A guest mentions a nut allergy. In the kitchen there is a blender that ground hazelnuts this morning and a fryer that cooks everything breaded. The question is not whether that is a risk. The question is what the law requires of you, and what you will do differently tomorrow.
The answer surprises most people: in loose sale, you do not have to declare cross-contamination. You do still have to be able to prove something. This article shows where the line runs, which numbers are in the law, and what the smallest version of allergen management that actually counts looks like.
How the 14 allergens themselves get declared is covered in Declaring allergens in a restaurant. This piece is about what happens between the recipe and the plate.
On the legal quotations in this article. Swiss food law is published in German, French and Italian. There is no official English version of the ordinances quoted here, so every passage below is an unofficial working translation provided for information only, unless labelled otherwise. The binding wording is the German text linked in the sources at the end.
Where does cross-contamination actually happen in a kitchen?
On shared equipment and in shared fat. Not in the air, and not evenly everywhere.
The practical guide published by Bern University of Applied Sciences names convenience products carrying traces, and work with pans, appliances and serving utensils that are not clean, as the typical sources. In restaurants specifically it rates the risk as high, with a reason every chef knows: space in the kitchen is limited, appliances get used for several dishes in succession, and large amounts of an allergenic ingredient add up fast.
In practice it comes down to five places:
- The fryer with one tank for everything. The oil is the only place in the kitchen where everything breaded sits together for hours.
- Flour at the pastry station. The one source that wiping the surface does not fix, because flour dust does not stay on the surface.
- The board and blender the nuts are ground in. Not “nuts” in general: the appliance is the problem, not the ingredient.
- The shared appliance used across several dishes. The stick blender that made the celery soup and then the cream sauce. More common than the fryer, and considered less often.
- Serving utensils at the buffet and the pass. The salad buffet tongs are the obvious one. The ladle that moves between two sauces is not.
When is an allergen an ingredient and when is it a contamination?
The quantity does not decide it, the route into the dish does. This is the distinction that goes wrong most often in practice, and it carries two completely different legal consequences.
The practical guide illustrates both with a single fryer. If chips are fried in peanut oil, then peanut is an ingredient and must be declared. If fish was fried in the same oil beforehand, then that is a contamination and does not have to be mentioned when the chips are sold. Same oil, same pan, two different answers.
The mistake in the other direction is just as common. Anything that reaches the dish through a compound ingredient is an ingredient, not a contamination. Use a stock containing celery and you declare celery. Add mayonnaise and you declare egg. That holds however small the quantity is, and it is the most common genuine declaration error in Swiss kitchens. Which products carry an allergen is set out in the list of the 14 allergens.
The rule of thumb: if it is in the recipe, it is an ingredient. If it arrives via the equipment, it is a contamination.
Does cross-contamination have to be declared in a restaurant?
No. For food placed on the market loose, art. 5 para. 1 let. f LIV states that unintentional mixing under art. 11 para. 5 does not have to be indicated.
For that sentence not to be misread, the boundary has to come with it. Food placed on the market loose is food placed on the market without packaging, plus any food that does not count as prepacked (art. 2 para. 1 no. 12 LGV). The plate, the buffet and the counter all fall under it. And the flip side matters more than it sounds: food that is wrapped or packed at the point of sale at the customer’s request, or prepacked with a view to immediate supply, also does not count as prepacked (art. 2 para. 1 no. 11 LGV).
So the sandwich you wrap on request stays goods in loose sale. The sandwich you wrap the evening before and put in the chiller the next day does not. From that moment the figures in the next section apply.
What never goes away is the second duty. Art. 11 para. 6 LIV requires the responsible person to be able to prove that all measures required under good procedural practice were taken to avoid unintentional mixing or contamination under para. 5, or to keep it as low as possible. So the business does not have to write anything on the menu, but it does have to be able to show it has this under control. What that looks like is below.
What happens when the recipe ingredients themselves are declared wrongly or not at all is covered in the article on the declaration duty.
The same boundary runs through a market stall. Someone who bakes at home and supplies there also faces the question whether the activity has to be notified to the canton (Art. 20 LGV), and Selling homemade food keeps the two questions apart.
At what quantity does unintentional mixing have to be declared?
