Relation of Omphalotus japonicus Color Tone to Thelephoric acid Concentration

This study clarified the relation between thelephoric acid, the coloring molecule of a simple method of identifying Omphalotus japonicus using a beam reagent (5 w/v% potassium hydroxide ethanolic solution), and the color tone of the pileus epidermis and stained area of the stem base. Correlation was found between the shade of the pileus epidermis and stained area of the stem base and the thelephoric acid concentration. Identification methods of two types were used: direct method and extraction method. Results suggest that selecting an appropriate identification method according to the fruiting body condition will improve identification accuracy and conservation of labor.Furthermore, no correlation was found between illudin S, a toxic component of O. japonicus, and thelephoric acid concentration. Therefore, analyzing illudin S as usual is considered necessary when identifying the cause of food poisoning associated with O. japonicus.