Frying is the process of cooking the food in a suitable oil at a temperature of 150-200 ℃ in order to gain the desired color and flavor. For this process, mostly canola, safflower, corn, olive oil and sunflower oil are used.
During frying, some reactions such as hydrolysis, oxidation and polymerization occur and as a result, decomposition products such as free fatty acids and hydroperoxides are released. In addition, if the used oils are reused, fried at high temperatures and the processing time is prolonged, more decomposition products appear and it is stated that their consumption creates health problems. As it is known, oils are used many times both in kitchens and industrially, but when the oils are fried again, even at low temperatures, they break down and form a component in an undesirable odor called acrolein.
Fatty acid composition is important when choosing oil. The higher the unsaturated fat ratio, the lower the oil's resistance to temperature. Sunflower, rapeseed, non-refined extra-virgin olive oils should be preferred for frying as their fatty acid composition is suitable. If the oils are to be reused, they must be pre-treated, especially if the particles are separated, and attention must be paid to the hygienic cleaning and dryness of the equipment used. Experts state that oils that have not changed in smell, that have not started to become bitter at the taste point and that do not have a dark tone are used for reuse, but the oils can be used in 10 frying processes at most.
Source:
https://www.gidabilgi.com/Makale/Detay/kizartma-yaglarinin-tekrar-kullanilmasi-sakincali-midir-252ea8
