Effect of Roasting on Volatile Flavor Compounds of Stropharia rugoso-annulata Analyzed by Headspace-Solid Phase Microextraction-Gas Chromatography-Mass Spectrometry Combined with Electronic Nose

In this study, the volatile flavor compounds in Stropharia rugoso-annulate were qualitatively and quantitatively analyzed by headspace-solid phase microextraction-gas chromatography-mass spectrometry (HS-SPME-GC-MS). The volatile odor profiles of S. rugoso-annulata roasted at different temperatures (0, 100, 120, 140, 160 and 180 ℃) were distinguished using an electronic nose. The aroma characteristics of roasted S. rugoso-annulate were determined by sensory evaluation. The results showed that a total of 87 volatile compounds were identified, including 13 aldehydes, 17 esters, 18 alcohols, 4 alkanes, 9 ketones, 8 acids, 4 pyrazines and 14 other compounds. A total of 25 volatile compounds like isovaleraldehyde and gamma-valerolactone were shared by the six samples. After roasting, the total contents of aldehydes, alkanes and pyrazines were increased, and the fruity, rose-like and cocoa-like aromas were enhanced, while the total content of alcohols was decreased significantly. From the perspective of overall odor perception, the electronic nose could effectively distinguish the volatile flavor profiles of S. rugoso-annulata roasted at different temperatures. Totally 34 key flavor compounds were identified according to their relative odor activity (ROV) values. Among them, isovaleraldehyde contributed the most to the flavor, being responsible for the malty and fruity aromas. The largest number (63) of flavor substances was found in S. rugoso-annulata roasted at 140 ℃. Roasting at 140 ℃ improved the richness of flavor, increased the malty, rose-like, nut-like and cocoa-like aromas, and improved the overall flavor of S. rugoso-annulata. The sensory evaluation showed that roasting enhanced the volatile flavor of S. rugoso-annulata, which was consistent with the above results.