Insight into the conformational and functional properties of myofibrillar protein modified by mulberry polyphenols

This paper investigated the conformational and functional properties of myofibrillar protein modified by five phenolic compounds, including cyanidin 3-O-glucoside, cyanidin 3-O-rutinoside, caffeic acid, quercetin and rutin, dominantly presented in mulberry polyphenols-enriched sausage. These phenolic compounds significantly affected the structure of myofibrillar protein as indicated by the remarkable losses of carbonyl and epsilon-NH2 and the obviously fluorescence quenching effect (P < 0.05). Modified myofibrillar protein increased antioxidative activity but decreased thermal stability. Myofibirllar protein modified with rutin had no change in thermal stability but improved emulsifying properties. Quercetin has little effect on secondary structure of myofibirlliar protein. Caffeic acid triggered the conversion of a-helix to beta-sheet in myofibrillar protein, and the resulted protein exhibited the strongest fluorescence quenching, solubility and antioxidant activity among all samples. Overall, the results suggested that all phenolic compounds involved in the changes of meat product quality, with caffeic acid and rutin being the most critical ones.