"May contain mustard" means something different
Now we reach perhaps the most misunderstood three words in allergen labelling:
May contain mustard.
If mustard appears in the ingredients list, the manufacturer is telling you that mustard was intentionally used as an ingredient.
A "may contain" statement is different.
It is a form of precautionary allergen labelling, often shortened to PAL.
It warns about the possibility of unintended allergen presence — usually because of cross-contact somewhere in production.
Imagine a factory producing two sauces.
Sauce A contains mustard.
Sauce B does not.
If the same equipment is used for both, the manufacturer needs systems to prevent mustard from Sauce A contaminating Sauce B.
Those controls might include production scheduling, physical segregation and validated cleaning procedures.
But if a genuine residual risk remains that cannot be adequately controlled, precautionary allergen labelling may be appropriate.
Current FSA guidance says precautionary allergen information should follow a thorough risk assessment where a real risk of allergen cross-contact has been identified and cannot be removed through risk-management measures. It should not be used as a substitute for good hygiene and allergen control.
That last point matters.
"May contain" should not mean:
"We haven't really checked, so we're covering ourselves."
"May contain" doesn't tell you how much
This is where consumers encounter a frustrating limitation.
A packet saying:
May contain mustard
doesn't tell you the probability that mustard is present.
It doesn't tell you the quantity.
It doesn't tell you whether mustard has ever actually been detected.
And another packet with no precautionary warning doesn't mean that the manufacturer can promise the absolute absence of every trace under every conceivable circumstance.
PAL communicates risk, not certainty.
This creates a difficult real-world problem for allergic consumers.
If precautionary labels are applied too readily, enormous numbers of foods become unnecessarily unavailable.
If they are applied too sparingly, people may unknowingly encounter genuine risks.
The goal of good allergen management is therefore not to put "may contain" on everything.
It is to understand and control the manufacturing risk well enough that the warning is used meaningfully.
That distinction will become increasingly important as allergen science moves towards more quantitative risk assessment rather than treating every theoretical trace as identical.
Cross-contact is not quite the same as "cross-contamination"
The two expressions are often used interchangeably, and ordinary conversation will probably continue to do so.
But cross-contact is increasingly useful when talking specifically about allergens.
Traditional food cross-contamination often makes us think of bacteria — raw chicken contaminating cooked food, for example.
Cooking the contaminated food sufficiently may destroy many harmful microorganisms.
Allergen cross-contact is different.
If mustard protein moves from one food to another, reheating the second food cannot be relied upon to remove the allergen.
Remember Sin a 1 and its structural resilience.
You aren't trying to kill a living organism.
You're trying to prevent a protein from getting into the food in the first place.
That difference explains why allergen control in kitchens involves much more than simply "cooking everything properly".
It brings us to chopping boards, utensils, fryers, grills, hands, gloves, cloths, condiment bottles and the surprisingly complicated question of what people mean when they promise to prepare something "separately".