Inhibition of EGCG on myofibrillar protein degradation of Nile tilapia (Oreochromis niloticus)

Nile tilapia (Oreochromis niloticus) is an important economic fish species and has been farmed widely in south China. In order to study the inhibitory effect of EGCG on the degradation of myofibrillar protein in tilapia, the tilapia muscle was treated with EGCG with the concentrations of 0.002 5%, 0.01%, 0.02% and 0.03% respectively. The effects of different concentrations of EGCG on the myofibrillar protein salt solubility of tilapia muscle were investigated during storage. In addition, the targeted proteins of degradation inhibited by EGCG were studied by SDS-PAGE gel electrophoresis and mass spectrometry. The results showed that all of the different concentrations of EGCG had inhibitory effects on myofibrillar degradation, especially when the concentration of EGCG was 0.01%, the myofibrillar protein content was decreased from (82.42±0.65) mg/g on day 0 to (51.89±0.68) mg/g on day 12 (37.0% of descent rate), while the myofibrillar protein content of control group was decreased from (80.86±1.18) mg/g to (35.33±1.16) mg/g (56.3% of descent rate). The results of SDS-PAGE gel electrophoresis and mass spectrometry identification showed that targeted proteins of degradation inhibited by EGCGE were MHC, MLC and actin, respectively. The results of this study have some guiding significance for the preservation research of O. niloticus.