The Romans mixed unfermented grape juice, known as must, with ground mustard seeds (called sinapis) to make “burning must”, mustum ardens. That’s the source of the name “must ard”. Mustard sales are $300 million annually. French’s is the top brand with a third of the market. Private labels are second with around 20%. Kraft’s Grey Poupon has 15% for third place. Nutrition-wise, a serving of mustard (1 teaspoon) has less than 20 calories, no sugar, no fat, and only 55 mg of sodium.
National Mustard Day is celebrated annually on the first Saturday in August.