The Fresh Loaf

News & Information for Amateur Bakers and Artisan Bread Enthusiasts

Is "bread flour" bleached or not?

soupcxan's picture

Is "bread flour" bleached or not?

Is there any way tell if your flour is bleached/bromated? For example, I bought some Pillsbury "Bread Flour" that is labelled as enriched. It doesn't say anything on the label about bleached or unbleached. Pillsbury also offers "All Purpose" flour in two varieties - they are clearly labelled as bleached and unbleached. If flour has been bleached, is it required to list "bleached" on the label somewhere?

I compare this to a bag of Harvest King Gold Medal "Unbleached White Flour" which says that it's unbleached - both of them seem to be about the same color but I can't tell if the Bread Flour is really whiter as if it had been bleached. They both have 4g of protein per serving (I've been told that higher protein is the point of bread flour) so maybe there's no benefit to using the Pillsbury "bread" flour instead of the Harvest King.

pjkobulnicky's picture

My assumption has always been that flour is bleached unless it says "unbleached". My other assumption is that the effect of bleaching on the final bread product, aside from a whiter final crumb, is negligible.  


Paul Kobulnicky

Baking in Ohio

syllymom's picture

I would go with the thought as well that if is doesn't say unbleached, it's not then.  The other way is to check the ingredient list for bleaching agents.  Below I copied a piece in about flour.  Here is the link to the whole doc.


Natural aging occurs when freshly milled “green” flour is exposed to air for several weeks or more. In naturally aging flour, air is added to it. Air is a powerful additive, causing two main changes. First, it whitens the flour. Second, it strengthens the gluten that forms from flour.

Actually, the active ingredient in air is oxygen, which is considered an oxidizing agent. Oxygen oxidizes the carotenoid pigments in flour, changing their chemical structure and whitening them. Oxygen also oxidizes gluten-forming proteins, allowing them to form stronger gluten. Yeast doughs made from aged flour are easier to handle than those made from green flour, because doughs with stronger gluten are less sticky and less likely to tear when stretched. This, in turn, allows for higher volume and finer crumb on the baked bread.

Natural aging has a few disadvantages. First, it requires time, often several weeks or months. During this time, the flour takes up valuable silo space and is not paying the bills. Besides, the longer flour sits in silos, the more likely it will support mold growth or become infested with insects or rodents. Natural aging also can be inconsistent, and it is not as effective as many chemical bleaching and maturing agents. However, consumers sometimes prefer flours that have been naturally aged over those that contain bleaching and maturing agents. Naturally aged flours are often labeled “unbleached.”


Maturing agents are additives that change the baking properties of flours. Maturing agents are added to flour by the miller or are found in many dough conditioners that are added by the baker.

Some maturing agents strengthen gluten, while others weaken it. Because the same term—maturing agent—is used to describe additives that have completely opposite functions, it can be confusing. In this text, maturing agents that strengthen gluten, such as potassium bromate and ascorbic acid, will be called maturing agents that strengthen, while those that do not will be called maturing agents that weaken. In either case, only very small amounts—parts per million— of maturing agents are necessary to cause the desired changes.

One maturing agent that strengthens is potassium bromate. When it is added to flour, the flour is said to be bromated. Potassium bromate has been in use since the early 1900s, and it is the standard against which all other maturing agents are judged. Despite this, potassium bromate is no longer allowed as a flour additive in Canada or in Europe. Potassium bromate is considered a carcinogen because it has been shown to cause cancer in laboratory animals. While still approved for use in the United States, its use is slowly diminishing. In California, products containing potassium bromate must carry a warning label.

Many companies are searching for “bromate replacers” to strengthen their flour. While several bromate replacers are available, ascorbic acid is one of the most popular. Another name for ascorbic acid is vitamin C. While ascorbic acid is not as effective as potassium bromate and it works a little differently, its use is increasing because of concerns over the safety of potassium bromate.

Bleaching agents whiten carotenoids. Two common flour bleaching agents are benzoyl peroxide and chlorine gas. Benzoyl peroxide is used in all types of flour because it is extremely effective at whitening and because it contributes no maturing effects. It is commonly used in bread, high-gluten, all-purpose, cake, and pastry flours that are leached.

