How to fry without oil and which oil to fry in is less harmful: an overview of different types of oils. Which oil to use for frying is strictly not recommended

Hello friends and all fried food lovers! In this article I want to tell you why frying in oil is harmful? And then everyone around says that frying is harmful, but few people know why it is harmful. And you will also learn how the chemical composition of a particular oil affects the degree of harmfulness of the frying process itself? And most importantly: what oil can you fry in?, and whether there are safe oils for frying or is this a myth? So get ready to absorb and digest the information. Perhaps today you will learn something new about frying.

Why is frying harmful?

All vegetable oils in their raw form contain healthy Omega-3, 6 and 9 fatty acids. Some oils contain more of one acid, some – another, but the essence frying in vegetable oil It doesn’t change because of this. The fact is that during any heat treatment, the temperature of which is above 100 degrees, beneficial fatty acids Omega-3 and Omega-6 are converted into very toxic and poisonous substances.

A small addition to make the picture complete:

• The boiling point of water is 100 degrees
• Braising temperature on the stove – 80-95 degrees
• Simmering temperature – 60-80 degrees
• Frying temperature in a frying pan – 120-180 degrees
• Oven baking temperature – 150-250 degrees
• Frying temperature over an open fire is over 220 degrees.

We see that the boiling point of oil in a frying pan ranges from 120 to 180 degrees. And already at temperatures above 110 degrees, fatty acid molecules are split off from unsaturated fatty acids and their further decomposition occurs with the formation of toxic isomers - aldehydes and ketones. This suggests that literally from the first minutes of frying, ANY vegetable oil, which contains a lot of polyunsaturated fatty acids (and this is more than 70% of all oils), turns into nothing more than drying oil! And the healthier the oil, the more it contains primarily Omega-3 and Omega-6 polyunsaturated fatty acids, the faster the chain of aldehydes and ketones is split off, and the more toxic this oil becomes!

The same applies to vegetables, which are so rich in polyunsaturated fatty acids.

The healthiest oils are rich in Omega-3 fatty acids: flaxseed, hemp, pine nut oil. So they are the most dangerous when heat treated above 100 degrees.

And just a few words about the dangers of these same aldehydes and ketones that are formed during frying.

These toxic compounds come in the form of free radicals, which destroy our cells, tissues and organs. Thanks to them, the rate of wear and tear of all organs accelerates several times, and the aging process of the body occurs tens of times faster... In simple words, they clog the body, settling on the walls of blood vessels, making them fragile and vulnerable.

So we found out that frying in oil is harmful due to the fact that POLYUNSATURATED fatty acids form very dangerous and toxic compounds at high temperatures. And first of all the most harmful frying oils, these are precisely the oils that are rich in these acids.

From the table we see that not all oils are rich in polyunsaturated fatty acids; there are those that consist of 50-70% monounsaturated or saturated fatty acids. And from here we will start, finding out whether there is safe frying oil or not.

What oil can you fry in without harm?

Looking ahead, I immediately warn you that, unfortunately, completely harmless frying in oil does not exist, I say this so that you do not indulge yourself with illusions and do not run to buy all the “safe” oils in the supermarket. But it is true that there are LESS harmful cooking oils. And now we will figure out what kind of oils these are.

Before moving on to the list, you need to understand why some oils can be used for frying, while others absolutely cannot.

Firstly, it depends on the amount of polyunsaturated, monounsaturated and saturated fatty acids. The more polyunsaturated fatty acids an oil contains, the more beneficial it is in its raw form, but it becomes dangerous and toxic when heated (we found this out in the first part of the article). The more monounsaturated and saturated fatty acids an oil contains, the safer it is when cooked. Hence, analyzing the composition of a particular oil (see table above), below I have listed several types of oils that are suitable for frying.

COCONUT OIL

Edible COCONUT OIL comes first. This is the only oil that does not break down or become toxic when heated. It consists of almost 90% saturated fatty acids of plant origin. Because of this, it can withstand temperatures up to 350 degrees, so it can be used for frying and even baking your favorite foods. Scientists have proven that coconut oil is completely digestible and is not stored as fat, since the fatty acids that make up coconut oil are converted by the body into ketone bodies, which are subsequently used as a direct source of energy, so it can be safely used in your daily routine. diet as a source of healthy fats. But there is one disadvantage of this oil - it is not cheap (200-250 UAH for 300 ml)... And its consumption for preparing the same pancakes or cheesecakes is several times more than any other vegetable oil... But if this is not a problem for you , then you can safely buy it and fry whatever you want in coconut oil. By the way, it is used not only for baking, but also for preparing any hot dishes: soups, side dishes, vegetable and even meat and fish dishes. This may sound crazy, but in fact, pilaf cooked in coconut oil turns out incredibly tasty)) Try experimenting sometime, I think you’ll like it.

