I am experimenting with some gluten free breads and have noticed in the potato starch and flakes that they contain sulfur dioxide and sodium bisulphite I think both as preservatives and whiteners, my thoughts are that these would tend to kill of the sourdough organisms, anyone know more about that. Paddy

Paddy Murray wrote:
> I am experimenting with some gluten free breads and have noticed in
the potato starch and flakes that they contain sulfur dioxide and
sodium bisulphite I think both as preservatives and whiteners, my
thoughts are that these would tend to kill of the sourdough organisms,
anyone know more about that. Paddy

Sulfites levels can be high in those products; and it can influence
dough performance
I had these problem several years back while trying to add potato flour
and starch heavily treated with sulfites while working on
R&D/product development with yeast raised donuts. In my observation it
tends to weaken the gluten resulting that the donut have inferior
appearance and eating quality .But the fermentation pattern was not
well affected.
Looking at the way sulfites acts by means of reduction of the
disulfide linkage in gluten structure it does not perform the same way
on starchy products where the glucose linkage in the starch molecule is
stable to it.

If we think about it to winemaking, where sulfites are added which
will release sulfur dioxide in solution. It is known to inhibit the
activity of the acetic and lactic acid bacteria but wild yeast are
known to be tolerant to it( I hope that Saccharomyces exiguus is
tolerant as well).
Relating that peculiarity to sourdough, that contains lactobacilli
also, there is a likelihood that it might affect its performance.
But you really have to check it out to confirm or deny it<g>.
And the best way to find out is to check it out with a trial bake
supposing you already had a workable recipe for gluten free sourdough
bread.
Roy

Thanks Roy, will give my cultures a go with the potato starch and potato flakes. I have to develop cultures which are grain free(grain based flours). I am developing a grain free bread, so all experimental baking. In trying to source ingredients in Aust. it is difficult to get detailed product knowledge. I have some imported, South America, quinoa flour, but it is over 12 mths old now and is quite bitter, it may be rancid. According to the webb it is supposed to be kept quite cool and has a shelf life of 3 to 6 mths. Anyone know of a quinoa flour supplier that has a good product. Paddy
----- Original Message -----
From: Roy
Newsgroups: rec.food.sourdough
To:
Sent: Tuesday, March 08, 2005 3:53 PM
Subject: sulfor dioxide



Paddy Murray wrote:
> I am experimenting with some gluten free breads and have noticed in
the potato starch and flakes that they contain sulfur dioxide and
sodium bisulphite I think both as preservatives and whiteners, my
thoughts are that these would tend to kill of the sourdough organisms,
anyone know more about that. Paddy

Sulfites levels can be high in those products; and it can influence
dough performance
I had these problem several years back while trying to add potato flour
and starch heavily treated with sulfites while working on
R&D/product development with yeast raised donuts. In my observation it
tends to weaken the gluten resulting that the donut have inferior
appearance and eating quality .But the fermentation pattern was not
well affected.
Looking at the way sulfites acts by means of reduction of the
disulfide linkage in gluten structure it does not perform the same way
on starchy products where the glucose linkage in the starch molecule is
stable to it.

If we think about it to winemaking, where sulfites are added which
will release sulfur dioxide in solution. It is known to inhibit the
activity of the acetic and lactic acid bacteria but wild yeast are
known to be tolerant to it( I hope that Saccharomyces exiguus is
tolerant as well).
Relating that peculiarity to sourdough, that contains lactobacilli
also, there is a likelihood that it might affect its performance.
But you really have to check it out to confirm or deny it<g>.
And the best way to find out is to check it out with a trial bake
supposing you already had a workable recipe for gluten free sourdough
bread.
Roy

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