| Objective: Termitomyces albuminosus (T. albuminosus) is an edible fungus of the class basidiomycetes. It is extremely tasty and highly valued due to its rareness and difficulty in cultivation. This mushroom is widely distributed in tropical and subtropical regions of Africa and Asia. In china, it’s widely distributed in Yunnan, Guizhou, Sichuan province and other regions to the south of Yangtze River. T. albuminosus is one of the two most favorite edible mushrooms in China. It was reported to contain a high content of protein, minerals, nucleosides and nucleobases. So far, the distribution, ecological relationship and morphology of T. albuminosus was studied and reported. However, to the best of our knowledge, the nutritional value, characteristic flavor and the optimum conditions for extracting polysaccharide from wild T. albuminosus (PWTA) have not been reported. The objective of the present study was to determine the composition and content of moisture, ash, crude fat, crude protein, crude polysaccharides, minerals and amino acid of wild edible Termitomyces albuminosus to evaluate the nutritional value, to determine the content of heavy metals to evaluate the nutritional value and to investigate the effect of different extraction parameters on the extraction yield of PWTA and to obtain the optimal extraction conditions.Methods:1. The content of main nutrient ingredient of T. albuminosus were determined by related method.2. The content of heavy metals (Pb, As, Cd, Hg) of T. albuminosus were determined by Inductively Coupled Plasma Atomic Emission Spectrometry (ICPAES).3. The effect of different extraction parameters on the extraction yield of PWTA was investigated by phenol-sulfuric acid method and the optimal extraction conditions was obtained by using an orthogonal L9(3)4 test and RSM employing a five-level, three-variable central composite design (CCD).4. The flavor ingredients of T. albuminosus were extracted with organic solvent extraction method and then identified by Gas Chromatography-Mass Spectrometry (GC-MS) method.Results:1. The content of most of main nutrient ingredient are higher than usual food me- terials and the composition of amino acid is closed to essential amino acid composite- on in reasonable protein recommended by WHO. However, the content of mineral el- ement Ca is much lower than vegetables and the content of heavy metals (Pb, As, Cd, Hg) are almost all over the national food hygienic standards showed the strong ability to accumulate heavy metal elements.2. The extraction temperature, extraction time, and powder to water ratio were found to have a significant influence on the extraction yield of PWTA. The extraction temperature was the most significant variable affecting the extraction yield of PWTA. The optimum conditions were: extraction temperature 95.9°C, extraction time 3.02 h, and powder to water ratio at 1:33.4. Under these conditions, the experimental extraction yield of PWTA was 7.25%, which is well matched with the predictive extraction yield by the RSM model, indicating that the RSM model was adequate for the extraction process.3. 73 chemical components were identified and determined, amounting to 87.6% of the total area of the peaks. The main flavoring compounds are: 1-butanol-3-methyl, 9,12-octadecadienoic acid, methyl ester, octadecanoic acid, ethyl ester, ylangene, propanoic acid, tetradecanoic acid, pentadecanoic acid, palmitic acid, heptadecanoic acid, stearic acid, oleic acid, linoleic acid. Linoleic acid accounted for 24.9 percent of total volatile oil, had the highest content among all components.Conclusion: The content of most of main nutrient ingredient of T. albuminosus are higher than usual food meterials. It also maintain a high content of polysaccharide. The extraction yield of polysaccharide of T. albuminosus reached a higher level after using the optimum extraction condition. The characteristic flavor of T. albuminosus may contributed by the pyrazine compounds in it. However, the content of heavy metals (Pb, As, Cd, Hg) are almost all over the national food hygienic standards showed the low edible safety of T. albuminosu. |
PDF Full Text Request