Study Of Synergistic Interactions Between Rosemary Extract And Tea Polyphenol Palmitate On Oil

Oil oxidation is one of the key factors affecting food quality.At present,antioxidants addition is an effective way to inhibit oil oxidation.Given the potential toxicity of synthesis antioxidants,natural antioxidants have been attracted more attention for their green,safe and low toxic properties.However,there are also some limitations in the utilization of natural antioxidants,so how to enhance the antioxidation ability of natural antioxidants needs to be solved urgently.Combined antioxidants play an important role in oil antioxidation.However,synergetic antioxidants are now identified stochastically and blindly,and there is a lack of study on the synergistic mechanism in oil antioxidation.Therefore,this research was aimed to select the optimal antioxidant combination by Prieto model and investigate the effect on oil antioxidation,analyzed the synthesis mechanism,and provided the theoretical and scientific basis for the application of natural antioxidant combination.The main contents and results are as follows:1.Six natural antioxidants were studied in this research.Priteo model was used to evaluate the scavenging effects of antioxidant alone and binary compound on DPPH and ABTS~+radical,screened the compound group with high antioxidation and optimized its composition raio.The scavenging ability of antioxidant alone on DPPH radical were ranked as follows:Ascorbic acid (AA)>Tea polyphenols palmitate(TP)>Tea polyphenols(T)>?-tocopherol(?-T)>Ascorbic acid palmitate(AP)>Rosemary palmitate(RE),ABTS~+radical:AA>T>AP>TP>?-T>RE;In addition,6 combinations showed a synergistic effect in DPPH radical scavenging and10 combinations showed a synergistic effect in ABTS~+radical scavenging;Among them,the combination of RE and TP showed the highest values in DPPH and ABTS~+radical scavenging,reaching 6.03%and 5.29%respectively;The optimal ratio of RE and TP was 5:3 in theory.2.Based on the theoretical optimal ratio of RE and TP,the feasibility of its application in several vegetable oils was investigated,and the influence of different complex ratios on the oxidation stability of sunflower oil was evaluated.The results showed that the antioxidant effects of RE and TP all showed the synergistic effect in different vegetable oils,indicating the feasibility of Priteo model prediction.The combination showed the optimal synergistic effect for sunflower oil at 5:3 ratio,prolonged the oxidative induction,and inhibited the generation of primary and secondary oxidation products,indicating the suitability of the chosen ratio.The electron spin resonance(ESR)results showed that RE was more inclined to combine with alkyl radicals,while TP was more inclined to combine with alkane peroxy radicals,the combination could effectively inhibit the generation of free radicals in the system.In the heated volatile products,TP had greater ability to inhibit the formation of aldehydes than RE,while RE had greater ability to inhibit the formation of acids than TP.The combination of RE and TP can synergistically reduce the formation of volatile products.3.Antioxidant patterns of the main active components in RE and TP were systematically investigated in methyl linoleate system and then explained the synergistic mechanism of RE and TP in oil oxidation.The results showed that the main active substances of RE and TP were carnosic acid and epigallocatechin gallate(EGCG)respectively,and the two antioxidant active substances also showed synergistic effects in the methyl linoleate system.During the antioxidant process,carnosic acid was converted into quinones.The intermediate bond of EGCG was broken and decomposed into flavonoids and phenolic acids.When both carnosic acid and EGCG were present,the carnosic acid was preferentially degraded and played a major role in antioxidation.The synergistic mechanism was that the RE and TP can act on different stages of oxidation,play a complementary role,and delay the whole process of oxidation.