Fabrication Of Lipid-soluble Tea Polyphenol Antioxidant And Its Application

Food antioxidants was effective to inhibit oxidation and rancidification of oils and the foods rich in lipids.The synthetic antioxidants are commonly used have potential toxicity and pathogenic risk,there is certain limitation in its applications in some cases,the development of low-cost and high-efficiency natural antioxidants is becoming focus in food antioxidants in the future.Tea polyphenol is a sort of highly efficient natural antioxidant with strong scavenging ability of free radical,especially the effect of EGCG(Epigallocatechin Gallate),a monomer component of catechin in tea polyphenol,is particularly prominent.Since it has a plurality phenolic hydroxyl groups in its structure,it is water-soluble.This structural feature limits its application in the lipid system.In this study,water,polyglycerol polyricinoleate(PGPR)and tea polyphenols were mixed,using stirring method to prepare lipid-soluble tea polyphenol antioxidant,which is semi-solid and brown,it is applied to edible vegetable oil system to investigate its antioxidant activity.The results were as following.Firstly,the Rancimat method was used to investigate the antioxidant effect of different preparation factors on lipid-soluble tea polyphenols antioxidant in soybean oil,the OSI(Oil Stability Index)value of soybean oil is the idealized value when the TP antioxidant was prepared under these condition:the tea polyphenol content is 10%,PGPR with water ratio is 1:2,dissolution time of TP in soybean oil is 15 min,stirring time is 4 h and mixing speed is 1000 rpm during preparation.But the XRD Diffraction(X-Ray Diffraction)result indicates that the lipid-soluble tea polyphenols is amorphous.Secondly,lipid-soluble tea polyphenols antioxidant were added to soybean oil with the equal concentrations of TBHQ(Tert-butyl hydroquinone)and V_E(Tocopherol)as controls,then oven accelerated oxidation experiments were carried out at 55?.The results showed that TP had a great antioxidant effect on soybean oil,which could effectively inhibit the formation of primary and secondary oxidation products of soybean oil.The order of TP inhibition of soybean oil oxidation products from strong to weak was:0.04%TP>0.02%TP>0.01%TP.Compared with TBHQ and V_E at the same concentration,the TP of 0.01%,0.02%,0.04%inhibited POV(Peroxide value),TBA(Thiobarbital acid value),CDV(Conjugated diene value),AV(Acid value),and p-AV(p-anisidine value)was weak than the same concentration of TBHQ,but it was stronger than the same concentration of V_E.The effect of TP on the content of conjugated triene is not that strong.Next,0.04%level of lipid-soluble tea polyphenols were added to the different edible vegetable oil(including camellia oil,rapeseed oil,walnut oil,linseed oil,peanut oil)systems,using 0.02%level of TBHQ as control,the oven accelerate oxidation experiment experiments were carried out at 55?,the results showed that adding 0.04%TP for those different kinds of vegetable oil has great antioxidant activity,it can effectively reduce the content of primary and secondary oxidation product;The antioxidant effect of 0.04%TP was less effective than 0.02%TBHQ.After 10 days accelerated oxidation experiments,the POV,TBA,CDV and p-AV produced by 5 vegetable oils which containing TP from highest to lowest all conform to the following result:walnut oil>flaxseed oil>rapeseed oil>peanut oil>camellia oil;The content of conjugated triene value was from large to small:flaxseed oil>walnut oil>peanut oil>camellia oil;The change of acid value from high to low was as follows:walnut oil>peanut oil>rapeseed oil>linseed oil>camellia oil.Last,the antioxidant mechanism of lipid-soluble tea polyphenols antioxidant was investigated.The scavenging ability of TP on different types of free radicals,as well as the chelation ability to metal ions and the reducing power of TP were determined.The results showed that when the TP oncentration increased to 80?g/mL,it had stronger scavenging ability on hydroxyl radicals than TBHQ and V_E;when TP concentration was over 10~-33 mg/mL,it showed great scavenging ability on DPPH(1,1-Diphenyl-2-picrylhydrazyl)free radicals and exceeded TBHQ and V_E;when the TP concentration is more than 0.05mg/mL,it exhibits an excellent reducing power.Compared with V_E,TP has better scavenging effect on superoxide anion,ABTS radical(2,2'-azino-bis)and alkoxy radical,and can effectively chelate ferrous ion.The experiment research indicates that this new method can be utilized to prepare the lipid-soluble tea polyphenols antioxidant,which can successfully applied to system of edible oils.0.04%of lipid-soluble tea polyphenol antioxidant can effectively inhibit the primary and secondary products of oil oxidation.The main antioxidant mechanism of this antioxidant may ascribed to the ability of scavenging free radicals and powerful reducing power,also chelating the transition metal ions.