Hot topic: Holder pasteurization of human milk affects some bioactive proteins.

The aim of this research was to investigate the effect of Holder pasteurization (HoP; 62.5°C, 30 min) on the protein profile and activities of glutathione peroxidase (GPx) and lysozyme (LZ) in human milk. Over 6 mo of lactation, human milk samples were analyzed before (raw) and after HoP for GPx and LZ activity and electrophoresis protein profile. Holder pasteurization reduced human milk lactoferrin, immunoglobulin fractions, and GPx activity. In addition, GPx activity, which is high in colostrum and transitional milk, was naturally reduced over the 6-mo lactation period. In contrast, HoP did not affect human milk LZ activity. Besides its critical cellular antioxidant role in protecting the organism from oxidative damage, GPx decreases the redox potential of milk, stimulating the growth of anaerobic microorganisms, such as the probiotic Bifidobacterium. Considering the role of lactoferrin in infant health, we conclude that an important part of its function has been inactivated by pasteurization. These compounds should be replaced by human milk banks after the HoP step to recover lost functionality. Otherwise, an alternative technology to HoP that better retains human milk properties should be used by milk banks to eliminate the risk of transmission of infectious agents.