Improving tenderness and quality of camel meat through ultrasound and papain treatment: Insights from structural and proteomics analysis

We investigated the tenderization effects of papain (PT), ultrasound (UT), and their combined treatment (CT) on camel meat and explored the underlying mechanisms. All treatments significantly reduced shear force and cooking loss, increased the myofibril fragmentation index (MFI), and decreased lightness while increasing yellowness of camel meat. PT effectively delayed myoglobin oxidation and preserved heme pigments, whereas UT and CT accelerated this oxidation. Treated samples displayed a disorganized muscle microstructure with widened gaps and visible cavities. SDS-PAGE analysis confirmed that both papain and ultrasound exerted significant proteolytic effects, which further altered the secondary structure, thermal stability and thermodynamic properties of myofibrillar proteins. Proteomic analysis identified 422, 258, and 134 differentially expressed proteins (DEPs) in the UT, PT, and CT groups, respectively, with 50 key DEPs strongly correlated with meat quality attributes. The combined treatment proved the most effective for tenderization while causing minimal proteomic alteration.