| Lentinus edodes is renowned in China and is popular for its rich nutrition and unique flavor. The unique flavor of shiitakes is one of the important reasons for its favor. The study on the volatile components of shiitakes becomes a research hotspot in recent years. It is usually dried for preservation and the pleasant flavor of mushrooms is also closely related with the drying process. In this paper, Volatile compounds of shiitake mushroom were extracted from the pileus and stipe of dried Lentinous edodes, respctively, using Simultaneous Distillation-Extraction Method and analyzed by GC-MS; using the single factor experiments and orthogonal experiment designs to determine the optimal extraction conditions of Lenthionine from the cap of dried shiitake mushrooms; and it is also the first time systematically establishing the method for determination of the content of Lenthionine from Lentinus edodes using an internal standard method by gas chromatography (GC) analysis. The impact of drying process on the flavor of shiitake mushroom is also researched by GC and GC-MS analysis; and the technology of enzymolysis of the shiitake concrete is studied, to prepare for latter processing of Lentinus edodes Complex spices and flavor product. The main results of this study were summarized below:Volatile compounds of shiitake mushroom were extracted from the pileus and stipe of dried Lentinous edodes, respctively, using Simultaneous Distillation-Extraction Method and analyzed by GC-MS. There were 76 volatile components identified,36 from pileus and 63 from stipe of dried mushrooms.23 volatile componets could both be found from pileus and stipe including 10 sulfur compounds. And the rest of them were acids, alkanes, aldehydes and alcohols, etc. Although the kind and relative content of the volatile compounds were different between pileus and stipe, there were no significant differences about the sulfur compouds containd in them, which were the key odorants of the specific shiitake aroma.27 out of 76 volatile compounds identified were being reported for the first time as components of shiitake mushroom. Using the Simultaneous Distillation-Extracter (SDE), the single factor experiments and orthogonal experiment designs to determine the optimal extraction conditions of Lenthionine from the cap of dried shiitake mushrooms. They are shiitake mushroom powder 30.0 g with 60 mesh as the pulverized degree, adding 10 times distilled water in 2000ml round-bottomed flask, distilling and extracting for 2 hours. Lenthionine reached 13.5μg/g.It is also the first time systematically establishing the method for determination of the content of Lenthionine from Lentinus edodes using an internal standard method by gas chromatography (GC) analysis. Applying n-hexane as the solvent and dipropyl disulfide as an internal standard to measure the absolute amount of Lenthionine, the method is sensitive and accurate. It provides an theoretical basis for developing the natural flavor of shiitake mushrooms products.The impact of drying process on the flavor of shiitake mushroom is researched by GC and GC-MS analysis. Most sulfur-containing compounds were produced during drying, the trend is:Lenthionine produced more at 60℃oven temperature than at 50℃during the same time; more at 70℃,2h than 60℃12h. Similarly,1,2,4,5-terathiane could not be found at 40℃and 50℃, and it emergenced at 60℃for 4h. when drying at 70℃, the content of it downward for longlasting drying.There were 11 volatile components identified in fresh shiitake mushroom with 3 sulfur compouds,24 in dried mushroom with 12 sulfur compouds and 26 in re-dried mushroom with 11 sulfur compouds.Using the single factor experiments and orthogonal experiment designs to determine the optimal extraction conditions of enzymolysis of the shiitake concrete by Cellulase and flavor protease. They are pH 5.0, content of Cellulase 0.4%, content of flavor protease 0.1%, heating temperature 50℃, heating time 1.5h, the reducing sugar got 15.32mg/g, amino nitrogen got59.5mg/g. |
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