THE POSSIBILITY OF USING ULTRA-HIGH-FREQUENCY ENERGY IN THE TECHNOLOGIES OF STERILIZATION OF PLANT RAW MATERIALS

ABSTRACT

This article discusses the possibilities of using ultra-high-frequency energy in the technologies of sterilization of plant raw materials and food production in order to find solutions to preserve quality during storage and processing of fresh plant raw materials and reduce losses associated with the growth of microorganisms.

АННОТАЦИЯ

В данной статье рассматриваются возможности применения СВЧ-энергии в технологиях стерилизации растительного сырья и производстве пищевых продуктов с целью поиска решений сохранения качества при хранении и переработке свежего растительного сырья и снижения потерь, связанных с ростом микроорганизмов.

Keywords: sterilization, canning, processing, nutritional value.

Ключевые слова: стерилизация, консервирование, обработка, пищевая ценность.

An important national economic task is the year-round provision of the country's population with high–quality fruit and vegetable products - an important national economic task. Every year the consumption of fruits and vegetables is growing, their range is expanding, the quality is improving. But the uniform supply of fruit and vegetable products according to the seasons of the year is possible only in conditions of a well-established system of its long-term storage in fresh form, as well as during canning.

There are many ways of preserving vegetables, fruits and berries – drying, pickling, quick freezing, ambassador, pickling and others. Nevertheless, the most reliable method of preserving food products is considered to be their preservation in hermetic containers by means of heat treatment or pasteurization. That's right, canned food is packaged and processed foods. During storage and processing, biochemical processes take place in the raw material, which, with the wrong technology, can lead to deterioration of the nutritional value of food and even their spoilage [6].

In view of this, it is so important to know the technological features of raw materials that respond to external influences during processing by changing their chemical and biochemical composition. Error-free alignment and organization of canning is possible only taking into account the technological features of raw materials, which largely depend on the variety and varietal farming techniques. Of the vegetables, fruits and berries grown fresh from year to year, 30-35 percent of the harvest is consumed, the rest is sent for processing and storage.

Such methods of storing fruits and vegetables as canning, pickling, pickling, boiling have long been used in the food and processing industry. Currently, the main industrial methods of processing vegetables, fruits and berries are canning, sterilization and pasteurization in hermetic containers and rapid freezing of prepared products at lower temperatures with subsequent storage in frozen form [4].

One of the most important differences of canning technology is the comparative ease and accessibility for both large highly mechanized and medium– and even small-capacity enterprises. Modern processing enterprises are provided with the necessary technological equipment and have combined processing lines. Manufactured or finished canned products in their composition and quality meet the standards that are established for the products of state-owned enterprises and factories.

Currently, the food industry pays special attention to physical methods of influencing raw materials, semi-finished products and finished products, which are able to intensify heat exchange processes, ensure microbiological safety, as well as improve and increase the nutritional value of raw materials [5]. Heating in an electromagnetic field is a physical method capable of achieving these goals.

Scientists have investigated the possibility of using ultra-high-frequency energy in the technologies of sterilization of plant raw materials and food production in order to find solutions to preserve the quality of plant raw materials during their storage and processing, as well as to reduce losses associated with the growth of microorganisms. The advantages of dielectric heating are considered. The features of the use of ultra-high-frequency heating and its effectiveness in the technology of sterilization, pasteurization and disinfection of plant raw materials are shown. In the food industry, a microwave field is used, which operates at frequencies of 915 MHz and 2.45 GHz. The process of microwave sterilization of short-term high-temperature treatment is used not only for the biosynthesis of pathogenic microorganisms, but also to minimize the decline in food quality throughout the shelf life. The use of microwave heating contributes to the loss of activity of enzymes that reduce the organoleptic qualities and nutritional value of fruits and vegetables. When processing products and raw materials with low humidity, microwave energy supply has the advantage of a shorter processing time. For many types of plant raw materials, prolonged exposure to microwave energy causes irreparable damage, changing the physicochemical quality indicators.

Ultrahigh frequency radiation is electromagnetic radiation that includes a centimeter and millimeter range of radio waves (from 30 cm - frequency of 1 GHz to 1 mm - 300GHz).

Ultrahigh-frequency heating makes it possible to speed up the technological processes of food production related to heating products, as well as to develop new types of them, especially combining Ultrahigh-frequency heating with traditional methods of energy supply, such as drying, sterilization, cooking, pasteurization, defrosting, sublimation, etc [1].

With ultra-high-frequency heating, it is possible to implement waste-free and energy-saving technologies in the food industry, significantly increase the output of finished products without large capital costs for the construction of enterprises, improve sanitary and hygienic working conditions [2].

For the design and operation of ultra-high-frequency heating installations, it is necessary to justify the parameters of the technological process, to know about the electrophysical properties of the products and the basics of calculating the process.

However, despite the advantages of ultra–high-frequency heating, one should not forget about the advantages of traditional methods; a reasonable combination of them is the most effective and constructive way [4].

In the process of heat treatment, food products undergo profound changes affecting their dielectric properties, which, in turn, affects the course of ultra-high-frequency heating.

Figure 1 shows a schematic diagram of an ultrahigh-frequency apparatus consisting of the following elements: a power source: an ultrahigh-frequency energy converter; a device for supplying ultrahigh-frequency energy; a communication device transmitting energy to the load (product); a device that creates a uniform distribution of energy during heating; the heating chamber itself with a transport device; a system of ultrahigh-frequency traps and sealing seals that prevent radiation into the environment, as well as control systems with feedback between the elements.

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Figure 1. Schematic diagram of the ultrahigh frequency apparatus:

1 – power supply; 2 – ultrahigh frequency energy converter; 3 – a device for transmitting ultra-high-frequency energy; 4 – energy transmitter; 5 – heating chamber; 6 – ultrahigh frequency trap system; 7 – energy distributor; 8 – control system

Heating of food products in an electromagnetic field differs from heating them due to thermal conductivity or convection in that the elements of the medium separating the generators of electromagnetic oscillations and heating objects do not participate in the transfer of heat. And therefore, in such systems, the heat flow is not continuous, and the energy is transferred in the form of electromagnetic vibrations. Heat arises in the heating objects themselves when they interact with the electromagnetic field.

The dielectric properties of food products depend mainly on their nature, humidity, temperature and frequency of field fluctuations [7]. The interaction of the amount of heat released and the depth of penetration of the ultrahigh-frequency field leads to the need to select the thickness of the product so that its outer and inner layers do not overheat.

Ultrahigh frequency heating has a number of advantages over traditional methods of heat treatment:

• high and uniform heating speed;

• preservation of vitamins and other essential components of food raw materials;
• possibility of soft heat treatment mode, pulse heat supply;
• creation of the required temperature unevenness during the heat treatment of food products by selecting the shape of the working bodies of the microwave generator;
• high efficiency of the process;
• improvement of working conditions by reducing the release of gaseous substances, steam and heat into the environment.

But however, with dielectric heating, it also has a disadvantage, which consists in the absence of a specific toasted crust on the surface of the raw material. Therefore, dielectric heating is recommended to be used in combination with infrared heating and traditional methods of heat treatment.

References:

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2. Ибрагимов Р.Р. Стерилизация плодов и овощей в свч поле. Международная научно практическая конференция «Наука и инновационные технологии в производстве продуктов питания», Бухара 21-22 октябр 2022 г., с.312-315
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