GHI OIL

Next to “possible” frying oils refers to Ghee butter. It is a type of ghee and is very widely used in South Asian countries. It can withstand temperatures up to 250 degrees without emitting any harmful substances. But this type of oil can not often be found on supermarket shelves, but you can easily order it on the Internet, fortunately now this is not a problem for most). And this oil is already 2 times cheaper than coconut oil (from 100 UAH per 500 ml).

GRAPE SEED OIL

Next in line is grape seed oil. Due to its high content of oleic acid and low content of Omega-3 fatty acids, grape oil is highly resistant to heating to high temperatures (the smoke point of this oil is 216 degrees), and therefore it can be used for frying or baking in the oven (up to the specified temperature, not higher). The price of this oil is on average 200 UAH per 1 liter.

OLIVE OIL

Following oil for frying, this is olive oil. And you may have heard somewhere that olive oil is not suitable for frying, this is not true. Due to the fact that olive oil is 76% monounsaturated fatty acids, which, as we have found, are more resistant to oxidation, it is considered one of the safest oils that can be used for frying.

It’s even better to fry not in oil, but in lard (melted lard) or goose fat. I know that this is possible, for most it will seem wild and unpleasant, but from a health point of view, lard is rich in monounsaturated acids, so frying with it is much safer than with sunflower or butter.

- avocado oil (270 degrees)
- peanut (225 degrees)
- rice (255 degrees)

Well, that's probably the whole list "safe" oils for frying. I put this word in quotes, because I still think that frying is not a very good process, and you definitely won’t get any benefits from frying, but you will get a lot from stewing or heating. Therefore, try to slowly retrain yourself to alternative and healthier ways of cooking. Personally, I find a lot of advantages:

• no need to buy oil every month (or even more often);
• it is much easier and more pleasant to wash a frying pan when there is not a drop of fat on it;
• Products do not lose their natural taste when cooked;
• the benefits of cooked dishes without the use of oil are much greater, since even in “safe oils” for frying, although in small quantities, polyunsaturated fatty acids are still present, which break down into toxic aldehydes and ketones. Therefore, to say that the oils listed above are 100% safe for frying would be wrong and dishonest. Still, a certain percentage of carcinogens are formed even in these “chosen ones”.

I hope I was able to answer the questions: why frying in oil is harmful And is there safe cooking oil?

But if you want to know my personal opinion and attitude towards the frying process, then it is this: personally, I have not used any oil when preparing my dishes for a long time (except for very rare cases of using coconut oil) and I feel great, which is what I wish for you!

Sincerely yours, Janelia Skripnik!

Often in culinary recipes we are recommended to fry this or that product in butter. Sometimes this is dictated by the future taste of the entire dish, and sometimes by concern for our health. After all, it is known that mixing butter and vegetable oil when frying is harmful to the stomach, liver, and blood vessels. Therefore, if the recipe, for example, calls for the addition of sour cream or cream, then it is safer to use butter when frying.

However, many housewives claim that it burns in a frying pan, and when they come across such recommendations in a recipe, without hesitation, they use margarine. This is the worst thing you can do! Although frying with it is more convenient, the harm from margarine is much greater than if you mix animal and vegetable fats. It is this that increases the risk of heart attack and stroke, is deposited on the body in the form of extra pounds and contributes to the manifestation of cancer.

In addition, the taste of a dish prepared using margarine is strikingly different from that when natural butter is used. Therefore, if it is written: “fry with butter,” then you need to do exactly that.

How to fry in butter without it burning?

1. First of all, if the cooking time is short, then it will not have time to do this. For example, if you cook scrambled eggs.

2. If we fry longer, we should not heat the pan too much. The algorithm is as follows: put the frying pan on the fire; wait until it warms up well; put a piece of butter; when it melts, add the desired product; then reduce the heat and continue cooking, not allowing the oil to burn.

