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Breastfeeding and the working mother: effect of time and temperature of short-term storage on proteolysis, lipolysis, and bacterial growth in milk.
Pediatrics 1996; 97(4):492-8Ped

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.

Authors+Show Affiliations

Department of Pediatrics and Physiology and Biophysics, Georgetown University Medical Center, Washington, DC 20007, USA.No affiliation info availableNo affiliation info availableNo affiliation info availableNo affiliation info available

Pub Type(s)

Journal Article
Research Support, Non-U.S. Gov't
Research Support, U.S. Gov't, Non-P.H.S.

Language

eng

PubMed ID

8632934

Citation

Hamosh, M, et al. "Breastfeeding and the Working Mother: Effect of Time and Temperature of Short-term Storage On Proteolysis, Lipolysis, and Bacterial Growth in Milk." Pediatrics, vol. 97, no. 4, 1996, pp. 492-8.
Hamosh M, Ellis LA, Pollock DR, et al. Breastfeeding and the working mother: effect of time and temperature of short-term storage on proteolysis, lipolysis, and bacterial growth in milk. Pediatrics. 1996;97(4):492-8.
Hamosh, M., Ellis, L. A., Pollock, D. R., Henderson, T. R., & Hamosh, P. (1996). Breastfeeding and the working mother: effect of time and temperature of short-term storage on proteolysis, lipolysis, and bacterial growth in milk. Pediatrics, 97(4), pp. 492-8.
Hamosh M, et al. Breastfeeding and the Working Mother: Effect of Time and Temperature of Short-term Storage On Proteolysis, Lipolysis, and Bacterial Growth in Milk. Pediatrics. 1996;97(4):492-8. PubMed PMID: 8632934.
* Article titles in AMA citation format should be in sentence-case
TY - JOUR T1 - Breastfeeding and the working mother: effect of time and temperature of short-term storage on proteolysis, lipolysis, and bacterial growth in milk. AU - Hamosh,M, AU - Ellis,L A, AU - Pollock,D R, AU - Henderson,T R, AU - Hamosh,P, PY - 1996/4/1/pubmed PY - 1996/4/1/medline PY - 1996/4/1/entrez SP - 492 EP - 8 JF - Pediatrics JO - Pediatrics VL - 97 IS - 4 N2 - 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. SN - 0031-4005 UR - https://www.unboundmedicine.com/medline/citation/8632934/Breastfeeding_and_the_working_mother:_effect_of_time_and_temperature_of_short_term_storage_on_proteolysis_lipolysis_and_bacterial_growth_in_milk_ L2 - http://pediatrics.aappublications.org/cgi/pmidlookup?view=long&pmid=8632934 DB - PRIME DP - Unbound Medicine ER -