SU49777A1 - Milk pasteurizer - Google Patents

Description

The use of electricity for pasteurizing milk has long attracted the attention of specialists in the dairy industry.

In this direction, numerous experiments were presented, which led to the widespread use of electric pasteurisation in foreign dairy plants.

However, until now there is no clarity on the issue of the bactericidal effect of current, especially since foreign dairy plants mainly use the heat effect of current, heating milk with current to 60-65 °.

By the experiments of the author, it was found that the electric current, both constant and alternating, has a bactericidal effect independently of the thermal effect. The bactericidal effect of the current is determined mainly by the strength of the current applied to the cross section in the bacterial liquid, and the nature of the electrodes, the resistance of the liquid, its temperature significantly affect the sterilization effect of the current.

The bactericidal effect is determined by the fact that it significantly reduces the number of microorganisms in the fluid through which the current flows. For example.

with a current density of 20-30 amperes per 1, the amount of microorganisms in milk is reduced by 80-85% with a very short current passing time of a few fractions of a second, as a result of which the liquid does not have time to heat up by more than 5-10 °. Microorganisms can be destroyed by more than 70% with the instant discharge of large capacitors; meanwhile, the heating in this case does not occur, the liquid is heated by no more than 1 °.

It is possible to reduce the number of microorganisms (except spores) to 100 ° / o, if we apply repeated destruction of bacteria by current several times, switching the current on to the tube along its entire length, where the test fluid flows.

The task in this case is to achieve maximum current densities in the liquid, provided that significant heating, burning of the liquid and spraying of the electrodes are eliminated.

In this case, it turns out that the size of microorganisms is also essential: the smaller the microorganisms, the greater the current density needed to destroy them.

The bactericidal action of constant and alternating current, depending on the above data and at carbon electrodes, can be close to the truth expressed by the following empirical formula

.a.r.l.t

where / is the number of microorganisms in a liquid before exposure to current, F is the number of microorganisms remaining after exposure to current, k is the proportionality coefficient, y is the conductivity of the liquid, and is the average size of microorganisms, T is the temperature, / is the current strength liquid cross-section, -time.

When a fluid moves, the effect will also depend on the flow velocity, and it will be inversely proportional to the velocity. With metal electrodes, the bactericidal effect will also depend on the electrochemical properties of the electrodes.

For high frequencies and ultrashort waves, this relationship changes.

The present invention aims to carry out electro-pasteurization of milk on the basis of the above conditions, and it is possible to carry out the sterilization by the longer exposure of the current to the milk using a large number of vessels described below.

The drawing shows a schematic of the proposed pasteurizer.

The pasteurizer consists of a series of 2 dielectric vessels 1 enclosed in a vessel, the walls of which are provided with many tiny holes. Electrodes 3 are located in vessels 1 and 2 and are connected in parallel or with a current source A with a voltage of 220-500 volts or with a voltage and a capacitor.

In the openings of the vessel 1, through which the electro-pasteurized fluid flows continuously, high current densities are created.

Vessels 1 and 2 with electrodes 3 arranged in them are connected in series, which makes it possible to reduce the number of bacteria to any desired value, and in each of vessels 1--2 occurs at the above-mentioned current density a decrease in the number of microorganisms in milk by 80%. the vessel through which the milk passes through to the pressure applied by pump B at a current density of up to 20-30 amperes per 1 heating of milk does not exceed 5-10 °.

In order to prevent the passage of the liquid from overheating, refrigerators 5 are alternately turned on in series with the vessels 1-2, where the liquid is cooled and then pasteurized in the next group of vessels 1-2.

Thus, the electro-pasteurized liquid is practically not heated. It is also possible to work by heating with a current of liquid, then an improved conventional electropasteurization will be carried out.

It is advisable to install carbon electrodes in the pasteurizer, or have at least one central electrode carbon, while the other can be made of aluminum, silver or stainless steel. Electrodes 3 can be removed for cleaning from vessels 1-2 through cover 4.

In the molche flowing through the electro-pasteurizer, the fluid is subsequently heated and cooled, which itself has a bactericidal effect. It is practically rational to apply oscillations of alternately heating and cooling a liquid with an amplitude of temperatures of 30-40 °, although generally it is not necessary at large current densities.

The subject matter of the invention.

Claims (2)

1. A device for pasteurizing milk with electric current, consisting of two concentric vessels 1 and 2 with electrodes 3 located in them, characterized in that the internal vessel 1 is made of a dielectric and provided with small holes for the pasteurization of milk with a high-density current during passage milk through these holes. 2. The form of the device according to claim 1, characterized in that, in order to alternately heat and cool the milk, pasteurizers are recruited successively into the battery with the inclusion of refrigerators for milk through several pasteurizers.