Effects of high-pressure processing on immunoglobulin A and lysozyme activity in human milk

Banked human milk, processed using low-temperature/long-time or Holder pasteurization, inactivates pathogenic microorganisms but degrades important biochemical components. High-pressure processing kinetics favor inactivation of microorganisms with retention of biochemical activity and nutritional quality of foods. The effects of high-pressure processing (400 MPa) and low-temperature/long-time pasteurization (62.5 degrees C, 30 minutes) on total immunoglobulin A and lysozyme activity in human milk were investigated. Indirect modified enzyme-linked immunosorbent and a Micrococcus lysodeikticus turbidimetric assay were performed to measure immunoglobulin A immunoactivity and lysozyme activity, respectively. Pressure-treated samples retained significantly higher (P < .05) levels of immunoglobulin A and lysozyme activity compared to samples treated with low-temperature/ long-time pasteurization. These data suggest that high-pressure processing is a potential alternative to thermal pasteurization of human milk that can give greater retention of some bioactive components. Further research is needed to determine whether high-pressure processing can inactivate pathogens of concern in donor human milk.