Maintenance of breast milk immunoglobulin A after high-pressure processing

Human milk is considered the optimal nutritional source for infants. Banked human milk is processed using low-temperature, long-time pasteurization, which assures microbial safety but involves heat denaturation of some desirable milk components such as IgA. High-pressure processing technology, the subject of the current research, has shown minimal destruction of food macromolecules. The objective of this study was to investigate the influence of pressure treatments on IgA content. Moreover, bacterial load was evaluated after pressure treatments. The effects of high-pressure processing on milk IgA content were compared with those of low-temperature, long-time pasteurization. Mature human milk samples were heat treated at 62.5°C for 30min or pressure processed at 400, 500, or 600MPa for 5min at 12°C. An indirect ELISA was used to measure IgA in human milk whey obtained after centrifugation at 800×g for 10min at 4°C. All 3 high-pressure treatments were as effective as low-temperature, long-time pasteurization in reducing the bacterial population of the human milk samples studied. After human milk pressure processing at 400MPa, 100% of IgA content was preserved in milk whey, whereas only 72% was retained in pasteurized milk whey. The higher pressure conditions of 500 and 600MPa produced IgA retention of 87.9 and 69.3%, respectively. These results indicate that high-pressure processing at 400MPa for 5min at 12°C maintains the immunological protective capacity associated with IgA antibodies. This preliminary study suggests that high-pressure processing may be a promising alternative to pasteurization in human milk banking.