JP4139877B2 - Sterilization method and apparatus - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a sterilization method and an apparatus therefor, and more particularly, to a sterilization method and an apparatus therefor that require significantly less time to sterilize various types of bacteria and viruses.
[0002]
[Prior art]
Foods such as meat, fish and shellfish, vegetables, and fruits are sterilized with an aqueous sodium hypochlorite solution, alcohol, ultraviolet light, ozone, etc. before being shipped to general retail stores or department stores. This drastically reduces the number of pathogenic Escherichia coli such as O-157 and cell-invasive Escherichia coli such as Salmonella, as well as the number of small spherical viruses, astroviruses, rotaviruses, etc., thereby preventing food poisoning. The
[0003]
However, in the sterilization using the sterilizing agent as described above, there is a problem that the odor of the sterilizing agent remains in the food material or the color of the food material changes. Then, when fish shellfish are washed, for example, as proposed in Patent Document 1, it is recalled to obtain seawater that performs bactericidal and antiseptic effects without using a sterilant.
[0004]
[Patent Document 1]
JP 2002-307070 (paragraphs [0021] to [0023])
[0005]
[Problems to be solved by the invention]
By the way, in the method described in Patent Document 1, sterilization is performed by applying a constant voltage to seawater for about 8 to 10 seconds. Regarding this sterilization time, further time reduction is desired.
[0006]
The present invention has been made in connection with the above-described technology, and provides a sterilization method and apparatus having a sterilization ability against various bacteria, bacteria and viruses and having a remarkably short time required for the sterilization treatment. Objective.
[0007]
[Means for Solving the Problems]
To achieve the above object, the present invention is a sterilization method for sterilizing fungi present in a liquid,
A first step of supplying a current flowing from the first electrode to the second electrode between the first electrode and the second electrode in contact with the liquid;
A second step of energizing the current by reversing the direction of the current from the second electrode to the first electrode;
Have
The energization time in the first step and the second step is both 1 second or less. In the present invention, “fungi” is a general term for fungi, bacteria and viruses, and “sterilization” includes killing of bacteria and viruses.
[0008]
Since the direction of current flow is frequently reversed in this way, charges such as ions move violently in the liquid. For this reason, it is assumed that the electric charge collides with the fungus with a large momentum, and as a result, the fungus is quickly killed. This significantly reduces the time required for the sterilization process.
[0009]
The liquid sterilized in this way may be used as a cleaning liquid for foods, etc., or the above first step and second step may be alternately repeated after the foods and affected parts are immersed in the liquid. Good.
[0010]
Preferable examples of the liquid include water containing chlorine ions. Chlorine ions may be obtained, for example, by dissolving NaCl in water. Since this NaCl serves as an electrolyte, the electrical resistance of water is reduced, so that energization in the first step and the second step can be easily performed.
[0011]
In this case, in order to avoid generation of chlorine gas by combining chlorine ions with electrons, it is preferable that both energization times in the first step and the second step be 0.01 seconds or less.
[0012]
According to the present invention, it is possible to sterilize a liquid having an electric resistance of 1 × 10 ⁶ Ω · cm or more, that is, an insulator such as pure water or ultrapure water. In this case, an ion exchange membrane is interposed between the first electrode and the second electrode, and a liquid is circulated or stored in a conductor electrically connected to the first electrode and the second electrode. What is necessary is just to perform a process and a 2nd process.
[0013]
In any case, the current is preferably supplied as a rectangular wave. In this case, since the direction of current flow is rapidly reversed, the charge momentum is larger than when a general alternating current, which is a sine wave, is applied, and thus the fungi are killed in a relatively short time. Because it can.
[0014]
Furthermore, it is preferable to vibrate the liquid during energization. For example, when a sterilization process is performed by immersing the food material in a liquid, the fungi are easily detached from the food material by vibration. For this reason, fungi can be surely killed.
