In short
- Oil can look acceptable and already be degraded: colour and smell are not enough.
- Polar compounds measure the degradation. Many countries set a limit of about 24 to 27 %.
- Check daily with a tester and log the result, the temperature and the date of each change.
Frying oil goes through heat, water and food for hours every day. It breaks down into polar compounds, which affect taste, make food absorb more oil and are unwelcome for health. Changing too early wastes money. Changing too late is a quality and safety problem. A tester removes the guessing.
What polar compounds are
When oil oxidises and breaks down, new, more polar molecules appear. The share of total polar compounds (TPM, or TPC) is the standard measure of how used the oil is. The laboratory method is ISO 8420, and kitchens use dielectric or other handheld testers that give a percentage within seconds.
The limit
There is no single EU limit. Many European countries set a maximum in the range of 24 to 27 % of polar compounds, and 25 % is widely used as a rule of thumb. In Morocco, check with your authority which value applies. Your own procedure can be stricter, for example at 22 %, so you act before the limit.
A simple routine
- Measure at the end of service, with the oil at about 50 to 60 °C, and not right after loading a wet product.
- Write down the reading, the date, the fryer and the initials of the person.
- Filter the oil every day and top up with fresh oil.
- Change the oil when you reach your action level, or sooner if it foams, smokes at low heat or smells acrid.
- Clean the fryer tank at each change.
What lengthens oil life
- Keep the temperature at or under 175 to 180 °C.
- Salt food away from the fryer.
- Drain and dry food before frying.
- Skim crumbs often and cover the fryer when idle.
- Top up with small amounts of fresh oil rather than mixing large batches.
The lab check
A laboratory analysis two times a year checks your tester and gives you a reference. Keep the results and the oil change log together as part of your HACCP records.
This article is general information, not legal advice. Rules and limits change: confirm the current text with your food safety authority (ONSSA in Morocco, your national authority in the EU) and with your accredited laboratory.
Questions
What polar compound level means I must change the oil?
Many European countries set 24 to 27 %, and 25 % is common. Check the rule that applies to you and set an internal action level a little lower.
Is a colour chart enough?
No. Oil can be dark and still within limits, or pale and degraded. A polar compound tester gives a measurable result.
How often should I measure?
Daily or at least weekly for each fryer, and more often when the fryer is busy. Always log the result.
