Abstract: Purpose: Glyceraldehyde-3-phosphate (GAP) is an intermediate metabolite of glycolysis, which can be catalyzed into NADH by glyceraldehyde-3-phosphate dehydrogenase (GAPDH), and NADH can improve metmyoglobin reduction resulting in improved meat color stability. However, it is not clear whether the formation of NADH catalyzed by GAPDH can be directly used for the reduction of metmyoglobin. Therefore, the purpose of this study was to investigate the effect of adding GAP on the stability of meat color and to elucidate the underlying mechanism. Methods: In situ and in vitro models were used in the present study. GAP was added to mutton samples in the in situ model, and then instrumental color parameters and NADH content were determined; the myocardial mitochondria isolated from sheep were incubated with metmyoglobin and GAP, respectively, and the proportion of metmyoglobin was measured in in vitro model. Results: The addition of GAP to mutton significantly increased redness and NADH content in in situ model. The proportion of metmyoglobin was reduced significantly in in vitro model; meanwhile, the oxygen consumption rate increased during the incubation. Conclusion: The addition of GAP could increase the color stability of mutton, which was catalyzed by GAPDH into NADH to directly reduce metmyoglobin, thereby inhibiting the accumulation of metmyoglobin and consequently leading to higher color stability.

Key words: meat color, GAP, GAPDH, NADH, reduction of metmyoglobin