Do you actually know anyone who doesn't like the taste of fried food? I really don't. In all cuisines, as well as in vegan, fried foods have their place. And while we've all heard that fried foods are not the healthiest, we do not exclude them from our diet. At least, with the following article, we can learn how to continue frying our food, limiting its harmful effects. And the first thing we need to do is to choose the healthiest and the most proper oil for this use.

Desired characteristics of frying oil

The most important and defining properties of the oil to be used in frying should be:

Stability and difficulty in oxidation

The compound with oxygen is called oxidation. The oxidation leads to the extremely good harmful free radicals, compounds that are directly linked to cancer and heart attacks. When the oil has saturated fats (low-quality oils), it oxidizes more easily.

High smoke point

It's the temperature at which an oil produces smoke. When this happens, there is extended diversification and destruction of nutrients and formation of dangerous compounds (aldehydes and lipid peroxides). So, the higher the smoke point of the oil, the more it "tolerates" high temperatures and does not alter.

Existence of natural antioxidants

They help in the absorption of vitamins and act competitively in the action of harmful free radicals.

Low to no amount of acrolein and acrylamide

These are two particularly harmful substances that create the distinctive "burn" in our throats. When they were detected in potato chips, a food scandal had erupted. They are produced by high frying temperature (above 180°C/356°F), as well as by multiple fryings of low-quality oils.

Content of "good" fats

Monounsaturated and polyunsaturated fats have very positive effects on our health. You can read more about fats here.

Frying oils

The oils we usually use for frying are:

Olive oil

It's more expensive, but it's also the best. It is low in saturated fats and high in unsaturated fats. This, of course, is defined by its quality. The monounsaturated and polyunsaturated fats combination defines the high biological value of olive oil.

All three categories of olive oil are used for frying:

  1. "olive oil",
  2. "virgin olive oil"
  3. and "extra virgin olive oil", which is the best.

The best way to enjoy its taste and absorb its nutrients is to eat it raw or add it at the end of cooking. But it is also used in frying because it's the safest. It has a high smoke point and high stability and resistance to oxidation. The amount of olive oil required when frying is smaller than the one required with seed oils, while the triglycerides in our blood increase less after eating fried food.

Seed oils

Sunflower oil,canola oil, corn oil, soybean oil, cottonseed oil, etc, apply in this category. They are rich in polyunsaturated fat. They have a low temperature stability, and a satisfying smoke point, so they're not the most suitable oils for frying. They can, carefully, be used at low temperatures - below 160°C/320°F.

Which oil should we prefer?

The answer is easy. Of course, we prefer olive oil, especially extra virgin. It is rich in vitamins, antioxidants and is very resistant. Its disadvantages are its price, since it's more expensive, and the many cases of adulteration.

Extra virgin olive oil is up to five times more high heat-tolerant than seed oils. It is followed by the "virgin" and then the plain "olive oil", which may include refined kernel oil (up to 30%). As a result, in some degree, it has the disadvantages of seed oils.

From the seed oils, the one that seems more stable and suitable than the others is canola oil, which could tolerate frying temperatures near 170°C/338°F depending on its quality.

One of the urban myths, which has been mainly cultivated by advertisements, is that seed oils are "lighter" than olive oil and therefore more suitable for frying, since the food absorbs less fat. In fact, seed oils, regarding calories, are the same as olive oil. However, they are far too low in vitamins, antioxidants and less resistant to frying, resulting in the production of very dangerous substances.

A very interesting research took place at Leicester School of Pharmacy of De Montfort University of Leicester. In a large sample of people, participants, after frying their homes for a few days with a particular type of fat, sent what was left in the pan to the laboratories. The purpose was to analyze the differentiations of each type of fat, after some frying. Expected "champion" was the extra virgin olive oil. Sunflower oil, soybean oil, and corn oil were forbidding for frying, due to their temperature-sensitive polyunsaturated fats. These oils should hardly be heated at all, but should only be consumed raw. Also, cottonseed oil is of low quality because it has an increased percentage of saturated fatty acids and should be completely avoided.

In people with circulatory system problems (heart and blood vessels), avoiding fried foods, especially in seed oils, and consuming only olive oil is recommended. (Boskou, 2008).

Saving oil in frying

Filtering the frying oil is the first thing we need to do, if we want to use it again. Store it in a dark place, in a cupboard, and in a tightly sealed jar, to avoid contact with air. It should also be kept at room temperature or lower and should not be mixed with new oils.

The right temperature and frying time

The right temperature and frying time vary, depending on the quality of the oil. As mentioned, the main purpose is to prevent oxidation and the formation of harmful substances.


  • Extra virgin olive oil can "tolerate" 180°C/356°F for a maximum of 20 minutes and for more than 5 re-uses.
  • Plain olive oil can "tolerate" 160°C/320°F for 5 minutes and no more than 3 re-uses.
  • Seed oils should be heated to even lower temperatures than plain olive oil and they can only "take" one frying.

It is preferable to fry for 5 or more times with extra virgin olive oil (provided the frying times and temperatures are met), rather than once with seed oil!

Can we understand the quality of frying oil in restaurants?

It is extremely difficult to understand the type of oil used, only by the taste or appearance of the fried food. At least in Greece, there is no provision in the legislation about the quality of the used oil in restaurants. It is obvious that, with few exceptions, they will be used cheap, of poor quality and multi-used oils, particularly dangerous to our health.

It is common, for example, for French fries to have a taste of another food. This means that the oil will probably have been left in the pan for a long time and will almost certainly be unsuitable for consumption. Prolonged frying time, as mentioned, destroys nutrients and develops substances that are extremely harmful to our body.

The moment we'll feel the "burn" in our throat, which means we're tasting acrolein, or see the dark, bubbly oil, is the moment it is about to be classified as industrial!