The Effects Of Fatty Acid Compositions And Endogenous Antioxidants Of Peanut Varieties On Oil Stability

Recently, people focus on the effects of fatty acids and endogenous antioxidants on peanut oilstability. In this research, the oil stabilities of45peanut varieties were determined, the fatty acidscomposition and the proportional modes,-VE, γ-VE,-VE, campsterol, stigmasterol, β-sitosterol andsqualene contents of the varieties were tested, the correlation analysis was conducted betweenendogenous components and oil induction time in order to study the relationship between oil stabilityand endogenous components content, and the endogenous components differences among districetswere comparised. In the end, the effects of antioxidants and synergists to improve peanut oil stabilitywere studied. The main conclusions were summarized as follows:The oil contents ranged from42.11%to58.59%, the highest and the lowest oil content varietieswere Yuhua9327and Zhonghua8respectively, the varities ratio which oil content were higher than56.00%was8.89%. Within the peanut varieties selected, the rank of oil content of peanuts fromdifferent districts was Jiangsu>Henan>Shandong>Guangdong>Fujian, thereinto oil content of peanutsfrom Jiangsu and Henan were extremely significant higher than peanuts from Fujian (P<0.01). Thecoefficient variations of each basic quality indexe of all peanut oil varieties were39.92、43.15、49.74、56.04、96.78, respectively. The longest induction time is Shanhua7(5.76±0.07h), suggested that the oilof the varity is the most stable.The contents of fatty acid compositions of peanut varieties were determined, the differences ofC16:0and UFA/SFA among districts were compared. The ranges of SFA、UFA、UFA/SFA、MUFA、PUFA、O/L in peanut were15.79%～31.22%、64.13%～80.05%、2.05%～4.62%、32.55%～48.69%、24.48%～42.46%、0.84～1.72. Within the peanut varieties selected, C16:0from Henan and Guangdongwere significantly higher than Shandong, Jiangsu and Fujian (P<0.05), UFA/SFA from Guangdong andFujian were significantly higher than Henan (P<0.05). OSI and linoleic acid were significantly negativecorrelated(P<0.01，r=-0.57), OSI was significantly negative correlated with PUFA (P<0.01，r=-0.50),significantly positive correlated with O/L(P<0.01，r=0.47).The endogenous antioxidants such as VE(-VE, γ-VE,-VE), phytosterol (campsterol, stigmasterol,β-sitosterol) and squalene of peanut varieties were determined, the endogenous antioxidants differencesamong districts were compared, and the correlations between oil induction time and endogenousantioxidants were analyzed. The ranges of total VE、、γ、-VE、campsterol、stigmasterol、β-sitosterol、squalene were17.47～42.61mg/100g、9.36～33.98mg/100g、2.88～16.93mg/100g、0.26～1.30mg/100g、3.89～67.39mg/100g、0.31-22.62mg/100g、38.82～115.70mg/100g、3.77～16.45mg/100grespectively. Within the peanut varieties selected, among different districts, the rank of-VEcontent wasGuangdong>Henan>Fujian>Shandong>Jiangsu, the ranks of γ-VEand-VEcontents were Fujian,Guangdong, Jiangsu, Shandong, Henan, the rank of total VEcontent was Guangdong, Henan, Shandong,Fujian, Jiangsu, the rank of stigmasterol content was Henan, Shandong, Fujian, Guangdong, Jiangsu,campsterol content of peanuts from Henan was significantly higher than Fujian (P<0.01), the rank ofβ-sitosterol content was Henan, Shandong, Guangdong, Jiangsu, Fujian, the rank of squalene content was Henan, Guangdong, Shandong, Fujian, Jiangsu, squalene content of peanuts from Hanan wassignificantly higher than Jiangsu (P<0.01), so peanut varieties with high endogenous antioxidantcompositions from different districts can be chosen. The correlations between oil stability and-VE,γ-VE,-VE, campsterol, stigmasterol, β-sitosterol and squalene were all very low, which showed that theendogenous antioxidants in peanut had little effects on peanut oil stability.The antioxidant effects of TP, phytosterol, TBHQ, AP, VE, BHT, phytic acid, citric acid and VConpeanut oil and their best proportion with synergists were researched. The best synthetic and naturalantioxidants to peanut oil were TBHQ and TP respectively, and the induction times were17.90±0.71h、11.43±0.27h when added to peanut oil separately, moreover, the effect of TBHQ on peanut oil stabilityis significantly higher than TP (P<0.01). Antioxidants which Pf values were between2～4were TP、AP and TBHQ. Within the limits additive dose of national standard, the best additive doses of TBHQand TP were0.02%and0.03%respectively, which induction time were18.91±0.54h and14.93±0.09h.VCcan significantly enhance the antioxidation effect of TBHQ, and the induction time was21.05±0.26h when0.02%TBHQ+0.02%VCwere added to peanut oil, followed by citric acid, thesynergistic effect of phytic acid to TBHQ is not significant. All the three synergists have no synergisticeffect to TP.