[0015]
Further, the present invention is a sterilization apparatus for sterilizing fungi present in a liquid,
A first electrode and a second electrode in contact with the liquid;
A current supply mechanism comprising a current reversing mechanism for reversing the direction of the current flowing between the first electrode and the second electrode;
It is characterized by having.
[0016]
By adopting such a configuration, it is possible to easily and simply reverse the direction of current flow, and eventually, sterilization can be easily and reliably performed.
[0017]
And an ion exchange membrane interposed between the first electrode and the second electrode; a conductor electrically connected to the first electrode and the second electrode; and a liquid applied to the conductor. It is preferable that a passage for circulation is provided. In this case, a current flows between the first electrode and the second electrode due to the movement of ions through the ion exchange membrane. For this reason, it becomes possible to sterilize the liquid which is an insulator.
[0018]
Note that the current supply mechanism preferably includes a DC power source that supplies a DC current and a switching circuit as a current reversing mechanism. As a result, an alternating current whose waveform is a rectangular wave can be supplied, and eventually the momentum of the electric charge present in the liquid can be increased.
[0019]
And it is preferable to have a vibration member that vibrates the liquid. By performing sterilization while vibrating the liquid with the vibration member, for example, fungi can be easily detached from the food, and the food can be easily and reliably sterilized.
[0020]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, preferred embodiments of the sterilization method according to the present invention will be described in detail in relation to an apparatus for performing the method, and will be described in detail with reference to the accompanying drawings.
[0021]
In FIG. 1, the schematic block diagram of the sterilizer which concerns on this Embodiment is shown. The sterilizer 10 includes a container 12 for storing a liquid, a first electrode 14 and a second electrode 16 installed in the container 12, and a direct current electrically connected to the first electrode 14 and the second electrode 16. The power supply 18 includes a switching circuit 20 interposed between the DC power supply 18 and the first electrode 14 and the second electrode 16.
[0022]
In this case, the container 12 is a resin bottomed cylindrical body having an inner diameter of 30 mm and a height of 50 mm, and the liquid stored in the container 12 is 20 cm of tap water W in which NaCl is dissolved at a concentration of 3%. ^{3 are} accommodated.
[0023]
The first electrode 14 and the second electrode 16 are inserted into the tap water W, whereby the first electrode 14 and the second electrode 16 are in contact with the tap water W. The first electrode 14 and the second electrode 16 are formed by coating a titanium surface with platinum having a thickness of 2 μm. Further, the width, height and plate thickness are set to 0.95 mm, 100 mm and 10 mm. In addition, the distance between the 1st electrode 14 and the 2nd electrode 16 can be 10 mm.
[0024]
The first electrode 14 and the second electrode 16 having such a configuration are electrically connected to the DC power supply 18 through lead wires 22 and 24. The lead wires 22 and 24 are provided with a constant current circuit 25 for stably supplying a current as a constant value and the switching circuit 20.
[0025]
The switching circuit 20 incorporates an oscillator (oscillator) (not shown). Therefore, when energized through the switching circuit 20, a current flow directed from the first electrode 14 to the second electrode 16; A flow of current directed from the second electrode 16 to the first electrode 14 occurs alternately.
[0026]
An ultrasonic vibrator 26 is immersed in the tap water W, and the ultrasonic vibrator 26 is connected to a power supply unit 28 via a cable 27. When power is supplied from the power supply unit 28, the ultrasonic transducer 26 vibrates at a predetermined frequency.
[0027]
Next, the sterilization method according to this embodiment will be described. In this sterilization method, a first step of supplying a current flowing from the first electrode 14 toward the second electrode 16 and a second step of turning on the current by reversing the direction of the current from the second electrode 16 to the first electrode 14. And have.
[0028]
First, in the first step, when a direct current is supplied from the direct current power source 18 to the first electrode 14 via the lead wire 22, the constant current circuit 25, and the switching circuit 20, the tap water W has conductivity. A direct current flows from 14 toward the second electrode 16. Of course, the DC current returns from the second electrode 16 to the DC power supply 18 via the lead wire 24, the constant current circuit 25, and the switching circuit 20. The set voltage value and the set current value may be set to 12 V and 1 A, for example.
