Cross-Linking Modifications of Different Phenolic Compounds on Myofibrillar Protein of Common Carp

Common carp (Cyprinus carpio) is an important and popular fish in Asia, but due to the short length and low cross-linking degree, fish myofibrillar protein is easy to break and deteriorate, which shows some negative impacts on the quality of fish meat. In present study, the cross-linking modifications of different phenolic compounds on myofibrillar protein of common carp were investigated, and their action mechanism was further explored. Phenolic compounds including gallic acid (GA), chlorogenic acid (CA), epigallocatechin (EGC), epigallocatechin gallate (EGCG), and tannic acid (TA) could increase the average particle size of myofibrillar protein from 61 to 65, 102, 97, 118, and 127 μm individually, and the solubility decreased by 7.7, 16.1, 13.6, 21.1, and 19.2%. The increased particle size and decreased solubility could promote the aggregation of myofibrillar protein, which indicated phenolic compounds exhibited the cross-linking effects on fish myofibrillar protein. Then, hydrogen bonds were found to be the main molecular force for the cross-linking effects. Meanwhile, the contents of sulfhydryl decreased by 13.5, 18.9, 29.7, 35.1, and 40.5%, and the disulfide bonds in myofibrillar protein decreased by 12.9, 11.9, 14.4, 22.3, and 26.7% when treated with GA, CA, EGC, EGCG, and TA, respectively. In addition, the secondary and tertiary structures of myofibrillar protein were both changed with phenolic compounds, which indicated that its spatial structure was changed to be loose. Furthermore, the thermal stability and gel properties of myofibrillar protein were improved with phenolic compounds. Different phenolic compounds showed various cross-linking effects on fish myofibrillar protein, which was due to the content and reactivity of hydroxyl groups in phenolic compounds. All results suggested that phenolic compounds had potential value to modify the length and cross-linking degree of fish myofibrillar protein, so as to improve the quality of fish meat in the food industry.