Why should people who want to lose weight avoid fried dishes?
During the frying process, the fat on which we fry is absorbed by the fried product and then consumed with it. Of course, the amount of fat absorbed depends on the type of frying and the product. (The most fat is absorbed by deep fried products – fries, donuts, faworki, and all breaded dishes – especially fish.) Frying usually leads to an increase in the fat content, lowering the water content in the product, and thus to a significant increase in the energy value of the meal.
Let’s see how this is presented in practice
If one of our dietary assumptions is, for example, limiting energy of fat origin to 20%, then we should definitely exclude the process of frying from our culinary repertoire. Why? For example, fries so popular in any bar or restaurant, contain about 15% fat, up to 555 water, and up to 30% carbohydrates and proteins together. Let us now calculate the percentage of energy derived from fat for 100.g of French fries. (I remind you that the energy value of fats is – 9kcal, while proteins and carbohydrates – 4 kcal.)
Calories of fat 15g x 9kcal
————————– x 100% = 53% of energy from fat. Calorific value of the whole product (15g x 9kcal) + (30g x 4kcal)
Let’s see what it looks like in the case of a soute fried chicken fillet (in the case of breading, the amount of absorbed fat would be twice as large as that which I give for absorbed in the absence of breading)
Chicken breast fillet contains 23% protein, 2% fat, the rest is water. Let’s count now the amount of energy from fat, assuming that 100g of our fried fillet on both sides can absorb 7g of fat (it is 1 teaspoon of tea).
Calorie fat 9g x 9kcal
———————— x 100% = 47% of energy from fat.
Caloricity of the whole dish (9g x 9 kcal) + (23g x 4kcal)
Let’s now calculate the amount of energy also coming from fat for the same fillet of chicken breast, but this time baked on the grill.
Calorie content of fat 2g x 9kcal
———————— x 100% = 16.5% of energy from fat.
Caloricity of the whole dish (2g x 9kcal) + (23g x 4kcal)
The above examples show us why all products fried in fat, even those seemingly lean (like fish, poultry) are definitely not suitable for a diet in which the amount of fat energy is to be relatively small. I think it is clear why all people who want to lose weight on a low-fat diet should exclude all foods that have a frying process.
For consolation, I can add that the case does not look so tragic, if, for example, even such unfavorable nutrition fries we give with a fillet of grilled and salad. (After all, apart from the fries, the remaining products kill us the amount of energy from fat to a decent level. (However, despite this, it will be hard for us to go below 30% of energy of fat origin).
Why is a large part of fried dishes unhealthy and what does it depend on?
If so much energy in the case of fried dishes can come from fat, we pay close attention to the quality of fat used for this purpose. (I know that in a few aspects I will now repeat the information contained in previous articles, but in this way I will consolidate a lot of readers’ knowledge).
During frying, fat fats the process of hydrolysis, i.e. the evaporation of hot water and the formation of so-called free fatty acids, which in turn leads to a significant reduction in the temperature of frying fat (This is best seen when frying in butter). The above phenomenon is possible because fatty acids have smaller molecules than glycerols and distil together with water vapor during frying. Smoke then arises, and even at higher temperatures, ignition can occur. It must be admitted, however, that partially hydrolyzed fats are easier to digest than those in which this process did not begin.
During frying, oxidation (oxidation) may also occur. This is the case when long-term frying of vegetable fats with double unsaturated bonds is used. (Soy, sunflower, corn oils). Then oxygen from the air joins the double bond between carbon atoms, causing the formation of hydroperoxides.
The more double bonds, the faster the oxidation process. (Or rancidity – “aging of stored oils, because rancidity also involves oxidation, except that this process is incomparably slower than in the case of frying.) Remarkable for the stability of healthy oils is the fact that each subsequent double bond increases susceptibility for oxidation up to 10 times. The above phenomenon explains why eg soybean oil or cold pressed flaxseed oil is spoiled (rancid) 100 times faster than lard stored under the same conditions.
Returning to hydroperoxides, it must be said that these compounds are extremely unstable, the consequence of their decomposition, rancidity is the case of volatiles (aldehydes, ketones) giving the characteristic odor of rancid fat.
However, in the case of consumption of hydroperoxides (in the case of frying), which destroys in our digestive system, is the formation of oxidative polymers that irritate the gastrointestinal mucosa causing indigestion, and in further consequence have carcinogenic properties (Mutagenic for cells).
If it comes to secretion of hydroperoxides during frying in our kitchen, we notice it after the frying on the eaves, characteristic smells burning oily fumes.
As you can see, changes during long-term frying on vegetable fats have a negative impact on the nutritional value (destruction of essential fatty acids, fat-soluble vitamins, indigestion in the digestive system) as well as the sensory quality (taste) of the prepared products?
The above facts determine that in the mass catering industry, healthy vegetable fats are not used, and usually lard, palm oil or sometimes refined oils (lacking EFA and vitamins), allows for long-term use of fat without its replacement.
If someone does not want to get rid of the taste of fried products, and at the same time to consume healthy vegetable fat, then for frying you should recommend oils with high nutritional values sunflower oil, corn oil and olive oil.
In the conditions of short frying and pouring of oil after each cycle, oxidative changes are just beginning, and the nutritional value of such fat is still quite high.
Certainly do not fry on cold pressed oils, which on their labels have the phrase “intended for consumption raw in a salad dressing, because such oils even under short-term frying, very quickly will undergo adverse changes.
A curiosity is the fact that when frying fresh fats, the best quality of the product is not obtained. In fresh fat, the product fry for a long time and before it undergoes a characteristic browning, it becomes excessively dried (without water). The compounds needed to make the product faint, unfortunately, are produced as peroxide breakdown products, along with the duration of the frying process. Therefore, after long-term frying, a product may become brown, obtaining a tasty crunchy crust, and the inside is not yet properly fried.
There is, therefore, an optimal temperature and time to achieve it, at which the fat before a single frying should be well warmed before inserting the product intended for frying.
When making a short summary, we can conclude (apart from the fact that every person seriously thinking about slimming should definitely exclude products fried from their diet) that all vegetable oils have a high nutritional value, which worsens with the duration of the frying process. Therefore, you should fry on them briefly and only once, and then they will remain a good source of essential fatty acids and fat-soluble vitamins. Lard, palm oil, or hydrogenated frying margarines recommended for gastronomy are very slow to change, allowing for less frequent oil changes convenient for entrepreneurs. While respecting the time of oil change, the products fried on them are durable and safe for health, but they will never have the nutritional characteristics of short-fried products on healthy vegetable oils. So there is nothing like eating at home.
You can read also: What oil is the healthiest for frying?