Characteristic fingerprints and comparison of volatile flavor compounds in Morchella sextelata under different drying methods

Morchella sextelata is a precious and popular commercial edible fungus that was developed recently in China. This research aimed to characterize the volatile profiles of M. sextelata under three dehydration methods (freeze, hot air, and natural air drying). Comprehensive two-dimensional gas chromatography-time-of-flight mass spectrometry (GC × GC-ToF-MS) was shown to the best choice to discriminate the volatile profiles of M. sextelata Characteristic flavor substances of M. sextelata were eight-carbon-containing (C8) compounds, hexanal, 2(5 h)-furanone, and benzaldehyde. Drying methods had significant influences on the volatile flavor profiles of M. sextelata, and 104 differential compounds were screened by multivariate statistical analysis. Freeze-dried samples had the most abundant volatile compounds and maintained more alcohols, ketones, aldehydes, and esters described as mushroom, sweet, and green flavor, like 1-octen-3-ol, 1-octen-3-one, nonanal, 2,3-butanedione, and so on. Hot air-drying promoted the production of heterocycles and ketones with roasted flavor due to the thermalreaction, such as 2-cyclohexen-1-one, furan, 3-phenyl-, etc. Natural air-drying resulted in acids releasing an unpleasant flavor, e.g., acetic acid, 2-methylbutanoic acid, etc. Overall, thermal reaction combined with vacuum conditions might be suitable for maintaining and enriching the aroma flavor of dried true morels.