Patent Application
20130098408
The present invention relates to a washing method using water containing a hydrogen radical and/or a carbon radical, and to an apparatus for use in the washing method.
Recently in Japan, as increasing of imported foods, the problem of safety due to residual post harvest agricultural chemicals used for vegetables and fruits has been focused. In domestic farm goods, a problem of safety due to residual pre harvest agricultural chemicals used in culture has also been focused although the residue is known to be quantitatively smaller than that of post harvest agricultural chemicals. On the other hand, farm goods cultured without agricultural chemicals or produced by organic farming have increased year after year. These farm goods are not necessarily safe because harmful bacteria can be adhered, although residual agricultural chemicals are small.
Therefore, it is important to sufficiently wash the farm goods for securing safety and sanitation of foods.
Conventionally, washing and sterilization have been conducted using chemicals, however, from the concern about the influence on a human body, various methods in which foods are washed and sterilized sufficiently in such a manner that a human body is not influenced have been proposed recently. As one exemplary method, a washing method using a hydroxyl radical is proposed. A hydroxyl radical is generated, for example, by a method of irradiating ozone water with ultraviolet.
However, since a hydroxyl radical has a short life time (10″6M−1S−1), even if water containing a hydroxyl radical is produced, and the water is taken out of the system and allowed to act on an object to be processed, a sufficient effect is difficult to be obtained. Therefore, it is necessary to conduct ultraviolet radiation in a condition that ozone water and an object to be processed are in contact with each other, or it is necessary to utilize a hydroxyl radical generating method using chemicals. However, if ultraviolet radiation is conducted in a condition that ozone water and an object to be processed are in contact with each other, deterioration of the object by the ozone water and/or gas leakage into the operation environment can occur, and problems arise that ultraviolet fails to transmit due to debris in an aqueous solution, that a hydroxyl radical generates only on the irradiated face, and the like. On the other hand, in utilizing a hydroxyl radical generating method using chemicals, a post washing may be necessary or use of chemicals themselves is sometimes avoided.
For example, Japanese Patent Laying-Open No. 2001-231525 (Patent document 1) discloses a method of conducting sterilization more efficiently by making an aqueous solution containing a hydroxyl radical into collision with an object to be processed at high speed in a shower mode. However, there still remains a problem of short life time of a hydroxyl radical as described above.
For example, Japanese Patent Laying-Open No. 2005-237230 (Patent document 2) discloses a method of reducing ozone consumption by organic substances released from foods by separately providing an ozone water washing water bath, an ozone water sterilization water bath, and an ozone water freshness keeping water bath. However, the method disclosed in Patent document 2 has a drawback that the apparatus is bulky because of requirement of two-step or three-step process.
The present invention was made to solve the above problems, and it is an object of the present invention to provide a novel method capable of exerting sufficient washing effect without using chemicals, and an apparatus for the method.
The present invention provides a method of washing an object to be processed using water containing at least either one selected from a hydrogen radical and a carbon radical.
Preferably, the water containing at least either one selected from a hydrogen radical and a carbon radical used in the method of the present invention exhibits decrease from 800 mV to 200 mV of oxidation-reduction potential at a decreasing rate of 100 mV/second or less.
Preferably, the water containing at least either one selected from a hydrogen radical and a carbon radical used in the method of the present invention is produced by causing generation of a hydroxyl radical in water containing a water-soluble organic substance, or by causing generation of a hydroxyl radical in water mixed with gas containing at least either one selected from a hydrogen atom and a carbon atom.
Preferably, in the method of the present invention, the water containing at least either one selected from a hydrogen radical and a carbon radical is brought into contact with an object to be processed in a dipping mode or in a shower mode. Among these, it is more preferred to bring the water containing at least either one selected from a hydrogen radical and a carbon radical into contact with an object to be processed in a shower mode. In this case, an object to be processed may be washed by supplying water containing at least either one selected from a hydrogen radical and a carbon radical in a shower mode from above a processing bath so that water containing at least either one selected from a hydrogen radical and a carbon radical is pooled in the processing bath in such an amount that the object to be processed can be dipped in a condition that the water containing at least either one selected from a hydrogen radical and a carbon radical after process is discharged from the bottom of the processing bath.
The present invention also provides a washing apparatus including a processing bath for washing an object to be processed, and a means for supplying the processing bath with water containing at least either one selected from a hydrogen radical and a carbon radical.
