Abstract
This study provides the first comprehensive nanoscale and functional evaluation of camel myofibrillar proteins subjected to long-term frozen storage. A combination of atomic force microscopy (AFM), biochemical assays, and electrophoresis was employed to investigate structural integrity, gelation capacity, and protein stability in Biceps femoris and Longissimus lumborum muscles, analyzed in both fresh and preserved states (-20°C for 1 year), including post-heating conditions simulating gel formation. AFM revealed significant topographical alterations in preserved samples, particularly in L. lumborum, including increased surface roughness, disrupted fibrillar architecture, and enlarged cross-sectional dimensions. These nanoscale changes were accompanied by increased solubility and surface hydrophobicity, alongside significantly reduced sulfhydryl group availability, which results in oxidation, aggregation, and compromised gel matrix stability. In contrast, fresh samples retained a compact, homogeneous network with smoother surfaces, reflecting superior molecular organization and functional integrity. SDS-PAGE confirmed progressive degradation of key myofibrillar proteins-MHC, actin, α-actinin, troponin T, and MLC, with preserved L. lumborum exhibiting additional low-molecular-weight bands, indicative of extensive proteolysis. These structural disruptions correlated with reduced gel cohesiveness and potentially diminished water-holding capacity, key quality attributes in muscle-based food systems. Overall, this study demonstrates that prolonged freezing induces pronounced nano-structural and functional destabilization of myofibrillar proteins, with responses that differ according to muscle-specific composition.