Lost rum of the Japanese Bonin islands. 1908

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This was translated from German as part of operation #RumBabelFish

Note about the molasses rum fermentation on the Bonin Islands (Japan).
By K. Saito, Tokio.

The inhabitants of the Bonin Islands prepare an alcoholic beverage from cane sugar molasses, of which they produce about 300 koku [1 koku = 180.39 L] per year.

To make this beverage, pour the moderately diluted molasses into barrels that are left to stand still in a warm room. As soon as the fermentation begins after a few days, a white foam cap is created. It gradually becomes larger and denser, until finally, at the end of the fermentation, the whole surface of the liquid is covered with foam. The fermented mass is then distilled. This gives clear, colorless rum of a somewhat acidic taste, the composition of which, according to my own experiment, is characterized by the following analytical findings, namely:

Specific Gravity (at 15° C)                        0.95429
Alkohol (Volume %)                                  38.537
Acid (as acetic acid)                                   0.174 %.
Acetic acid reaction                                   clearly
Furfurol reaction                                        clearly
Fusel oil                                                          trace

In the molasses I found a copious amount of a yeast species. which was isolated from it. The investigations of this yeast carried out by me have given the following results:

The yeast forms on Kojidekokt [koji decoction?] or wort at 30 ° C a delicate, dry, white Kahmhaut [film yeast], which sinks easily to the ground. The cells are not variable in shape, usually round or oval, occasionally containing one or more vacuoles, 6-10 μ in diameter. Not infrequently, sausage-shaped cells also occur (FIG. 1). Giant colony on beer wort gelatin shows an uneven and dry surface of floury-white color. The development apparently takes place with preference in higher temperatures; in beer wort z. For example, the maximum temperature is 38 ° C, the minimum is 10 ° C, while 30 ° C is the most desirable for growth.

The spores form at least 18 to 30 ° C, but the time of sporulation is not sufficiently determined at a number of different temperatures. The skin on beer wort or Kojid kokt contains an ample amount of Asken. The spores are usually round, sometimes a little compressed or flattened. Its diameter is 2.5-3 μ. 1-4 spores develop in one cell, usually 2-3, and germinate by ordinary budding (Figure 2).

Fig. L. Cells from young skins. (X 900.)
Fig. 2. Sporulation and germination. (X 900.)

4.8 Vol. Alcohol [the fermented mash contained 2.4% alcohol] formed in the Kojidekokt (15 ° Balling) after 7 days at 30 ° C; Sown in wort, but only traces of fermentation appeared. In both cases, the yeast develops on the surface of the liquid and sinks slightly to the bottom.

In fermentation experiments in a hollow slide, the yeast fermented only dextrose and fructose, while fermentation did not occur in nutrient solution containing cane sugar, without any indication of the formation of reducing sugars. Skin formation appeared abundantly.

This yeast still grows at an alcohol content of 20 vol. in the Kojidekokt. Exuberant skin formation occurs even in such a concentrated nutrient solution) as 50 percent glucose.

It is clear from the above descriptions that we have here a yeast which must be reckoned to the genus Pichia. Most likely is Pichia californica (Seifert) Klöcker, which was first found in California red wine; but the above-mentioned descriptions are not crucial, because the spore curve in my Hefeart [yeast species?] not yet established.

Since this yeast is only able to ferment dextrose and fructose, it is easy to understand that the alcohol formation in the cane molasses takes place only at the expense of the invert sugar contained therein. My yeast is the causative agent of alcoholic fermentation in molasses, but it does not necessarily have to be active or present as long as rum preparation is dependent on spontaneous fermentation.

Botanisches Institut, Tokio, Mai 1908.


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