A long-life oil is stable, which means it can withstand high temperatures and repeated exposure to oxygen, water and food, better than other oils can.
All oils degrade eventually, but standard frying oils do so far more quickly than long-life oils.
What causes oil to degrade over time?
- Exposure to heat
- Exposure to oxygen
- Food particles
How does it degrade?
Oxygen and heat produce chemical changes such as oxidation, which creates aldehydes and ketones, that are linked to health problems. Using a long-life oil lowers this risk, since the oil takes longer to degrade.
Chemical changes alter the viscosity and colour of the oil, and these changes continue every time the oil is heated. In time, high temperatures break the oil molecules into bigger molecules, which makes the oil more viscous.
What makes an oil stable?
All oils and fats are a mixture of three types of fatty acid chains:
The higher the proportion of polyunsaturated fat, the less stable the oil will be.
Conversely, oils which are rich in monounsaturated or saturated fats will be more stable at high temperature. This means that they will last longer in the fryer, extend your fry life quality window, and reduce the need to change your oil as frequently.