THE POSSIBILITY OF USING ULTRAVIOLET RADIATION TO EXTEND THE SHELF LIFE OF FRUITS

THE POSSIBILITY OF USING ULTRAVIOLET RADIATION TO EXTEND THE SHELF LIFE OF FRUITS

Jasur Safarov

DSc, professor Tashkent State Technical University,

Uzbekistan, Tashkent

Shakhnoza Sultanova

DSc, professor Tashkent State Technical University,

Uzbekistan, Tashkent

Murodjon Pulatov

Researcher Tashkent State Technical University,

Uzbekistan, Tashkent

The world population is estimated to be 9,100 million in 2050, 34% more than today, which means a 100% increase in global food demand over what is currently produced. This fact presents an important technological challenge for the transition to more sustainable agricultural and food systems (FAO, 2017). This situation, together with consumer demand, makes the production, transportation and distribution of food one of the most important global synergies for the nutrition of the population. In addition to positive effects at the economic level, this global demand also has its negative consequences. The consumer is accustomed to eating any food regardless of its origin and season, which gives rise to a global food market, where transportation to bridge the gap between production and consumption is of fundamental importance. In addition, having plenty of food at all times adds a variable food surplus, which inevitably leads to wastage of food, as many are not sold, while others are, even if purchased by consumers, they are never consumed.

Various food preservation methods aim to increase the useful life of food during storage by applying methods that prevent microbiological changes while maintaining quality. The effectiveness of these methods depends mainly on hygiene in its production, the purpose of which is to reduce the microbial load and prevent its development. To this end, many foods are subjected to heat treatment, which often changes both the organoleptic characteristics (texture, taste and color) and the nutritional properties (mainly loss of vitamins) of the food. Due to these adverse effects of processing at high temperatures, non-thermal preservation processes, also referred to as soft technologies, are being developed. They are not very aggressive and have the advantage of offering products that are similar to fresh and therefore in line with the current market requirements, but do not lose their safety guarantees [1-2].

For several years, the effect of light on bacteria and other organisms has been studied, which began with the idea of cell damage caused by the incidence of solar radiation on living organisms. Subsequently, the influence of monochromatic radiation of the ultraviolet spectrum (UV) was studied. This method is used to disinfect air, water and surfaces of materials with possible biological contamination (viruses, bacteria, spores, mold, yeast) [3].

In the food industry, it is used to disinfect (between 250-270 nm) conveyor belts, sheets and lids, containers, the surfaces of some solid foods including fruits, vegetables, fish and liquids such as juices and water. It is also used in aquaculture, for example for flow protection and recirculation in freshwater or marine aquariums. Currently, the most used system is continuous. It consists of permanently switched on emitters that act on liquid or solid products with UV radiation.

When exposed to UV-C radiation on vegetables and fruits, a decrease in the initial microbial load on the surface occurs, a phenomenon called the hormetic effect (the phenomenon of stimulation at low doses of a substance and inhibition at high doses).

This effect may increase resistance to certain micro-organisms such as molds and yeasts, as it may stimulate the production of phenylalanine ammonia lyase, which produces phenolic compounds (phytoalexins) that are toxic to them.

Due to the effectiveness of ultraviolet light as a disinfectant, various studies have been carried out to expand its use in the food industry, for example in fruits for fresh consumption, in freshly cut fruits as fourth (IV) range products. For this reason, it is necessary to mention the critical process factors, differences in equipment, experimental conditions of the studies carried out and the variety of substrates used, which determine the effectiveness of ultraviolet light on microorganisms. Another group that can be used is flours and cereals, where UV radiation can reduce microbial load, especially the decontamination of pathogens such as Bacillus. cereus [4-5].

Its use is also important in those products that do not have any microorganism reduction step in their process, such as heat treatment. Despite differences in study conditions, conclusions were drawn that can serve as a model for future research in this area.

Advantages and disadvantages of using UV-C.

Benefits:

• it does not cause organoleptic changes in most foods;
• a physical method in which the energy is a bactericidal medium that does not form unwanted by-products;
• processing does not produce chemical residues or radiation;
• effective for disinfection of various surfaces;
• effective for the inactivation of many microorganisms. This easy to apply;
• Low cost and maintenance.

Disadvantages:

• organisms surrounded by solids (particles, dust or coatings) are not affected;
• negligible penetration into solid materials and opaque liquids;
• personnel exposed to UV-C radiation for a long time may damage their eyesight and get burned;
• The UV-C plant or equipment should be located as close as possible to the product to be processed.

Ultraviolet light is electromagnetic radiation with a wavelength shorter than that of visible light and longer than that of X-rays, remaining invisible to the human eye. The use of UV technology for disinfection purposes includes the ultraviolet region of the electromagnetic spectrum with a wavelength range of 100 to 400 nm. This can be divided into:

- UV-A (315-400 nm);

- UV-B (280-315 nm);

- UV-C (200-280 nm);

- Vacuum-UV (100-200 nm ) (sometimes considered UV-C or UV-Extreme).

Ultraviolet light has the greatest bactericidal effect in the wavelength range from 250 to 270 nm, and the maximum disinfection efficiency falls precisely at a wavelength of 254 nm. This is a form of non-ionized radiation that does not penetrate surfaces. The UV component in the spectrum of electromagnetic radiation is shown in Figure 1.

Figure 1. UV component in the spectrum of electromagnetic radiation

UV-C radiation causes photochemical changes, the consequences of which may vary depending on the species of microorganism in question. The lethal mechanism of action depends on its absorption of DNA, which can stop cell growth and cause death.

The possibility of using UV-C radiation as a technology to extend the shelf life of fruits will depend on the availability of reliable information on the limits that lead to the preservation effect of those products that degrade quality.

References:

1. Bezlepkin A.I., Translators V.I., Shlifer E.D. Development of an installation for the disinfection of liquid and solid objects by combined exposure to microwave and UV radiation and ozone. "High-voltage and converter technology". M., VEI Publishing House. 2001, pp. 137-143.
2. Wasserman A.L. Design and operation of ultraviolet bactericidal installations / Ed. Yu.B. Popovsky. M., 2009, 56 p.
3. Dzharulaev D.S. Scientific and technical principles for creating intensive technologies for the processing of fruit and berry raw materials using an electromagnetic field of ultrahigh frequency: Abstract of the thesis . ... doctor of technical sciences: 05.18.01. Krasnodar, 2005. 49 p.
4. Shaumarov Kh.B. Islamov S.Ya. Technology of storage and primary processing of agricultural products. - Tashkent, 2011. 124-p. 4. Shaumarov Kh.B., Mirzaev M.M., Joraev R.J., Fayziev Ya.N. Recommendations for farmers on the storage and primary processing of fruits, grapes and vegetables. - T., 2007. - 22 p.
5. Rusanova L.A. Modern ways of storing fruits, vegetables, berries and grapes / L.A. Rusanova // Service sector: innovations and quality. - 2013. - No. 13. – 11 s.