Deep frying is a cooking method in which food is submerged in hot oil or fat. Overheating or over-using the cooking oil can pose hazards due to oil deterioration, polymerization, oxidation, and harmful components formation such as acrylamide. Deterioration of cooking oils is generally followed by changes in color of the used oil , free fatty acid level, an increase in trans fat, Polycyclic aromatic hydrocarbons (PAHs) and polarity of the oil.

The level of polar components or total polar compounds is a good indicator to determine the quality of oil. The maximum levels for polar compounds of cooking oils is at 25g/100 g oil or 25%