Exploring the impact of cooking methods on the nutritional, oxidative, and sensory qualities of Sichuan fragrant rapeseed oil using integrated metabolomics and flavoromics.

Abstract

Sichuan fragrant rapeseed oil is a premium edible oil valued for its distinctive flavor and nutritional profile. Its inherent antioxidants contribute to high oxidative stability, enabling preservative-free storage and offering advantages over many refined vegetable oils. However, the systematic influence of typical Sichuan cooking techniques on these properties remains insufficiently understood. This study systematically investigated the impact of five cooking methods, which are stir-frying (SF), air-frying (AF), microwaving (MW), hot-oil stirring (HO), and deep-frying (DF), on the nutritional and sensory characteristics of Sichuan fragrant rapeseed oil using integrated metabolomics and flavoromics approaches. Gas chromatography analysis revealed that MW- and HO-treated oils retained the highest polyunsaturated fatty acid (PUFA) content, whereas DF significantly increased saturated fatty acid levels. Spectrophotometric and LC-MS/MS analyses indicated that phenolic compounds were highly susceptible to thermal degradation, with the most severe losses occurring under SF and AF treatments, followed by MW. In contrast, DF and HO better preserved specific phenolic compounds. Headspace solid-phase microextraction coupled with two-dimensional gas chromatography-mass spectrometry identified 366 volatile compounds, classified into 10 categories. Electronic nose analysis demonstrated that the flavor profile of HO-treated oil was most similar to that of the control. Colorimetric analysis further indicated that SF had the least impact on the oil's overall color. In summary, for consumers prioritizing PUFA preservation and minimal oxidation, MW is the most suitable method, while HO is preferable for those seeking maximal retention of the original flavor profile. Therefore, HO and MW are more suitable than SF, AF, and DF for maintaining the premium quality of fragrant rapeseed oil during culinary applications.