3. But what to do if the dish must be cooked for quite a long time?

You'll have to work a little harder here. Let's make ghee from butter. We’ll prepare it just once, but we’ll be able to enjoy the fruits of our labor for a very long time.

Look, I deliberately threw 2 pieces of butter onto a hot frying pan and took a photo. In the photo: on the left is the regular one from the store, on the right is the baked one. The usual starts to burn very quickly, the melted melts without burning.

How to melt butter correctly?

This can be done in a regular thick or ceramic frying pan over low heat, or in a stainless (but not aluminum!) saucepan with a thick bottom if you intend to heat a lot of oil at once in reserve.

I do it differently. In a saucepan I put a piece of thick fabric folded in half at the bottom, pour water and put it on the fire. I put butter, cut into pieces, into a glass jar and place the jar on a cloth. That is, I cook ghee in a water bath. A half-liter jar holds approximately 450 grams of the original product.

After the water boils, I reduce the heat to the lowest setting so that the boiling is barely noticeable. If this cannot be done on your stove, then I recommend another method to prevent the glass jar from bursting.

You can use two pans of different sizes so that one of them is a few centimeters smaller in diameter than the other. Pour water into a large pan, put the smaller one inside so that its handles rest on the sides of the larger one and are immersed in water. This is another version of a water bath.

The oil heats up quite quickly, but this is not the product we want to get, so we wait for foam to appear on top. You should not remove it right away, since the milk protein will still separate for some time under the influence of temperature.

After about half an hour (more is possible), carefully remove the foam, turn off the heat and let the oil cool slightly.

Cover a fine sieve with gauze or a wide bandage folded 4 or 8 times, and carefully pour the oil into another bowl. Make sure that no white mass comes from the bottom, otherwise you will need to strain again.

You can put the strained product in the refrigerator to use if necessary. We put what remains unstrained in the refrigerator and wait for it to harden. You will see that a thick layer of butter has formed on top, and regular milk on the bottom. This oil can also be used, but do not store it for long.

We still have some foam left. In order not to fool myself, I immediately spread it on bread and eat it with pleasure. No foam - no problem.

It should also be mentioned that the longer the oil is heated, the longer it can be stored without refrigeration.

Ghee can be used for baking, sandwiches, porridge, pasta and other dishes where you would normally add butter. And most importantly, you can fry in this oil.

The taste of ghee is different, however, many people like it even more than usual. In addition, it does not contain milk proteins, and therefore everything prepared with it can be safely eaten by people with lactose intolerance.

We clearly explain why you should fry food in olive or rapeseed oil. Or, if you really want, then creamy.

Yes, yes, of course, grilling is much better. But pancakes are not pancakes without butter, cheesecakes are not cheesecakes when baked, and cabbage schnitzel without frying is also not cabbage schnitzel. Well, everyone has their own favorite list of things to fry. Question: on what?

I've come across a lot of nutritional opinions. And that we fry an animal on an animal, and a vegetable on a vegetable. And that any plant is healthier than an animal. And about the fact that, in principle, you can’t fry anything except in a dry frying pan. I am for common sense. One of the valuable and authoritative opinions for me both as a mother and as a specialist is the opinion of the doctor, company nutritionist. And, of course, I don’t forget about the results of independent research. I'm telling you.

Olga Pashkova, nutritionist: “I am in favor of adding any oil to a finished dish. Especially if you are cooking for kids. But if you still want to fry your food a little, then use olive oil. It contains less polyunsaturated fatty acids, so it is less oxidized. You can fry fish, vegetables, some dough products, and less often meat in olive oil. You can also sauté vegetables and add a little oil to dishes when stewing. If you fry pancakes or cheesecakes - something dessert - you can use coconut.

In other vegetable oils, when exposed to high temperatures, especially for a long time, valuable fatty acids and vitamin E are destroyed, and harmful oxidation products accumulate. Therefore, flaxseed oil, grape seed oil, sesame oil, mustard oil, walnut oil, sunflower oil are best used without heat treatment - in salads, vinaigrettes.”

Chemistry of the issue

When we talk about oil, we talk about fats -polyunsaturated, monounsaturated(vegetable oils) andsaturated(dairy products, animal fat).

When we fry or bake with oil - that is, heat it above 180 degrees - the molecular structures of the oils change. Interacts with oxygen and forms And – in a word, oxidation occurs. That is, oxidation is the rancidity of oil. The aldehydes produced are dangerous - if we ingest them or even inhale them, they increase the risk of developing heart disease and cancer.

