Improvement of Refined Rapeseed Oil Thermal Resistance by Native Antioxidants Present in Rapeseed, Coriander, and Apricot Cold-Pressed Oils

The research aimed to evaluate the effect of high monounsaturated cold-pressed oil addition on the inhibition of refined rapeseed oil degradation during heating at frying temperature. Cold-pressed rapeseed, coriander seed, and apricot kernel oils were added in amounts of 5 and 25%. Refined rapeseed oil without additives and refined rapeseed oil supplemented with tert-butylhydroquinone (TBHQ) were negative and positive control samples, respectively. Blends were heated in a thin layer at 170 and 200 °C. Considering the increase in total polar compounds (TPCs) and oxidized triacylglycerol monomer (ox-TAG) content, natural additives demonstrated protective properties and were more effective than the TBHQ additive, especially at 200 °C. The lowest increases in TPC and oxTAG were found in AO5% at 170 °C (10.17% and 1.40 mg/g oil, respectively) and in AO25% at 200 °C (5.71% and 47.53 mg/g oil, respectively). The presence of triacylglycerol (TAG) dimers was found only in samples heated at 200 °C, and the lowest was in the sample with 25% coriander oil. It can be concluded that the addition of cold-pressed oils limited the TAG oxidation process. The addition of 25% coriander oil was effective in inhibiting the TAG polymerization process, and it may be a powerful alternative to synthetic antioxidants in improving stabilization of frying oils.