Mustard, celery and sulphites: allergen advice for caterers

In the final article of our series, we look at the key watch-outs for three allergens


Commonly recognised as an ochre-coloured paste that’s added to sauces and accompanies roast dinners, mustard is derived from the seeds of the mustard plant.

Mustard allergies are rare in the UK but when they do occur, reactions to it are severe and, in extreme cases, result in life-threatening anaphylaxis.

So while we commonly associate mustard with jars of golden paste, it does come in many other forms and is used widely, so it’s worth taking careful note.

Download and print the final part of our allergen guide

Look out for:

  • Mustard is a common ingredient in many sauces and condiments, including BBQ, ketchup, mayonnaise, salad dressing, vinaigrette, béchamel, béarnaise, hollandaise, pickles, fish sauce and fish paste
  • It’s also used as a spice in the form of mustard powder and mustard seeds, most commonly in Indian dishes, but also in prepared deli meats and sausages
  • Ready-made spice mixes and rubs are also likely to include mustard powder or seeds.

Mustard substitutions

You can try swapping out mustard powder for horseradish powder. As it is spicier than mustard, only use half the measure.

“Mustard allergies are rare in the UK but when they do occur, reactions to it are severe”
- Les Mohammed, Senior Trading Controller, Unitas Wholesale


Sometimes known as sulphites, sulphur dioxide is a preservative used to extend shelf life in foods and drinks. Sulphites is a general term to describe a group of chemicals that includes sulphur dioxide and sodium or potassium metabisulphite.

Sulphites can induce both allergic and non-allergic reactions. They release sulphur dioxide gas, which is the component that preserves food and drink. In some people, this gas can cause the airway to become irritated or constricted. This is a non-allergic reaction because it is not a response of the immune system.

Common symptoms of a non-allergic reaction include wheezing, tight chest, cough and, in some cases, a rash. People with asthma are more likely to experience non-allergic reactions to sulphites.

True allergies to sulphites are extremely rare, however, they can occur and it is good to be mindful of them. Make sure your team is aware.

Look out for:

  • Processed meats such as sausages and burgers
  • Soft drinks, fruit juice concentrates, carbonated drinks, cordials and vegetable juices
  • Dried fruits and vegetables such as raisins and prunes
  • Wine, beer and cider
  • Pickled foods and vinegar
  • Guacamole
  • Dehydrated vegetables such as dried onions and pre-cut or peeled potatoes
  • Maraschino cherries and glacé cherries
  • Coconut milk
  • Salad dressings
  • Pre-prepared mustard
  • Frozen raw potato products
  • Fresh or frozen prawns
  • Tofu/bean curd.


Allergies to celery are quite rare in the UK with the most common type of celery allergy being pollen-related. Pollen food syndrome is caused by the body’s reaction to proteins in plants which are similar to pollen. Unsurprisingly, pollen food syndrome is more common in people who suffer from hay fever.

Look out for:

  • Celeriac is a type of celery which is likely to contain very similar allergens to celery. So those with celery allergies should also avoid it
  • Celery is widely used as a base with onion and garlic in Italian cooking – a ‘soffrito’
  • Celery is used in food in multiple forms, including sticks, leaves, spice, salt and seeds. Be sure to check labels carefully for all forms
  • Stocks and sauces
  • Canned soups
  • Crisps
  • Salads.
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