Brown Mustard

When it comes to mustard, yellow tends to hog all the glory, zigzagging up ballpark franks and cornering the market on pretzel-stand squeeze bottles. But here at the test kitchen we like brown mustard, too, for its spicy, robust flavor. Unlike the yellow stuff, which gets its bright, mild character from white mustard seeds, brown mustard is made from the smaller, hotter brown seeds along with some of their bran, the tough outer layer of the seed that gives the mustard its speckled look. We use brown mustard to pack a punch when we’re eating rich foods like pastrami, ham, or eggy breads.

Which mustards didn’t pass muster? Our tasters expected their spicy brown mustard to be, well, spicy. We wanted to feel the burn, and in every taste test, hotter mustards scored higher. Mustard’s heat is a defense mechanism of the mustard plant against insects looking for something to chomp on; when its seeds are crushed, enzymes are freed and start to convert dormant chemicals into hot mustard oil. We measured the amount of mustard oil in each product, but surprisingly, the results didn’t line up. Some of the hotter products that we preferred had plenty of mustard oil, but so did the product that ranked lowest, which tasters called “weak” and “wimpy.” If we liked hotter mustards, why did one of our lowest-ranked products contain so much of the very compound that makes mustard hot?

A couple of the mustards boast “#1 grade mustard seed” on their ingredient lists, so we turned first to the quality of the seeds. But when we looked into it and found that all the mustards that we tested are made with top-grade seeds, whether stated or not, we realized that it was time to examine the mustard-making process. Mustard is created by mixing crushed seeds with a cold liquid (a cooler temperature is required to correctly activate the enzymes). Then an acid is added to slow the formation of mustard oil, keeping the mustard from becoming blow-your-head-off spicy. The most common acid, used by every product that we tasted, is vinegar because of its three-pronged effect of taming heat, prolonging shelf life, and adding tang. But when there’s too much vinegar, the formation of mustard oil is slowed too much, and the condiment loses its characteristic burn.

If more vinegar means less heat, we now understood why some products with lots of mustard oil fell flat and why tasters consistently rated overly tart products low in both heat and overall flavor. We measured each mustard’s acidity to get at vinegar content and found that more acidic products, usually those with more vinegar, rated lowest in our taste tests. In sum: Mustards with both a high percentage of m... read more