Potential mechanism of different gelation properties of white and red muscle fibre from crocodile (Crocodylus siamensis) meat: Study of myofibrillar protein

The present study was performed to investigate the effects of myofibrillar proteins (MPs) extracted from crocodile (tail, legs, torso) on gel formation mechanism and gel characteristics. The results showed that protein compositions and ratios were different in the three body parts. The tail MPs had a higher surface hydrophobicity than the legs and torso MPs, while the leg MPs had more reactive sulfhydryl groups than the tail and torso MPs (P < 0.05). According to the Raman spectroscopy results, before heating, the leg MPs' β-sheet content was significantly higher than that of tail MPs (P < 0.05). Heating significantly reduced the contents of α-helices in the legs and torso, and there were significant differences in β-sheet content between the legs and tail (P < 0.05). Moreover, with increasing myosin content, a denser microstructure of the tail gel was observed by scanning electron microscopy, leading to its gel strength and water-holding capacity being significantly higher than those of other parts. The tail MPs revealed a higher storage modulus (G′) and spin–spin relaxation time (T21) than those in the other two parts. In conclusion, the tail of crocodile (white muscle) has stronger protein gelation properties than other parts (red muscle), which is conducive to producing gel products.