Study On The Effect Of Tea Polyphenol On The Oxidative Stability Of Palm Oil And Instant Noodles During Frying Of Instant Noodles

Tea polyphenol(TP)is a general term for natural phenolic substances with antioxidant activity extracted from tea.TP has a strong anti-oxidation effect and various biological activity such as anti-cancer,anti-oxidation,and prevention of cardiovascular diseases.TP can improve the oxidative stability of instant noodles,extend its shelf life,and increase the nutritional value of instant noodles.The use of TP can enable the instant noodle industry to transform in the direction of individualization,delicacy and nutrition.Therefore,this article studied the effect of TP on the oxidative stability of palm oil and instant noodles and the loss of TP during intermittent frying.Furthermore,the effect of TP on the oxidative stability of palm oil and instant noodles during frying was further explored by means of continuous oil supplementation.Finally,by measuring the flavor substances in the fried instant noodles,the effect of TP in the frying process was determined.First,we fry instant noodles intermittently at a temperature of 150±5℃.The blank oil and the oil added with 100mg/kg tert-butyl hydroquinone(TBHQ)are the control group.It is used to study the effect of TP(50 mg/kg,100 mg/kg,200 mg/kg)at different concentrations on the oxidation stability of palm oil and instant noodles.The results showed that the effects of TP and TBHQ on the acid value change of palm oil during frying were not significant(P>0.05).When the added concentration is 200 mg/kg,TP have the best effect of inhibiting the increase of palm oil peroxide value,anisidine value and total oxidation value.Adding 200mg/kg TP and 100 mg/kg TBHQ can inhibit the loss of unsaturated fatty acids during intermittent frying.The addition of antioxidants has no significant effect on the changes of palm oil triglycerides during the intermittent frying process;at the same time,the increase in the concentration of TP will cause the palm oil color to gradually darken during the frying,but it has no significant effect on the color of the instant noodles.Compared with the blank sample,the addition of antioxidants can significantly increase the oxidation induction period of palm oil and instant noodles during frying.The effect ranked as 200 mg/kg TP >100 mg/kg TP >100 mg/kg TBHQ >50 mg/kg TP.Secondly,after studying the loss of TP during intermittent frying at 150±5℃,it was found that different concentrations of TP and TBHQ would be quickly lost during the intermittent frying of instant noodles.And the main loss method of TP is transformation.Different concentrations of TP and TBHQ can delay the depletion rate of tocopherols and tocotrienols in palm oil.The protective effects on tocopherols and tocotrienols ranked as 200mg/kg TP > 100 mg /kg TBHQ>100 mg/kg TP >50 mg/kg TP.In addition,the loss rate of tocopherols and tocotrienols in palm oil is the same during intermittent frying.Finally,after analyzing the change trend of the oxidation degree of the blank and antioxidant-added palm oil during intermittent frying at 150±5℃,the blank oil,the oil added with 200 mg/kg TP and oil added with 100 mg/kg were used for continuous fried frying experiments.The results show that during the continuous frying process,200 mg/kg TP and100 mg/kg TBHQ can effectively inhibit the changes in palm oil anisidine value,total oxidation value,and content of polar components,and the inhibitory effects are the same.Compared with the blank sample and the sample with 100 mg/kg TBHQ,200 mg/kg TP has the best effect of increasing the oxidation induction period of palm oil and instant noodles during continuous frying,there by prolonging the shelf life of instant noodles.Through the flavor analysis of instant noodles,it is found that(E,E)-2,4-decadienal is the primary flavor source of fried instant noodles;in the first 25 frying cycles,adding TP or TBHQ can reduce the amount of aldehydes produced in fried instant noodles,with the increase of frying times,TP and TBHQ can promote the increase of the total amount of main flavor substances.The presence of TBHQ conversion products—tert-butyl terephthaloquinone(TQ)and trace amounts of TBHQ were detected in the flavor substances of palm fried instant noodles with 100 mg/kg TBHQ added.The content of TQ and TBHQ decreased with the increase of frying times.In addition,no substances related to tea polyphenols were detected in the volatile components.The main reason is that tea polyphenols are not easily volatile during frying.