Brevibacteriulm linensの揮発性物質生成に関する一般性状

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The close relationship of B. linens and a characteristic cheese flavor of Limburgar and Brick which are ripened by the micro-organism has long been recognized but no work on the role of actions of it to the flavor production seems to have been undertaken. This paper is a general preliminary report on the behavior of B. linens during incubation for the purpose of investigating this problem. In this experiments liquid standard medium (Meidum-S; peptone 1%, glucose 1%, bouillon 1%, NaCl 0.5%, pH 7.0) was used for the most part. B. linens was incubated at 21℃ for various prescribed time in the Medium-S and other media varying pH and the concentration of only one component from the Medium-S, then changes of pH, NH₃-N contents, and amounts and components of volatile acids, bases, neutral substances separated from cultures by steam distillation were observed qualitatively and quantitatively by the methods of gaschromatography (G. C. ), paper partition chromatography (P. P. C. ) and others. The results obtained are summarized as follow. (1) B. linens scarcely glew under the initial pH 4.0 to 5.0. In initial pH 6.0 or above, however, it glew remarkably. Especially, near in initial pH 7.0 was the most favorable condition for its growth. After incubation for 7 days pH in cultures were constantly brought to near 8.5 (Fig. 2). The contents of NH₃-N in cultures increased but no sigmoid curve during incubation, and it was observed larger in the cultures incubated for 5, 9 and 11 days under initial pH 6.0 to 7.0 (Fig. 1). (2) Near in the initial pH 7.0 of media was the most favorable condition for the production of volatile bases and acids during incubation (Fig. 4). Volatile bases were always quantified larger amounts than volatile acids and neutral substances in each medium and their contents were increased but no linear during incubation as NH₃-N contents (Fig. 3). It is quite possible from the facts that volatile bases were main components of the characteristic cheese flavor ripened by B. linens. On the other hand contents of the volatile acids and neutral substances were also quantified no linear during incubation such as that of the bases. (3) The higher concentration of bouillon, pepton or glucose in media proportionally increased the production of volatile acids, and 5 % NaCl content was the most proper condition for their production (Fig. 5). Form the data of G. C., acetic, propionic, iso-butyric, n-butyric, iso-valeric and caproic acids were commonly found in media. Among these fatty acids acetic, iso-valeric and caproic acids were found a remarkable heigher (Table 1), especially, iso-valeric acid was the most interesting because of no such high production had been found in the other cheese starters. (4) Bouillon or pepton in medium was also useful component to produce the volatile bases, and 3 % NaCl was favorable to its production (Fig. 5). Volatile amines were isolated and identified by P. P. C. and spot tests. Histamine, thyramine, dibutylamine, monoethylamine, monomethylamine, diethylamine and cadaverine were then comformed (Fig. 6). Histamine was found larger amounts than the others and crystalized easily from the distilate. (5) As neutral volatile substances, three neutral carbonyl compounds and four alcoholes have been detected by G. C. and spot tests. They were formaldehyde, acetoaldehyde, aceton, ethanol, iso-propanol, n-propanol and iso-butanol. Their production were also effected by a medium components, especially, bouillon or pepton were effected remarkably on the production of acetoaldehyde and aceton (Table 2).
信州大学農学部の論文
1966-12-25

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細野明義
信州大学大学院農学研究科

Brevibacteriulm linensの揮発性物質生成に関する一般性状

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