[0029]
On the other hand, by energizing the ultrasonic vibrator 26 by energizing the power supply unit 28, the ultrasonic vibrator 26 is vibrated at a predetermined frequency.
[0030]
Here, when energized direct current is set voltage value and set current value above a predetermined time elapses, Cl NaCl that was generated by ionization in the tap water W in ^- first electrode 14 ion is positive And moves to the first electrode 14 to combine with electrons to form chlorine gas. In other words, toxic chlorine gas is generated from the first electrode 14.
[0031]
In order to avoid the occurrence of such a situation, in the present embodiment, the direction of the current is reversed by the switching circuit 20 before the chlorine gas is generated. That is, in the second step, the current supplied from the DC power source 18 is energized to the second electrode 16 via the lead wire 24, the constant current circuit 25 and the switching circuit 20, and further directed to the first electrode 14. And then return to the DC power supply 18 via the lead wire 22, the constant current circuit 25 and the switching circuit 20. Of course, also in this case, the ultrasonic vibrator 26 is vibrated at a predetermined frequency.
[0032]
Then, before the chlorine gas is generated from the second electrode 16, the direction of the current is reversed by the switching circuit 20. That is, the first step is performed again, and then the direction of the current is reversed by the switching circuit 20 before chlorine gas is generated from the first electrode 14, and the second step is performed again.
[0033]
In this way, energization is performed until a predetermined time elapses while avoiding the generation of chlorine gas.
[0034]
FIG. 2 shows the relationship between each energization time in the first step and the second step in this case and the amount of chlorine gas generated when 20 seconds have passed since the first first step was started. From FIG. 2, it can be understood that generation of chlorine gas can be avoided by setting each energization time in the first step and the second step to 0.01 seconds (10 milliseconds). Here, the amount of chlorine gas generated is a value obtained as a dissolved amount in the tap water W.
[0035]
By reversing the direction of the current every 10 milliseconds, the tap water W is supplied with a current having a rectangular waveform as shown in FIG. When such a rectangular wave current is energized, the number of fungi present in the water is drastically reduced as compared to the case where a general alternating current whose waveform is a sine wave as shown in FIG. 4 is energized. . That is, sterilization of water proceeds.
[0036]
Specifically, a sample is collected from the tap water W that has been energized for a predetermined time, cultured from the sample in culture soil, and the number of fungi (unit: CFU) is measured 48 hours later. Thus, in the sample after 0.003 seconds (3 milliseconds), the number of fungi does not increase. This means that there is no fungus capable of growing in the sample after 3 milliseconds after the start of energization, that is, the fungus has been killed in an extremely short time of 3 milliseconds.
[0037]
The tap water W thus sterilized can be used when cleaning foods and food processing equipment. In this case, since there is no need to use a sodium hypochlorite aqueous solution or alcohol, there is an advantage that a chlorine odor or the like does not remain in the food or the food does not change color.
[0038]
Furthermore, since vibration is given to water, the sterilization process proceeds efficiently.
[0039]
Of course, it is also possible to sterilize water in rivers, harbors, lakes, ponds and the like in the same manner.
[0040]
In addition, in this sterilization method, it is possible to kill skin resident bacteria, Legionella bacteria, and the like existing in water. Therefore, the sterilization method can also sterilize hot water used in a circulating bath, a pool, or a Kurhaus that circulates hot water. Of course, in this case as well, there is no need to sterilize with chlorine, ultraviolet rays, ozone, or the like, so hot water having no irritating odor can be used.
[0041]
Furthermore, this sterilization method can also be employed when disinfecting and sterilizing germs that have propagated in affected areas such as burns and trauma. In this case, the affected part may be immersed in a water tank filled with a physiological saline solution having a concentration of about 0.9%, and the above first step and second step may be alternately repeated. Similarly, it is possible to treat skin diseases caused by the propagation of Aspergillus, for example, athlete's foot.
