increased over 72 h storage (P<0.05). Under-18℃ freezing condition, fat, protein, TS, energy and IL-6 decreased from 72 h to 12 w storage (P<0.05); carbohydrates and sIgA also decreased from 4 w and 8 w storage, respectively (P<0.05). Under -80℃ freezing condition, fat, protein, TS, energy and IL-6 decreased over 24 W storage (P<0.05).Conclusions The macronutrients, immune substance, and bacteria indicators of human milk were affected obviously by cold storage. Refrigerated at 4℃ should not be longer than 72 h, -80℃ freezing condition should be chosen for more than two months storage.