Baking Basics 101 – Flour Oxidation

Happy New Year and welcome to the first installment of Baking Basics 101 for 2009! As mentioned in the previous post entry, we've got a full schedule of articles coming out soon. If you've got suggestions for any topics that we can write about, let us know through the Contact Us link above, or through the Comments section after every post!

When we think of a freshly baked bakery product, we usually think of fresh ingredients as being important. However, just like fine wine, properly aged wheat flour will go a longer way towards a better final product than the freshly milled flour, or as they call it in the industry, green flour. As a side note, green flour is not the same flour that you would see in the supermarkets. All of the flour available in the markets is aged using chemical or natural additives.

Why is green flour not advised and what can be done?
Green flour is often difficult to handle in dough form and does not have the same glutinous capability of aged flour. This results in baked loaves that have dense volume and coarse crumb.

In order to age the flour (usually a process that takes many months to get proper aging) it must be stirred often while exposed to the open air. What this means to the flour is that certain parts of the protein molecules called thiol groups exchange their sulfur for an oxygen molecule. Thus the thiol groups cannot interact with the protein bonds that form as gluten is being developed. Because the gluten matrix is developed as the dough is worked, broken or interrupted protein bonds would mean that the dough cannot be worked like normal (the dough would break), cutting into the dough’s ability to stretch.

To phrase it another way, think of an athlete (let’s call him athlete A) who stretches before a heavy workout allowing his muscles to warm up, compared to athlete B who does not stretch first and gets into a heavy workout right away. In the case of athlete A, they would have no problem enduring the workout, while athlete B may feel tightness and cramps in the muscles. Bread elasticity is like body muscle.

Methods of Oxidizing
Aside from the technique mentioned earlier, through natural oxidation, there are also some chemical methods available. Most of these methods will be virtually guaranteed to go much faster than the months required for ordinary oxidation, along with the added effect of a more uniform result for all grains of flour. The historic first oxidizing agent used by the bread industry, since early 1900s, is potassium bromate (roughly 75 parts per million). There was an overall improvement that allowed strengthening of the dough for handling, and reduced both fermenting and mixing times. Wide use of bromated flour was reduced in the early 1990s because it was tested as a possible carcinogen. Then the FDA in the U.S. pursued other chemical alternatives to potassium bromate such as ascorbic acid (vitamin C, can be easily found in most Mercury Drug stores under their vitamin sections and is also quite cheap to use), azodicarbonamide (ADA), iodate of calcium, and iodate of potassium. Of those chemicals mentioned, ascorbic acid is probably the safest and most easily found additive. It is frequently used in the U.S. and for Germany & France, it is the only additive legally allowed.