First microstructure insights into the dynamic degradation of structural proteins components of shrimp Litopenaeus vannamei during refrigeration and its association with texture deterioration: Based on histochemical staining and biochemical analysis

This study aims to establish a histological protocol to visualize the process of structural protein degradation in shrimp Litopenaeus vannamei during refrigeration. After fixed in Carnoy’s fixative for 15 h at room temperature and combined with Masson’s trichrome staining, the structural components of myofibrils and collagen were effectively visualized and the pathological analysis revealed the widened gaps between muscle bundles and the disrupted myofibrils were observed. Moreover, the lighter staining in collagen component was observed during the cold storage, indicating its progressive reduction in content. Quantitatively, the myofibril cross-sectional and longitudinal volume fractions dropped from (91.03 ± 1.37) % and (93.39 ± 0.91 %) to (41.14 ± 3.78) % and (24.36 ± 3.67) % (Day 5, P  < 0.01), respectively. Meanwhile, the collagen and myofibril areas were negatively correlated with the parameters of hardness and elasticity ( P  < 0.05), confirming their role in inducing texture quality deterioration. Collectively, by visualizing the degradation process of structural components collagen and myofibril in shrimp muscle during refrigeration, the association between structural proteins degradation and texture deterioration was identified. This study identifies a potential biomarker of early muscle softening in refrigerated shrimp L. vannamei and provides a solid foundation for its industrial application in quality control of shrimp during preservation.