| 摘要 |
1,165,455. Preserving yeast. CANADIAN PATENTS & DEVELOPMENT Ltd. 9 June, 1967 [18 June, 1966], No. 26688/67. Heading A2D. [Also in Division C6] A process for producing yeast cells or spores having improved resistance to dehydration and improved storage properties comprises dispersing mature vegetative cells or growth in an aqueous solution containing 0.1 to 0.5% wt./vol. acetic acid radicle (provided as acetic acid or potassium acetate) at a pH of 5.5 to 6.5, aerating the suspension and as the acetic acid is metabolized and the pH rises, continually feeding acetic acid to adjust the pH to approximately 4.8 to 6, for at least 10 hours. The yeast cells are preferably maintained in the acetic acid suspension until at least one-half of the cells have formed spores, after which the pH is adjusted to approximately 4.0 to 5.5 with sulphuric, hydrochloric or citric acid and sporulation is allowed to continue for a further 6 to 12 hours. The spores and spore-containing yeast cells are then separated from the medium, dehydrated to a low moisture content and stored at room temperature or under refrigeration in a dry atmosphere, e.g. in the presence of silica gel. The yeast cells may, however, be dehydrated before (or without) spore formation. High yeast cell densities of 100 to 250 million or more cells per ml. are used.
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