Weight-volume ratios in gluten-free baking

In my last posting giving a rice, tapioca and soy gluten-free flour mix, I provided the quantities in weight measures:

8oz/225g white rice flour
8oz/225g tapioca starch
8oz/225g defatted soy flour

These are also provided in the original recipe book,  Gluten-Free Baking with The Culinary Institute of America, in terms of volume measures:

1 1/2 cups white rice flour
1 3/4 cups  tapioca starch
2 1/4 cups defatted soy flour

However, it’s worth remembering that different flours have varying weight to volume ratios. Given that ‘alternative’ non-wheat flours can be prepared in many ways, one cannot be sure that the type used by the recipe book author is the same as the one you are using. For example, I’ve noticed that white rice flour produced for Chinese cooking seems to be finer and more white than white rice flour available in Indian grocery shops, and of course these are quite different from the brown rice flour from the organic shop.Even for regular, non-gluten-free baking, it’s always better to use weight measures for accuracy. (See also my page on Flours.)

In Gluten-Free Baking with The Culinary Institute of America, the base measurement is in weight, as each flour blend recipe makes up 1.5lb, so it’s better to go with the weight measures rather than the volume measures.

In my case, I also substitute flours a lot. As I mentioned, I replaced the white rice flour with brown rice flour and defatted soy flour with regular organic soy flour (US product, purchased in Phoon Huat; possibly different from Asian soy flours and homemade soy flours). So if you are a reckless substituter like me — I must be congenitally predisposed to being unable to follow recipes exactly :) — always use weight measures.

After substitution, these are the approximate weight-volume ratios I ended up with — quite different from the ones in the recipe book:

8oz/225g brown rice flour = slightly less than 1 3/4 cups
8oz/225g tapioca starch = 1 3/4 cups + 1 Tbs
8oz/225g soy flour = slightly less than 2 cups