发面饼, 鲜酵母块

[ noun ]
small cake of compressed moist yeast
<noun.food>

Yeast \Yeast\, n. [OE. [yogh]eest, [yogh]est, AS. gist; akin to
D. gest, gist, G. gischt, g["a]scht, OHG. jesan, jerian, to
ferment, G. gischen, g["a]schen, g["a]hren, Gr. ? boiled,
zei^n to boil, Skr. yas. [root]111.]
1. The foam, or troth (top yeast), or the sediment (bottom
yeast), of beer or other in fermentation, which contains
the yeast plant or its spores, and under certain
conditions produces fermentation in saccharine or
farinaceous substances; a preparation used for raising
dough for bread or cakes, and making it light and puffy;
barm; ferment.

2. Spume, or foam, of water.

They melt thy yeast of waves, which mar
Alike the Armada's pride, or spoils of Trafalgar.
--Byron.

{Yeast cake}, a mealy cake impregnated with the live germs of
the yeast plant, and used as a conveniently transportable
substitute for yeast.

{Yeast plant} (Bot.), the vegetable organism, or fungus, of
which beer yeast consists. The yeast plant is composed of
simple cells, or granules, about one three-thousandth of
an inch in diameter, often united into filaments which
reproduce by budding, and under certain circumstances by
the formation of spores. The name is extended to other
ferments of the same genus. See {Saccharomyces}.

{Yeast powder}, a baling powder, -- used instead of yeast in
leavening bread.