The high temperatures of the oil produce a crunchy texture and a characteristic taste.

Frying is one of the oldest cooking techniques. Fried foods are enjoying increasing popularity; They are consumed by people of all ages. This is due to its distinctive flavor and aroma, attractive appearance and crisp texture. In addition, its preparation is usually easy and fast. And its practically total microbiological safety.

The definition of frying already indicates the characteristic parameters of this type of cooking: totally or partially immersing food products in a fat bath at temperatures above 150ºC, where the lipid, by transmitting heat, produces rapid heating of the food.

The high temperatures that are reached when frying achieve a faster and more uniform penetration of the heat towards the interior of the product that is being cooked; at the same time, they favor the Maillard browning reaction and rapid dehydration, resulting in a crispy finish.

A key element in this type of cooking is the fat used. We distinguish between the oil and the frying mass. Both can have an animal or vegetable origin. However, at room temperature the oil is in a liquid state and the dough is in a solid state.
Olive oil is the most emblematic of the Mediterranean area. The so-called virgin is obtained only through mechanical procedures, cold pressing at temperatures below 35 oC. He
Olive oil corresponds to a mixture of virgin and refined oil obtained by extraction techniques, but without modifying the basic structure. And finally we also find refined sansa oil, which comes from the pressing paste (sansa or pomace).
Worldwide, the most used oils for frying are seed oils: soybean, peanut, sunflower, high oleic sunflower, cotton, wheat germ, rapeseed, grape seeds and mixtures of these. Frying masses can be classified into animal fats (pork fat) and vegetable fats (cocoa, coconut and palm butters). Anhydrous fats and margarines would also fall into this section.
If we fry with a pot or a pan, we will obtain external heating of the fat. In a fryer, however, the heating is internal.

The most common fried foods are usually without coverage (direct). In these, the food is immersed directly in the oil or frying dough; The best-known example corresponds to French fries. Another popular technique is flouring (with coating), where the product is covered in flour or starch before frying. Called in Spain “Andalusian frying”, it is what we find in fried sardines and anchovies. Another type of coverage is obtained by covering the food with a first layer of glue (egg) and a subsequent layer of breadcrumbs, and then frying it. We are referring to “breading”, which is usually applied to chicken fillets (schnitzel).

This category would also include batter, a coating with flour and then egg. An important example is battered squid (“Roman style” in some areas). Témpura, Orly and pastina, among others, also belong to the batter techniques.
When preparing a fried dish, the cook faces a real challenge. How to ensure that food acquires the appropriate texture and color, without absorbing too much oil and without losing its organoleptic and sanitary quality?

There are numerous scientific works on fried foods. In 2007, E. Barrado, from the University of Valladolid, and his collaborators published an investigation on the fat content of various foods in Clinical Nutrition and Hospital Dietetics. Among them, hamburgers and fries stood out, with 50 and 35 percent fat respectively.
Cooking at high temperatures can generate toxic compounds. To avoid the presence of acrylamide in French fries, food and health authorities recommend soaking and blanching them before frying, and preferably in an acidic medium. Based on the review of numerous works, the Center for Research and Development in Fats and Oils of the University of Chile has collected a series of standards and production and marketing parameters that allow reducing the acrylamide content in foods.
Regarding the frying device, it is recommended to use fryers with temperature control and electric resistance inside; In a pot the oil degrades more quickly and it is impossible to control the frying temperature. Food must be dried beforehand to avoid accidents caused by rapid evaporation of residual water. These must be perfectly submerged to uniform cooking. Do not let the oil smoke, as this is synonymous with degradation. Finally, after frying, it is advisable to filter the oil, since food remains make it easier for it to degrade. It would be desirable for future fryers to incorporate an oil quality detector. This way we could taste healthier fried foods.