Study of Ca2+-ATPase Activity and Solubility in the Whole Kuruma Prawn (Marsupenaeus japonicus) Meat During Heating: Based on the Kinetics Analysis of Myofibril Protein Thermal Denaturation
2016
Mao, Weijie | Li, Xiaolong | Fukuoka, Mika | Liu, Shucheng | Ji, Hongwu | Sakai, Noboru
Protein denaturation is considered to be the main cause of physicochemical changes in prawns during heating. However, no studies have been analyzed the kinetics of protein denaturation and the relationship between the degree of denaturation and chemical changes. Therefore, we investigated the changes in Ca²⁺-ATPase activity, protein solubility, and total sulfhydryl content of whole prawn meat during heating by determining the thermal denaturation kinetics of the proteins. Activation energies (E ₐ) for the denaturation of myosin (183.2 kJ/mol) and actin (178.8 kJ/mol) were obtained by non-isothermal differential scanning calorimetry analysis. Using the kinetic parameters, the distribution of protein denaturation was predicted in whole prawns under arbitrary heating conditions. The results revealed an uneven distribution of the protein denaturation in prawns that was dependent on the heating conditions. Ca²⁺-ATPase activity decreased with increasing heating times at 51 or 85 °C and was strongly related to the average degree of protein denaturation. The results of protein solubility analysis suggested that hydrogen bonds, hydrophobic interactions, and ionic bonds changed with protein denaturation. The number of ionic bonds was reduced, while hydrogen content was enhanced at both temperatures. Hydrophobic interactions increased gradually at 51 °C (p < 0.05). At 85 °C, hydrophobic interactions increased notably at first (p < 0.05); however, as heating continued, no significant changes were observed (p > 0.05). Our results indicate that the extent of protein solubility is significantly correlated with the average degree of protein denaturation during the heating process.
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