Gas Chromatography-Ion Mobility Spectrometry and Electronic Nose to Detect Flavor Release from Cooked Indica Rice during Oral Processing

In order to study flavor release from cooked indica rice during oral processing, boluses of cooked indica rice from volunteers at different mastication stages were collected and analyzed for volatile components by gas chromatography-ion mobility spectrometry (GC-IMS) and electronic nose. The differential marker volatile compounds among different mastication stages were investigated. The results of electronic nose indicated that the flavor of cooked rice significantly differed before and after mastication. A total of 33 flavor compounds were identified by GC-IMS. Compared with that before mastication, the content of aldehydes in 25%, 50%, 75% and 100% boluses decreased by 62.01%, 47.60%, 69.19% and 71.78%, respectively; the alcohol content increased by 59.89%, 42.59%, 29.94% and 17.73%, respectively; the ketone content decreased by 31.92%, 17.87%, 34.92% and 38.45%, respectively. Through partial least squares-discrimination analysis (PLS-DA), 11 compounds were selected as characteristic markers, including hexanal and its dimer, octanal, heptanal, 1-propanol, 1-butanol, 2,3-pentanedione, 2-heptanone, 2-pentylfuran and limonene and its dimer.