Seasonal variation of myofibrillar protein thermal stability of scallop (Patinopecten yessoensis)

To explore the seasonal variation of commercial farmed scallop Patinopecten yessoensis, primary characteristics, ATP-related compounds and ATPase of scallop in spring (April), summer (July), autumn (October) and winter (January) were analyzed. The thermal stability changes of striated muscle and smooth muscle were analyzed by Mf-Ca²⁺ATPase to explore the seasonal changes of thermal stability of adductor muscle. The results showed that P. yessoensis was the fullest in spring. The condition index of gonad was as high as 6.96%, and only 1.79%-2.95% in other seasons. There was no significant seasonal difference in protein, fat and ATP contents in adductor muscle. The adductor muscle was rich in protein which accounted for 75%-80% of the dry basis. The fat content was very low, only 0.63%-1.00%. It was worth noting that the total sugar content of the adductor muscle in spring and summer was significantly higher than that in autumn and winter, 11.14% and 13.84%, respectively, and the lowest in winter is only 2.67%. ATP content in striated muscle was higher than that in smooth muscle in all seasons, 4.3-5.0 μmol/g, and 1.2-1.6 μmol/g, respectively. There was no significant difference in ATP and related compounds between striated muscle and smooth muscle in different seasons. In addition, striated muscle has similar thermal stability to smooth muscle. The Mf-Ca²⁺ATPase of striated muscle and smooth muscle did not change significantly after 30 min heating at 30 °C and 35 °C. It decreased at 40 °C, and changed obviously at 45 °C. The protein was almost completely inactivated within 10 min heating at 50 °C. Mf in adductor muscle had the fastest inactivation in spring, while the inactivation rate of striated muscle was slightly higher than that of smooth muscle, yet with little difference in winter, autumn and summer. Because of difference of thermal degeneration rates in Mf, it was presumed that there were two types of myosins with different stability in adductor muscle of P. yessoensis, which needs further analysis and elucidation.