Research results

In July 2015 published the results of a study conducted by a group of scientists(University de Montfort). They heated sunflower, corn, sesame, coconut, cold-pressed canola oil, olive oil, butter, lard and goose fat. The goal is to identify the most harmless oil for frying by measuring the level of aldehydes produced.

Head of the research group, professor Martin Grootveld: “We found that oils rich in polyunsaturated fats—corn oil and sunflower oil—produced very high levels of aldehydes. […] Sunflower or corn oils can only be used if you do not heat them, such as frying or boiling. It's a simple chemical fact that something that is supposed to be good for us turns into something not good at all at standard frying temperatures."

The lowest indicators are inolive, coconut, rapeseed And creamyoils And goose fat. Conclusion: use oil for frying, boiling or bakingwith the lowest level of polyunsaturated fats.

• Use olive, butter or canola oil for frying.
• Do not fry at high temperatures.
• Don't pour oil into the pan - grease it.
• Do not fry for a long time - wait for the crust, and remove from the heat - finish cooking in the oven (cutlets, cheesecakes), after removing any remaining oil from the food.
• Do not fry in the same oil twice - change and wash the pan, add a new portion of oil.
• Remove any remaining oil from cheesecakes, pancakes, cutlets and vegetables with a paper napkin before eating.
• Don't fry in oil every day - make frying part of the "holiday".
• Make cooking without cooking oil the basis of your daily menu.

Recipes for delicious dishes prepared with the addition of oil to the finished dish are in our section.

24/11/2017 05:44

Vegetable oils are an integral part of the human diet. They contain fatty acids that help break down solid fats of animal origin. The phenomenon of the balance of cholesterol and polyunsaturated fatty acids in our body lies in the usefulness of consuming vegetable oils. However, a positive effect on the body is possible only with the correct use of this product. Of course, it is best to eat raw oils. But having learned how to properly use vegetable fats in cooking, subjecting them to heat treatment, you can safely use them without harm to the body.

Choosing the right oil for frying – which one is less harmful to fry with?

Harm from frying in oil appears at the moment when overheating occurs and free radicals begin to be released. They get into food, poisoning the body, and excess free radicals cause cancer.

To learn how to fry without harm to your health, it is worth remembering that free radicals appear at the smoke point of the oil. Therefore, you need to fry food over moderate heat, reducing the heat treatment time, changing the oil more often and not using an unwashed frying pan several times.

It is also important to know that refined oil has already been processed and cannot be used for cooking at high temperatures.

For frying, it is advisable to use unrefined oils, which have a higher smoke point.

Table 1 shows the smoke point of various types of oils.

Table 1. Smoke point of oils

The table shows that the most suitable for frying are: coconut, mustard, rice, sesame, olive, avocado and grape seed oil. For quick frying, you can use peanut oil.

Corn and rapeseed oil are not used in technological processes with high temperatures, as many toxins are formed, despite the high smoke point.

The following oils are absolutely not suitable for frying: flaxseed, walnut. Unrefined sunflower oil has a low smoke point, and frying it with refined oil will not benefit the body.

A healthy combination of oils and vegetables: what to dress the salad with?

Oils, sauces and dressings based on them give salads a special piquancy and aroma:

• Flaxseed oil complements sauerkraut perfectly. It can also be used in other vegetable mixes where a pleasant bitterness is appropriate.
• Salads made from fresh and boiled vegetables are seasoned with olive oil. Dressings and mayonnaise are prepared on its basis.
• Cedar oil gives a unique aroma.
• Sea buckthorn oil will add an unusual taste and a spicy note.
• Salads made from boiled vegetables and meat will acquire a new taste if you season them with pumpkin oil.
• In Chinese, Indian and Indian cuisines, these dishes are drizzled with sesame oil.
• Traditional vinaigrette is seasoned with sunflower or corn oil. You need to use unrefined, cold-pressed oil.
• Salads made from carrots, kohlrabi, radishes, turnips, and daikon go well with peanut butter.
• Dressings are also prepared using coconut and rice oil to complement vegetable mixes.

Do not use refined oils for refueling. It is also worth remembering that the shelf life of an opened bottle is limited. Oil will be beneficial if stored in accordance with the conditions indicated on the packaging. Failure to comply with the conditions may cause harm to health.

Which oil is healthier to season porridge or side dish?

