Effect Of Tea Polyphenols Andvitamins’ Synergistic Effect On The Antioxidant Activity Of Edible Oil

Because of the effect of light, heat, metal and other factors, edible oils was easyoxygenated when processed, transported and stored. Using antioxidants can effectivelyprevent the oxidative rancidity of oil.Synthetic antioxidants such as BHT and TBHQ arewidely used. But the security of them should be doubted, therefore, natural antioxidant whichis safe and efficient is necessary.As a natural antioxidant,Tea Polyphenols (TP) has become ahot spot of research and development. It has the characteristics of antioxidant, scavenge freeradicals, safe with no side effect. TP used in this study was extracted from green tea fromXixiang Tea Experimental Station.The extraction rate and purity of TP were detected first, andtransformed fat-soluble TP by chemical modification.TP extracts was added to edible oilsaccording to certain mass fraction of oils at70℃, then POV was determined in a certain time.Meanwhile, the influence to stability lipid oxidation of edible oils were determined at otherconditions such as different temperature, different antioxidant and synergy with Vc and VE.The best ratio of TP and VC,VEwas confirmed to provide the theory basis to develop apractical natural antioxidant. The results were as follows:(1) The more TP added, the slower POV of oil changed.The best amount of lard is0.03%,rapeseed oil and soybean oil are both0.02%.(2) The antioxidant activity of TP to oil was better on the condition of low temperature.(3) When0.03%TP was added to lard, considering the synergistic effect of TP with VCand VE,the optimum ratio was3:5and1:1.The synergy of VCwith rapeseed oil and soybeanoil reach the best ratio were1:2and2:3when0.02%TP was added, TP and VEwere1:2and2:5.(4) In lard, the antioxidant activity on the condition of TP:Vc=3:5was better than BHT,similar as TBHQ; as TP:VE=1:1, the antioxidant effect was best. To rapeseed oil, the best ratioof TP and Vc was better than BHT and TBHQ; TP and VEwas better than BHT, a litter betterthan TBHQ. In soybean oil, TP and Vc,VEwere all better than BHT and TBHQ.(5). According to Arrhenius equation, the shelf life of edible oil by different treatment inthis test was predicted. TP can obviously prolong the shelf life of edible oils. The more TPadded, the longer the shelf life in the range of0~0.04%. The synergistic effect between TP and VC,VEmake a longer shelf life than the effect of TP itself.