Flavor Components of Miso: Basic Fraction

Basic flavor components were isolated from various types of miso and determined qualitatively and quantitatively by gas chromatography and mass spectrometry. 12 pyrazines, 3 pyridines, N-methylpyrrolidone, 2-acethylpyrrole and benzothiazole were identified. All but tetramethylpyrazine had not been reported previously for their presence in miso. Concentrations of the basic components, except for pyridines, varied considerably, depending on the type of miso. The factors which influenced the levels of these components were primarily a soy bean cooking condition and a koji ratio. The flavor contribution of alkylpyrazines to each type of miso is also discussed on the basis of the additivity of odorous mixture. Alkylpyrazines were judged to contribute to miso flavor, particularly in the soy bean miso.