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Part 5 of 7 · Allergen checker series ~5 min read

How a substitution gets caught

A substitution is a supplier or a kitchen deciding, reasonably and at short notice, that one thing will do instead of another. It is normal, it is frequent, and it changes the allergen profile of everything it touches.

Key takeaways

  • Substitutions come from the supplier and from the kitchen; both change the dish.
  • The receiving step is where a supplier substitution can be caught.
  • A kitchen substitution needs a way to record it in seconds, or it will not be recorded.
  • The pre-service check is a short list of what is different today.
  • A substitution that adds an allergen should stop the dish being sold until reviewed.

Two sources

Three sources of substitution that change a dish's allergensThree boxes stacked on the left. Supplier substitution, where they were out of stock and sent an alternative, labelled caught at receipt. Kitchen substitution, where we ran out and used something else, labelled caught only if recorded. And Recipe deviation, a different method on the day, labelled hardest of all. All three converge on The dish changed and the menu did not, and that leads down to a Pre-service check asking what is different today. A note says the second lane is the common one and it depends entirely on ease of recording.Supplier substitutionout of stock,sent an alternativecaught at receiptKitchen substitutionwe ran out,used something elsecaught only if recordedRecipe deviationa different methodon the dayhardest of allThe dish changedand the menu did notPre-service checkwhat is different today?The second lane is the common one and it depends entirely on ease of recording.
Fig 1. Three ways a dish differs from its recipe on a given day. Only the first has a natural capture point; the other two depend on how easy recording is.
  • Machine learning
  • Management
  • Front-end & mobile
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At receipt

This connects directly to the packing slip checker from Day 114. A substituted product code is already flagged there for quantity and suitability reasons; the allergen check is the same event with an additional consequence.

The receiving person does not need to know anything about allergens. They record that a substitution happened, which the system already asks them to do, and the allergen comparison runs automatically against the substitute’s specification if one is held, or flags it as unknown if not.

Recording a kitchen substitution

How a kitchen substitution is recorded and checked for allergen changesA vertical chain of five steps entered by a box labelled We have run out, often mid-service. Step one records the substitute chosen by whoever is cooking. Step two takes two taps to record: the dish, and what was used instead, with a side box noting that if it takes longer it will not happen. Step three computes the allergen delta immediately. Step four asks whether anything was added under contains or may contain; if not it exits to Note it and carry on, with no allergen change. Step five stops the dish being sold until somebody reviews. A note says the last box is severe on purpose, and it is why the recording has to take seconds.AWS ACCOUNTWe have run outmid-service, oftenSubstitute chosenby whoever is cookingTwo taps to recorddish, and what insteadIf it takes longerit will not happenAllergen deltacomputed immediatelyAnything added?contains or may containNote it and carry onno allergen changenoStop selling ituntil somebody reviewsThe last box is severe on purpose, and it is why the recording has to take seconds.
Fig 2. How a kitchen substitution is captured and assessed. The two-tap requirement is a design constraint rather than a preference: anything slower is not used during service.
  • Compute
  • App integration
  • Machine learning
  • Security & identity
  • Management
  • Analytics
  • Front-end & mobile
  • People

Two taps, or it does not happen

This is the same constraint as the receiving doorway in Day 114 and it is more acute. A substitution decision is made in the middle of a service by somebody with both hands occupied, and any recording mechanism that takes more than a few seconds will be skipped entirely.

Which means the design has to be a short list of the dishes on today’s menu, a short list of plausible substitutes for the ingredient that ran out, and nothing else. No free text, no reason field, no confirmation dialogue.

Stopping a dish

Stopping the sale of a dish because a substitution added an allergen is a strong action and it is the correct one, because the alternative is selling a dish whose printed allergen information is now wrong.

The review is quick: somebody looks at what changed, decides whether the dish can be sold with amended information communicated to staff, and clears it. That takes a couple of minutes and it is the difference between a controlled change and an undocumented one.

The pre-service check

The pre-service allergen briefing produced each dayA horizontal row of five boxes. Before service: two minutes. What is different today versus the menu. Usually nothing, and that is stated. Sometimes two dishes, named with the change. Briefed: everybody on the floor. A note says explicitly saying nothing has changed today is what makes the exceptions land.THE TWO MINUTES THAT MATTERBefore servicetwo minutesWhat is differenttoday, versus the menuUsually nothingand that is statedSometimes 2 dishesnamed, with the changeBriefedeverybody on the floorExplicitly saying 'nothing has changed today' is what makes the exceptions land.
Fig 3. The daily briefing output. Stating that nothing has changed on most days is what gives the occasional exception its weight.
  • Machine learning
  • Management
  • Analytics
  • People

The value of a briefing that usually says nothing is easy to underestimate. A daily statement establishes that the check happened, which means the day it says something the statement carries weight, and staff have a habit of hearing it.

What this connects to

Every substitution recorded here is also a cost event for Day 123, a receipt event for Day 114, and occasionally a supplier finding for Day 113. Recording it once and letting several systems read it is the case for keeping these things as events rather than as notes in separate places.

Next: what all of this costs to run.

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