A probe thermometer measures the core temperature of food and equipment — the single most useful objective measurement in a working kitchen. It is also the most misused tool on site: inserted in the wrong place, never calibrated, sanitised once a week if at all, and the reading written in the log without context. Getting probe use right turns three of your CCPs (cooking, hot holding, chilled storage) from "we think so" into "we know, and we can prove it."
Pick the Right Probe for the Job
- Hand-held digital probe: the workhorse for spot checks — core temperature of cooked food, hot holding, refrigerator temperatures.
- Infrared (laser) thermometer: good for surface temperatures (a hot-hold cabinet vent, a chilled display cabinet) but not for core checks. Useful as a quick screening tool only.
- Logging probes: continuous-monitoring devices for fridges, freezers and blast chillers — set alarms and log readings automatically; well worth the cost for any business holding stock.
- Bayonet probes: thicker, for resistive items like joints of meat — easier to clean, slower to read.
Calibration: The Step Most Kitchens Skip
Every probe drifts over time. The standard UK calibration check uses two reference points: an iced-water slurry at 0°C and boiling water at 100°C (allow for altitude — negligible across England, but a degree or so off at altitude in Scotland or Wales). A reading within ±1°C of the reference is normally acceptable; outside that, recalibrate per the manufacturer or replace the probe. Check at least monthly, and immediately after any drop or abuse. Record the result against the probe's serial number, not a generic "probe checked" tick.
Sanitising Between Uses
A probe used on raw chicken and then directly on cooked food has just become a cross-contamination tool. Probe wipes — usually 70% IPA — are the working standard between uses. Wipe before insertion, wipe after withdrawal. Replace dispensers when empty rather than topping up. A pot of grey water with a probe sitting in it is not a sanitiser, no matter how it is labelled.
Insertion Technique That Actually Reads the Core
- Insert into the thickest part of the food, away from bone, gristle and any cooked surface artefact.
- For liquids, stir before reading so the liquid is at uniform temperature.
- Wait for the reading to stabilise — most modern probes take 5 to 10 seconds.
- For thin items (burgers, fillets), use a needle probe and insert from the side so the sensor sits in the centre.
For cooling specifically, the rule is the same — see our guide to cooling cooked food safely for how the probe reading drives the 90-minute cooling window.
Recording: Numbers, Times and Initials
A reading without a time and an initial is not a record — it is decoration. Build the temperature log so each entry captures: the time taken, the temperature read, the location or dish, the action taken if out of range, and the person's initial. Our HACCP template for restaurants gives you the standard layout; adapt it to your menu.
Common Mistakes on Audits
- "Probe checked daily" with no calibration record — that means the probe is checked, but never verified.
- A single probe shared between the raw and cooked side of the kitchen with no sanitising step.
- Logs full of identical numbers — fridge always 4.0, hot hold always 70 — a tell-tale sign of pre-filling.
- Probe stored in a knife drawer with no protective sleeve, snapping the tip and going unreplaced.
Train Once, Reinforce Often
A probe is only as good as the hand holding it. Our Level 2 Food Safety and Hygiene course covers temperature control with practical demonstrations, and a 10-minute team huddle every quarter with the actual probes in your kitchen does more for compliance than another printed poster on the wall.
Frequently Asked Questions
How accurate does a kitchen probe need to be?
±1°C is the working tolerance for catering probes. Equipment used for HACCP verification should be specifically rated as such by the manufacturer; cheap plug-and-play thermometers may drift faster.
Do I need a separate probe for raw and cooked food?
You can use one probe across both if you sanitise it correctly between uses. Many kitchens find it easier to colour-code two probes — red for raw, blue for cooked — to remove the decision under pressure.
What if my probe is out of range during a check?
Take the reading, document it, and act: recalibrate or replace the probe before the next use. Re-check the food it was reading using a known-accurate probe before deciding to serve it.
Not sure your team is using probes properly? Take the free risk assessment for a snapshot, or book a consulting visit for a hands-on review.
Written by Carren Amoli, BSc (Hons), RSPH Registered
