Ash in Flour Explained

What Is Ash in Flour and What Does It Tell Us?

The wheat kernel consists of three parts: the endosperm, bran, and germ. The endosperm, which contains all the gluten-forming proteins, makes up the majority of the wheat kernel. What we refer to as “white flour” is essentially just the endosperm, separated from the bran and germ; On the other hand, wholemeal flour is made from the entire wheat kernel and includes both the bran and germ. The more bran a flour contains, the closer it is to being considered “whole wheat”.
_{(For further reading about flour in general, please refer to the following article: A Guide to Understanding Flour – Types, Role in Baking, Characteristics, and Essential Knowledge).}

The ash content is the tool used to measure the amount of bran that remains in the flour. Typically, the ash content in flour ranges from 0.35% to 2%.

The ash content in flour is technically an indicator of its mineral content. To determine the ash content, a sample of flour is burned at a high temperature. Only the minerals ‘survive’ this process, so the resulting “ash” represents the mineral content of the flour sample.

The ash obtained after burning is then weighed in relation to the weight of the original flour sample, which gives the ash content of the flour. For example, if the original flour sample weighed 100 grams and the resulting ash weighed 0.5 grams, the ash content of the flour would be 0.5% (0.005 = 100 / 0.5).

Most of the minerals in flour are found in the bran; Therefore, the ash content provides insight into the amount of bran remaining in the flour after milling, or in other words, how “pure” the flour is and how effectively the bran has been separated from the endosperm. The lower the ash content, the more “refined” the flour is, indicating that it contains less bran (and also contains fewer nutrients, as the bran and germ hold most of the wheat kernel’s nutrients).

To conclude: Higher ash content = Higher mineral content = Flour that contains more bran.

Flour with a higher ash content will be darker (see photo above), which will result in a darker color for the baked product. A higher ash content can also affect the texture, flavor, and nutritional values of the baked product due to the increased presence of bran (and sometimes germ).
Additionally, the water absorption capacity of flour increases with higher ash content, due to the higher presence of bran.

In the past, the ash content in flour was used as an indicator of its quality (a lower bran content was considered a sign of higher quality, as it suggested better separation between the endosperm and bran). However, as bakers today, the ash content is not significant to us and is merely a technical measurement that primarily concerns flour mills for quality control and regulatory compliance purposes.

Classification of Flour Based on Ash Content

All European flours are primarily classified based on their ash content. Below is the classification of Italian, French, German, and American flours. For additional European flour standards, please refer to this presentation.

It is important to note that the classification of flours above is based solely on their ash content. Aside from meeting the specified ash content range, these flours can possess a wide range of characteristics. For instance, Italian “00” flours can vary in protein content (and other characteristics), ranging from 9% to 14%; The only information conveyed by “00” flour is simply that it contains an ash content of 0.55% or less. The same applies to all other types of European flours, be it German, French, or Italian (for specific classification of other European countries, refer to the presentation linked above).