October 4, 2014 - 9:36am
Ascorbic acid?
I see it listed as a flour additive for commercial bread flour and I am wondering why it is used. I read that it is an antioxidant, but it didn't explain what it does specifically in the flour to contribute to the making of bread with the commercial wheat flour. What does it do exactly?
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I recall reading in The Village Baker years ago that a small amount (maybe 0.02% or less) of ascorbic acid/vitamin C powder will improve the tolerance of the dough; that is, it will make the dough a little better at withstanding some improper mixing and overproofing.
Hamelman says that it is believed to improve loaf volume and says it can noticeably increase dough elasticity, and recommends caution in adding it, since overly elastic dough can be very difficult to shape. He suggests adding 20 ppm (parts per million) to avoid overdoing it.
So basically, it seems it makes the bread flour stronger and more elastic. This seems to be more related to the acidity and less to the antioxidant properties you mention.
its strengthening action is indirect. When it's oxydized to de-hydro ascorbic acid this latter acid behaves as an oxydant (the opposite of ascorbic acid that is a reducing agent); in particular DHA oxydizes thiolic bonds to disulphide bonds, the main carrying structure of gluten. It's generally recommended to use no more than 100 mg of AA per KG of flour, but it really depends: with some very weak flour I used even 500 mg/KG getting incredible results that I couldn't have obtained otherwise with that particular flour.
Does some of the gluten get damaged during the processing of the flour? Is that why the AA is needed in the commercial flour?