What happens when you reuse your cooking oil, a doctor explains
Do you use your leftover oil again and again for cooking? You may be inviting many diseases, a doctor tells us why.
We love to eat puris and pakoras on special occasions but a big disadvantage of whipping up all the tasty and crispy fried stuff is that it could lead to wastage of edible oil. So, we are at times tempted to reuse it for cooking. But have we ever thought what happens to the oil when we use it again and again and what it does to our body?
According to studies, reheating of cooking oil leads to release of toxic substances and also increase free radicals in the body causing inflammation and various chronic diseases. FSSAI (Food Safety and Standards Authority of India) guidelines say the re-heating should be avoided and in case you have to reuse oil, a maximum of three times is permitted to avoid formation of trans-fat.
“Re-heating and reuse of oil should be avoided as far as possible. Avoid using left over oil wherever possible. However, vegetable oil having developed Total Polar Compound more than 25% shall not be used,” adds the guidelines further.
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Dr. Soumyadeep Mukhopadhyay, Lab-In-Charge, MitraSK Food Testing Services tells us in detail about the harmful effects of reusing oil after one frying cycle.
“The number of times that one can safely reuse it depends on what kind of food is being fried in it, the kind of oil it is, what temperature was it heated to, and for how long,” says Dr. Mukhopadhyay.
He also explains harmful effects of consuming food cooked in such oil:
It releases toxic substances, gives bad odour
Oil heated to high temperatures releases toxic fumes. Fumes are given off even before the smoke point is reached but increases dramatically when the temperature goes above smoke point.
Each time oil is heated, its fat molecules break down a little. This causes it to reach its smoke point and give off a bad odour, more quickly each time it is used. When this happens, unhealthy substances are released both into the air and into the food being cooked.
It increases your cholesterol levels
At high temperatures, some of the fats in oil change into trans fats. Trans fats are harmful fats that increase the risk of heart disease. When oils are reused, the amount of trans fats gets even higher.
It can increase your blood pressure
The moisture contained in the foods, atmospheric oxygen, high temperatures produce reactions such as hydrolysis, oxidation and polymerization. These reactions change and modify the chemical composition of the used frying oil, releasing free fatty acids, and radicals that produce monoglycerides, diglycerides and triglycerides. These are grouped under Total Polar Compounds which is a reliable benchmark for measuring degradation of cooking oil. The toxicity of these compounds formed after repeated frying may cause lipid deposition, oxidative stress, hypertension, atherosclerosis, etc.
Now that we know how harmful re-heating of oil can be, it is best to make a proper estimate of the amount of oil required for frying, cooking etc, for staying healthy and disease-free.