Study On Effects Of Different Antioxidants On The Stability Of Frying Oil

With the rapidly developing of food frying industry,oil safety is becoming more and more important.Although antioxidants can effectively delay the oxidation of oil under indoor temperature,their effects on oil under frying conditions have not reported enough.This study studied the effects of different antioxidants on the frying stability of blend oil,soybean oil and rapeseed oil and the effects of tea polyphenols on the frying different materials in soybean oil.The frying life of oil was determined by the determination of acid value and polar composition content of oil samples.The influence of different antioxidants on the quality of frying oil was comprehensively determined by combining the fatty acid composition,trans fatty acid content,sterols,VE,PAHs,3-MCPD and GEs content in oil samples.(1)Testing a blend oil and compare it with soybean oil and hoping that this blend oil can be with enough nutritions and has frying stability.To explore the effect of a natural compound antioxidant on the frying stability in soybean oil and blend oil,respectively,so as to prolong the using life of oil.With fresh soybean oil and mixed blend oil as frying oil,respectively set oil without antioxidant as control.Added TBHQ,the natural antioxidants mentioned above(mainly composed of tea polyphenols,rosemary,vitamin E,the ratio is secret)to the soybean oil,blend oil,respectively.So we got blank soybean oil,soybean oil with TBHQ,soybean oil with compound natural antioxidant,blank blend oil,blend oil with TBHQ,blend oil with natural antioxidant and used them frying twisted dough-strips continuously 32 h respectively,and every 2 h took Fried sample for each indexs were determined.The results showed that after 32 hours of continuously frying,the frying life of them was 26 h,26 h,20 h,28 h,26 h,28 h and 28 h respectively.The acid value(KOHmg/g)of soybean oil(control,TBHQ,compound natural)increased from 0.15 to 1.61,1.30,1.19,while that of blend oil(control,TBHQ,compound natural)increased from 0.20 to 1.10,1.10,1.28,respectively.The effect of natural compound antioxidant in soybean oil frying was not good and it was not obvious in blend oil.(2)It was found by(1)that soybean oil was rich in polyunsaturated fatty acids so that leading it to poor frying stability.In this chapter,we hope to improve the frying stability of oil by adding antioxidants to soybean oil,and comprehensively investigate the effects of antioxidants on the risk substances in oil during frying.Contrast with blank soybean oil,add tea polyphenols(catechin content > 90%),rosemary(sage phenol content < 20%),TBHQ,natural antioxidants in fresh soybean oil,respectively,with the concentration of 0.04%,0.07%,0.02%,0.05%,respectively.Experiment result was carried out as after 32 h frying,5 kinds of soybean oil(control,tea polyphenol,rosemary,TBHQ,natural compound antioxidant)acid value(KOHmg/g)increased from 0.15 to 1.61,1.34,1.64,1.19,1.30,respectively;The limit of polar components of frying oil stipulated by GB 2716-2018 ?27% was taken as the evaluation index,and the frying life of 5 kinds of frying oil was 26 h,28 h,28 h,26 h and 20 h,respectively.The total amount of TGO,TGD,ox-TG and other oxidized polymerization products in polar components increased from 3.54% to 30.36%,25.31%,27.41%,28.55%,34.22%,respectively.The total amount of hydrolysates in polar components changed from 3.10% to 3.63%,2.80%,2.70%,2.02% and 2.84%,respectively.All four kinds of antioxidants can control PAH4 content in oil.Tea polyphenols and TBHQ inhibited the production of 3-MCPD and maintained the GEs content at a low level.It had been proved that tea polyphenols were the best antioxidant that can control the increaseing of oil acid value and polar components at the same time,and can effectively control some risk components in soybean oil,which should be used as the antioxidant in soybean oil frying.(3)The above experiments improved that those antioxidants showed effects in soybean oil frying,whether they can play the same role in rapeseed oil that is in good stability already.Therefore,tea polyphenols and rosemary TBHQ were selected in this chapter to explore their effects on the frying stability of rapeseed oil with high oleic acid.Tea polyphenols,rosemary and TBHQ in(2)were added to fresh rapeseed oil and prepared into frying oil,with the antioxidant concentrations of 0.04%,0.07% and 0.02%,respectively.The blank rapeseed oil was set and the continuously frying experiments were carried out for 32 h respectively.The results showed that the acid value(KOHmg/g)of four rapeseed oils(blank,tea polyphenols,rosemary,TBHQ rapeseed oil)increased from 0.10 to 4.50,1.40,2.20,2.90,respectively.The content of polar components increased from 3.90% to 25.8%,28.62%,46.01% and 46.64%,respectively.The total amount of TGO,TGD,ox-TG and other oxidized polymerization products in polar components increased from 1.99% to 21.55%,28.50%,42.16%,41.94%,respectively.The total hydrolysates in polar components increased from 2.23% to 4.26%,2.69%,3.86% and 4.81%,respectively.The effects of three antioxidants on the frying stability of rapeseed oil were evaluated by acid value and polar component content.However,the effects of three antioxidants on the production of oxidative polymerization products and food safety during rapeseed oil frying process were investigated at the same time.(4)According to the previous research results,it was found that the addition of tea polyphenols was beneficial to improve the comprehensive quality of oil frying when frying Fried dough sticks with soybean oil.However,due to the differences in the main components of different ingredients,the reactions of different ingredients to oil frying are different.This chapter mainly explored the influence of tea polyphenols on oil frying stability when different ingredients are Fried in soybean oil.In this chapter,soybean oil with and without tea polyphenols was used to fry tofu,French fries,Fried dough sticks and chicken wings respectively,to compare the antioxidant performance of tea polyphenols when frying different food materials in soybean oil.After 32 hours of frying,the acid value(KOHmg/g)of Fried dough stick(tea polyphenols,control)increased from 0.15 to 1.30,1.61 and 1.15 and 1.46 respectively.The acid value(KOHmg/g)of oil samples(tea polyphenol-tofu,tofu,tea polyphenol-chicken wings,chicken wings,tea polyphenol-French fries,French fries)increased from 0.05 to 0.49,0.53,0.71,0.77,0.58,0.94,respectively.The polar component content of youtiao(tea polyphenols,control)increased from 6.15% to 28.11% and 34.00% respectively.The polar component content of the oil sample of other ingredients(in the same order as above)increased from 6.38% to 17.13%,18.01%,20.13%,21.00%,29.84% and 40.84%,respectively.The oxidation content of polar components in oil strips(tea polyphenols,control)increased from 3.54% to 25.31% and 30.36%,respectively.The oxidation content of other polar components in oil samples(in the same order)increased from 3.86% to 14.83%,14.87%,17.48%,18.68%,27.21% and 37.32%,respectively.The content of PAH4 in soybean oil with tea polyphenols decreased by 0.47,0.75 and 1.86 ?g /kg respectively.When tea polyphenols were added to soybean oil to fry chicken wings,tofu and Fried dough sticks,the content of 3-MCPD decreased by 7.44,0.38 and 1.06 mg/kg respectively,while GEs content decreased by 7.97,12.77 and 17.45 mg/kg respectively when tea polyphenols were added to fry French fries,tofu and Fried dough sticks.To sum up,adding tea polyphenols into soybean oil and frying different ingredients can control the increase of acid and polar components,prolong the frying life of oil and control the formation of GEs.Tea polyphenols can inhibit the increase of different risk components for different frying materials.Therefore,the addition of tea polyphenols as antioxidants to soybean oil is conducive to soybean oil frying.