Pamphlets on Biology Volume 687; Kofoid Collection (Paperback)

This historic book may have numerous typos and missing text. Purchasers can download a free scanned copy of the original book (without typos) from the publisher. Not indexed. Not illustrated. 1897 Excerpt: ...and more pronounced when the pH of the medium drops below 3.5. Of all the berries tested only loganberry goes lower, namely to pH 3.3. Loganberry juice was inoculated with yeast cultures grown on loganberry agar through ten transplant generations with the hope that adaptation to the pH of the loganberry juice would occur. The results of the 9th Series show, however, that instead of adaptation the yeast cultures became attenuated, for the parallel set of media inoculated with yeast carried on the ordinary malt extract agar gave higher alcohol yields. The same Series (9) showed that when loganberry juice is used, nitrogen deficiency due to dilution and not she pH, was more important. (Compare media No. 3 and No. 6 with No. 2 and No. 5 or No. 1 and No. 4, Series 9). under individual yeast strains, in the table that follows. In describing media and treatment of each test fermentation, the following abbreviations and symbols are used: (a) Mnats used: G.j.--grape juice Log.j.--loganberry juice Log.--loganberries Rasp.--raspberries (b) Added carbohydrate source: Cerel.--cerelose (corn sugar) Dex.--dextrose Sue.--sucrose c) Incubation temperature: 26-21 indicates that the culture was at first incubated Et 26C., and then at 21C. Laboratory Work by Alex M. Partansky and R. R. 3IcPherson Although the alcohol producing power of the various yeast strains had been previously ascertained, as reported in the above section, it was realized that it would be necessary to determine optimum conditions for the growth of the yeast as well as for the former characteristic. It is a recognized fact that these factors, namely, growth of the organism and the production of alcohol need not be directly correlated. However, in order that satisfactory fermentation take place within the t...