How to Use Oil in Your Cooking

If you deep fry, as some Asian recipes call for, then you will want to know how to use oil the correct way. For instance, you should have answers to the following questions - How many times should oil for frying be used before you throw it away? How should oil used to fry different types of food be segregated? What should be done to keep oil clean and good for reuse?

If possible, for health and flavour concerns, cooking oil should not be reused. It has been generally agreed by food chemists that frying items in very hot oil produces small but definite quantities of potentially carcinogenic components. While their precise long-term impact on health is not known yet, it is better, if possible, to not reuse cooking oil.

Some of these compounds result from heat degradation of the oil. These factors cause oil to oxidise and deteriorate: heating it to a high temperature and/or keeping it over heat for a long time; frying salty foods in it; allowing tiny bits of food to remain in the oil; and prolonged exposure to light and warmth before or after cooking.

Therefore, just about any use of cooking oil will oxidise it at least slightly. Furthermore, the methods most likely to land you with a lot of used oil that you'd be loath to waste, such as deep-frying, are the same methods that are likely to cause the speediest loss of quality in the oil.

If you really must reuse oil, strain it through a fine mesh sieve and/or muslin cloth a couple of times to remove absolutely all food particles, then examine the oil.

Save it for reuse only if it is not much darker or more viscous than it was when fresh and if it has no off-smells. Store it in an airtight container in the fridge. It may cloud a little when it gets cold, but this is normal.

Also never mix oils from different bouts of cooking for reuse. Oil used to fry fish, for instance, takes on an odour. If, when you are heating the oil, the reused oil foams, smokes or darkens excessively, throw it out and use fresh oil.