Studies on Physiological and Chemical Properties and Postharuest Keeping Quality of Mushrooms Part V. Effect of Harvest Seasons on the Contents of Free Amino Acids, Nucleotides, and Nucleic Acids and the Activities of Nucleic Acid-degrading Enzymes and Protease in Shii-take (Lentinus edodes (Berk.) Sing.) Mushrooms Takahisa MINAMIDE** and Takashi IWATA** Summary Shii-take mushrooms, var. Tokushima No. 4, were harvested in May, August, November, and January at their harvest maturity,

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... , and the effects of harvest seasonson the contents of flavoring constituents and nucleic acids and the activities of protease and nucleic acid-degrading enzymes were investigated. Glutamic acid, glutamine, aspartic acid, arginine, and ornithine were identified as major components of free amino acids, and the contents of these as well as total free amino acids were considerably higher in the materials harvested in November and January than those in May and August. In raw materials, guanine-5'-monophosphate, a main flavoring compound in dried shii-take, was scarcely detected. Other 5'-nucleotides, and RNA and DNA, precursors of nucletides, were contained most abundantly in the materials in January as compared with those in other seasons. The activities of protease, RNase, and DNase were significantly higher in the materials harvested in November, while with PMase and PDase no difference was found among harvest seasons.