Is it safe to reheat cooking oil?

Oil is an integral part of cooking, specially in India. It is used for frying, to enhance the flavor or to give a particular texture to the food. Many households reuse the oil again and again to reduce wastage and save money. The question that comes to mind is “Is it SAFE to reuse oil ?”. Simple answer is “NO”.

Deep frying means cooking food by immersing it in hot oil. As it cooks, it forms a type of lock that the oil cannot penetrate. At the same time, the moisture inside the food turns into steam, cooking the food from the inside. The steam also helps keep the oil out of the food. The ideal temperature for this is around 176–190°C (350–375°F).

Factors that decide if an oil can be reheated or not are :

• the type oil being used
• how long it was heated
• whether it was used for deep frying or shallow frying and
• type of food cooked in it.

Reasons why oil should not be reheated :

• Cooking oils contain trans fatty acids, which increase upon being reheated. Trans fats are worse as they increase the levels of bad cholesterol and also decrease the levels of good cholesterol.
• Changes the chemical composition of oil, and apart from producing harmful substances that can cause complications, it also becomes stale.
• Reheating certain oils like sunflower or corn oil release a higher concentration of Aldehydes, toxic chemicals that have been associated with many conditions like cancer, heart disease, Alzheimer’s, dementia and Parkinson’s. Another toxin called 4-hydroxy-trans-2-nominal (HNE) is released upon reheating vegetable oil, which disturbs the functioning of DNA, RNA and proteins.

How to filter used oil?

If you have not overheated oil for the first time, and it is also well stored, then can be used one more time. Food particles in the oil can spoil the oil. So, avoid the accumulation of food particles in first heating.

Cool down the leftover oil and then transfer into an airtight container through a strainer/cheesecloth. Use this oil within a month. Bacteria feed on food particles left in the oil.

How to discard the used oil?

Oil should never be poured down the drain. This is because fats, oil and grease solidify to form blockages. Let the oil cool. Once cool transfer the oil into container/cover that can be thrown away. Place it in a plastic bag to prevent leakage and then throw it in the garbage. Or take it to your nearest drop off site to be recycled (cooking oil is processed into clean biofuel). Before washing the pan, wipe it with a cloth or paper towel to remove any remaining oil.

Conclusion :

Try to limit the quantity of oil used. Use only how much is actually required. Using fresh oil each time is one of the best way to have a healthy life.