Healthy cereals and side dishes seasoned with vegetable oil will taste better and be better digested. Some oils do not lose their properties when heated, so they can be used during the cooking process. Those that lose their properties are best added to the finished dish - on a plate before eating.

Flavored porridges and side dishes:

• Sesame oil is used to fry meat into pilaf. It gives spaghetti a special taste.
• Flaxseed is added to a plate with buckwheat, rice and stewed vegetables. A mixture of flaxseed, sunflower, peanut and olive oil can serve as a tasty and healthy addition to side dishes. They can also be used separately.
• The piquant notes of cedar oil are combined with wheat, millet, spelled, pearl barley porridge and vegetable dishes.

Baking with vegetable oil

The technology for preparing dough often involves adding a large amount of butter. Adherents of a healthy diet, refusing animal fats, adapted the recipe, completely or partially replacing butter with vegetable oil.

Vegetable oil for baking – which one to add:

• Without compromising the taste and texture of the text, half the amount of butter can be replaced with sea buckthorn.
• Grapeseed oil can be added to muffin batter as it handles heat well and infuses baked goods with a grape aroma.
• Non-sweet baked goods will be perfectly complemented by the aroma of cedar oil.
• Pumpkin oil is added to the dough for baked pies with sweet filling.

Canned food in vegetable oil is beneficial

Vegetable oil for preservation - which one to add:

• Traditionally, sunflower, olive, and corn oil are used for canning vegetable preparations. An important condition is a long shelf life and the absence of a strong odor, which can spoil the taste of the product during storage.
• Grape seed oil is added to the preparations in small quantities, but on condition that the preparations are eaten within 6 months - this is the shelf life of this oil. The same storage conditions for canned food containing sesame oil.
• Beech nut oil is well suited for long-term preservation of vegetable preparations. Its taste is reminiscent of olive oil.
• But it is best to use mustard oil for canning. It has properties that contribute to better preservation of canned products: it does not oxidize, does not go rancid, and is a natural antiseptic. Its shelf life is 2 years. That's more than anyone else.

Flaxseed, cedar, sea buckthorn and pumpkin oils cannot be used for canning. This is due to the short shelf life and rapid oxidation.

How to fry without oil: 9 proven recipes

Oil-free frying technology

Sometimes it can be difficult to give up fried foods. Sometimes this is required by a diet that must be followed according to the recommendations of a doctor or to reduce the calorie content of foods in order to lose weight.

The harm of fried foods does not lie in the heat treatment of the product, but in the use of frying oil, which overheats and harms the body or increases the calorie content of the dish. It turns out that you can fry without using oil! Such products have virtually no contraindications.

To expand the range of dishes, it is better to stock up on special utensils:

• You can fry without oil in a Teflon frying pan. You just need to buy dishes from well-known manufacturers. The pan should be fairly heavy, with a layer of Teflon evenly applied.
• Products made from bioceramics are suitable for cooking vegetables.
• A cast iron grill pan will become indispensable - you can fry both vegetables and meat on it without oil.
• Thick-walled cookware with a double bottom made of stainless steel is useful for preparing various healthy dishes.

Recipe No. 1. Scrambled eggs in a frying pan without oil

A Teflon frying pan or a bioceramic vessel will do. Pour 2-3 tablespoons of water into the bottom and wait until it boils. At this point, pour in the eggs, salt and pepper as desired. Wait until the protein curls and the water evaporates. Carefully remove the scrambled eggs from the pan. Eggs prepared in this way are very tender, and the product is easily absorbed by the body.

Recipe No. 2. Mushrooms with onions, fried without oil

Heat a Teflon frying pan, pour the onion into it, after cutting it into cubes or half rings. Add 2 tablespoons of water and fry until translucent. You can add 1 tablespoon of water as needed during the frying process. When the water has evaporated and the onion is ready, you need to add the mushrooms, cut into thin slices. There is no need to add water to the mushrooms - they will release enough liquid on their own. As a rule, when it evaporates, the dish is ready. This fry can be used as an independent dish, as a seasoning for soup, or added to mashed potatoes.

