Table mustard is a mixture of seeds from yellow mustard (Sinapis alba) and black mustard (Brassica nigra). Outside Europe, oriental mustard (Brassica juncea) is commonly consumed. The mustard plants belong botanically to the family Cruciferae (Brassicaceae).
Other members of the Brassicaceae family are rape seeds, broccoli, Brussels sprouts, cabbage, cauliflower, turnip-cabbage, swede, radish, horseradish and water cress. Many proteins in different species of the same botanical family are similar and allergic individuals might therefore react also to closely related food (cross-reactivity). However, cross-sensitivity between Brassicaceae species, except among mustards, seems to be rare.
Allergic reactions to mustard have been reported, in particular from France. Mustard allergy seems also to be common among children. Two cases of allergy to mustard have been reported to the Food Administration. Those affected were children with multiple food allergies.
Typical symptoms of allergy to mustard are itching and swelling of lips and mouth, urticaria, facial edema, laryngeal edema, asthma and difficulty in breathing. Even serious anaphylactic reactions have been reported.
The major allergens of yellow mustard and of oriental mustard have been characterized and were found to be closely related in structure. Mustard allergens are heat-resistant and resistant to enzymatic degradation and therefore not markedly affected by food processing.
Milled mustard seeds are ingredients in table mustard. Table mustard can be an ingredient of mayonnaise, mustard sauce, Cumberland sauce, salad dressing and marinades. Powdered mustard seeds are common ingredients in curry. Mustard seeds also appear in spicy sausages, in cucumber mixes and in pickles.
Labeling
The presence of mustard and products thereof must always be declared, see further in LIFSFS 2004:27 Livsmedelsverkets föreskrifter om märkning och presentation av livsmedel [in Swedish] (see link to the right).
Examples of methods of analysis
Commercial test kits for the analysis of mustard in food are available. The limit of quantification is about 1 mg mustard seed protein/kg.
Mustard can also be identified with specific DNA methods. A positive result in a DNA analysis indicates the presence of mustard in a sample.
Allergic reactions / Doses
Few studies have been performed to determine the minimum tolerable dose in mustard sensitized individuals. One study reported reactions in one individual at 1 mg powdered mustard seeds. Most patients in the study reacted to 153 mg mustard seeds. Another study reported reactions on 13.5 mg mustard seeds. Other studies report that doses as low as those remaining on cooking utensil might be enough to elicit reactions.