Investigation of the physicochemical properties and the chemical components of chili rapeseed oil via different preparation oil temperatures

Chili rapeseed oil (CRO) is a widely used seasoning in Chinese food. This research studied the influence of preparation oil temperature on CROs, specifically focused on the physicochemical properties and chemical components. Both the prepared samples with chili flakes after maceration and the filtered CROs were presented in dark red color, and the color of chili flakes changed dramatically as oil temperature increased due to the extraction effects and vigorous reactions between chili flakes and rapeseed oil. The increasing oil temperature also led to a rising acid value (AV) and total phenolic content along with a decreasing peroxide value (PV). No significant differences in the fatty acid compositions were observed. The liquid chromatography-tandem mass spectrometry (LC-MS/MS) screened 537 metabolites in the CROs with 214 differential metabolites. The oil temperature of 140 °C seems to be the boundary from 100 and 120 °C to 160 and 180 °C. Both the up-regulation and down-regulation metabolites raised as oil temperature increased compared with 100 °C samples, indicating the violent variation in the compound constitution of CROs. This research offers experimental evidence to elucidate that the increase in preparation oil temperature could enrich and diversify the chemical composition of CROs, resulting in varied CROs.