Analysis Of Bioactive Compounds And Antioxidant Capacity Of Tartary Buckwheat Oils From Different Cultivars

As a unique food medicine dual-use cereal crop,tartary buckwheat(Fagopyrum tataricum)has been reported to be containing a wide range of nutrients,including starches,dietary fibers,proteins,unsaturated fatty acid as well as polyphenols,carotenoids,sterols and have many pharmacological activities such as antioxidant,antihyperlipidemia,antidiabetes,antiinflammation and antitumor and so on.Specially,tartary buckwheat seeds with higher performance in antioxidant capacity are attracting more attention because of the increasing concern about disease prevention and health promotion through diets.There are two main types of antioxidant compounds containing hydrophilic antioxidants like rutin and quercetin and lipophilic antioxidants such as tocopherol and carotenoids.However,little attention has been paid to the components of nonpolar antioxidant components and their effects on human diseases.The materials of typical fifteen buckwheat cultivars in this study were chosen from seven buckwheat planting areas in China and planted identically in Yulin,Shaanxi.This study incorporated organic and analytical chemistry,GC-MS and normal and reverse HPLC chromatographic skills as well as multivariate statistical analysis techniques.The fatty acid composition,tocopherols and carotenoids profiles were investigated and were used to character different cultivars.Also,we analyzed the effect of tartary buckwheat cultivars on the antioxidant properties of tartary buckwheat oil and the contribution of invested bioactive constitutes under the instruction of free radicals and anti-oxidation theories,hoping that our study can provide the foundational information for tartary buckwheat industry and breeding as well as its healthcare function.The major conclusions of this study are as follows:1)The lipid contents of the fifiteen tartary buckwheat seeds were lower(less than 2% DW)and were significant difference under the identical cultivating environment and agronomical activities.Qianku NO.4,Xiqiao NO.3 and Fengku NO.2 had the higher oil contents,while Yu 6-21 had the lower content.Similar fatty acid profiles were found among the tested oils.C18:1 and C18:2 were the two main fatty acids with their percentage approximately 1:1,while C16:0 was the principal saturated fatty acid.Sinificant differentce was obtained with the fatty acid contents among the tested varieties.Fengku NO.2 had the highest content of C18:1,whereas Chuanqiao NO.1 had the highest contents of C18:2 and C18:3.2)Tartary buckwheat oils were rich in VE with three main tocopherols of α-,γ-and δ-tocopherol isomes.γ-tocopherol was the most abundant accounting for 83.66% of the total tocopherol content,followed by δ-tocopherol(8.57%)and α-tocopherol(7.77%).Significnat difference of the tocopherol content was observed among different varieties with Chuanqiao NO.1 having the highest content of the three tocopherol isomers.In term of the tocopherol composion,tartary buckwheat oil can be complementary tocopherol source of wheat oil.3)β-carotene and lutein were the two major constitute of the total carotenoids in tartary buckwheat oil.Lutein contributed to the larger amounts,which was approximately ten times of β-carotene.Among the tested oils Chuanqiao NO.1 had the highest content of lutein,while β-carotene in Qianku NO.4 was the highest.The concentration in tartary buckwheat oil was far higher than that in wheat bran oil,wheat germ oil and corn oil,indicating that tartary buckwheat oil can be a good source of dietary carotenoids.4)Three different antioxidant models were shown that tartary buckwheat oil had strong antioxidant capacity with Chuanqiao NO.1 the highest DPPH· scavenging ability,the highest ABTS·+ scavenging ability and the highest oxygen radical.Stronger relationship was observed between tocopherols and antioxidant capacities,demonstrating that tocopherols were the major contributor for the tartary buckwheat oil actioidant capacity.5)The result of principal component analysis and hierarchical cluster analysis showed that tocopherols and carotenoids were much more suitable to separate tartary buckwheat variety.Fifteen variety could be divided into three groups.The first group includes Qianku NO.4,Zhaoku NO.2,Fengku NO.2,Xinong 9940 and Chuanqiao NO.1,which have higher the content of tocopherols and carotenoids.The second group contains Qianku NO.2,Xiqiao NO.3,Qianku NO.5,Zhaoku NO.1 and Chuanqiao NO.3,which have lower content of carotenoids.The third one has Xunqiao NO.1,Jinqiao NO.2,Jiujiang kuqiao,Xinong 9920 and Yulin 6-21,which possess the lower tocopherol contents.