Antioxidant Properties of Human Milk Fractions

Abstract

Human milk (HM) contains antioxidants such as vitamins (A, C, E) and enzymes (SOD, GPx, CAT) which can reduce radical‐mediated diseases among infants. The current study is aimed at identifying novel antioxidants that might help to reduce some diseases of prematurity and to enhance infant formulas for babies who cannot be breastfed. To achieve our goal, pooled HM samples were freeze‐dried and initially separated into lipid, whey and casein proteins. The antioxidant power of each fraction was measured using the oxygen radical absorbance capacity (ORAC) assay: results were 67.2 μmol Trolox/g for whole milk; 7.1, 13.1, and 205.6 μmol Trolox/g for lipid, whey and casein, respectively. The HM sample was subsequently digested with pepsin, pancreatin and bile salt to mimic the infant digestion system. ORAC (μmol Trolox/g) values were 172.4 for the whole pepsin‐pancreatin digested milk, 234.3 for peptides above 3000 Da, and 146.9 for peptides below 3000 Da. The resulting fractions were separated by preparative HPLC and the fractions dried. Antioxidant capacity of each fraction was obtained and the identity of four antioxidant peptides confirmed by LC‐MS/MS. This work is supported by the Advanced Food and Material Network (AFMNet), the Manitoba Institute of Child Health and Canadian Institutes of Health Research (CIHR).