Analysis of Nutritional Components and Volatile Flavor Compounds in Common Edible Fungi

Edible fungi were rich in nutrients and were potential sources of high-quality protein. In this study, nutritional components such as moisture, ash, protein, total sugar and L-ergothione in 18 kinds of edible fungi were analyzed, and headspace solid phase microextraction combined with gas chromatography-mass spectrometry (HS-SPME-GC-MS) were used to analyze the fruit-body, mycelium and fermentation broth of 6 edible fungi (Lentinula edodes, Agaricus bisporus, Coprinus comatus, Pleurotus eryngii, Auricularia heimuer and Ganoderma lucidum). The results showed that the water content of 18 edible fungi ranged from 6.7 to 13.77 g/100 g, ash content from 2.24 to 10.9 g/100 g, fat content from 0.3 to 2.92 g/100 g and total sugar content from 2.11 to 10.5 g/100 g. The crude protein content of 18 edible fungi ranged from 7.88 to 35.87 g/100 g, among which the protein content of Agaricus bisporus was as high as 35.87 g/100 g. There was no significant difference in the content of other nutrients. The amino acids were rich and contained 8 kinds of essential amino acids necessary for human body. Principal component analysis showed that the amino acid composition ratio of Lentinula edodes, Auricularia heimuer, Grifola frondosa, Volvariella volvacea, and Flammulina velutipes was most similar to that of egg, but significantly different from that of meat, soybeans and wheat. The results of high performance liquid chromatography showed that Lentinula edodes was rich in ergothioneine, and the content was up to 336 mg/kg. The ergothioneine content of edible fungi such as Grifola frondosa, Morchella, Agaricus bisporus and Coprinus comatus were also higher than 100 mg/kg. A total of 34 volatile compounds, including aldehydes, ketones, esters, alcohols, phenols, ethers, alkanes and heterocyclic compounds, were identified by HS-SPME-GC-MS in 6 edible fungi. Ganoderma lucidum mycelium was rich in hexal, methylnonylketone, trans-2-octenal, 2-n-amylfuran, 2,4-nononadienal and other volatile compounds, which were significantly different from the other 17 samples. The flavor substances of the fermentation broth of the six edible fungi were similar, and all of them had special flavor substances such as ethyl heptanate and 18-crown-6. Pleurotus eryngii mycelium and the fruiting bodies of Ganoderma lucidum and Coprinus comatus contained butylated hydroxytoluene, methyl benzoate and other unique substances. This study provides data basis for the development of high value edible fungi by analyzing the nutritional components and flavor substances of common edible fungi.