Studies On The Mechanism Of Mulberry Polyphenols On The Quality And Protein Oxidation Of Cantonese Sausage

Mulberry polyphenols are rich in biologically active ingredients,such as flavonoids,phenolic acids,and anthocyanins etc.,which are natural antioxidants and have broad application prospects in the food,cosmetics and pharmaceutical industries.Previous studies have found that plant polyphenols could effectively regulate the oxidation of meat products.However,the oxidation regulation mechanism and the fate of the polyphenols in the processing and storage of meat products are still unclear.Therefore,in the present study,mulberry polyphenol was used to investigate its effect on the quality of Cantonese sausages,and to analyze its changes during the processing and storage of Cantonese sausages.Meanwhile,the regulation effect of mulberry polyphenols on sausage protein oxidation was also investigated.The results showed that mulberry polyphenols had a certain effect on the physicochemical properties of Cantonese sausage,which showed to reduce the brightness(L* values)and redness(a* values)of the sausages.However,its effect on the chroma of the sausages weakened as the extension of storage time.Mulberry polyphenols significantly inhibited the protein and lipid oxidation of sausage,and the results showed that the TBARS value and carbonyl content were decreased,while the SH group content was increased.In addition,mulberry polyphenols significantly improved the biological safety of sausage,and effectively controlled the nitrite residues,the volatile salt-base nitrogen(TVB-N)formatted and the microorganism's growth.The effects of different extraction methods on the yield of phenolic compounds in the sausage were compared.Finally,the simulated in vitro gastric digestion method was established as the optimal extraction method for phenolic compounds in polyphenol enriched sausage(the amount of polyphenol added was 420.31 mg/kg),the total phenolic content in this extraction solution was the highest,reaching 332.106 mg/kg.Mulberry polyphenols could effectively improve the antioxidant activity of the sausages.At the end of storage,DPPH scavenging rate and ABTS scavenging rate and FRAP value of sausages incorporated with mulberry polyphenols were 1.52,and 1.94,2.29-fold of those in the control,respectively.After analysis by liquid chromatography mass spectrometry,the phenolic compounds in the polyphenol-rich sausage mainly included flavonoid derivatives,phenolic acid derivatives and anthocyanins.Degradation and transformation of mulberry polyphenols were observed during processing and storage of sausage.For instance,cyanidin-3-O-glucoside and quercetin were converted to protocatechuic acid and caffeic acid,respectively.Rutin,quercetin,and caffeic acid are the three main non-anthocyanins in mulberry polyphenol enrich sausages.All of them could effectively inhibit the conversion of protein sulfhydryl groups to disulfide bonds.However,the different phenolic compounds have different regulatory mechanisms on protein oxidation.Rutin worked by directly inhibiting the oxidation of sarcoplasmic and myofibrillar proteins in salami,and maintains the stability of protein structure.Caffeic acid mainly inhibited proteins oxidation by inhibiting the formation of Schiff base and dimeric tyrosine of myofibrillar protein.However,the high concentration of quercetin(0.32 g/kg)had less inhibition effect on the oxidation of sarcoplasmic proteins(carbonyl derivatives,SH groups,and disulfide bonds)than the low concentration of quercetin(0.16 g/kg).