In the apparatus of the present invention, it is preferred that the means for supplying the water containing at least either one selected from a hydrogen radical and a carbon radical has a means for supplying water containing a water-soluble organic substance and a means for causing generation of a hydroxyl radical in the water containing a water-soluble organic substance, or has a means for mixing gas containing at least either one selected from a hydrogen atom and a carbon atom into water, and a means for causing generation of a hydroxyl radical in water mixed with the gas.
Preferably, the apparatus of the present invention includes a shower head having a means for supplying water containing a water-soluble organic substance or water mixed with gas containing at least either one selected from a hydrogen atom and a carbon atom and generating the hydroxyl radical in the water, wherein water containing at least either one selected from a hydrogen radical and a carbon radical is supplied to the processing bath via the shower head in a shower mode.
Preferably, the apparatus of the present invention includes a processing bath configured so as to discharge water containing at least either one selected from a hydrogen radical and a carbon radical after process in the bottom, and a means for supplying water containing at least either one selected from a hydrogen radical and a carbon radical in a shower mode via a shower head from above the processing bath, wherein the means for supplying water containing at least either one selected from a hydrogen radical and a carbon radical preferably has a configuration to supply water containing at least either one selected from a hydrogen radical and a carbon radical into the processing bath so that water containing at least either one selected from a hydrogen radical and a carbon radical is pooled in the processing bath in such an amount that an object to be processed can be dipped in a condition that the water containing at least either one selected from a hydrogen radical and a carbon radical after process is discharged from the bottom of the processing bath.
Preferably, in the apparatus of the present invention, the processing bath is formed into mesh in its bottom only.
Preferably, in the apparatus of the present invention, the processing bath has a pump, for discharging water containing at least either one selected from a hydrogen radical and a carbon radical after process in its bottom.
Preferably, the apparatus of the present invention is able to keep water level of water containing at least either one selected from a hydrogen radical and a carbon radical in the processing bath constant.
Preferably, in the apparatus of the present invention, the processing bath is able to oscillate. Preferably, the apparatus of the present invention also has a means for supplying bubbling air provided in the bottom of the processing bath.
According to the present invention, by using a radical generating in a chain reaction originally from a hydroxyl radical, sufficient washing effect is exerted on an object to be processed. Since the water containing at least either one selected from a hydrogen radical and a carbon radical used in the present invention can exert sufficient effect even when it is acted on an object to be processed in a shower mode, it is possible to constantly supply fresh water containing at least either one selected from a hydrogen radical and a carbon radical, and to obtain a uniform and high washing effect. Further, the present invention is advantageous in that adverse affect on a processing environment and an object to be processed is small because washing is achieved by chemical action of a radical.
1, 21, 41 washing apparatus, 2, 22 processing bath, 3 conduit, 4 tank, 5 chemical feeding device, 6 concentration meter, 7 ozone generator, 8 mixing pump, 9 reaction tower, 9a ultraviolet lamp, 10 conduit, 11 concentration meter, 12 conduit, 13 conduit, 14 shower head, 15 radical water, 16 oxidation-reduction potentiometer, 17 conduit, 18 conduit, 19 concentration meter, 23 bucket, 24 shower head, 25 radical water, 26 bucket bottom face, 27 radical water, 28 pump, 29 conduit, 30 ultraviolet lamp, 31 conduit, 32 bubbling air supply path, 33 valve, 42 ultrasonic sensor, 43 electrode sensor, 44 control means
The present invention provides a method of washing an object to be processed by removal of bacteria or particles using water containing a hydrogen radical (H.) and/or a carbon radical (R.) (hereinafter, referred to as “radical water”). The radical water used in the present invention may only contain at least either one of a hydrogen radical and a carbon radical. Preferably, the radical water in the present invention is water containing both a hydrogen radical and a carbon radical. Inclusion of a hydrogen radical and/or a carbon radical in water can be confirmed by subjecting the water to electron spin resonance (ESR) (also called as Electron Paramagnetic Resonance) using a free radical monitor JES-FR30 (manufactured by JEOL Ltd.) and examining whether there is a peak that indicates existence of a hydrogen radical, or a carbon radical from the obtained ESR chart.
