Vegetable oil is, of course, a healthy, tasty and simple product, but sometimes the abundance of different-colored bottles with various oils can confuse a novice cook. To freely navigate the sea of "raw" and "refined", nut and fruit, smoky and smokeless oils, it is worth familiarizing yourself with the different types of their classification, which will help you make the right choice.
Vegetable oils are usually classified in different ways, depending on which characteristic is taken as the "starting point". One of the simplest divisions is based on the raw materials from which the oil is obtained. It comes in two types: seeds and the flesh / heart of the fruit of the plant. So, according to this classification, the two most popular types of vegetable oil in Russia belong to different groups: sunflower oil is produced from sunflower seeds, olive oil - from olive fruits. Flaxseed, soybean, corn, rapeseed, sesame oil, oils from melon seeds (watermelon, melon, pumpkin), fruit seeds (apricot, peach, argan) and many others are in the same row with sunflower oil. Olive oil is adjacent to all nut oils, avocado oil, palm oil. This classification is, of course, simple and straightforward, but not very informative. The resulting subgroups have neither the same properties nor common application characteristics.
It is much more practical to subdivide vegetable oils according to the method of production and refining. The oldest method of extracting oil from plants is pressing or squeezing. It is known that all supporters of a healthy diet strive to purchase a first, cold-pressed product. Why is he so good? The cleaned and crushed raw materials are placed under a press, a valuable product is squeezed out of it, similar in properties to freshly squeezed juice - it retains all the useful substances originally inherent in seeds or fruits, besides, the aroma does not disappear anywhere. This oil turns out to be expensive, not because, well, or not only because the producers are greedy, but because from a kilogram of, for example, magnificent olives, about 250 ml of oil will turn out, or, an even more illustrative example, from 6 kilograms of pumpkin seeds the producer will receive no more than 1 liter of oil.
If there is a "first spin", then should there be a second? It exists, but it is no longer cold. From the processed product, without special tweaks, it will not be possible to extract "another drop" of oil. But if you warm up the squeeze a little, sometimes adding a little water, and send them under the press again, and even with a higher pressure (which, by the way, together with the frictional force, raises the temperature of the one that comes into contact with the raw material of the press), then from a kilogram olive oil cake will produce about 400 ml more oil or, in the example with pumpkin seeds, 2 liters of product. Well, is it bad? But not so good. When heated, some of the nutrients evaporate, the taste, color and aroma of the oil change. How much "poorer" the product has become depends on the original raw material, but, in any case, it is no longer "liquid gold".
At the same time, there are fruits and seeds in which the oil content is initially extremely limited and you cannot squeeze it out with any press. This is where extraction or extraction comes to the rescue. This process can in no way cause delight among adherents of natural products, because it is based on "continuous chemistry". The crushed raw materials are mixed with solvents, the resulting oil solution is processed again, separating only one oil. In the process, the aroma, taste "suffer" and, of course, the content of nutrients decreases. By the way, some zealous producers also extract the cake left after numerous pressing of high-oil crops. There is no need to even talk about vitamins and minerals, their quantity is vanishingly small. Extraction is also used for processing substandard raw materials. Since from it, by squeezing, you still won't get a high-quality product, isn't it better to immediately process it with "chemistry" and get more than 90%, albeit not so useful, but oil?
Pressing or extraction is often not the last stage in the production of vegetable oil. Then it is subjected to various cleaning. Even the first pressing oil often needs the simplest filtration, with the help of which the smallest pieces of oil cake are removed from it. Such oil still remains, as the culinary experts say, the extracted oil, the production process of which was completed by separation, will also be raw, raw will be. The oils that have undergone minimal purification are still much more useful than their "fellows in the group", but they have to pay for the insignificance of the intervention with a short shelf life.
Unrefined oil is not crude. Such an inscription on a product does not at all mean that it is unprocessed. Rather, she reports that the product has not gone through a very long pre-sales chain. It was filtered, hydrated, removing useful phospholipids, which tend to precipitate, and neutralized by removing free fatty acids. Unrefined oil is stored much longer than raw oil, but in exchange it gives up some of the beneficial properties.
