Oxidative stability of high oleic palm and hazelnut skin oil blends

High oleic palm oil (HOPO) with high oleic and palmitic acid contents is a new vegetable oil that needs to find further use in food applications, while hazelnut skin oil (HSO) with high oleic acid content is a by-product of hazelnut oil production and have no commercial value. The aim of the study was to obtain new oil blends for new food formulations with high oxidative stability and low (or reasonable) saturated fatty acid content using HOPO and HSO. For this aim, they were blended in the proportions of 0 to 100% (wt/wt), and fatty acid and tocol compositions, induction period and storage stability of the blends were evaluated. Tocotrienols (560.94 mg/kg) constitute the majority of the tocol content of HOPO, while tocopherols (437.69 mg/kg) were the major tocols of HSO. HOPO has a higher saturated fatty acid composition and lower monounsaturated fatty acids content than HSO. In general, it was determined that increasing the HSO ratio in oil blends reduced their oxidative stabilities, which is most likely because HSO is richer in total unsaturated fatty acids (91.8%) than HOPO (68.4%). In addition, tocotrienols are known to be stronger antioxidants than tocopherols. Although HOPO is rich in gamma-tocotrienol, which has a strong antioxidant activity, it also has some disadvantages such as having a high price and containing significant levels of saturated fatty acids (mainly palmitic acid). The optimum blend ratio was then determined as 50% HOPO:50% HSO considering oxidative stability and fatty acid compositions.