Flavoromics approach in monitoring changes of aroma profiles in rapeseed oils with different fragrance styles caused by frying and heating processes

Abstract In this study, four typical fragrance types of rapeseed oils were investigated under short-term frying of French fries and heating processes. Volatile flavor profiles, aroma compounds, and sensory attributes were evaluated by gas chromatography–mass spectrometry (GC-MS), gas chromatography–olfactory (GC-O), and sensory evaluation. The examination showed 140 volatiles, 28 aroma compounds, as well as 8 sensory attributes were detected. Aldehydes, nitriles, and acids were principal groups in unheated delicate fragrance rapeseed oil (DFRO) and refined rapeseed oil (RRO), as well as nitriles, acids, and heterocycles in unheated strong fragrance rapeseed oil (SFRO) and umami fragrance rapeseed oil (UFRO). During heating process, the total amount of volatiles had significant increases in DFRO and RRO, whereas it was the opposite in SFRO and UFRO. Aldehyde became the most predominant group, with significant increases under thermal treatments. Compared with heated oils, most volatiles presented lower contents in fried oils. Among the volatiles, 24 compounds were formed during heating process and 6 compounds were detected solely in fried oils. Among 8 sensory attributes, the deep-fried flavor attribute was formed in thermal-treated oils. According to the statistical analysis, remarkable differences were observed among unheated and thermal-treated samples, and the differences were diminished under thermal treatments, especially frying process; however, fried SFRO and DFRO still showed obvious distinctions with the others in flavor profiles.