Rapid Estimation of Tocopherol Content in Linseed and Sunflower Oils-Reactivity and Assay

Molecules

Tjaᘚ Prevc²  Alenka Levart³  Irena Kralj Cigić¹  Janez Salobir³  Nataᘚ Poklar Ulrih²  Blaž Cigić² 

[1] Faculty of Chemistry and Chemical Technology, University of Ljubljana, Večna pot 113, Ljubljana 1000, Slovenia; E-Mail:;Department of Food Science and Technology, Biotechnical Faculty, University of Ljubljana, Jamnikarjeva 101, Ljubljana 1000, Slovenia; E-Mails:;Department of Animal Science, Biotechnical Faculty, University of Ljubljana, Groblje 3, Domžale 1230, Slovenia; E-Mails:

关键词: plant oil;    α-tocopherol;    γ-tocopherol;    vitamin E;    DPPH;    antioxidants;    solvent;   

DOI  :  10.3390/molecules200814777

来源: mdpi

【 摘 要 】

The reactivity of tocopherols with 2,2-diphenyl-1-picrylhydrazyl (DPPH) was studied in model systems in order to establish a method for quantifying vitamin E in plant oils. The method was optimized with respect to solvent composition of the assay medium, which has a large influence on the course of reaction of tocopherols with DPPH. The rate of reaction of α-tocopherol with DPPH is higher than that of γ-tocopherol in both protic and aprotic solvents. In ethyl acetate, routinely applied for the analysis of antioxidant potential (AOP) of plant oils, reactions of tocopherols with DPPH are slower and concentration of tocopherols in the assay has a large influence on their molar reactivity. In 2-propanol, however, two electrons are exchanged for both α- and γ-tocopherols, independent of their concentration. 2-propanol is not toxic and is fully compatible with polypropylene labware. The chromatographically determined content of tocopherols and their molar reactivity in the DPPH assay reveal that only tocopherols contribute to the AOP of sunflower oil, whereas the contribution of tocopherols to the AOP of linseed oil is 75%. The DPPH assay in 2-propanol can be applied for rapid and cheap estimation of vitamin E content in plant oils where tocopherols are major antioxidants.

【 授权许可】

CC BY   
© 2015 by the authors; licensee MDPI, Basel, Switzerland.