Difference in Flavor among Boletus edulis Dried by Different Drying Methods Analyzed in Terms of Aroma and Taste Substance Characteristics

This study aimed to understand the flavor and taste characteristics of dried Boletus edulis products prepared by different drying methods and to explored the difference in flavor among the dried products. The volatile flavor substances and non-volatile taste substances of B. edulis dried by three different drying methods including hot air drying (HAD), vacuum freeze drying (VFD) and vacuum drying (VD) were measured and analyzed. Totally 64 and 85 volatile organic compounds (VOCs) were identified by gas chromatography-ion mobility spectrometry (GC-IMS) and gas chromatography-mass spectrometry (GC-MS), respectively. The fingerprint analysis results showed large differences among the dried products, the most significant differential characteristics being found in the VD dried product. Orthogonal partial least squares-discriminate analysis (OPLS-DA) selected 17 and 22 differential characteristic markers based on the results of GC-IMS and GC-MS, respectively. Relative odor activity value (OAV) analysis showed that the key VOC was 1-octen-3-ol. The analysis of non-volatile taste substances indicated that the highest contents of both free amino acids (FAAs) and 5’-nucleotides were found in the HAD-dried product, which were 234.57 and 27.870 mg/g, respectively. Among the 16 free amino acids (FAAs), glutamic acid was the major contributor to umami taste. In summary, HAD is more conducive to the accumulation of taste substances in B. edulis, while VD results in a higher number and amount of flavor compounds. This study could provide a reference for the selection of a method for the postharvest drying of fresh B. edulis.