Understanding Ash Count

Ash count is one of the three primary characteristics that flour is tested for (protein level and moisture content are the other two). Understanding what the ash measure means and how ash levels affect the baking process can help you to choose the flour that will give you the baking results you're looking for.

What is ash count?

The ash count listed for a specific flour is simply a measure of its mineral content. The higher the ash count, the more minerals are present in the flour.

How is ash count measured?

To calculate ash count, the miller puts a sample of flour into a container (called an ash muffle), and incinerates it in a very hot oven to burn off all the organic material, until all that remains is the mineral residue. This residue (or ash) is then weighed in relation to the original sample weight to calculate the ash count for that flour.

Why is ash testing done?

Ash testing originated in the 1920s as a means of measuring the quality of the milling process. The theory was that minerals were concentrated in the wheat's aleurone, the layer between the bran and the endosperm. If the miller did a good job of separating the wheat, the resulting flour would contain less bran and aleurone—and therefore fewer minerals (and a lower ash count). Low ash levels gave bakers an indication that they were buying a more refined or "purer" flour.

This theory has never been entirely true because the endosperm itself contains some minerals. But today, ash count has even less of a relationship to milling quality than it did a few decades ago. Why? Because new wheat varieties and richer soils have made higher ash levels the norm. The semi-dwarf wheats introduced in the 1970s, for example, contain more minerals in their endosperm. In addition, changes in agricultural practices have made more minerals available for the endosperm to absorb. As a result, a flour can be very pure and still have an ash count that would have been considered high in the past.

How does ash count relate to flour performance?

Ash levels vary with each type of wheat and each grade of flour. Higher protein flours typically have a higher ash content. A good ash range for short patent flours, like Progressive Baker® Qualitate® flour, is between .48 and .50. A good ash range for longer patent flours is between .53 and .54.

In artisan baking applications, higher ash often plays a positive role. First, the extra minerals may result in a stronger dough and a finished product with more nutrition and better color. Plus the ash particles feed the yeast, while acting like tiny grains of sand to gently wear down the dough's gluten structure—conditions that facilitate optimum fermentation activity and improve the dough's tolerance. Sometimes, higher ash flours may enhance flavor as well.