Analysis of Chemical Compositions of 15 Different Cold-Pressed Oils Produced in Turkey: A Case Study of Tocopherol Analysis

Abstract

Many people tend to prefer natural foods and supplements nowadays. Considering this tendency, this study assessed the most significant in quality and purity parameters tocopherol and fatty acid compositions of cold-pressed oils, namely black cumin, sesame, sunflower, poppy, pomegranate, nettle, pumpkin, grape, safflower, flax, canola seed, wheat germ, peanut, hazelnut, and walnut. This study deals with the sample preparation and validation of tocopherols using an HPLC-FLD method for simultaneous determination of α-β-γ-, and δ-tocopherols, and analysis of fatty acid methyl esters (FAME) with using GC-FID. The validated HPLC method was applied for the tocopherols’ analysis and measurement uncertainty was calculated for tocopherols and some fatty acids. The obtained data were evaluated by using principal component analysis to show the relationship between quality parameters and seed oils. Wheat germ, hazelnut, safflower, and sunflower oils have the highest tocopherol contents respectively with a predominance of α-tocopherol. Seed oils’ fatty acid compositions were classified according to proportions of oleic, linoleic, and other fatty acids. This study shows that the evaluated seeds are valuable sources of natural antioxidants and some specific and polyunsaturated fatty acids. The applied method can also be helpful for the industry to obtain quality analysis approach.