Comparative characteristics of oxidative modification intensity of proteins in infant milk formulas

Abstract

Cow's milk is mainly used in the production of infant milk formulas. However, the protein composition of cow's milk differs significantly from the proteome of breast milk. In addition, various technological factors significantly affect the properties and structure of proteins, susceptibility to oxidative processes. This article uses a method of complex evaluation of the products of oxidative modification of proteins to characterize the total level of carbonyl compounds with the analysis of the ratio of aldehyde-dinitrophenylhydrazones (ADNPH) and ketone-dinitrophenylhydrazones (CDNPH), which increases the possibility of determining the severity of protein damage. The purpose of the study was to compare the level of indicators of oxidative modification of proteins in adapted milk infant formulas. Material and methods. The research objects were 4 dry adapted milk infant formulas, as well as ultra-pasteurized cow's milk. The intensity of oxidative modification of milk proteins was determined spectrophotometrically by the reaction of carbonyl compounds with dinitrophenylhydrazine (DNFG). Results. With spontaneous oxidation in infant formula, the total area of carbonyl derivatives of proteins (Sомб) was increased compared to the indicators of ultra-pasteurized cow's milk. The greatest change occurred in relation to ADNFG indicators (SАДНФГ), the level of which increased in 3 formulas by 48.6-59.4%. The content of ketone derivatives (SКДНФГ) did not differ significantly in the studied mixtures from milk indicators. The level of carbonyl derivatives of proteins in milk infant formulas was even more elevated during the induction of oxidation by the addition of iron ions and hydrogen peroxide to the incubation medium. The content of both total and various fractions of carbonyl compounds exceeded the corresponding indicators of cow's milk by 2.0-2.6 times. Conclusion. The results of the study indicate a greater susceptibility to oxidative damage of proteins in milk infant formulas, compared with cow's milk.