[0042]
FIG. 5 also shows the number of fungi measured in the same manner as above using tap water in which NaCl was dissolved at a concentration of 0.9%, orange juice with 100% fruit juice, and milk as samples. From FIG. 5, it can be seen that the fungi have been killed within 0.1 seconds (100 milliseconds) in all liquids except for mineral water described later.
[0043]
Thus, according to the sterilization method according to the present embodiment, a sterilization process can be performed even for liquids other than tap water W. Of course, it is possible to sterilize beer, soy sauce, sauce, and the like.
[0044]
In particular, in the sake brewing process and soy sauce manufacturing process, if germs are mixed in, the growth of yeasts and koji molds decreases and the production efficiency decreases. In this case, manufacturing efficiency can be improved by selectively sterilizing various bacteria.
[0045]
In addition, what is necessary is just to set an electric current value and energization time suitably, in order to selectively sterilize various germs. For example, the current and energization time required to kill bacteria having cell membranes are smaller than the current and energization time required to kill gonococci having cell walls. Therefore, selective sterilization can be performed by setting the set current value and the energization time to a condition that is sufficient for killing bacteria having cell membranes and not killing gonococci having cell walls. .
[0046]
When sterilizing foods such as meat, fish and shellfish, vegetables, fruits, etc., the first step and the second step may be repeatedly performed on the water after the food is immersed in water. At this time, since the ultrasonic vibrator 26 vibrates, water also vibrates. This vibration makes it easy to remove the fungus from the food.
[0047]
That is, by applying vibration, sterilization of food can be more reliably performed.
[0048]
Thus, according to the sterilization method according to the present embodiment, the sterilization process can be completed in an extremely short time of 100 milliseconds or less. The reason for this is that, as the direction of current flow is frequently reversed, the charges such as ions move violently in the liquid, and finally the violently moving charges collide with fungi with a large momentum. This is presumed to be due to this.
[0049]
In addition, water with a very small amount of impurities, such as pure water or ultrapure water, or mineral water commercially available as drinking water, has an electrical resistance of 1 × 10 ⁶ Ω · cm or more. It is. In order to sterilize the liquid having such a high electrical resistance, a sterilizer 30 shown in FIG. 6 may be used.
[0050]
The sterilizer 30 includes a cation exchange membrane 32 interposed between the first electrode 14 and the second electrode 16, and a first electrode electrically connected to each of the first electrode 14 and the second electrode 16. A power feeding body 34 and a second power feeding body 36 are provided, and a path 38 is provided in the second power feeding body 36.
[0051]
The first electrode 14 and the second electrode 16 are electrically connected to the DC power source 18 via the lead wires 22 and 24, and the constant current circuit 25 and the switching circuit 20 are connected to the lead wires 22 and 24. It is the same as the above-described sterilization apparatus 10 that it is mounted and the oscillator is built in the switching circuit 20.
[0052]
As the cation exchange membrane 32, a proton conductor capable of moving protons (H ⁺ ) is selected. A suitable example of such a membrane is Nafion (trade name, manufactured by DuPont).
[0053]
When sterilizing mineral water with this sterilizer 30, mineral water is circulated through the passage 38. In this state, the first step and the second step are repeatedly performed according to the above. The first electrode 14 and the second electrode 16 are energized through electrode plates installed on the end surfaces of the first power supply 34 and the second power supply 36.
[0054]
In this case, in the first step, as indicated by an arrow A in FIG. 6, protons move in the cation exchange membrane 32 from the first electrode 14 toward the second electrode 16. The second process is started before the protons that have moved are combined with electrons at the second electrode 16 to generate hydrogen gas. As a result, as indicated by an arrow B, protons move in the cation exchange membrane 32 from the second electrode 16 toward the first electrode 14. Of course, the first step is resumed before protons and electrons are combined at the first electrode 14 to generate hydrogen gas.
[0055]
During the sterilization process in this way, a sample is collected from the mineral water that has been energized for a predetermined time, and the result of counting the number of fungi after 48 hours from the sample is shown in FIG. From FIG. 5, it is clear that even the mineral water that is an insulator can kill the majority of fungi in a short time of 0.5 seconds (500 milliseconds).
