Thermal oxidation, 3-MCPD and glycidyl esters formation in hazelnut oil enriched with natural extracts during French fries production

The aim of this study is to investigate the effect of propolis, quinoa (Chenopodium quinoa Willd.) seed and uckun (Rheum ribes L.) extracts to increase the oxidative stability of hazelnut oil used as frying oil. Studies on the use of these extracts in frying oils are limited. In addition, the effects of these extracts on the formation of 3-MCPD and glycidyl esters were the novelty of this study. In the study, uckun, quinoa and propolis extracts and as well as BHT were added to refined hazelnut oils. The total phenolic content of uckun, quinoa, and propolis extracts was determined as 2778.44, 245.16, and 1431.09 mg GAE/kg, respectively. The highest 2,2-diphenyl-1-picrylhydrazyl (DPPH) and 2,2′-azino-bis-3-ethylbenzthiazoline-6-sulphonic acid (ABTS) values were found in BHT. It was followed by propolis, uckun, and quinoa, respectively. Free fatty acids (0.57–1.39% oleic acid), peroxide value (0.79–11.49 meqO2/kg), p-Anisidine (p-AV) (1.30–67.52), totox (5.20–92.11), conjugated diene (2.81–11.09%), conjugated triene (1.64- 5.65%), color analyses, total polar compound (0.00–14.17%), and viscosity analyses were performed in oil samples taken during frying periods. In addition, 3-MCPD esters (1.443–5.114 mg/kg) and glycidyl esters (0.646–1.289 mg/kg) analyses were performed. The results showed that propolis and quinoa seed extracts have significant potential as natural antioxidants for nut oils during frying and slow the formation of monochloro compounds.