Introduction
It is no secret that deep frying is a key step for your tonkatsu or goreng pisang to have a crispy and flavourful texture. It is also common for cooking oil to be reused several times before being disposed. How then, can cooking oil be reused safely?

What are the potential food safety risks in reusing cooking oils?
During frying, cooking oil goes through chemical reactions, which results in darker and thicker oil. Foam and smoke are also formed.
When oils are heated at high temperatures repeatedly and for a long time, especially for deep-frying (typically ranging from 177 to 232 °C), the organic matter within breaks down more quickly. This decreases the oil’s smoke point (the temperature oil starts to smoke and burn) and forms compounds that are potentially harmful to health. These compounds include polycyclic aromatic hydrocarbons and aldehydes which, when consumed, increases the risk of cancer and cardiovascular diseases. Consequently, this presents health risks and results in fried foods that are less tasty, flavorful, and aromatic.