[0056]
The time from when mineral water enters the passage 38 to when it is derived, in other words, the stay time in the course of mineral water may be set longer than 0.5 seconds, for example, 1 second.
[0057]
Thus, according to the present embodiment, it is possible to sterilize even a liquid having a high electrical resistance. Even in this case, since the direction of the current is frequently reversed, the sterilization process can be terminated before the mineral water undergoes electrolysis.
[0058]
Moreover, even in this case, the sterilization process can be completed within a short time of 1 second or less. For this reason, the time required for the sterilization treatment can be shortened, and the time until the food is distributed can be remarkably shortened.
[0059]
In the above-described embodiment, the ultrasonic transducer 26 is vibrated. Alternatively, gas bubbling may be performed.
[0060]
Further, as understood from the above, the liquid stored in the storage part such as the container 12 may be energized, or the liquid flowing through the pipe such as the passage 38 may be energized. You may make it perform.
[0061]
【The invention's effect】
As described above, according to the present invention, the direction of current flow is frequently reversed. For this reason, electric charges such as ions move violently and collide with fungi with a large momentum. As a result, the fungi can be quickly killed, and the time required for the sterilization treatment can be significantly shortened. This effect becomes more remarkable by vibrating the liquid.
[0062]
In addition, in this case, generation of chlorine gas or the like can be avoided, so that the irritating odor remains in the sterilized liquid or food material, or the food material can be prevented from being discolored.
[Brief description of the drawings]
FIG. 1 is a schematic configuration diagram of a sterilization apparatus according to an embodiment.
FIG. 2 is a chart showing the relationship between each energization time in the first step and the second step and the amount of chlorine gas generated (dissolved amount).
FIG. 3 is a graph showing waveforms of currents applied in the first step and the second step.
FIG. 4 is a graph showing a general alternating current waveform;
FIG. 5 is a chart showing the measurement results of the number of fungi 48 hours after collecting and culturing various liquids that have been sterilized according to the present embodiment.
FIG. 6 is a schematic longitudinal sectional view of a sterilization apparatus for performing a sterilization process on a liquid having a high electrical resistance.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 10, 30 ... Sterilizer 12 ... Container 14, 16 ... Electrode 18 ... DC power supply 20 ... Switching circuit 25 ... Constant current circuit 26 ... Ultrasonic transducer 32 ... Cation exchange membrane 34, 36 ... Feeding body 38 ... Passage

Claims (6)

A sterilization method for sterilizing fungi present in a liquid,
A first step of supplying a current flowing from the first electrode to the second electrode between the first electrode and the second electrode in contact with the liquid;
A second step of energizing the current by reversing the direction of the current from the second electrode to the first electrode;
Have
The liquid is an insulator, and the liquid is circulated or stored in a conductor that is electrically connected to the first electrode and the second electrode that interpose an ion exchange membrane,
The sterilization method characterized in that both energization times in the first step and the second step are 1 second or less. In sterilizing method according to claim 1 Symbol placement, the current sterilization method characterized by being energized as a rectangular wave. The sterilization method according to claim 1 or 2 , wherein the liquid is vibrated during the energization. A sterilizer for sterilizing fungi present in a liquid,
A first electrode and a second electrode in contact with the liquid;
A current supply mechanism comprising a current reversing mechanism for reversing the direction of the current flowing between the first electrode and the second electrode;
An ion exchange membrane interposed between the first electrode and the second electrode;
A conductor electrically connected to the first electrode and the second electrode;
I have a,
Sterilization apparatus according to claim that you have passages for flowing is provided the liquid to the conductor. 5. The sterilizer according to claim 4 , wherein the current supply mechanism includes a DC power source that supplies a DC current and a switching circuit as the current reversing mechanism. 6. The sterilizer according to claim 4 , further comprising a vibrating member that vibrates the liquid.

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