On the prepacked side the ordinance names exact figures. Ingredients also have to be indicated when they reach a food unintentionally, where their content exceeds, or could exceed, the following (art. 11 para. 5 LIV):
| What gets in unintentionally | Declaration threshold |
|---|---|
| Sulphites | 10 mg SO₂ per kilogram or litre of food ready for consumption |
| Gluten-containing cereals | 200 mg of gluten per kilogram or litre |
| Vegetable oils and fats containing fully refined peanut oil | 10 g of peanut oil per kilogram or litre |
| Lactose | 1 g per kilogram or litre |
| All other cases | 1 g per kilogram or litre |
Those values only become usable together with the question of who they apply to:
| Placed on the market loose | Prepacked | |
|---|---|---|
| Notice of unintentional mixing | not required (art. 5 para. 1 let. f LIV) | mandatory once the values above are exceeded, or could be (art. 11 para. 5 LIV) |
| Voluntary notice below the values | possible at any time | expressly permitted (art. 11 para. 7 LIV) |
| Being able to prove the measures | yes (art. 11 para. 6 LIV) | yes (art. 11 para. 6 LIV) |
Two details apply to the package. The mandatory notice goes immediately after the list of ingredients (art. 11 para. 8 LIV), which gives “may contain peanuts” as its own example. And for a voluntary notice, art. 11 para. 7bis LIV allows a group term: the German text permits “Glutenhaltiges Getreide” for no. 1 of Annex 6, and any of “Hartschalenobst”, “Schalenfrüchte” or “Nüsse” for no. 8. The permitted group terms are set by the binding language versions and differ between them, so a business labelling in French or Italian should take them from that language’s text rather than from this translation.
Now the limit without which this section misleads. These values say when you must declare. They say nothing about the quantity at which an allergic person reacts. A dish with less than 200 mg of gluten per kilogram is not “gluten-free” and is not suitable for people with coeliac disease. They are declaration thresholds, not safety thresholds.
And no kitchen measures gluten in milligrams. The ordinance does not ask it to: it says exceeds or could exceed, so what is called for is a judgement, not a lab result. What the figures do give you is a way of sorting by order of magnitude. A smear of flour dust on a worktop is in a different world from a shared fryer or a shared flour bin. That distinction is exactly the point.
What do you have to be able to prove, and what does it look like?
One sheet. And the law expressly allows it to be short.
The chain behind it is short enough to read once in full. Anyone who produces food or places it on the market is obliged to carry out self-monitoring, and official inspection does not release them from it (art. 26 LMG; in the fedlex English translation, which has no legal force, “Official inspection does not imply an exemption from the obligation to carry out self-supervision”). That duty includes ensuring good procedural practice (art. 75 let. a no. 1 LGV), and good procedural practice is defined as good hygiene practice plus good manufacturing practice (art. 2 para. 1 no. 8 LGV). Good hygiene practice covers, among other things, maintenance, cleaning and disinfection, process control in producing goods from raw materials or semi-finished products, and staff training (art. 76 para. 2 LGV). That is what art. 11 para. 6 LIV points back to when it asks you to be able to prove your measures.
Something has to be written down in any case: art. 85 para. 1 LGV requires the self-monitoring concept and the measures taken to implement it to be documented in writing or by an equivalent procedure. The decisive part then sits in the paragraphs nobody quotes: self-monitoring has to be ensured in a form adapted to the safety risk and the production volume (art. 74 para. 4 LGV), the same applies to its documentation (art. 85 para. 2 LGV), and micro-businesses may reduce that documentation appropriately (art. 85 para. 3 LGV). One sheet is therefore not a shortcut, it is the intended form for a small business.
Careful here: a micro-business is a business with up to nine employees (art. 2 para. 1 no. 6 LGV), and the relief applies solely to the extent of the documentation. It is not an exemption from allergen information. Neither art. 5 nor arts. 10 and 11 LIV make any distinction by business size. The claim circulating online that businesses with fewer than nine employees are exempt from allergen declaration is false.
The smallest version that counts
Two things, under a quarter of an hour together.
