I have debated using the "converting from metric to imperial" feature on my recipe cards, but listen, I want to set you up for success. Using a scale to weigh gluten-free flours is SO important for a positive outcome of your baking. Let's explore why!
Mass vs. Volume
Grams are a unit of mass. Cups are a unit of volume. Changing between the two involves a conversion factor (the density of the ingredient).
In gluten-free baking (this is especially true with breads), a good recipe should be very intentional in the hydration ratio of the flour. This ratio is measured as MASS of liquids divided by MASS of flour. If the recipe writer used mass to fine tune his/her recipe, let's honor that by using the recipe in mass, as it was intended!
Accuracy
Furthermore, volume is unfortunately not very accurate. For example, manufacturers may calibrate the "cup" amount slightly differently, such that a cup of water from one brand could differ by a few grams, as shown below.
Not only that, but if I measure one cup of water three times, I may actually get 3 different amounts of water. That's because volume is measured in an instrument that is analog, making human error inevitable. However, a scale is a digital instrument; the number you see is the number you get!
And while a gram here and a gram there may not be a big deal in some recipes, when we bake gluten-free, precision is key.
Density Differences
All-purpose (wheat) flour is one ingredient, it has one density. We can get a little bit mathy/geeky, and say that d=m/v (the density of a substance is its mass divided by its volume), so if we want to convert from say cups to grams, we can use m=dv (the mass is equal to the density multiplied by the volume). Easy.
Here's where it gets complicated. Gluten-free flour is not ONE ingredient. It's a mixture of many different flours, starches and hydrocolloids. And each of those flour components have different densities. Check out these photos of ¼ cup of potato starch and ¼ cup of tapioca starch: the scale shows huge differences in mass!
And so what I'm trying to say is if you measure 1 cup of Bob Red Mill 1:1 flour, it has a different mass than 1 cup of Better Batter, which also has a different mass than 1 cup of King Arthur Measure for Measure, and so on. However, if we measure 100 grams each of these flours, we will get an amount of flour that behaves in baking like 100 grams of flour.
Flour Temperature
Many of us keep gluten-free flours in the fridge or freezer. Did you know that cold flour granules shrink slightly? Which results in more flour fitting in a cup, therefore more mass? In other words, one cup of cold flour will weigh slightly more than one cup of room temperature flour.
Cleaning
Let's talk quality of life upgrades. When baking and measuring in cups, you're going to have many dirty cups at the end! Weighing your ingredients saves on clean up! I just put a bowl on my scale, and tare after each dry ingredient I add.
Conclusion
Remember, when we write gluten-free recipes, we are SO intentional about the hydration of the flour mix. You as a baker will get better more consistent results when weighing ingredients because one, volume is not precise, and two, volume doesn't yield the same mass of flour depending on what flour you use.
I do not yet have affiliate marketing set up (yet), but I am happy to recommend the scales I use. This Taylor scale is my go-to for large quantities like flour and water, while still having a decimal point for accuracy. Then, I use this super sensitive Zencro scale for weighing small amounts like yeast, salt, and xanthan gum.
I hope I have convinced and converted you to using a scale in gluten-free baking. Happy baking!
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