Refined oil undergoes all previous procedures, as well as refining or bleaching or discoloration, in which most of the pigments are removed, and with them proteins and phospholipids, freezing, after which waxes and waxy substances disappear from the product, often cloudy oil, deodorization, depriving the oil of odor, by removing aromatic substances and distillation neutralization. It deprives the oil of the "last" - most of the fatty acids and odor residues. And on this product, devoid of almost all the benefits, taste, color and smell, there is often a proud inscription from the manufacturer - "7 degrees of purification".
Many culinary specialists are often concerned about the usefulness of the product almost in the least, because they are accustomed to the fact that most delicacies can hardly be called healthy food. It would seem that for them the decisive argument in favor of any oil is taste and aroma, but an experienced chef knows that sometimes they also have to be sacrificed. It happens that precious cold-pressed olive oil will only spoil itself and spoil the dish where simple, refined sunflower oil is ideal. This is exactly what happens when frying.
Here, the most important selection factor is temperature or smoke point. Any oil, when heated, not only loses useful substances, but also forms toxic ones. The temperature at which this "transformation" begins is called the smoke point. It got this name due to the fact that a visible warning signal of the beginning of changes becomes gray smoke, formed from volatile compounds rapidly evaporating from the oil. Why, then, deep-frying virtuosos, Asians, are often advised to heat the oil to a "haze" and only then lay the food?
The fact is that the fastest roasting can only occur at high temperatures. By dipping small pieces of food into boiling oil, we seal the nutrients and delicious juices in them. White smoke indicates that vegetable fat is heated to the maximum possible temperature, without harm to health, while, as soon as food is immersed in it, it immediately drops, "goes" to heat them. By the way, this is why all oriental chefs persistently warn against putting cold food in deep-fried food. It will lower the temperature of the oil so much that the crust will not set, healthy and tasty substances will slip away, and the cooking time will increase.
The healthiest, crude oils tend to have a low smoke point, but there are two lucky exceptions - mustard oil and rice bran oil. The disadvantage of these oils is that not everyone likes their taste and smell. Refined refined oils have a higher smoke point than their unrefined counterpart, because they contain a minimum of combustible impurities. Unrefined oils such as sunflower, safflower, linseed, walnut, peanut, sesame, soy and coconut oils, as well as high-quality olive oils, do not tolerate heat well, have a low smoke point. But they have a pronounced taste and aroma, they are able to "share" them with other products, ennobling the dish. They are used to prepare salad dressings, they are irrigated with ready meals, bringing new, elegant notes.
Oils in the middle of the smoke point list are universal oils. They work well for baking, giving them a crumbly texture and withstanding the necessary heat. They can be fried on if the recipe does not require the highest possible temperatures. They can be supplemented with various ingredients, as the fat enhances the extraction of the flavor and aroma of other foods. These oils include extra virgin olive oil, grape seed oil, and almond oil.
Raw or refined, any vegetable oil, in one way or another, is sensitive to heat, light and oxygen. Treated oils will last longer under adverse conditions, but their shelf life will be reduced.
The ideal container for oil are bottles made of dark, practically opaque glass, with a glass stopper, or tin cans with screw caps. They should be kept cool, not refrigerated. Only small amounts of oil can be stored directly next to the stove, which you use up faster than they start to deteriorate.
Another classification of oils is made by the presence of various beneficial fatty acids in them. So, praised by nutritionists, oleic acid, which helps keep the cardiovascular system healthy, has a positive effect on the skin and hair, and prevents excess weight, contains not only popular olive oil, but also avocado, peanut, safflower, pistachio oil.
Sesame, sunflower, hemp oil, wheat germ and grape seed oil are rich in indispensable, vital linoleic acid.
Until recently, erucic and eicosenic acids were considered almost dangerous, but, according to recent studies, it turned out that they may help to avoid various types of cancer. These acids are found in mustard and rapeseed oil.
Unrefined oils are high in various vitamins, minerals and other beneficial substances. They boost immunity, fight fungi, have antioxidant properties, and reduce the risks of cardiovascular disease and diabetes.
