Old flour
 

Can someone explain to me the mechanism by which using old flour in
raised bread baking would lead to a lower volume, denser loaf?

I'm presuming it's because the gluten proteins have oxidized over
time. Is this correct?

If so, then I'm further presuming that removal of the oxygen would
greatly retard any breakdown of the flour, at least so far using it to
bake raised breads are concerned?

This would be for refined white flour - all purpose or bread flour
specifically.

I've been Googling around trying to find the answer to this, but I'm
not putting the search terms together properly it seems because
nothing I find really answers the question of why it happens, just
that it does happen.

Thanks for any light you can shed on this.

......Alan.


--
Curiosity killed the cat -
lack of it is killing mankind.

Old flour
 

Old flour
 

Thanks for the response, Roy. I was hoping someone like you would
respond. This is what I was looking for.

On 13 Nov 2003 20:19:53 -0800, (Roy Basan) wrote:
>Aging the flour will lead to maturation and later degradation of
>flour.
>
>If the flour is old that it smells musty the mechanism of its
>degradation is contributed primarily by the fatty acids present in the
>flour fat.These is done by the fat degrading enzymes as well as
>oxidation- reduction enzymes such as the lipoxygenase , oxidases and
>even protein degrading enyzmes;proteinases.

OK, so if I'm understanding this correctly it's not simply a matter of
oxidation breakdown but also a matter of other enzymes that do not
need the presence of free oxygen in order to function? This seems in
keeping with other aspects of food storage. Oxidative rancidity is
the primary cause affective shelf-life but once that is addressed
there are still other causes that eventually will do the same damage,
just in a larger time frame.

Further, refined white flour suffers the same problems as whole-wheat
flour but at a slower pace because it's fat content is much reduced,
but not completely eliminated.

>Removal of oxygen is not the solution, as the dough to be functional
>need the sufficient oxygen and if you mixed the dough under high
>vacuum the bread quality is inferior or similarly in pure nitrogen
>atmosphere meaning that oxygen is required.
>Some high speed machines mixes dough under partial vacuum but the
>amount of oxidants needed is maximum. Which is the same reasoning that
>there really is a need for oxygen in the dough development.

I'm looking at this as two seperate problems.

The first is how to keep flour in good condition while in storage, or
at least getting a feel for how long it can be stored before it really
begins to go off. White flour specifically - we'd just mill
whole-wheat flour on the spot. This particular flour that I'm dealing
with wasn't supposed to be kept so long but between the time I
purchased and repackaged it and now circumstances changed and we ended
up keeping it a lot longer than originally anticipated. If I had
planned on keeping it this long at the time of purchase I'd have
packed it with some oxygen absorbers which would have given me a
longer shelf-life, but as you seem to be pointing out even in a
no-free-oxygen enviroment other processes will still be ongoing that
puts a definite limit on shelf-life. I am presuming the only thing
that would affect that would be to lower the temperature of the
storage area. Not really an option for me, but others might be able
to do so.

The second would be in the dough itself. I'm thinking that the act of
measuring and mixing the dry ingredients before incorporating the
liquid ingredients would reoxygenate the flour. Is this correct?

>The best solution for using overaged flour is to blend it with large
>amounts normally aged flour or even freshly milled flour and you can
>still obtain satisfactory baking peformance.
>That can be confirmed by your baking tests.
>Roy

This is what we're doing with the old white bread flour. Mixing in
small quantities into the whole wheat flour we're making bread with.
We seem to be getting good rises this way and the bread is pretty
good.

Do you know of any place on the Internet that I could go and read up
on this that doesn't require a cereal chemist's knowledge depth to
understand?

......Alan.

--
Curiosity killed the cat -
lack of it is killing mankind.

Old flour