If you have celiac disease or are otherwise just sensitive to gluten, you’ll have to avoid all foods containing gluten, a type of protein. Gluten comes from wheat, rye and barley, although it can also be hidden in foods that come into contact with these grains. Cream of tartar itself is indeed gluten-free; however, the food it’s in may not be gluten-free.

Cream of tartar is a type of potassium salt of tartaric acid and contains no grains that have gluten. It’s often a staple ingredient in baked goods like meringue and angel food cake, since it’s used to keep egg whites stable. Read the nutrition facts label and watch out for flour, malt, wheat starch, bulgur or wheat germ. These are just a few ingredients in some processed foods that probably contain gluten, as well as cream of tartar. Manufacturers are required to list allergens on the label though, so even if a gluten-containing ingredient isn’t obvious, you should see a term such as “gluten-free,” “free of gluten,” “no gluten” or “without gluten” printed right on the label.