Food First Blog | Tip of the Week: The difference between bleache

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Tip of the Week: The difference between bleached and unbleached flour
Tip of the Week: The difference between bleached and unbleached flour
What's the difference between bleached and unbleached flours? 

It's a question that Aaron Clanton, AIB International Baking Training Manager, received during a Clean Label Q&A. The first step in describing the difference is showing a visual. 

Freshly milled flour in its natural unbleached state usually has a creamy, yellowish color. Wheat naturally contains yellow pigments in the starchy interior of the wheat kernel, called the endosperm. These pigments tend to impart a yellowish tint to the flour milled from it. The types of pigments (xanthophyll, carotene, flavones, etc.), and the amounts present, vary with the wheat variety.

Bakers historically liked to produce white breads, rolls, and buns with a light, bright white crumb color. Nature’s way of bleaching is by natural oxidation as flour absorbs oxygen from the air. However, this natural aging is slow and requires several months to complete. Since much of the flour used by bakers is shipped in bulk and used within a few days after milling, the flour no longer has the time to age at the mill or in the bakery. Many years ago, cereal chemists discovered that the bleaching process could be accomplished in a shorter time by the use of bleaching agents.

Bleaching best describes the process of color removal. The bleaching process removes some of the yellow pigment by oxidation and the flour appears whiter. The bleaching process has a minimal effect on the baking performance. When the baker specifies a bleached flour, the miller will treat the flour with a bleaching agent to remove the pigments. The bleaching process takes place by oxidation of unsaturated carbon chains (containing a double bond between two adjacent carbon atoms) in the coloring bodies.

The most effective and widely used bleaching agent for bread flours is benzoyl peroxide. Its action is not instantaneous and it requires several days before the bleaching action is complete. Benzoyl peroxide has no maturing effect on the flour and it is, therefore, often used in combination with ADA, which has no bleaching effect. Whether the flour is treated with one or with both of these agents, it must be labeled as “bleached.”

One additional bleaching agent is chlorination. Chlorine treatment is not typically used for bread flours as it not only alters the flour color, but also the baking performance. Chlorine treatment is added to improve the color and baking performance of cake flour, especially that used in high-ratio cakes where the sugar level is over 120% of the flour weight. Chlorine is also used in cookie flour to help control cookie spread and in all-purpose family flours. In certain applications, bakers have found similar results to chlorination by using heat treated flour.

High quality, great tasting baked goods can be made from both bleached and unbleached flour. The choice of bleached vs. unbleached flour is really up to bakers and their customers.

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Showing 4 Comments
Avatar  Dev Gautam last yearReply

Does Bleaching have any cultural issues?

Avatar  AIB International last yearReply

We are not aware of any cultural issues with bleaching. Some people avoid chlorinated flour based on preference.

Avatar  Amie Balder last yearReply

Rather a question as opposed to a comment...
What are the side effects of bleaching on our health?

Avatar  AIB International last yearReply

According to International Agency for Research on Cancer, benzoyl peroxide is not classified as a carcinogen. The Joint FAO/WHO Expert committee on Food Additives (JECFA) had evaluated benzoyl peroxide and concluded that the intake of benzoyl peroxide should be considered with other sources of dietary intake of benzoic acid. JECFA also concluded that benzoic acid is of low acute and chronic toxicity and the Codex Alimentarius Commission (Codex) has allowed its use in many food types. In addition, FDA allows for the use of benzoyl peroxide, which is Generally Recognized as Safe (GRAS), as a direct human food ingredient with no limitation other than current GMPs (21 CFR § 137.105).

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