RU2568061C2 - Method and device for milk disinfection through physical factors complex impact - Google Patents

Abstract

FIELD: food industry.

SUBSTANCE: invention relates to food industry, in particular, to milk disinfection. The milk disinfection method includes exposure of milk to UHF electrical field with frequency equal to 2450 MHz and specific power equal to 4 W/g in a running mode with superimposition of a bactericide UV radiation flow by a 240 W lamp and of an ultrasonic field with frequency equal to 40 kHz and specific power equal to 0.625 W/g; the exposure duration is 250 s until the milk temperature equal to 57…58 °C is reached. The installation for the method implementation contains a cylindrical screening body with supply and drain nipples with a cylindrical volume resonator concentrically positioned inside the body, the resonator lower base perforated and interfaced with the reservoir of the ultrasonic generator to the lower base whereof piezoelectric elements are attached; positioned through the volume resonator within the horizontal plane is a uviol glass tube including a gas discharge lamp of high UV radiation pressure with the tube butt ends are choked with overlays made of a ferromagnetic material.

EFFECT: invention allows to reduce milk bacterial count.

2 cl, 10 dwg

Description

The invention relates to the food industry, in particular for the disinfection of liquids (water, milk, etc.).

There is a method of increasing the efficiency of microwave ovens, implemented in an installation containing a heating chamber made of thin sheet metal, on the upper wall of which a strip antenna is installed, the elements of which are a radiator. A source of ultrasonic vibrations is installed on the lower wall of the heating chamber [1].

Also known is a device for bactericidal treatment of a liquid, comprising a microwave generator, a transmission line with a microwave energy emitter and a UV optical radiation source in the form of an axisymmetric electrodeless microwave gas discharge lamp having a microwave and UV transparent vacuum-tight shell, characterized in that the transmission line is with an energy emitter The microwave is made in the form of a circular waveguide with a working wave type TE ₀₁ (H ₀₁ ) [2].

The main disadvantage of existing methods and technical means for the disinfection of milk is the lack of effectiveness of the bactericidal treatment of milk.

The present invention is intended for disinfection of liquid products in a flow mode by the combined action of physical factors, such as an electromagnetic field of an ultrahigh frequency, a bactericidal flux of ultraviolet rays and ultrasonic vibrations.

An object of the invention is to reduce the bacterial contamination of milk by developing an installation that provides a complex effect of physical factors in effective modes.

The specified technical result is achieved by the fact that:

- they are exposed to a microwave field with a frequency of 2450 MHz, a specific power of 4 W / g in flowing mode with the application of a bactericidal flux of UV radiation by a 240 W lamp and an ultrasonic field with a frequency of 40 kHz and a specific power of the ultrasonic generator of 0.625 W / g, while the exposure duration will be 250 s until milk temperature reaches 57 ... 58 ˚С.

- installation for the disinfection of milk by the combined action of physical factors, containing a cylindrical shielding case with supply and discharge pipes, inside which a cylindrical volume resonator is concentrically located, the lower base of which is perforated and joined to the upper base of the ultrasonic tank, while piezoelectric elements are mounted from the lower base an ultrasonic generator, and through a volume resonator, a tube from iolevogo glass, inside which there is a high pressure ultraviolet lamp, and the ends of the tubes plugged plates of ferromagnetic material.

In FIG. 1 shows a diagram of an installation for the disinfection of milk by the combined action of physical factors: 1 - a generator unit with a radiator; 2 - volume resonator; 3 - shielding case; 4 - lamp bactericidal flux of UV rays; 5 - tube made of uvolev glass; 6 - shielding pad; 7 - perforated lower base of the resonator; 8 - ultrasonic tank; 9 - piezoelectric elements of the ultrasonic generator; 10 - pipe for draining the finished product; 11 - milk in an ultrasonic tank and in a volume resonator; 12 - transcendental waveguide - pipe for supplying milk; 13 - valve.

In FIG. 2 shows the dynamics of milk heating under the influence of microwave EMF.

In FIG. 3 shows the dynamics of heating milk under the influence of ultrasonic vibrations.

In FIG. 4 shows the dynamics of milk heating under the complex influence of physical factors.

In FIG. 5 shows a nomogram for coordinating the design and technological parameters of a milk disinfection unit.

