Effects of pasteurization on osteopontin concentrations in human breastmilk

BACKGROUND: Osteopontin (OPN) is an important breastmilk protein involved in infant intestinal, immunological, and brain development. However, little is known about how common milk pasteurization and storage techniques affect this important bioactive protein. METHODS: Human milk osteopontin concentration was measured in single-donor fresh (n=1) or frozen (n=20) breastmilk, pooled Holder-pasteurized donor breastmilk (n=11), and a shelf-stable (retort pasteurized) breastmilk product (n=2) by ELISA. Single-donor breastmilk samples were subjected to pasteurization and/or freezing before measuring osteopontin concentrations. RESULTS: Holder pasteurization of breastmilk resulted in an similar to 50% decrease in osteopontin concentration within single-donorsamples. Breastmilk from mothers of preterm infants trended toward higher osteopontin concentration than mothers of terminfants; however, samples from preterm mothers experienced greater osteopontin degradation upon pasteurization. A commercial breastmilk product that underwent retort pasteurization had lower osteopontin concentration than a Holder-pasteurized pooledbreastmilk product. Finally, freezing breastmilk prior to Holder pasteurization resulted in less osteopontin degradation than Holderpasteurization prior to freezing.CONCLUSIONS:Commonly used breastmilk pasteurization and storage techniques, including freezing and Holder pasteurization,decrease the concentration of the bioactive protein osteopontin in human breastmilk. Holder pasteurization reduced osteopontinconcentration by an average of 63%, while freezing resulted in an 8-12% decrease.