Hidden Names for Mustard and Celery on UK Food Labels

Mustard and celery are two easy-to-miss UK allergens. Here are the names to look for, including celeriac, celery salt, mustard flour and where they hide.

Mustard and celery are two of the most frequently overlooked allergens on the UK list of 14. They rarely arrive as a recognisable spoonful of mustard or a visible stick of celery. Instead they slip into stocks, sauces, sausages and spice blends in powder or extract form. Because they are so well hidden, they reward careful label reading more than almost any other allergen. This guide covers the names to look for and the foods where each likes to hide.

Celery and its many forms

Every part of the celery plant counts as the same allergen, so the names below all mean celery:

• Celery stalk and celery leaves.
• Celeriac, which is the root of the celery plant.
• Celery seed, often used whole or ground in cooking and pickling.
• Celery salt, a seasoning blend of salt and ground celery seed.
• Celery extract or celery powder, sometimes used as a flavouring or a natural source of nitrites in cured meats.

If you see any of these in an ingredients list, treat the product as containing celery.

Mustard and its many forms

Mustard is similar. It often appears as a processed component rather than the familiar yellow condiment:

• Mustard flour and mustard powder, ground from the seed and used widely in cooking.
• Mustard seed, whole or cracked, common in pickles, chutneys and spice mixes.
• Mustard oil and mustard extract.
• Prepared mustard or simply “mustard” in a sauce or dressing.

Some traditional Indian and South Asian dishes use mustard seed and mustard oil heavily, so these are worth extra attention when buying ready meals or eating out.

Where both tend to hide

Mustard and celery share many of the same hiding places, which is why it is worth checking for them together:

• Stocks and stock cubes. Celery is a classic stock vegetable, and many stock blends contain both celery and mustard.
• Gravies, soups and sauces. Both add savoury depth, often in powder form.
• Salad dressings and mayonnaise. Mustard is a common emulsifier and flavour in dressings.
• Sausages, burgers and processed meats. Both can appear in the seasoning, and celery extract is sometimes used in cured products.
• Spice mixes, curry pastes and marinades. Mustard seed and celery seed are common blend ingredients.
• Ready meals and pre-made meal components. They can carry both allergens through their sauces and seasonings.

Because neither is usually visible, the ingredients list is the only reliable way to know they are there.

How the labelling helps

UK law requires mustard and celery, as two of the 14 main allergens, to be declared and emphasised in the ingredients list of prepacked food, usually in bold. That bold lettering is your best friend here, since you often cannot spot either allergen by eye. A “may contain mustard” or “may contain celery” statement is something different. It is voluntary precautionary labelling, used to flag a possible risk of accidental traces from shared equipment or a shared site, rather than a deliberate ingredient. Many people who avoid these allergens still treat the warnings as important.

For food prepacked for direct sale, such as a soup or sandwich made on the premises, Natasha’s Law requires a full ingredients list with allergens emphasised. This is genuinely helpful for mustard and celery, since they hide so easily in freshly made stocks, dressings and fillings.

The habit that protects you most is remembering that celeriac, celery salt and celery seed all mean celery, and that mustard flour and mustard seed all mean mustard. Read every ingredients list carefully, every time, especially on stocks, sauces and spice blends. If you want help spotting a hidden mustard or celery name, use The Food Allergy Lab to check before you buy.

Written and reviewed by the Food Allergy Lab editorial team.