Is mustard gluten free? In its raw seed form, yes, but when it is mixed into prepared mustard paste, flour, beer, or malt vinegar is sometimes added. This is a “read the label every time” products but if the ingredient list doesn’t include flour, beer or malt vinegar, go ahead an enjoy it.
Commercial mustard comes in many forms from raw seeds to powdered mustard flour to rich creamy or oily spreads that go well with roasted meat and in sandwiches.
Mustard seeds are tiny round seeds – about 2mm or less than one eighth of an inch in diameter. The seed color ranges from almost white to black. These seeds are naturally gluten free and are vastly different in size from any gluten containing grain. When the seeds are separated from the pods and stems, a sieve with very small holes will also separate out any volunteer gluten-containing seeds. Most commercially exported mustard seed comes from Canada, the Russian Federation and Ukraine.
Mustard seeds are mixed with water, vinegar, oils, and other spices and flavourings to make the spreadable prepared mustard pastes. Depending on the type of seed and the processing traditions, the final product ranges from white to bright yellow to black. The seeds may be crushed into a fine powder or left whole. Prepared mustards may be thick or quite thin.
Dry mustard, mustard flour or mustard powder is very finely ground mustard seeds. It has a flour-like texture but it does not contain wheat flour. Mustard powder is often added as an ingredient in other commercially prepared foods as a flavoring agent.
Wheat flour is sometimes added to prepared mustards to adjust the texture, taste, and cost of the product. If wheat flour is added, it must be listed on the ingredient list. Beer is occasionally added to specialty mustard, making the product not gluten free it must also be included on the label. Malt vinegar does not seem to be used in commercial prepared mustards, but it often appears in recipes for home made mustards. If so, the mustard will not be gluten free.
As a summary, mustard has a very low risk for cross contamination at planting and harvesting. A few commercial prepared mustards use flour or beer as an ingredient. Homemade prepared mustard may use beer or malt vinegar. Don’t worry about mustard powder or seeds used as an ingredient in other condiments like mayonnaise or salad dressing.