In gas generating flasks (A) a suitable “wort” and a definite amount of yeast, to be tested, is dissolved and placed in a water bath. (B) is a second flask for the next following test. (C) is a pinch-cock, which is left open so long as (D) is kept closed. The generated carbonic acid gas forces the water out of the wide tube and is caught up at (G). The yeast which has the ability to displace the largest amount of water at stated periods is considered the best fermentation inciter. Before any readings are taken the water in both tubes is brought to the same level by means of cock (E).
If care be taken to use the exact proportions of materials in each test at even temperature, reliable conclusions are obtained from each individual yeast sample.
Water.—Next to flour, water is the most abundant compound used by the baker. It is the great solvent of Nature. Pure water is composed of the two gases, hydrogen and oxygen, in proportions of 1 to 8. It is colorless and tasteless.
Water as found in nature is never pure. Owing to its action as a solvent, it contains bodies like lime, magnesia and potash in solution, besides air, carbon dioxide and other mineral matters. Hard water is such as contains more than seven grains of mineral salts per gallon.
The hardness due to bicarbonate of lime may be neutralized by boiling. Other mineral salts are penniment.
In general, soft water is more adaptable for bakers’ use, as hard water retards fermentation and somewhat checks the softening changes going on in the dough during fermentation.
Doughs made with hard water require to lay longer to properly mature.
It is for this reason that the baker will find it necessary at equal dough temperatures to modify his methods when using hard or soft waters to get uniform results.