De ce nu e bine să consumăm frecvent alimente prăjite?

I’ve never known a French fry I don’t like.
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Fortunately (I think ), I study gastrotechnics (the science that investigates the transformations that take place in cooked foods and their effect on the body), and not gastronomy - even though it would be nice to talk now about how to prepare a good steak, right? Healthy eating does not take into account food preferences or taste buds, and without a minimum of nutrition knowledge, we do not understand WHY it is good to eat some foods and avoid others as much as possible.

Today we continue with a discussion about fried foods, as various studies have shown that the way food is prepared can be a harmful factor for our health. Let's dive in!

Changes happening in fried foods and oils smoke point

Frying is the process by which food is cooked in some kind of fat (oil, pork fat, butter etc.). Although they have an insane taste, by frying, food changes its structure and chemical composition, vitamins degrade and lead to the appearance of toxic elements, which encourages the limited use of this method in the diet. The longer the cooking time and the more reused the oil, the more harmful it is to health.

The smoke point of oils is when they start to burn and differ depending on their chemical composition. When the molecule is broken down or degraded, it releases toxic compounds into food. Therefore, some of the oils are good raw, for salads, while others can be used at higher temperatures.

The oils are divided into refined and unrefined (see the "wonderful" chart below). Unrefined oil is left in its natural state after pressing and is known as cold pressed, raw or virgin oil, also extra virgin (first press). It retains taste, vitamins, minerals and enzymes, but they also have a lower smoke point. Therefore, they are best used raw. Meanwhile, the refined oil is processed by heating, to remove certain compounds (including the beneficial elements) and increase the shelf life, thus increasing the smoke point.

It's ok… then I bake!

But is it better? Don't be fooled by the fact that you no longer hear the sizzling of hot oil or fat in the pan. Temperature and cooking time can be exceeded even in the oven , ending up with the same result. Moreover, even without oil, the meat also has a certain amount of fat, so pay attention to what temperature you cook it and for how long!

It should be noted that, in addition to the smoke point, we also take into account the omega 3: omega 6 ratio of an oil. Although some refined oils have a higher smoke point, they may contain more omega 6 fatty acids, known as inflammatory factors in the body (eg sunflower oil, sesame oil) than omega 3, strong anti-inflammatory factors, or omega 9 (like virgin olive oil). So, the best choice would be the virgin olive oil, cooked slowly, at temperatures below 160 degrees Celsius, up to an hour.

What are the consequences of eating fried foods?

By frying, food changes its nutritional value, forming harmful compounds. Two of the most important are acrolein and acrylamide, carcinogenic chemicals with harmful effects on genetic material (DNA and RNA), as discovered by researchers at the Swedish National Food Institute in 2002 and as specified by the FDA (US Food and Drug Administration ). Acrolein is a product obtained when we heat fats (either pork fat or sunflower oil, roasted hazelnuts, bread with seeds, etc.). Acrylamide is made up of carbohydrates cooked at a high temperature (craving for french fries? or coffee?), so it is commonly found in plant based foods (especially starches) cooked over high heat (e.g. roasting and baking), but not in whole foods which are steamed or boiled.

These elements are formed in the crust of french fries - so also in chips and other snacks, in the well-baked crust of pastries, in roasted coffee beans, in bread-type foods and… fast food. I think it's time to stop here … More examples in the table below, taken from here .

Comparing fried to baked potatoes, frying causes the highest acrylamide formation. Boiling potatoes and microwave baking whole potatoes in their skin does not produce acrylamide [based on FDA studies]. Soaking raw potato slices in water for 15-30 minutes before frying helps reduce acrylamide formation during cooking (soaked potatoes should be drained and dried before cooking to prevent sprinkling).

It should be noted that the smoke produced by frying affects the lungs through its inspiration. Acrolein is dangerous both ingested and inhaled, being a highly inflammatory chemical compound in the lungs. Reached into the bloodstream through the digestive tract or lungs, it acts as a strong free radical, cytotoxic (aging cells) and neurotoxic (affecting the nervous system) . The effects come slowly, so the consequences can appear in years, when diseases such as colon, lung cancer or Alzheimer's hit hard.

Recommendations

Steam cooking for vegetables, or boiling . I recommend buying a steamer, or slow cooker. Vegetables can be seasoned with different spices for taste.
Cooking oil-free in the oven at temperatures below 200 degrees Celsius . More recently, so-called 'air fryers' have appeared on the market. They fry food without oil and reduce the formation of acrylamide by up to 90%, but certain toxic compounds continue to form at those high temperatures, as this study shows;
Saute vegetables in some water , not oil. I started not using oil almost at all in cooking after I discovered this method;
If, however, food is fried, I do not recommend the use of oils with a high degree of unsaturation. Olive oil seems to be indicated, however, due to the high content of antioxidants, it degrades after about an hour of cooking at a temperature of 160 degrees Celsius;
If you fancy French fries, soak the potatoes in water for 30 minutes, drain and dry them. This will form less acrylamide during frying or baking. Also, choose to fry them until they are yellow, not brown. Likewise in the case of toast, overly baked, dark parts should be avoided!
The cooker hood is not only useful for removing unpleasant odors, but also for toxic substances in the air that invade our lungs. I say... let's use it!

So, my dear, I advise you to eat as few fried or hight temperature baked foods as possible, because regardless of the type of fat or food used, those carcinogenic compounds still risk to form, in a smaller or bigger number.