Abstract: In order to explore the effects of different production processes (cold pressing, leaching, and their combination) on the quality and flavor of soybean oil of third grade, the physicochemical properties and fatty acid composition of the three soybean oils were determined, and their volatile compounds were identified and analyzed by electronic nose, headspace-solid phase microextraction-gas chromatography-mass spectrometry (HS-SPME-GC-MS), and headspace-gas chromatography-ion mobility spectroscopy (HS-GC-IMS). Differential analysis of the volatile compound data among the soybean oils was performed by clustering heatmap analysis, principal component analysis (PCA) and orthogonal partial least squares discriminant analysis (OPLS-DA). The results showed that cold-pressed soybean oil had the lowest moisture content; the peroxide value of leached soybean oil was significantly higher and its color was the darkest. Fragrant soybean oil had the highest linoleic acid content and a higher nutritional value; and among the detected volatile components, alcohols, aldehydes and pyrazine compounds mainly contributed to the formation of soybean oil flavor, and the reasons for the formation of some flavor compounds were clarified. Finally, 45 volatile compounds with high contributions were selected by OPLS-DA, and a reliable model was constructed for identifying fragrant soybean oil. In addition, a correlation was found between the quality and flavor of soybean oil.

Key words: soybean oil; physicochemical properties; volatile compounds; headspace-solid phase microextraction-gas chromatography-mass spectrometry; headspace-gas chromatography-ion mobility spectroscopy; orthogonal partial least squares-discriminant analysis