Bacteria, yeasts, and molds in the home / by H.W. Conn.

  • Herbert William Conn
Date:
1903
Catalogue details

Licence: In copyright

Credit: Bacteria, yeasts, and molds in the home / by H.W. Conn. Source: Wellcome Collection.

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    is now extremely simple. But it has taken many centuries of experiment and trial to understand the subject well enough to bring it under proper control. In all nations, and apparently in all ages, people have been accustomed to make bread from meals obtained from the different kinds of grain. The earliest method of cook- ing such material was simply to mix it with water and then bake it, the result being a rather hard, tough material known as unleavened bread. The next step consisted of a spontaneous raising of the dough. If dough is left in a warm place for a number of hours, it becomes somewhat swollen with gas, appears lighter in character, and when baked produces a type of bread more easily masticated, better in flavor, and more easily digested. Flour from most cereals, if mixed with water and kept for a few hours in a warm place, will undergo a fermentation, due to the wild yeasts that may have found entrance to the meal. This method of fer- menting the dough gave the first form of raised, or leav- ened bread. Very early, even before historical records, it was dis- covered that a little of the dough thus raised would serve as a starter for a second batch, resulting in a quicker and more satisfactory raising than that obtained by spontane- ous fermentation. This was known as leaven, and as far back as the time of Lot we read of leavened and unleav- ened bread. The Egyptians also knew of this process. Leaven has been used from those early days to the pres- ent time. Even to-day leaven consists of a little dough which has already fermented and hence contains yeasts, and which is saved to be used in fresh dough for the
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