The relationship between the volatile nitrogen-containing and sulfur-containing compounds, and salt-tolerant yeasts.

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This study was carried out on the relationship between the volatile nitrogen-containing and sulfur-containing compounds which are important as aroma components of miso, and salt-tolerant yeasts essential for forming aroma in miso. Followings are the result of this study.1.The arrangement of the trapping apparatus for volatile components and the way of their analysis were established and reported.2.On the above study subject, examination was made using synthetic media consisting both of mixtures of glucose and 18 kinds of amino acids which had been designed in the arrangement of miso raw materials, and of salt. The volatile nitrogen-containing compounds commonly identified both in noninoculated yeast media and in cultured yeast media were acetylpyrrole, pyrazine and pyrazines with a side chain containing one carbon or with side chains containing two carbons in all. Pyrazine and pyrazines tended to decrease in cultured yeast media, and almost no nitrogen-containing compounds were formed … More anew by salt-tolerant yeasts. On the other hand, as volatile sulfur-containing compounds, dimethyl disulfide, dimethyl trisulfide and methional were identified. Further, in cultured yeast media, in addition to these compounds, 3-(methylthio)propyl acetate and 3-(methylthio)-1-propanol (methionol)were formed. The culture of yeasts decreased the volatile sulfur-containing compounds which had been identified in noninoculated yeast media. The rate of decrease of these compounds in cultured media was greater in Zygosacchromyces rouxii S84(Z.rouxii)in tested yeasts. Z.rouxii eliminated these compounds by as much as 55.2-99.4%. The formation and reduction of these volatile sulfur-containing compounds by Z.rouxii were also recognized both in noninoculated media and cultured media containing methionine as the sole nitrogen source. Moreover, it was recognized that, in addition to these compounds, ethyl 3-(methylthio)propanoate was formed by Z.rouxii.3.The analyzes were made on the volatile sulfur-containing compounds in two kinds of miso, using commonly called aseptic miso for one, in the maturation of which koji molds solely participate, and applying conventional miso for the other which develops maturation by the use of yeasts and lactic acid bacteria in addition to koji molds. In both misos, dimethyl disulfide, dimethyl trisulfide and methional were identified. These compounds were found to be less in amounts in the aseptic miso in comparison with in conventional miso. Besides, in conventional miso, ethyl 3-(methylthio)propanoate and methionol were also identified in addition to these compounds. Less