Deep-frying is becoming more and more popular. When deep-frying, the water contained in the product is used for cooking. The water is vapourised due to the hot oil, which is typically 170° to 175°C. In this way, a type of ‘vapour baking’ takes place. However, the cooking oil used has to be fresh.
Scientific research has shown that the polar components (TPM = Total Polar Materials) are a good indicator of the thermal oxidative load of cooking oil. They are also an indication of how used the cooking oil is. A high level of polar components indicates that the cooking oil has been used frequently.
Increasing polar components in cooking oil has the effect of changing the dielectric constant because the "polar components" are aligned in an electrical alternating field. The change in the dielectric constant is measured on a capacitive basis using a special sensor and is converted to the required % TPM display variable. In this way, fast electronic measurement of this reading is possible.
Testo AG have developed a compact, electronic hand-held instrument, testo 265 oil tester for daily use. The main part of the instrument is a sensor, developed by Testo, which can be immersed directly in the hot cooking oil. After 25 to 30 seconds, the instrument shows the number of polar components directly in the display. The current cooking oil temperature is shown in a second display line. 2 limits, which trigger a light emitting diode whose colours depend on the oil quality, can be set in the instrument making operation easy for all kitchen staff.
If this light emitting diode is green, the cooking oil is fresh; a yellow display indicates that the oil is slightly used; a red display indicates that the oil should be changed soon. Both limit values, threshold values from green to yellow or yellow to red, can be defined by the user. In this way, anyone can measure cooking oil quality quickly and efficiently.
The testo 265 cooking oil tester does not need to be adapted to the cooking oil used, therefore any standard oils and fats can be used. It is easy to clean the tester under running water if it comes into contact with cooking oil due to the ‘TopSafe’ protective case supplied. Since the TopSafe is resistant to heat, it can even be cleaned in the dishwasher.
The testo 265 cooking oil tester can measure cooking oils in the range from +40°to +200°C as a result of the built-in temperature compensation function. If this value is exceeded, it is shown clearly in the display. Due to the temperature display, it will no longer be necessary to have additional thermostat checks on the deep-frying bath using a separate electronic thermometer.