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Mustard: The seed, the condiment and the chemistry

Mustard ranks with plants that please us by irritating us and causing pain. They deliver volatile, pungent chemicals that begin in the food and travels through the air to irritate mouth and nasal passages.  Mustard, along with cousins’ horseradish and wasabi, are part of the cabbage family.

Mustard is one of the most popular and widely used spices and condiments in the world.

Excavations in the Indus Valley show that mustard was cultivated as far back as 1800 BC. The word mustard comes from Latin.  The first syllable is from Latin mustum, (“must”, young wine) – the condiment was originally prepared by making the ground seeds into a paste with must. The second syllable comes from Latin ardens, (hot, flaming). Dijon, France, became a recognized center for mustard making by the 13th century.  Dijon is often called the mustard center of the world.  Mustard as a hot dog condiment was introduced in the US at the 1904 St. Louis World’s Fair, when the bright-yellow French’s mustard was introduced.


It is often used as a condiment on cold meats. It is also used as an ingredient in mayonnaise, vinaigrette, marinades, and barbecue sauce.

Mustard is also a popular accompaniment to hot dogs, pretzels, and bratwurst.

In the Netherlands and northern Belgium it is commonly used to make mustard soup, which includes mustard, cream, parsley, garlic and pieces of salted bacon. Mustard as an emulsifier can stabilize a mixture of two or more immiscible liquids, such as oil and water. Added to Hollandaise sauce, mustard can inhibit curdling.


As a cream or as individual seeds, mustard is used as a condiment in the cuisine of India and Bangladesh, the Mediterranean, northern and southeastern Europe, Asia, the Americas, and Africa.  Many Indian recipes call for a quick frying of mustard seeds until they start popping.


When toasted or fried until they pop, the taste is nutty rather than fiery.


Mustard has great antibacterial properties, and needs no refrigeration for safety; it doesn’t grow mold, mildew, or harmful bacteria including e-coli, salmonella, and listeria. It lasts indefinitely without becoming inedible or harmful. However, it may dry out, lose flavor, or brown from oxidation. Mixing in a small amount of wine or vinegar may improve dried-out mustard. It is used in emulsifying, stabilizing, as an antioxidant, and for flavoring properties.


Long ago, mustard was considered a medicinal plant rather than a culinary one. In ancient Greece, Pythagoras used mustard as a remedy for scorpion stings and later Hippocrates used mustard in medicines and poultices. Mustard plasters were applied to treat toothaches and a number of other ailments. Mustard greens or leaves from the brown mustard plant are edible and cooked like spinach or simply eaten raw. The flavor of the greens is reminiscent of a perfumey prepared mustard.



What gives mustard its zing? When mustard seeds are crushed and liquid is added, enzymes activate that release pungent sulphurous compounds that quickly evaporate. An acidic liquid, such as wine or vinegar, produces a longer-lasting paste.  Prepared mustard loses its pungency over time. Keep it in a sealed container (opaque or in the dark) in a cool place or refrigerator to extend its life. The chemical reaction between ground mustard seeds and liquid creates the enzyme myrosinase and various glucosinolates such as sinigrin, myrosin, and sinalbin.


Myrosinase turns the glucosinolates into various isothiocyanate compounds known generally as mustard oil. The concentrations of different glucosinolates in mustard plant varieties, and the different isothiocyanates that are produced, make different flavors and intensities.


Zing: Isothiocyanates are responsible for the sharp, hot pungent sensation in mustards and in horseradish, wasabi, and garlic.


Unlike hot peppers these chemicals are volatile at room temperature and can make eyes water from across a room. This happens because heat and acidity sensing pain nerve cells in the mouth and nasal passages are stimulated. The heat dissipates with time due to gradual chemical break-up of the isothiocyanates.


Prepared mustard condiment may also have ingredients giving salty, sour (vinegar), and sweet flavors.  Ingredients added to mustard include, honey, chili, beer, sugar, salt, fruits, horseradish, dill and many others.  Turmeric is often found in commercially prepared mustards, mainly to give them a yellow color.


Mustard seeds can be soaked before being crushed or liquid can be added after grinding. Either way, cold liquid needs to be used to activate the chemicals inside the seeds. Heat damages this reaction, so to make a hot mustard you should use cold water, and warm water for mellower mustard.


There are more than 200 wild and 40 cultivated species of mustard. Practically speaking there are three main types of mustard plants, black, Brassica negra,

brown, Brassica juncea,

and white, Sinapis alba.   

                             Each has its own characteristics. Black and brown mustard have a higher content of glucosinolates and are more pungent than yellow mustard seeds. Black seeds are not in general use in the US.


Mustard seeds may also be ground (below in spoon) to make different kinds of textures in mustard.

The combination of mustard seeds and various other ingredients mean that there are an enormous variety of prepared mustards possible. These are examples of a few mustards: simple table mustard with turmeric coloring,

Bavarian sweet mustard,

Dijon mustard,

coarse pub mustard


and a whole grain beer mustard made  brown and yellow mustard seeds (above).

Making mustard, like brewing and winemaking, is extremely easy, but can also be amazingly complex. For an instructive read about mustard try On Food and Cooking: The Science and Lore of the Kitchen, by Harold McGee.  A good webpage is Also The Spruce is a very good food site: Go crazy and make your own. Don’t let the mustard elves have all the fun. Below is a Chinese style mustard that makes 8 oz. of mustard.



Chinese style Mustard directions


Equipment needed:


1 quart mixing bowl



Measuring cups

Ingredients needed:

½ cup water

3 oz. yellow mustard seeds

1/8 cup white vinegar

1 tsp sesame seed oil




This recipe gives you Chinese style mustard, similar to that which we have all seen in our take home bags.


Get out your blender and get ready to spin the blades. Pour the seeds in the blender and turn it on. Let it spin it until you reach a very fine powder.

Add ½ cup cold water.  Mix well. Cover and put in the refrigerator for 15 minutes. While waiting, put the mason jar and top into a pot, cover with water, and bring to a boil to sanitize. Remove with tongs and cool.

Remove mustard from refrigerator; add oil and vinegar and mix. If you like add more water until it is the consistency you like. Use the spatula to transfer mustard into sanitized Mason jar. Put lid on and refrigerate for 24 hours. The mustard seeds have a bitter component that fades away after a day. Try some of the mustard on the spatula. The next day when you try the mustard there will be a noticeable change.