title: Digestive enzymes in human milk: stability at suboptimal storage temperatures.
abstract: BACKGROUND
  Women who return to work outside of the home while still breastfeeding must often store the expressed milk at less than optimal temperatures. Human milk provides digestive enzymes (amylase and lipase) that compensate in the newborn for immature pancreatic function.
  
  
  METHODS
  We have assessed the stability of amylase and bile salt-dependent lipase after storage for 1-24 h at 15, 25, and 38 degrees C.
  
  
  RESULTS
  Both enzymes were stable at 15 and 25 degrees C for 24 h, whereas at 38 degrees C there was a 15 and 20% decrease in lipase and amylase activity, respectively. The stability of milk lipoprotein lipase was also tested. This very labile enzyme was more stable in milk than previously reported for blood and tissues, i.e., 20 and 50% decrease in activity after storage at 15 or 25 degrees C for 24 h, respectively. A two-unit drop in milk pH by 24 h of storage would not affect the activity of digestive enzymes, which are stable at pH > 3.5.
  
  
  CONCLUSIONS
  We conclude that milk provides the same compensatory digestive activity after short-term storage, even at relatively high temperature, as when fed fresh to the infant.
authors.affiliation: Department of Pediatrics, Georgetown University Medical Center, Washington, DC 20007, USA.
authors.forename: M
authors.initials: M
authors.lastname: Hamosh
authors.forename: T R
authors.initials: TR
authors.lastname: Henderson
authors.forename: L A
authors.initials: LA
authors.lastname: Ellis
authors.forename: J I
authors.initials: JI
authors.lastname: Mao
authors.forename: P
authors.initials: P
authors.lastname: Hamosh
mesh_terms: D000328:Adult; D000681:Amylases / Q000378:metabolism*; D004795:Enzyme Stability; D005260:Female; D006801:Humans; D006863:Hydrogen-Ion Concentration; D007774:Lactation; D008049:Lipase / Q000378:metabolism*; D008071:Lipoprotein Lipase / Q000378:metabolism; D008895:Milk, Human / Q000201:enzymology*; D013696:Temperature; D013997:Time Factors
chemical_list: D008049:Lipase; D008071:Lipoprotein Lipase; D000681:Amylases