###### Abstract
Gas chromatography-ion mobility spectrometry (GC-IMS) is an emerging mass spectrometry technique and is gaining increasing popularity, with automatic headspace sampling (HS) for the analysis of volatile flavor compounds [18]. When a mixture of volatile compounds is analyzed using GC-IMS, the analytes are first separated by the GC (retention time) and then the elution is separated in the ion mobility spectrometer (drift time) at atmospheric pressure, thereby producing a multidimensional spectrum including retention time, drift time, and signal strength [21; 22]. In addition, it can be used to distinguish between isobaric compounds and certain isomers, which usually are co-eluted from the GC column and hardly be distinguished by mass spectrometry, as well as distinguish the samples with nontargeted volatile fingerprints [23; 24]. Compared with GC-MS, GC-IMS has advantages such as intuitive visualization of data, high separation efficiency, high analysis speed, operation at atmospheric pressure, inexpensive maintenance, and possible portability [18; 25]. It can be applied in the establishment of volatile flavor fingerprints for food classification and adulteration detection, evaluation of food freshness and spoilage, detection of the off-flavor of food products, monitoring volatile metabolites during food processing, changes in volatile components during storage [26]. For instance, GC-IMS was applied to develop the flavor fingerprint of Tricholoma mustutake Singer and detect that the concentration of C8 compounds, including 3-octanone, 3-octanol, 1-octen-3-one, and 1-octanol, decreased after drying [25]. Moreover, the characteristic volatiles fingerprints of different parts of fresh and dried Tricholoma mustutake Singer were established by HS-GC-IMS and the formation of some volatile compounds (hexanal, heptanal, 2(5H)-furanone, acetophenone, nonanal, benzeneacetaldehyde) were observed after drying [27]. GC-IMS was also used to reveal that HAD caused considerable losses of volatile compounds except for volatile acids, while vacuum freeze-drying and combined drying preserved aroma compounds effectively [14]. However, GC-IMS is unable to replace the GC-MS. The lack of a library-like NIST mass spectral library of GC-MS and the non-linear response of IMS hider the qualitative and quantification of GC-IMS in flavor analysis [26; 28]. Therefore, GC-MS or GC-IMS could not be determined as the best analytical technique. However, either technique could be used as a complementary technique for the other one [29]. More comprehensive information of volatile compounds could be revealed and discrimination of food samples could be conducted by the combination of GC-MS and GC-IMS [27]. The collaborative analysis has been applied in a few studies in order to establish the characteristic volatiles fingerprints and investigate the volatile compounds among of Tricholoma matsutake Singer [27], finger citron [30], kiwifruit [21], white and yellow rice [17], and virgin olive oil [29]. The combination of GC-MS and GC-IMS is a hot topic and continued trend. Nonetheless, the combination of the two mass spectrometry methods is rarely performed regarding the flavor fingerprint and volatiles of shiitake mushrooms. Furthermore, aroma perception could not be provided only by chromatography analysis [14]. Descriptive sensory analysis (DSA) is an effective tool to detect and describe the qualitative and quantitative sensory attributes of products, and to determine the association of product characteristics and consumer perception [21; 31]. Quantifying the magnitude of the predominant sensory descriptors of shiitake mushroom by different drying methods has been reported by [PERSON] et al. [10]. However, little is documented in literature about the effects of different drying rate and drying degree on the aroma properties of shiitake mushrooms.