Effect of Phenols from Wood Vinegar of Bitter Almond Shell on Antiperoxidant Activity of Walnut Oil

SHI Lin,WEI Qin,ZHAO Zhong,LI Da-wen,YI Yun-yu(College of Forestry,Northwest A&F University,Yangling 712100,China)

bitter almond shell wood vinegar;antioxidant activity;walnut oil;peroxide value;acid value

Objective:To explore antioxidant activity of phenols extracted from wood vinegar of bitter almond shell.Methods:pH gradient extraction was adopted to separate phenols(E-WV) from wood vinegar.The antiperoxidant activity of phenols was evaluated by DPPH radical scavenging capability and inhibitory capacity against linoleic acid peroxidation.Peroxide value(POV) and acid value(AV) of walnut oil were used to estimate inhibitory capacity against peroxidation of nut oil.Results:Through pH gradient extraction,the content of polyphenols was up to 1570.370 mg/g,which revealed an enhancement by 1.96 fold when compared with the original wood vinegar.The antioxidant activity revealed a remarkable increase as the increase of E-WV content,and IC50 values of E-WV against DPPH free radicals and linoleic acid peroxidation were 0.724 mg/L and 4.632 mg/L,respectively.After storage at 70 ℃ in the dark environment for 5 days,the POV and AV of walnut oil were in an order from strong to weak of the control(CK),oil with 25 mg BHT(BHT-25) and oil with 25 mg E-WV(E-WV-25).The frying of nut oil resulted in an obvious increase in AV and POV.Subjected to three different periods of frying,AV and POV of nut oil were in the order of CK,BHT-25 and E-WV-25.Therefore,polyphenols from the vinegar of bitter almond shell has a remarkable antioxidant effect on nut oil under the conditions of high temperature or frying.