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.
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: D Handa; A F Ahrabi; C N Codipilly; S Shah; S Ruff; D Potak; J E Williams; M A McGuire; R J Schanler Journal: J Perinatol Date: 2014-10-02 Impact factor: 2.521
Authors: Amit A Somani; Kirstin Thelen; Songmao Zheng; Mirjam N Trame; Katrin Coboeken; Michaela Meyer; Katrin Schnizler; Ibrahim Ince; Stefan Willmann; Stephan Schmidt Journal: Br J Clin Pharmacol Date: 2015-10-30 Impact factor: 4.335