Effect of fermentation-driven acid-mediated protein degradation on chicken and its gel properties

This study systematically examines the impact of protein breakdown on the gel properties and texture of chicken under fermentation-induced acidic conditions. Chicken mince samples with different degrees of protein degradation were prepared by controlling fermentation time, followed by comprehensive analyses of physicochemical characteristics, protein structure, microstructure, and gel performance. Results showed that as degradation progressed, the pH value diminished from 5.86 in the control group to 4.19 at 50 days. Under acidic conditions, the surface hydrophobicity of myofibrillar protein was markedly increased (p < 0.05), evidenced by the myofibril fragmentation index (MFI) escalating from 43.62 to 110.17, with hydrophobic interactions and disulfide bonds emerging as the predominant forces. Scanning electron microscopy (SEM) images revealed that fermentation promoted protein aggregation and the formation of a dense and homogeneous three-dimensional network. However, excessive fermentation led to network disruption and structural collapse. Rheological measurements and texture profile analysis (TPA) confirmed that moderate proteolysis effectively reduced gel springiness and cohesiveness, thereby improving macroscopic texture. Although extensive protein degradation resulted in a decreasing ratio of free water, the gels formed from all fermented samples still met the textural criteria for fermented gels, providing preliminary textural evidence for their potential suitability as dysphagia-oriented foods. This study elucidates the structure-activity relationship of fermented chicken surimi gel, focusing on the pivotal variable of protein degradation degree and the influence of acidic conditions on protein. This research offers a theoretical foundation and technical methodology for the advancement of high-quality, meat protein-based dysphagia food tailored for specialized diets.