DIGESTIVE ENZYMES IN HUMAN-MILK - STABILITY AT SUBOPTIMAL STORAGE TEMPERATURES

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 comp ensate in the newborn for immature pancreatic function. Methods: We ha ve assessed the stability of amylase and bile salt-dependent lipase af ter storage for 1-24 h at 15, 25, and 38 degrees C. Results: Both enzy mes 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, res pectively. The stability of milk lipoprotein lipase was also tested. T his very labile enzyme was more stable in milk than previ ously report ed 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 digesti ve enzymes, which are stable at pH >3.5. Conclusions: We conclude that milk provides the same compensatory digestive activity after short-te rm storage, even at relatively high temperature, as when fed fresh to the infant.