Volatile compounds and fatty acid composition of crude and refined hazelnut oils

The volatile compounds, as well as fatty acid composition of crude and refined hazelnut oils, which are produced by different brands in Turkey, were analyzed by GC/MS, using a solid phase microextraction and GC/FID. Free fatty acid and peroxide value of samples were also determined. In crude hazelnut oils, there were significant differences between brands, in terms of propanoic acid, hexanoic acid, 1-octanol, heptanal, octanal, nonanal, cyclopentane and heptane. In contrast, only a few volatile compounds were determined in refined oil samples. In refined samples, major differences have been detected in terms of nonanal, trans-2-decenal and 2-octyl furan. The refining process usually decreased the amount and counts of volatile compounds. The industrial refining of the oils did not cause any significant changes in the fatty acid composition of the samples. However, the refining process caused a decrease in the free fatty acid content and the peroxide value of hazelnut oils.