母乳喂养与职业母亲：短期储存时间和温度对母乳中蛋白质水解、脂肪水解及细菌生长的影响

Breastfeeding and the working mother: effect of time and temperature of short-term storage on proteolysis, lipolysis, and bacterial growth in milk.

作者信息

Hamosh M, Ellis L A, Pollock D R, Henderson T R, Hamosh P

机构信息

Department of Pediatrics and Physiology and Biophysics, Georgetown University Medical Center, Washington, DC 20007, USA.

出版信息

Pediatrics. 1996 Apr;97(4):492-8.

PMID:8632934

Abstract

BACKGROUND

Women who breastfeed have to store expressed milk while at work for later feeding to their infants; however, storage conditions are often not optimal.

OBJECTIVE

Top assess microbial growth and stability of milk protein and lipid at 15 degrees C to 38 degrees C for up to 24 hours.

METHODS

Sixteen healthy women who breastfed exclusively, either at home (n=11) or who expressed milk for their infants (n=5), were studied during early (1 month) or late (5 to 6 months) lactation. Expressed milk was stored at 15 degrees C, 25 degrees C, and 38 degrees C for 1 to 24 hours for quantitation of pH, proteolysis, and lipolysis; bacterial growth was quantified at 0, 4, 8, and 24 hours of storage.

RESULTS

Milk pH decreased 2 units by 24 hours of storage at all temperatures tested. Proteolysis was minimal during milk storage at 15 degrees C or at 25 degrees C for 24 hours and was apparent only after 24 hours of storage at 38 degrees C. Lipolysis was rapid, starting in the first hours of storage and progressing to 8% at 24 hours. Thus, while the greatest increment in proteolysis products was a 40% increase above baseline after 24 hours of storage at 38 degrees C, free fatty acid concentration at this storage time was 440% to 710% higher than in freshly expressed milk. Bacterial growth was restricted mainly to nonpathogens, was minimal at 15 degrees C throughout the 24 hours of storage, was low at 25 degrees C for the first 4 to 8 hours, and was considerably higher at 38 degrees C even during the relatively short period of 4 hours.

CONCLUSIONS

Storage of human milk is safe at 15 degrees C for 24 hours, whereas at 25 degrees C it is safe for 4 hours. Milk should not be stored at 38 degrees C. Minimal proteolysis during storage suggests that milk proteins probably maintain their structure and function during short-term storage, while the marked lipolysis might slow bacterial growth during this time.

摘要

背景

母乳喂养的女性在工作时必须储存挤出的母乳，以便日后喂养婴儿；然而，储存条件往往并不理想。

目的

评估母乳在15摄氏度至38摄氏度下长达24小时期间微生物的生长情况以及乳蛋白和脂质的稳定性。

方法

对16名纯母乳喂养的健康女性进行研究，其中11名在家母乳喂养，5名给婴儿挤出母乳。研究在泌乳早期（1个月）或晚期（5至6个月）进行。将挤出的母乳分别储存在15摄氏度、25摄氏度和38摄氏度下1至24小时，以测定pH值、蛋白水解和脂肪水解情况；在储存0、4、8和24小时时对细菌生长进行定量。

结果

在所有测试温度下，储存24小时后母乳pH值下降2个单位。在15摄氏度或25摄氏度下储存24小时期间，蛋白水解作用极小，仅在38摄氏度下储存24小时后才明显。脂肪水解迅速，在储存的最初几个小时就开始，到24小时时达到8%。因此，虽然在38摄氏度下储存24小时后蛋白水解产物的最大增幅比基线高出40%，但此时游离脂肪酸浓度比刚挤出的母乳高440%至710%。细菌生长主要局限于非病原体，在15摄氏度下储存24小时期间极少，在25摄氏度下最初4至8小时较低，而即使在相对较短的4小时内，38摄氏度下的细菌生长也明显更高。