Chlorine is used in cake flour only. Besides whitening, chlorine improves the baking properties of soft wheat flour by substantially weakening gluten and by allowing starch to absorb water more quickly and easily. You can always tell from the label whether flour has been bleached, but you cannot necessarily tell which bleaching agent was used. Ask the manufacturer, if you would like to know.

Notice that chlorine’s action on gluten is very different from the action of natural aging or maturing agents like potassium bromate. Chlorine is a maturing agent that weakens, and it is used on soft wheat flour. Potassium bromate and ascorbic acid are maturing agents that strengthen, and they are used on hard wheat flour.

soupcxan's picture

Thanks for the info. I am mostly interested in determining if a flour has been bleached/bromaged for health reasons (why eat potential carcinogens if you don't have to)? I don't really care if my bread is ultra-white.

CharInCincy's picture

Not all states require that bromide need be listed. One site mentioned that California requires its listing. Basically, the listing of ingredients will vary from state to state.

pumpkinpapa's picture

Thanks for the great info Syllymom.

It's interesting to find bleached organic flour from time to time too. Or to hear someone say that you can only bake a certain product with certain results using bleached flours.

syllymom's picture

I have a grain mill and bought some wheat berries and baked up myself some bricks.  Not on purpose but they were bricks.  So I started reading about flour and stuff and am now confused.

If aging flour strengthen glutten, which results in better rising bread then why do I read about grind fresh flours to use immediately?  How are these people baking good loaves with fresh flour.  How quickly does the oil go rancid and what is an appropriate method for aging flour?

So if anybody can comment on this and tell me what you do I'd love to hear.


pmccool's picture


My experience with freshly milled flours is very limited.  One of the grocery stores nearby carries Wheat Montana products.  I can pick up flour that was milled at the Wheat Montana mill and shipped to the store, or I can mill the flour at the store using wheat berries and a mill supplied by Wheat Montana.  (Kinda like buying your coffee already ground and packaged or grinding it yourself at the store.)  In the first case, I have no idea how recently the flour was milled or how long it has been sitting on the shelf.  In the second case, it's still warm from the milling when I get back to the house.  Truth be told, I really don't notice a flavor difference between the two.  That may be my unrefined palate, or it may be that the previously ground and bagged flour is still pretty fresh, or it may be that each tastes a lot like the other. 

The primary thing that I am doing with whole-grain flours nowadays is storing them in the freezer to prevent them from becoming rancid.  I have kept flour unused at room temperature for too long previously and both the taste and odor become unpleasant as the oils become rancid.  As long as they are kept tightly sealed and used in a reasonable period of time (note that I haven't kept any flour in the freezer longer than 6 months), flours stored in the freezer do not develop 'off' tastes or odors.  I personally prefer a plastic bag over a rigid container for storing flour in the freezer because I can expel more of the air from the bag, which greatly reduces the likelihood of freezer burn.

Most of the writing that I have seen extolling freshly milled flours has been focused on either the flavor or nutrient qualities, not on the dough characteristics.  I'll concede that both the flavor and the nutrients are probably at their peak as the flour exits the mill.  That doesn't mean, though, that the freshly milled flour is able to produce a dough whose handling and baking characteristics are as good as those found in a dough made with aged flours. 

There is a significant body of literature and experience, similiar to what you posted earlier, that identifies fresh ("green", in bakers' speak) flour as the culprit in doughs that won't rise as expected.  I don't understand the chemistry, but the gluten strength in aged, versus "green", flours is much higher. 

If you like the results you are getting with freshly milled flour, then my advice would be to keep doing what you are doing.  Since you mention bricks, you may want to experiment with milling the flour and then storing it in the freezer for 2-4 weeks before using just to see if it gives you a better result.  You could even do a side by side bake-off using your aged flour and your freshly milled flour (all other things being the same) to see how the breads turn out. 

One other thing that I have learned, primarily because of what I have read here, is that a long autolyse works wonders in developing the gluten in whole-grain breads.


salma's picture

My Costco in NJ carries ConAgra 50# bags but unfortunately it is bleached and I have not bought it.  Anyone know of a place in NJ to buy flours in bulk, cheaaper?