Study On The Reduction Effect And Mechanism Of Polyphenols On Nitrification In Meat Products

Nitrite widely exists in meat products,which has the functions of bacteriostasis,antisepsis and color development.At the same time,excessive intake of nitrite can also lead to poisoning and even death.In addition,nitrite will react with amines in acidic environment,and further generate nitrosamines with carcinogenic and teratogenic effects.Polyphenols have good antioxidant and nitrite scavenging effects.By studying the effects of different types of polyphenols on nitrosation reaction,and discussing the mechanism of the reaction between polyphenols and nitrosation,it provides more theoretical basis for maintaining and improving food safety.Firstly,the effects of three polyphenols on nitrosation reaction in simulated gastric juice were discussed.The scavenging rate of polyphenols to nitrite and blocking rate of nitrosamine synthesis under different reaction time and different content were determined,and the inhibition effect of three polyphenols on nitrosation reaction was studied by using the combined action index CI.The results showed that the scavenging rate of procyanidin,catechin and gallic acid on nitrite and the blocking rate of nitrosamine synthesis increased with the increase of content and reaction time,and IC₅₀ values were 0.32,0.24,0.93 mg/m L and0.37,0.27,0.84 mg/m L,respectively.The ability of three polyphenols to inhibit nitrosation was catechin?procyanidin?gallic acid.After the three polyphenols were compounded in pairs,by comparing the combined action index CI and the total IC₅₀ value after compounding,it was found that catechin and gallic acid group had the strongest inhibition ability and synergistic effect on nitrosation reaction,while procyanidin and catechin group and procyanidin and gallic acid group had negative cooperativity effect on scavenging nitrite and synergistic effect on blocking nitrosamine synthesis.On the whole,the order of synergistic effect was catechin+gallic acid>procyanidin+gallic acid>procyanidin+catechin.Among them,when the ratio of catechin to gallic acid was 1:3,the scavenging effect on nitrite and the blocking effect on nitrosamine synthesis were the best,and the total IC₅₀ value and CI value after compounding were 0.42,0.15 mg/m L and 0.76,0.28,respectively.Therefore,all three polyphenols and their combinations can significantly inhibit nitrosation under simulated gastric juice conditions.The inhibitory effect of catechin was the best,and the synergistic inhibitory effect of catechin and gallic acid group was the strongest.Secondly,the effects of three kinds of polyphenols,sodium nitrite and curing time on nitrite reduction were studied by single factor experiment,and the effects of three kinds of polyphenols on nitrite residue were analyzed by orthogonal experiment to determine the best ratio.At the same time,the effects of three polyphenols on the quality of pickled minced pork,such as TBARS value,color difference value and color rate,were also discussed.The results showed that procyanidin and catechin had a slightly stronger effect on reducing nitrite residue in pickled pork minced meat than gallic acid,and all three polyphenols had a good effect on scavenging nitrite.The single factor experiment showed that the optimum amount of polyphenols,sodium nitrite and curing time were 400 mg/kg,50 mg/kg and 24 h,respectively.The nitrite residues of procyanidin,catechin and gallic acid were 30.16,29.94 and 31.75 mg/kg.Through orthogonal experiment,it was found that each factor affected the primary and secondary order of indexes:nitrite addition(**)>polyphenol addition(*)>pickling time.The best combination of each experimental group is A₃B₁C₂,that is,600 mg/kg polyphenol addition,50 mg/kg nitrite addition and 24 h pickling time.The optimized results of nitrite residues in each group were 27.07,26.92 and 29.03 mg/kg respectively.The addition of polyphenols can improve the quality of pork.With the increase of the amount of polyphenols,the TBARS value showed a downward trend and the color development rate showed an upward trend.Compared with the control group without polyphenols,the L*and a*values of the three polyphenol groups increased significantly.The results showed that procyanidin,catechin and gallic acid had good color development effect on pickled pork minced meat,and also improved the brightness and redness of pickled pork minced meat during pickling.All three polyphenols could significantly reduce nitrite residue in meat products.Finally,the products after the reaction were analyzed by HPLC,and the interaction of gallic acid,catechin and procyanidin B2 with nitrite under simulated gastric juice was discussed,and the mechanism of three polyphenols inhibiting nitrosation was further discussed.The results showed that after the reaction of three polyphenols with nitrite,the peak of liquid chromatography decreased and a new peak appeared,indicating that the content of three polyphenols decreased and new substances were formed after the reaction.During the reaction,the three polyphenols were oxidized by nitrite to form their semi-quinone free radical intermediates and nitrosated derivatives,while nitrite was reduced to nitric oxide(·NO).After gallic acid reacts with nitrite,the 2-or 6-hydrogen ion on the benzene ring is replaced by NO,resulting in nitroso-gallic acid.Procyanidin B2 lost the C6 hydrogen ion in A ring,and were converted into mononitrosoprocyanidin B2 and dinitroprocyanidins B2.After catechin reacts with nitrite,mononitrosocatechin and 6,8-dinitrocatechin are formed.Meanwhile,due to the loss of C6 and C8 hydrogen ions in catechin A ring,semiquinone radicals of catechin,mononitrosocatechin and 6,8-dinitrocatechin are also formed during the reaction.Therefore,all three polyphenols have the ability to inhibit nitrosation.Gallic acid,catechin and procyanidin B2 can reduce nitrite and combine with the produced nitric oxide(·NO)to form nitrosation derivatives.