Mitochondrial proteome basis for the biological variations in beef color stability of longissimus lumborum muscle differing in ultimate pH and packaging methods

Abstract

This study investigated the influence of ultimate pH (pHu) and packaging methods on color, color stability, and the proteomic profile of the mitochondrial fraction of longissimus lumborum muscle from Nellore bulls. Bulls were categorized based on pHu levels as intermediate (5.8 < pHu < 6.2) or normal (pHu < 5.8). Following14-d aging, two packaging methods were evaluated: vacuum packaging and high oxygen-modified atmosphere packaging (HiOx-MAP). The findings revealed significant variations in color parameters and color stability between pHu categories and packaging methods. Proteomic analysis identified a total of 972 proteins, of which 225 were mitochondrial. Both mitochondrial and non-mitochondrial proteins resulted in significant differences in pathways related to energy metabolism, muscle contractility, and antioxidant defenses. Specifically, beef with intermediate pHu packaged in vacuum showed an upregulation of mitochondrial proteins associated with the MICOS complex (Mitochondrial contact site and cristae organizing system; APOOL, CHCH3, and MICOS13) and VDAC2 (Voltage-dependent anion-selective channel protein 2), indicating enhanced mitochondrial integrity compared to beef with normal pHu in vacuum packaging. Vacuum packaging effectively preserved color stability and supported proteolytic processes during aging, while HiOx-MAP initially produced a desirable cherry-red color but resulted in increased discoloration and oxidative stress over time, particularly in beef with normal pHu. These findings highlight the critical interplay between ultimate pH and packaging methods in optimizing beef quality during storage and aging.