1. 1. Preparation and safety
      Before starting the test, place the tube in the anti-burn holder to ensure safe handling when working with hot frying oil.

   2. Sample collection
      Add frying oil at a temperature between 60 ºC and 80 ºC up to the lower mark indicated on the tube label.

      If the oil temperature is below the recommended range, it may be gently reheated in short intervals (approximately 5 seconds at a time) using a microwave or running hot water until the correct temperature is reached.

   3. Mixing
      After adding the oil, shake the tube vigorously for 30 to 60 seconds to ensure proper mixing of the reagents.

   4. Reaction time
      Allow approximately 2 minutes for the chemical reaction to stabilise.

   5. Result interpretation
      Compare the resulting colour with the reference colour chart provided.

      Level 5 corresponds to a concentration of polar compounds above 25%, which represents the legal maximum limit in Portugal (Ordinance No. 1135/95 of 15 September) and in several international regulations.

      If the result reaches level 5, the frying oil must be immediately discarded and should not be used for food preparation.

You can also watch this procedure in a short explanatory video (approximate duration: 1 minute).