Structural Equation Modeling for Interpreting the Influence of Diet on Muscle-Specific Color and Oxidative Stabilities in Extended-Aged Beef from Nellore Bulls

We aimed to evaluate the influence of muscle source [longissimus lumborum (LL) and psoas major (PM)], diet (grain-finished and pasture-finished), and days of refrigerated storage (0, 5, and 9) on instrumental color and oxidative stability of extended-aged (60 days) beef from Nellore bulls employing structural equation modeling (SEM). The SEM considers different mathematical models to demonstrate the effect and the causal relationships among the parameters analyzed. When the effect of muscle (LL and PM) was combined, the beef from both feeding systems (grain-finished and pasture-finished) exhibited similar color parameters. However, beef from pasture-finished animals exhibited a negative relationship with metmyoglobin-reducing activity (MRA), indicating a decrease in the color stability. When combining the effect of diet, the LL muscle exhibited an oxidative pattern (similar to that of PM muscles), which may be attributed to pasture feeding. During refrigerated storage, muscles from both grain-finished and pasture-finished animals decreased the color stability. The findings of the SEM approach indicated that diet plays an important role in post-mortem muscle metabolism and influences the color and oxidative stability of beef from Nellore bulls.