Human milk banking: influence of different pasteurization temperatures on levels of protein sulfur amino acids and some free amino acids

Human milk is frequently heat-treated in hospitals, particularly milk that is banked, to destroy contaminating bacteria and viruses, but this treatment simultaneously reduces the content of some vitamins, enzymes, and immunological and nutritional factors. This study was performed to find the optimal conditions for heat treatment. The effects of 2 pasteurization temperatures on levels of protein sulfur amino acids (methionine, cystine) and some free amino acids (taurine, glutamine, glutamic acid) in light of the oxidative instability that occurs especially during thermal treatment were examined. These substances in raw human milk and in milk treated at 56.5 degrees C and 62.5 degrees C for 30 min were compared. Samples of mature human milk from all feeds over 24 h were obtained from 13 healthy well-nourished mothers of term infants. Each sample was divided into 3 parts: raw, treated at 56.5 degrees C for 30 min, treated at 62.5 degrees C for 30 min. The results showed that the availability of sulfur amino acids and free taurine is the same after heat treatment, whereas milk processing increased positively the levels of free glutamic acid and glutamine, but there is significance only for glutamine. The mean quantities of considered amino acids were similar in milk treated at the recommended pasteurization temperature (30 min at 62.5 degrees C) and at 56.5 degrees for 30 min.