One of the main global trends of the XXI century is urbanization, and with the growth of the number of cities, the lifestyle of the population is changing, new habits are being formed [1]. Food delivery services, cafes and restaurants are in high demand to meet the food needs. There are more than 100 thousand cafes, bars, restaurants and bakeries in Russia [2].
The market of food delivery in Russia is developing at a record pace. The sales volume of the ready-made food delivery segment in Russia at the end of 2018 amounted to 35.8 billion rubles. In total, according to experts, the volume of the market for food ordering services of various degrees of readiness in Russia has grown by 35% over the past five years and amounted to 1.4 billion dollars [3].
Taking into account the trends in the development of the catering industry and the forecast of the category's growth for the nearest future, special attention should be paid to quality control of food products and raw materials from which they are prepared [4; 5]. One of the most popular methods of heat treatment of products, which is actively used in cooking in public catering, is deep-frying [6]. Quality control of frying oils at public catering enterprises is carried out by measuring the thermal oxidation index [7], however, such control can only be carried out by large enterprises with laboratories.
The purpose of the research was to determine the dependence of the thermal oxidation index of vegetable oil on the frying temperature and the type of vegetable oil. The product for frying was selected — French fries, which is one of the most products for frying.
The following methodology was used in the research. To approximate the conditions for the preparation of products at public catering establishments, experimental deep-fat frying was carried out in a stream according to the following methodology. The potatoes are pre-prepared for frying. To do this, they are cut into strips and kept for 10-15 minutes in cold running water to remove excess starch. After that, moisture is removed from the surface of the potatoes with a paper towel for subsequent immersion in vegetable oil heated to 175±5 °C. Deep-frying was carried out for 10 hours. To achieve flowability, frying was carried out in a home fryer in portions of 50±1 g The frying time of one portion is 5 minutes. Each new portion was laid for frying 5 minutes after taking out the previous portion. Thus, the preparation was carried out according to the formula: 5 minutes of cooking and 5 minutes of rest.