Proteomics Analysis of Changes in the Water-Holding Capacity of Yak Meat During Postmortem Aging

To elucidate the mechanism underlying changes in the water-holding capacity of yak meat during postmortem aging, yak longissimus dorsi muscle was used as the experimental material. Changes in pressure loss, drip loss, cooking loss, and pH were determined at 0, 0.5, 1, 3, 5, and 7 d postmortem (0-4 °C; RH 80-85%). Proteomic approaches were employed to identify key proteins associated with water-holding capacity and the related metabolic pathways at representative aging stages. The results showed that the pressure loss, drip loss, and cooking loss of yak meat all exhibited an initial increase followed by a decrease during the 7 d postmortem aging period, reaching their maximum values at 3 d (42.10%, 3.19%, and 42.82%. p < 0.05). In contrast, pH displayed an opposite trend and declined to the minimum value of 5.35 at 3 d. Furthermore, proteomics analysis conducted at 0, 3 and 5 d of aging identified a total of 1239 proteins and screened 41 differentially expressed proteins. Through correlation analysis, 14 key proteins significantly associated with the WHC of yak meat were identified. Protein-protein interaction analysis indicated that Titin isoform X3, Calpastatin isoform I, and small muscular protein might serve as indicator proteins for the WHC of yak meat during aging. Most of these proteins are metabolic enzymes, structural proteins and stress proteins, which may influence meat quality by affecting the microstructure and metabolic pathways of the muscle.