A new insight into the formation of special flavor during the drying process of boletes based on FTIR joint HS-SPME-GC-MS

Boletus bainiugan ( B. bainiugan ) is a common wild edible mushroom, which is popular among consumers for its unique flavor and high nutritional value. Drying is usually used to extend shelf life. The effect of drying temperature on its chemical composition and flavor has not been studied and analyzed. In this study, Fourier transform infrared spectroscopy (FTIR) was used for chemical information characterization, and volatile organic compounds (VOCs) were qualitatively and quantitatively analyzed by headspace solid-phase microextraction-gas chromatography-mass spectrometry (HS-SPME-GC-MS). Simultaneously, the flavor formation mechanism was analyzed and a prediction model for major flavor compounds was established based on FTIR. Three-step spectral analysis revealed that temperature caused differences in the chemical composition of boletes. HS-SPME-GC-MS detected 764 VOCs. PCA and OPLS-DA indicated remarkable differences in VOCs due to drying temperature changes. The Flavoromics association network reveals nutty, fruity, and green as the main flavors of B. bainiugan after drying. The principal compound for flavor contribution is (2S, 4R)-4-Methyl-2-(2-methylprop-1-en-1-yl) tetrahydro-2H-pyran. In addition, the PLSR results showed that the FTIR spectral data were well-fitted to the relative contents of the 20 major flavor components. In conclusion, the results inform the mechanism of flavor formation in boletes after drying. • Three-step IR spectroscopy was used to analyze the chemical composition of boletus. • Most volatiles accumulated during drying, with maximum values at 65 °C. • The important sensory flavors for Boletus bainiugan were nutty, fruity, and green. • The principal flavor contribution is (2S, 4R)-4-Methyl-2-(2-methylprop-1-en-1-yl)tetrahydro-2H-pyran. • PLSR results showed that FTIR was well-fitted to flavor components.