Our recommendation: With breaded and battered foods, reuse oil three or four times. With cleaner-frying items such as potato chips, it's fine to reuse oil at least eight times—and likely far longer, especially if you're replenishing it with some fresh oil.
Most oils should be changed after eight to ten uses. You need to remove oil from the deep fryer after each use, strain it and store it correctly until the next time. A good tip: keep the filtered oil (food residue left in the oil will give it a bad taste) in a cool, dark place until the next use.
It makes oil more carcinogenic
Cooking food by reusing cooking oil can also increase free radicals in the body, which can cause inflammation - the root cause of most diseases including obesity, heart disease and diabetes. High inflammation in the body can also reduce immunity and make you prone to infections.
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.
Remember, once your oil is caput, don't pour it down the drain. That's bad for your pipes and bad for the environment. Do place it back in that resealable container and throw it away. For bonus points (and good oil karma) use this handy site to find out where you can recycle cooking oil in your area.
Yes, it is OK to reuse fry oil.
A cool dark cupboard is fine for the short term, since exposure to air and light hastens oil's rate of oxidative rancidification and the creation of off-flavors and odors. But for long-term storage (beyond one month), the cooler the storage temperature the better.
You can normally reuse oil a couple of times but should throw it away immediately if it becomes dark, foamy or rancid-smelling.
So while oil in which you are cooking battered foods may last through a dozen or more batches, oil used for flour-dredged foods may break down after only three to four uses.
Can you pour vegetable oil down into the drain? No. You can't do that since grease will clog up pipes and damage the local wastewater mains. Better options include reusing the oil or storing it in a sealed/non-breakable container.
Repeated heating of vegetable oils at high temperatures during cooking is a very common cooking practice. Repeatedly heated cooking oils (RCO) can generate varieties of compounds, including polycyclic aromatic hydrocarbons (PAH), some of which have been reported as carcinogenic.
These are oils like soybean, corn, canola, sunflower, and safflower. They're unstable fats – they're not bound together tightly at all. Because they are unstable, they can produce higher levels of free radicals when they're heated.
Reusing cooking oil is common practice in quick-serve restaurants for frying up menu items like French fries.
Our recommendation: With breaded and battered foods, reuse oil three or four times. With cleaner-frying items such as potato chips, it's fine to reuse oil at least eight times—and likely far longer, especially if you're replenishing it with some fresh oil.
Double frying helps with that evaporation process. By letting the chicken rest and cool between the dips in the oil, additional water evaporates from the skin. When you put it back in to finish frying, the rest of the water evaporates, which allows the skin to brown and crisp quickly before the meat overcooks.
At a high-volume fast-food restaurant, it might be necessary to change oil every week or two, but this varies based on the size of the vats, the quality of the filters and the frequency of oil filtration. In those types of establishments where fryers are constantly in use, the filter should be changed daily.
If kept in the refrigerator, you can reuse the oil in place of fresh in any recipe. Use it for frying eggs (unless you also saved some bacon grease) or any time you stir-fry.
Yes. You can cook fish and chicken in the same oil. Make sure to fry the chicken first before the fish. It does not affect the taste of the fish if you fry it after the chicken.
Can you dispose of cooking oil in the garden? Yes, you can dispose of cooking oil in the garden for compost, but it should have been used to fry plant-based foods. If it was used to fry meat, it may attract rats, raccoons, and other pests, so just bear that in mind.
What else should you keep in mind when saving and reusing fry oil? Fry like with like. Frying fish will impart a particular flavor and smell to the oil and the same goes for chicken and other meats. To keep your crullers from tasting like catfish, make sure you save fish oil for frying fish and fish alone.
During the frying process, salt acts as a catalyst and accelerates oxidation. This causes the oil to become darker in color and release off-flavors, which affects the taste of the food.
Cooking oils, when heated, may form small amounts of trans fats. However, the concentration is minuscule – less than 1% - even with lengthy heating. All Oils will become unhealthy if heated past the smoke point.
When canola oil is heated (aka. when we cook with it), it produces high levels of butadiene, benzene, acrolein, formaldehyde and other nasty compounds. These chemical compounds, combined with increased free radicals create the perfect environment for cancer growth.