The significant influences of pH, temperature and fatty acids on meat myoglobin oxidation: a model study

Colour is one of the important quality traits affecting the meat purchasing decision by consumers, and myoglobin is the principal heme protein responsible for the meat colour. This study aimed to investigate the effects of pH (5.3, 5.8, 6.4 and 7.4) and temperature (4 and 25 degrees C) on oxymyoglobin (OxyMb) oxidation in model reaction mixtures containing OxyMb, fatty acids (C18:2n-6 and C18:3n-3) and vitamin E. A decrease of the OxyMb concentration with increased acidity was observed for all the reaction mixtures with/without fatty acids and vitamin E. After 48 h of storage at 4 degrees C, the OxyMb concentration decreased by approximately 60-70%, 61-69%, 53.7-53.9% and 40.93-41.84% in the reaction mixtures containing [OxyMb + C18:2n-6 or C18:3n-3] at pH 5.3, 5.8, 6.4 and 7.4, respectively. While, after 48 h at 25 degrees C, the OxyMb concentration decreased by 95-98% in all the reaction mixtures containing [OxyMb + C18:2n-6 or C18:3n-3] under all the pH conditions. The presence of vitamin E significantly inhibited the OxyMb oxidation in the reaction mixtures containing fatty acids under acidic conditions, but a higher level of vitamin E may be required for meat(s) containing high n-3 fatty acids content that are stored at high temperature.