First, one sheet, one line per place. This is what it could look like; cross out whatever does not happen in your kitchen:
| Where it happens here | What we do about it |
|---|---|
| Fryer, one tank for everything | Never breaded and unbreaded in the same run; where gluten matters, only in freshly changed oil |
| Flour at the pastry station | Flour work finished in the morning, surface and appliances cleaned afterwards |
| Board and blender the nuts are ground in | Dedicated board; blender taken apart and cleaned after nut work |
| Stick blender used across several dishes | Taken apart and cleaned between two dishes; allergen-free first |
| Serving utensils at the buffet and the pass | One utensil per container, no swapping when refilling |
Underneath it, the date and who wrote it. The right-hand column is an example, not a standard: what goes there has to describe what your business actually does.
Second, one question at the table. When a guest tells you about an allergy, a single follow-up question decides everything after it. The practical guide phrases it as asking whether it matters that you avoid traces of the allergenic ingredients during preparation. If the guest does not react to traces, the guide says part of the existing mise en place can be used and the kitchen does not have to cook an entirely new dish. If it does matter, the extended version applies to that one dish. The question costs ten seconds and saves a whole separate preparation in half the cases.
The sheet gets revisited when equipment, station or workflow change, not on every recipe change. That is what separates it from the allergen matrix, which has to be updated on every recipe, product and supplier change: the matrix describes recipes, this sheet describes the kitchen. In most businesses that means once a year.
The extended version
Whoever carries more risk does more. This is the extension, not the entry point: a second fryer or a second batch of oil rather than just a running order, flour and nuts stored sealed and low down, staff training recorded in writing, and the specification checked against the stored version on every delivery. That last one is the most underrated: suppliers are under no obligation to flag recipe changes.
What is a “may contain traces” notice worth?
On the plate it is legally unnecessary and practically harmful. On a package below the limits it is permitted and sometimes sensible.
The harm is concrete. Put a blanket “may contain traces of everything” on every line and real information can no longer be told apart from precautionary information, so the answer loses exactly the value the guest is asking for. Such a notice also does not replace a clean declaration of the ingredients actually in the recipe.
The other side is real all the same. According to the survey in the practical guide, around three quarters of affected people think it is important to be informed by the provider about potential contamination, particularly where they risk a severe reaction, and they often ask specifically. The guide therefore proposes a middle path: a notice naming the allergens the business actually handles and pointing guests to the staff. That is a different thing from the catch-all formula. It describes your kitchen, not all kitchens.
For prepacked goods the logic inverts: there the voluntary notice below the values is expressly allowed, and it may use a group term. Label a package and you have the choice. Serve a plate and you do not need it.
How do you keep track when recipes and suppliers change?
The ingredient side can be systematised, the kitchen side cannot. Keeping them apart is worth it, because otherwise both get done by halves.
Everything in the recipe can be systematised. That is exactly what we are building Trolevo for: recipes with nested sub-recipes whose allergens roll up automatically, from all ingredients and sub-recipes, into one allergen label per dish. If the new stock suddenly contains celery, the label changes in every dish using that stock, everywhere at once. By hand that means walking the whole chain, on every change, all year. This helps you meet the labelling duty; responsibility for correct information stays with the business.
What cannot be systematised is what happens on the shared pan. A recipe system knows your recipes, not your fryer. The sheet from two sections ago therefore stays a separate document, and no tool takes the question at the table off your hands.
What scaling does not change, incidentally, is the allergens: more portions mean more quantity, not different ingredients. For the conversion there is our free recipe scaler. Trolevo itself is in development – get early access.
Sources
The ordinances below are binding in German, French and Italian only; the German text is linked.
- LIV – FDHA Ordinance on Food Information, SR 817.022.16 (German, as of 1 July 2025)
- LGV – Foodstuffs and Utility Articles Ordinance, SR 817.02 (German, as of 1 July 2025)
- LMG – Foodstuffs Act, SR 817.0 (German, as of 1 October 2024; fedlex also publishes an English translation with no legal force)
- BFH – Practical guide to allergen labelling in loose sale, 2nd edition 2020 (PDF, funded by the BLV, with aha! Allergy Centre Switzerland) (German)
- BLV – Information in loose sale (German)
- GastroSuisse – Allergenic foods (German)
This article is general information, not legal advice. The binding texts are the statutes (LMG, LGV, LIV) and the information provided by the cantonal enforcement authorities.