Studies On Volatile Flavor Compounds In Boletus Edulis

With the improvement of living standards in China, demands for food flavor are growing. Boletus edulis, also called "da jiao gu", is an mycorrhizal fungi. It is popular with people all over the world for heavy flavor and abundant nutrients. The research on volatile flavor compounds in Boletus edulis can provide theoretical sense and applicational value. In this study, taking dried Boletus edulis as raw material, the optimum method and conditions of extracting volatile compounds were determined. The flavor compounds were identified by gas chromatography and mass spectrometry(GC-MS), gas chromatography-olfactometry(GC-O) and retention index(RI). Finally, the effect of different treatments on flavor of Boletus edulis when stored was investigated. The main research results are as follows:1. Solvent extraction, steam distillation, head-space solid-phase microextraction were compared for extraction efficiency of volatile components in Boletus edulis. The results showed that the optimum extraction method was head-space solid-phase microextraction. The optimized conditions for analysis were that a 65μm PDMS/DVB fiber was exposed to the vapor phase above for 30 min at 60℃.2.In optimum extraction conditions, the flavor compounds were identified by gas chromatography and mass spectrometry (GC-MS), gas chromatography-olfactometry (GC-O) and retention index (RI). The results showed that 53 volatile components were identified, of which 29 compounds contributing to flavor of Boletus edulis were determined. The main compounds as follows:hexanal (grass scent), methylpyrazine (nut flavor), 3-methylthiopropanal (burnt),2,6-dimethyl pyrazine (barbecue flavor), 1-octen-3-ol (mushroom flavor),2-pentyl furan (bean sweet),2-ethyl-6-methylpyrazine (roasted flavor), 3-octen-2-one (mushroom flavor), phenylacetaldehyde (floral), and so on. In addition, three compounds which can not detected by GC-MS, also played an important role in flavor.3. The effect of different treatments on flavor of Boletus edulis when stored was studied. The results showed that light treatment had great role in promoting characteristic flavor, while heat treatment makde the loss of a large number of volatile components. Cryopreservation has little effect on the flavor.