Changes Of Tert-butylhydroquinone By Thermal Traetment And Its Detection Methods

The antioxidation effect of tert-butylhydroquinone (TBHQ) with different contents onoils&fats was evaluated. The loss and transformation of TBHQ by thermal conditions andits influence on oils’ qualities were studied. The determination of TBHQ in oils&fats byTLC-FID and the rapid detection method were established.The antioxidant effect of TBHQ with0～200mg/kg concentration on soybean oil wasevaluated by Rancimat. The results showed as follows: the antioxidant effect of TBHQ onoils&fats was proportional to its content, and was inversely proportional to heatingtemperature. While the TBHQ content in oils&fats was less than50mg/kg or the heatingtemperature was higher than130℃, the antioxidant protection index approached1. Theantioxidant effect was bad. However, when the TBHQ content in oils&fats was equal ormore than50mg/kg or the heating temperature was equal or less than130℃, the antioxidantprotection index was equal or greater than1.38. The antioxidant effect was good.The variation of acid value, peroxide value and p-anisidine value of soybean oil andpalm oil with and without TBHQ (200mg/kg) was analyzed in details under different heatingtemperatures. The results were demonstrated that, TBHQ had almost no inhibition of theincreasing of oils&fats’ acid value, but it had strong inhibition effect on the increasing ofoils&fats’ peroxide value and p-anisidine value. After heating at80℃for96h, the peroxidevalue of oils&fats without TBHQ was6.79times than that with TBHQ, and the p-anisidinevalue without TBHQ was about3times than that with TBHQ. When the temperature washigher than135℃, the inhibition effect of TBHQ on the increasing of peroxide value andp-anisidine value of oils&fats was significantly weakened.The changes of TBHQ content in oils&fats and air by thermal treatment via HPLCwere researched in details. TBHQ’s loss was mainly in the form of volatilization loss, and thevolatilization loss rate of TBHQ was increased with the increasing of heating time andheating temperature. After heating at180℃for8h, the loss rate of TBHQ in oils&fats wasup to100%, but in the air its loss rate reached70%. However, after heating at80℃for36h,the loss rate of TBHQ in oils&fats was20%, but in the air it was almost no loss. In addition,a little of TBHQ by thermal treatment could turn into2-tert-butyl-1,4-benzoquinone (TQ)which was analyzed by GC-MS. The optimal conditions of detection TBHQ in oils&fats via TLC-FID method werestudied. The recovery was in the range of80.65%~100.00%. The relative standard deviationwas in the range of2.62%~9.53%, and the minimum detection limit was5mg/kg.Moreover, a rapid detection method of TBHQ in oils&fats was preliminarily studied.This method could be finished in10min. The absolute error was in the range of-20~5mg/kg.The recovery was in the range of75.00%~116.67%, and the minimum detection limit was5mg/kg.