Comparative Studies On The Antioxidant Activities In Different Systems Of Three Antioxidants

L-ascorbyl palmitate is a safe,efficient,nutritional synthetic antioxidant.Quercetin and(+)-catechin are widely distributed in nature and be known as ideal natural antioxidants.Despite of numerorous studies on them,the comparison of their antioxidant activity in different dispersions has not been reported currently.In this paper,we compared antioxidant activity of them in non-oil,linoleic acid bulk oil,linoleic acid O/W emulsion systems and studied the correlation between different oxidation evaluation methods and different dispersion systems.The main results were as follows:1.In non-oil system,6 methods were used to assess the antioxidant capacity of three subjects,including DPPH radical scavenging ability,superoxide anion radical scavenging ability,hydroxyl radical scavenging ability,Fe2+ chelating ability,ferric reducing ability and total antioxidant capacity.The results showed that DPPH radical scavenging ability,Fe2+ chelating ability,ferric reducing ability had the same order of quercetin>(+)-catechin>L-ascorbic acid palmitate.2.In linoleic acid bulk oil system,weight gain rate,Rancimat induction time,conjugated dienes,conjugated trienes and MDA were used to evaluate the effects of three test substances on the process of lipid oxidation and oxidation products formation.Inhibitory effect on weight gain rate and conjugated dienes formation:quercetin>(+)-catechin>L-ascorbyl palmitate,prolong effect of Rancimat induction time:(+)-catechin>quercetin>L-ascorbyl palmitate and inhibitory effect on MDA formation,conjugated trienes and MDA results showed similar antioxidant activity between quercetin and(+)-catechin.3.In linoleic acid OAV emulsion system,oxidation process was accelerated by AAPH,conjugated dienes,conjugated trienes and MDA were used to evaluate the antioxidant activity of three test substances.Results showed that there was no consistency among the three methods.The results of conjugated dienes showed the same antioxidant activity order with conjugated dienes of bulk oil system.Conjugated trienes and MDA had partial consistency with the results of bulk oil system.4.Extremely significant strong positive correlations were found among several methods,including ferric reducing ability,hydroxyl radical scavenging ability,superoxide anion radical scavenging ability,total antioxidant capacity of non-oil system;conjugated diene,MDA of bulk oil system.Significantly strong positive correlations were found between conjugated diene and MDA of L-ascorbic acid palmitate and quercetin,between conjugated trienes and MDA of quercetin in O/W emulsion system.What's more,quercetin showed significantly strong positive correlations between conjugated diene and MDA of bulk oil system and conjugated triene of O/W emulsion system.5.It will reduce the experimental workload and save cost by selecting the methods with strong correlations on the basis of getting credible experimental results.What's more,it helps a lot to predicte antioxidant activity of test substances in a complex system by the results of a simple system.