Recipe No. 3. Beef on an onion bed without water and oil

A deep stainless steel saucepan is suitable for this dish. The onion should be cut thinly, into rings or half rings. Beef meat should be chosen from a young animal. Prepare the slicing - thin slices 5-7 cm long, pointing the knife across the grain. Place onions in the bottom of a cold saucepan, and lay slices of meat on top, sprinkling them with salt, pepper, and spices to taste. Pour lemon juice over the meat (3 tablespoons are enough for 1 kg of beef). Turn on low heat, cover the saucepan with a lid, do not open it until cooked. Frying 1 kg of beef will take approximately 1 hour and 15 minutes - you should watch how the juice evaporates from the cooked dish so that it does not burn.

Recipe No. 4. Pan-fried fish without a drop of oil

The fish, peeled and cut into 2 cm thick slices, is placed in a thick-walled frying pan with foil on the bottom. It is important that the fish is on the glossy side of the foil, otherwise nothing will work. The golden crust and aroma of the dish in no way distinguishes it from fish fried in oil. In addition, there is no need to roll it in flour, which reduces the harmfulness and calorie content of the product.

Recipe No. 5. Pancakes, pancakes, pancakes

In a good quality Teflon frying pan, without chips or scratches, the dough is fried without problems. Compliance with the temperature regime affects the quality of the product. Medium heat set on the burner will allow the dough not to burn and to be sufficiently fried inside. Adding oil to the dough during kneading will add calories to the dish, but it will be fried differently - carcinogens will not be formed, and the product will taste like something fried in oil.

Recipe No. 6. Steak in a clean pan

Even steak can be fried without using oil. For this you will need a Teflon frying pan. It should be heated to maximum temperature. The bottom of the vessel is sprinkled with coarse salt, the meat is laid out and fried for 2 to 7 minutes on each side, depending on the preferred degree of frying. It is not recommended to touch the meat at this time. In 2 minutes you can get a rare steak, the degree of roasting is Rare, in 3 minutes – Medium rare, 4 minutes – Medium, 5 minutes – Medium well, 6-7 minutes – Well done.

Recipe No. 7. Frying various types of meat

There are several ways to fry meat in a frying pan without using oil. Small pieces of boneless meat can be cooked by adding 1-2 tablespoons of water to the pan. In this case, it is better to use a Teflon frying pan.

Chicken breast slices can be fried in modern stainless steel cookware. You need to place the meat in a very hot frying pan or saucepan, immediately cover with a lid and do not touch until the color of the meat becomes dull - then you need to turn it over and bring it to readiness.

Any meat can be cooked on the stove in a thick-walled vessel, preferably cast iron, wrapped in foil. Cooking time is determined based on the weight of the product.

Pork and veal can be fried in a frying pan without oil, after soaking the meat in a mustard or onion marinade. You need to cook it in a Teflon-coated frying pan. The marinade will prevent the meat from burning, it will not stick to the pan, and it will cook well.

Recipe No. 8. Grill pan - a godsend for frying without oil

A high-quality thick-walled grill pan is designed for frying without oil. It is suitable for heat treatment of any products: vegetables, fish, meat. It can be used to heat prepared foods without using oil. To give the products a special taste, they are pre-marinated in various sauces. It can be a mixture of soy sauce, honey and spices, onion-wine sauce or honey-mustard.

Recipe No. 9. What to do with cutlets

Fish and meat cutlets can be fried without harm to health. You can fry cutlets without oil in a branded Teflon frying pan. When heated, meat cutlets will release their own fat, in which they will be fried. Fish cutlets can be fried by adding water to the pan.

If you don’t have a Teflon-coated frying pan in your house, any thick-walled frying pan will help. You should put foil on its bottom. In this case, there is no need to pour water or oil. The foil will not stick to the pan and the product will fry well if the cutlets are placed on the glossy side. This is due to the fact that a glossy surface gives off heat, while a matte surface absorbs it.

Vegetable cutlets also need to be fried on foil to avoid deformation.

Finally

You should not buy a large supply of oils for home cooking. A good quality product usually has a short shelf life. In this case, the bottle must be protected from sunlight. People usually forget about it and it expires, so it’s better to buy small bottles.

When opened, some oils are stored for no more than 1-2 months, and then undergo oxidation. Consuming such a product can cause great harm. Therefore, you need to buy the next type of oil that you want to use for food after the previous one runs out. (No ratings yet)

Illustration copyright Thinkstosk

Choosing oil for cooking is a tricky business, writes Michael Moseley.

When it comes to fats and oils, we are spoiled for choice. Supermarket shelves are filled with all sorts of options. But lately, the choice has become confusing due to the huge number of discussions about the benefits and harms of consuming different types of fats.