In FIG. Figure 6 shows a comparative description of the results of research at the Federal State Institution “State Regional Center for Standardization, Metrology and Testing in the Czech Republic” of microbiological indicators of milk on the duration of exposure to electrophysical factors (except for the control sample). The ordinate axis of FIG. 6 represents the values of bacterial contamination in CFU / cm ³ and the abscissa axis - samples (samples) of the test milk:

1 - control sample - feed milk not exposed to any effect;

2 ... 8 - samples disinfected by various physical factors, namely:

2 - UV radiation,

3 - ultrasonic vibrations,

4 - combined exposure to UV radiation and ultrasonic vibrations,

5 - exposure to electromagnetic fields of ultrahigh frequency (EMF);

6 - combined exposure to EMF and UV radiation,

7 - combined exposure to EMF and ultrasonic vibrations,

8 - combined exposure to EMF, ultrasonic vibrations and UV radiation, exposure duration - 150 s;

9 - combined exposure to EMF, ultrasonic vibrations and UV radiation, exposure duration - 250 s;

10 - combined exposure to EMF, ultrasonic vibrations and UV radiation, exposure duration - 350 s;

A comparative characteristic is compiled on the basis of test reports No. 988, 1009, 1049, 1050 of the Federal State Institution “State Regional Center for Standardization, Metrology and Testing in the Czech Republic”, carried out in quadruplicate.

The milk disinfection unit contains sources of electromagnetic radiation: a microwave generator unit with an emitter, an ultrasonic generator with piezoelectric elements and a bactericidal flux of UV rays. The emitter of the microwave generator 1 is directed inside the cylindrical volume resonator 2, which is coaxially located in the cylindrical shielding case 3. The lamp of the bactericidal flux of UV rays 4 is located inside the tube of uvolev glass 5 and is mounted in the volume resonator 2 in a horizontal plane. To prevent outward emission of the ends of the tube from uvolev glass 5, extending outside the volume resonator 2, are drowned out by shielding plates 6. The lower perforated base of the volume resonator 7 is connected to the reservoir 8, on the bottom of which the piezoelectric transducers 9 of the ultrasonic generator are fixed and the branch pipe 10 is withdrawn to drain the disinfected milk 11. The discharge pipes 10 and the supply 12 are connected by a milk pipe to the valves 13.

The process of disinfection of milk is as follows. The valve 13 opens and through the supply pipe 12, milk 11 enters the volume resonator 2, the initial temperature of which is 10 ° C. Strictly observing the sequence, first turn on the microwave generator 1, and then the ultrasonic generator 9. In the installation, a high pressure gas discharge lamp 4 DRT-240 can serve as a source of UV radiation. Due to the microwave generator 1, an electromagnetic field arises in the cavity resonator, which causes endogenous heating of the milk and excites and maintains the microwave discharge in the gas discharge lamp 4. The effectiveness of the bactericidal effect on milk through uvolev glass 5 depends on the level of electric field strength. Due to the complex effect of the electromagnetic field of the microwave and the bactericidal flux of UV rays, the bacterial contamination of milk decreases. Next, the milk flows through the perforation 7 in the lower base of the volume resonator into the reservoir 8 of the ultrasonic generator with piezoelectric transducers 9, where it is subjected to the specific action of ultrasound and the edge flow of EMF microwave, which allows to further reduce its bacterial contamination. The specific effect of ultrasonic fields on milk 11 is due to cavitation processes occurring in it, as well as macro and micro flows in the volume of milk adjacent to the emitted surface of the tank — the lower base. The intensification of the disinfection process is ensured by the turbulization of milk during repeated pumping through the working chamber using a pump and its cavitation in the reservoir of the ultrasonic generator. When the milk temperature reaches 57 ... 58 ° C, it is necessary to open the valve of the discharge pipe 10 and drain into the cooler tank. Due to the shielding case 1 and the pads 6 near the installation, an acceptable level of the power flux of microwave radiation is provided.

The geometric parameters of the working chamber are determined by the dimensions of the cavity resonator and the ultrasonic tank. The diameter of the cavity resonator is equal to the wavelength of the electromagnetic radiation of the microwave range.

A nomogram for matching the technological parameters of the installation with the operating modes is presented in figure 5.

