Characterization of flavor frame in shiitake mushrooms (Lentinula edodes) detected by HS-GC-IMS coupled with electronic tongue and sensory analysis: Influence of drying techniques

New insight was systematically elucidated on variations of overall flavor characteristics in shiitake mushrooms (Lentinula edodes) affected by different drying techniques (hot air-drying (HD), vacuum freeze-drying (VFD), and VFD combined with HD (VFD-HD)). The volatile fingerprints of shiitake mushrooms were successfully established by headspace-gas chromatography-ion mobility spectrometry (HS-GC-IMS), and taste profiles and concentrations of non-volatile substances in mushrooms were analyzed. Comparison of aroma fingerprints associated with three drying approaches demonstrated that HD caused considerable losses of volatile compounds except for volatile acids, while VFD and VFD-HD preserved aroma compounds effectively. By application of PLSR analysis, strong "seasoning-like" and "fruity" aromas of VFD-HD mushrooms were closely correlated with 2,6-dimethylpyrazine and esters respectively. Additionally, the umami intensity of VFD-HD mushrooms was similar to HD samples and significantly higher than VFD ones. Furthermore, the correlation between the electronic tongue and sensory attributes was explored. The results obtained from this study revealed that VFD-HD could combine the advantages of single HD and VFD, producing high flavor quality mushroom products.