pikec@cadvision.com (C Pike) wrote:
>We were talking to a bread salesperson yesterday and she was
>saying that her bread had no yeast-it was sour dough bread.
>She said when you make the bread with sour dough there is
>no yeast left. I would like to know if this is true as my husband
>is not supposed to eat yeast.
This person obviously has no clue as to what she's talking about.
Sourdough bread depends on the presence of yeast to ferment it,
plus the presence of bacteria which create lactic acid, giving the
sour taste. Depending on how the sourdough starter was developed
(a commercial mix versus a home-grown mixture with wild yeasts
and bacteria), the yeast may be a slightly different strain than the
saccharomyces cerevisiae which is the strain generally used in
commercially available yeasts.
One has to remember that wild yeasts are everywhere, floating
around in the air, along with various other bacteria. (This is also
why the specific tastes of sourdoughs vary by region - no two
regions have exactly the same strains.)
The fermentation process in sourdough bread is essentially the
same as for regular bread. The yeast feeds on on the starches
and sugars which generates carbon dioxide and alcohol as
by-products. The CO2 is trapped by the developed gluten
structure of the bread, causing it to rise. When the bread is
baked, the heat bakes off the alcohol and kills the yeast in the
process.
In other words all fermented breads, sourdough and regular,
contain some strain of yeast.
I'm not sure why your husband is supposed to avoid the dead
yeast in baked bread given that the live stuff is floating all
around us 24 hours a day, but he'll get the same exposure
from sourdough that he will from any other bread.
- Mitch