Loss of antioxidant function in donor human milk after holder pasteurization: a pilot study

Human milk is considered the best food for infants. In certain instances, such as feeding premature babies, or babies with diseases requiring hospitalization, donor human milk (DHM) is used where mother's own milk is unavailable. DHM collection, treatment, frozen storage and distribution is managed by human milk banks, under strict Government regulations. Part of this process involves Holder pasteurization (HoP) of HM, which has been practiced for decades and is essential to ensure microbiological safety. However, HoP treatment also impacts on the nutritional and biological properties of HM. This study investigated the impact of HoP on the antioxidant properties of human milk (HM), focusing on its effects on free radical scavenging and metal ion chelation determined in vitro using standard biochemical assays on eight individual HM samples. The findings indicated that HoP significantly alters the antioxidant properties of HM. In particular, 1,1-diphenyl-2-picrylhydrazyl (DPPH) radical (↓18.4%, P < 0.001) and superoxide radical scavenging properties (↓ 9.1%, P < 0.05) and the potassium ferricyanide reducing capacity (↓ 17.4%, P < 0.01) of HM were all significantly reduced following HoP. In contrast, hydroxyl radical scavenging properties and iron chelation remained largely unaffected. Results further showed significant variability between individual HM samples, which may be attributed to maternal factors, genetic differences and varying lactation stages of the milk samples tested. Overall, these results underscore the need to develop new improved HM treatment protocols that maintain HM's nutritional and physiological properties during processing by milk banks, while at the same time ensuring equivalent microbiological safety.