Different changes in mastication between crisp grass carp (Ctenopharyngodon idellus C.et V) and grass carp (Ctenopharyngodon idellus) after heating: The relationship between texture and ultrastructure in muscle tissue

In order to study special mastication of Crisp grass carp (CGC), the relationships between the texture and ultrastructure in raw fresh and heated CGC and grass carp (GC) were studied. In raw samples, all textural results of raw CGC (RCGC) were higher than those of raw GC (RGC). From the ultrastructural results, short muscle fiber diameter, dense fiber density, large collagen amounts, narrow intermyofibrillar spaces and gaps determined the texture of fillets. In the heated samples, the hardness, chewiness, resilience and springiness of heated CGC (HCGC) were higher than in heated CG (HCG). Compared to raw samples, the hardness, fracturability, springiness and chewiness of HCGC were higher than those of RCGC. However, all textural results of HGC were significantly reduced. The ultra-structural results showed that the better mastication of HCGC was connected with denaturation and coagulation of myofibrillar and sarcoplasmic proteins, the low ratio of shrinking in inter-muscular connective tissue, large interstitial material, much less fiber-fiber detachments and myofiber-myocommata detachments.