The nomogram is represented by a graph of the dependence of the total microbial number on the duration of exposure to the bactericidal flux of UV rays (second quadrant of the nomogram), a graph of the dependence of the total microbial number on temperature (the first quadrant of the nomogram), a graph of the temperature versus the duration of exposure to electrophysical factors (fourth quadrant of the nomogram).

This nomogram is a sequence of actions during the registration of experimental and theoretical studies. A decrease in the bacterial contamination of milk during its irradiation in a turbulent mode through a milk pipe made of uvolev glass occurs according to the exponential law B = 4.7636 · e ^0.001τ .

The effect on milk of EMF and the ultrasonic vibrations in the working chamber is accompanied by heat in the volume of the product. The increase in the temperature of milk in the cavity resonator of the microwave generator is 41 ° C. At the expiration of milk in the ultrasonic tank there is a complex effect on the milk of the edge flow of EMF power and ultrasonic vibrations. The total increment in the temperature of milk in the working chamber reaches 47 ... 48 ° C. It is known that during cavitation exposure in milk, colloids and particles are destroyed, inside which bacteria may be contained, therefore microorganisms become vulnerable to subsequent physical effects of electromagnetic radiation. An assessment of the effect of cavitation treatment of milk in combination with the effect of the bactericidal flux of UV rays on the content of KMAFAnM showed that after cyclic treatment of milk in the developed installation, the number of microorganisms decreased from 5.1 · 10 ⁶ to 1.8 · 10 ⁶ CFU / cm ³ ; under the influence of EMFCH and ultrasonic vibrations, the bacterial contamination amounted to 0.9 · 10 ⁶ KOE / cm ³ .

The justification of the operating modes of the installation for milk disinfection is carried out taking into account the results of a study of the dynamics of heating of raw materials and the evaluation of microbiological parameters of processed milk. We used the planning matrix of the 3-factor active experiment 2 ³ and the software “Statistic V5.0”. The following factors were identified as the main factors affecting the process of milk disinfection: x ₁ - specific power of the microwave generator, W / g; x _2, is the duration of exposure, s; x ₃ is the specific power of the ultrasonic generator, W / g.

The optimization criteria were: Y ₁ - plant productivity, kg / h; Y ₂ - energy costs for the disinfection of milk, kW · h / kg; Y ₃ - increment of milk temperature, ° C; Y ₃ is the total microbial number in milk, CFU / cm ³ .

The selection of evaluation criteria is due to their greatest importance for the process of milk disinfection. As a result of statistical processing of experimental data, regression equations are obtained that adequately describe the process of milk disinfection under the influence of variable factors. Two-dimensional sections in contours and response surfaces of the following models are presented: installation performance (Fig. 7); a change in bacterial contamination during milk processing (Fig. 8); increment of milk temperature (Fig. 9); energy costs for the disinfection of milk (Fig. 10).

Effective operating conditions of the installation are achieved at R _{beats microwave frequency} = 4 W / g, P _beats = 0.625 W / g and a lamp power of UV radiation of 240 watts. The total increase in milk temperature as a result of exposure to EMFHF and ultrasonic vibrations is up to 57 ... 58 ° C, and a decrease in bacterial contamination of milk by two orders of magnitude.

Information sources

1. Device for increasing the efficiency of microwave ovens. IPC H05B 11/00, RF patent No. 2355136 dated 05/10/2009.

2. A device for combined bactericidal treatment of liquids. IPC A61L 2/00, RF patent No. 2173561 from 09.20.2001.

Claims (2)

1. A method of disinfecting milk, characterized in that the milk is exposed to an electric field of a microwave frequency of 2450 MHz, a specific power of 4 W / g in flow mode with the application of a bactericidal flux of UV radiation by a 240 W lamp and an ultrasonic field with a frequency of 40 kHz and specific power ultrasound generator 0.625 W / g, while the exposure time will be 250 s until the milk temperature reaches 57 ... 58 ° C. 2. The installation for implementing the method according to claim 1, comprising a cylindrical shielding case with supply and discharge nozzles, inside which a cylindrical volume resonator is concentrically located, the lower base of which is perforated and joined to the reservoir of the ultrasonic generator, to the lower base of which piezoelectric elements are fixed, and through volume resonator, in a horizontal plane a tube of uviole glass is laid, inside of which there is a high-pressure discharge lamp UV radiation s, and the ends of the tube plates blanked from a ferromagnetic material.

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