Intensity of induced carbonylation of milk proteins as an identifier of their preservation

Relevance. Preservation of anti-oxidative protection of milk is important for preservation of biological properties and taste of the product. The most sensitive marker of activation of free radical processes is oxidative modification of proteins, which served as the basis for determining its level during milk storage. The purpose of the study. Determine the intensity of spontaneous and metal-catalyzed oxidative modification of proteins in the early shelf life of milk. Material and methods. The material of the study was samples of drinking pasteurized milk. To identify the state of oxidative modification of proteins in the early shelf life, milk samples were stored at oxygen access and a temperature of 3-4 °C. In some samples of milk, dihydroquercetin was added at a dose of 0.25 mg/L. The formation of derivatives of carbonyl amino acid derivatives was determined by their reaction with 2,4-dinitrophenylhydrazine with the registration of dinitrophenylhydrazones on the UNICO 2800 spectrophotometer with various wavelengths from 230 to 535 nm. Results. When determining the spontaneous oxidative modification of proteins after 48 hours of milk storage under aerobic conditions, no significant accumulation of carbonyl protein derivatives was detected. In the induction of free radical processes by the addition of iron ions and hydrogen peroxide, the total content of all products of oxidative carbonylation of proteins increases after 48 hours of storage of milk under aerobic conditions by 53%, both due to aldehyde derivatives and ketones. Induction of oxidative processes by iron leads to the formation of carbonyl derivatives of amino acids of a neutral and basic nature. After 48 hours of milk storage, the re-serve-adaptation potential for both aldehydes and ketone-dinitrophenylhydrazones increases. Dihydroquercetin at a dose of 0.25 mg/l inhibits the activation of metal-catalyzed modification of milk proteins after 48 hours of milk storage under aerobic conditions at a temperature of 3-4 °C. Conclusion. Indicators of the level of Indicators of the level of carbonyl derivatives of milk proteins can serve as an additional marker for assessing the biological value and shelf life of milk.

oxidative modification of proteins, oxidative stress, milk, dihydroquercetin, aldehyde-dinitrophenylhydrazones, ke-tone-dinitrophenylhydrazones