In the Trust Me, I'm a Doctor program, we decided to look from the other side by asking the question: “Which fats and oils are best to cook with?”

To find out, we offered the people of Leicester different types of fats and oils and asked our volunteers to use them in their daily cooking. We also asked volunteers to save the remaining oils in order to analyze them later.

Participants in the experiment used sunflower oil, vegetable oil, corn oil, cold-pressed rapeseed oil, olive oil (refined and extra virgin), butter and goose fat.

Post-use samples of oils and fats were collected and sent to the School of Pharmacy at De Montfort University in Leicester. There, Professor Martin Grootveld and his colleagues conducted a parallel experiment in which they heated these same oils and fats to frying temperatures.

When you fry or bake at high temperatures (around 180 degrees Celsius), the molecular structures of the fats and oils you use change. They undergo oxidation - react with oxygen in the air and form aldehydes and lipid peroxides. At room temperature, something similar happens, only slower. When lipids go rancid, they are the ones who oxidize.

Consumption or inhalation of aldehydes, even in small quantities, has been linked to an increased risk of heart disease and cancer. So what did Professor Grootveld's team find out?

“We found,” he says, “that oils rich in polyunsaturated fats—corn oil and sunflower oil—produced very high levels of aldehydes.”

I was very surprised, because I always thought sunflower oil was healthy.

"Sunflower and corn oils can be used," says Professor Grootveld, "as long as you don't heat them, like frying or boiling them. It's a simple chemical fact that something that's supposed to be good for us is converted into something that is not at all healthy at standard frying temperatures."

Olive oil and cold-pressed rapeseed oil produced much less aldehydes, as did butter and goose fat. The reason is that these oils are rich in monounsaturated and saturated fatty acids, and these remain more stable when heated. In fact, saturated fatty acids undergo almost no oxidative reaction at all.

Professor Grootveld mainly recommends using olive oil for frying and other heat treatments: “Firstly, because fewer of these toxic molecules are produced, and secondly, the molecules produced are actually less harmful to the human body.”

His research also suggests that when it comes to cooking, frying in fatty acid-rich animal fats or butter may be preferable to sunflower or corn oil.

“If I had a choice,” he says, “between lard and polyunsaturated fats, I would use lard all the time.”

Our study came with another surprise, as Professor Grootveld's team discovered a couple of new aldehydes in several samples sent by our volunteers that had not previously been observed in oil heating experiments.

“We have discovered something new for science,” he says with a smile on his face. “This is a first in the world, I am very, very, happy about it.”

I'm not sure our volunteers would be as enthusiastic about the fact that their cooking produced new, potentially poisonous molecules.

So what is Professor Grootveld's general advice?

First of all, try to fry less, especially at high temperatures. When frying, minimize the amount of oil used, and also try to remove any remaining oil from fried food, using a paper towel.

To reduce aldehyde production, use oils or fats rich in monounsaturated or saturated lipids (preferably more than 60% of one or the other and more than 80% combined) and low in polyunsaturated fats (less than 20%).

Professor Grootveld believes that the ideal "compromise" oil for cooking is olive oil, "as it contains about 76% monounsaturated fat, 14% saturated and only 10% polyunsaturated - monounsaturated and saturated fats are more resistant to oxidation than polyunsaturated fats."

When it comes to cooking, it doesn't really matter whether the olive oil is extra virgin. "The levels of antioxidants found in virgin produce are not sufficient to protect us from heat-induced oxidation," he says.

His final piece of advice is to always store vegetable oils in a cupboard, away from light, and try to avoid reusing them, as this also leads to a build-up of harmful by-products.

What you need to know about fats

• Polyunsaturated fats Contain two or more carbon-carbon double bonds. They provide health benefits when consumed in foods such as nuts, seeds, fish and leafy greens. However, the benefits of consuming sunflower or corn oils, although rich in polyunsaturated fats, are much less clear.
• Monounsaturated fats They contain only one carbon-carbon double bond. They are found in avocados, olives, olive oil, almonds and hazelnuts, as well as lard and goose fat. Olive oil, which contains 76% monounsaturated fat, is a key component of the Mediterranean diet, which has been shown in studies to significantly reduce the risk of heart disease.
• Saturated fats They do not contain double bonds between carbon molecules. Although we are encouraged to avoid consuming saturated fat, especially dairy products and other animal fats, the benefits are still disputed.