The term “washing” used herein can exert an effect of removing bacteria or particles in addition to an effect of a so called washing (these effects are collectively called as “washing effect”). Here, “removing bacteria” means removing bacteria from an object to be processed. “Removing particles” means removing particles such as contaminants and debris from an object to be processed. It is natural that washing by the present invention encompass removing of agricultural chemicals remaining in a object to be processed such as vegetables from the object to be processed.
In the method of the present invention, the object to be processed is not particularly limited and it is suitably applied particularly for washing of objects to be processed containing abundant organic substances, such as cut vegetables, hen eggs, seafood, food producing machines, medical devices, linens, semiconductors, and electronic parts. It may also be suitably applied to objects to be processed made of materials such as metals, polymer compounds (in particular, a fluorine resin or a silicone compound having low hydrophilicity (hydrophobic)) and the like.
In the radical water used in the present invention, since a hydrogen radical or a carbon radical is sequentially generated by a chain reaction, the bacteria removing or particle removing effect is exerted for a long time compared to a hydroxyl radical (OH.) of which life time is 10−6M−1S−1. Such radical water in the present invention acts to neutralize electric charges of adhered particles or bacteria to remove them or make them less likely to adhere again because it has an electric property different from that of unprocessed water (for example, tap water) although it lacks such a strong oxidizing power and a sterilizing power as that of water containing a hydroxyl radical. Therefore, the radical water in the present invention is able to exert the bacteria removing or particle removing effect as described above without influencing on an object to be processed, and this effect is kept for a practical time level even when the generated radical water is taken out of the system for use. Therefore, such radical water is advantageous in that it can keep the effect even when it is applied to a shower mode exhibiting higher washing effect than a dipping mode as will be described later. Furthermore, since the radical water used in the present invention does not contain ozone, a washing process by removing of bacteria or particles can be conducted without exerting adverse affect on a processing environment and an object to be processed.
In the method of the present invention, it is preferred that the radical water exhibits decrease of oxidation-reduction potential from 800 mV to 200 mV at a decreasing rate of 100 mV/second or less. This is because when radical water exhibiting a decreasing rate of oxidation-reduction potential of more than 100 mV/second is used, content of a hydrogen radical or a carbon radical appears to be low and the washing effect tends to be low. More preferably, the decreasing rate of oxidation-reduction potential is 10 mV/second or less because more excellent washing effect is realized.
The decreasing rate of oxidation-reduction potential of radical water is measured using an apparatus having the same configuration as the washing apparatus of the present invention of the example shown in
The radical water used in the method of the present invention may be produced in any method as far as it is produced to contain at least either one of a hydrogen radical and a carbon radical. As one preferred method of producing the radical water, a method involving causing generation of a hydroxyl radical (OH.) in water containing a water-soluble organic substance, and causing generation of a hydrogen radical and a carbon radical by a chain reaction with a water-soluble organic substance originally from the a hydroxyl radical is exemplified. That is, this is a method in which a hydroxyl radical is caused to generate by a so-called advanced oxidation process, and the a hydroxyl radical is not directly used for the process, but a carbon radical and a hydrogen radical are caused to generate in a chain reaction originally from the a hydroxyl radical, and water containing the secondarily generated a carbon radical and/or a hydrogen radical (radical water in the present invention) is produced.
As the “water-soluble organic substance” used herein, known designated food additives and existing food additives may be preferably used, and for example, alcohols such as methanol, ethanol and isopropanol, acetone, hydrogen peroxide, and ethyl acetate can be recited. The “water containing a water-soluble organic substance” used herein also encompasses tap water (TOC<5 mg/h).
As a method of advanced oxidation process for causing generation of a hydroxyl radical in water containing a water-soluble organic substance as described above, for example, an ozone/ultraviolet combined method that itself is known in the art is recited. As a hydroxyl radical generating pathway in the ozone/ultraviolet combined method, for example, such a pathway is assumed in which an OH radical is generated via HO2 radical as ozone reacts with water in the processing liquid to autolyze in the following manner.
O3+H2O→HO3++OH−
HO3++OH−→2HO2.
O3+2HO2.→OH.+2O2
As a hydroxyl radical generating pathway in the ozone/ultraviolet combined method, such a pathway is also assumed in which an OH radical is generated via hydrogen peroxide by irradiating ozone with ultraviolet.
O3+H2O+hv→H2O2+O2
H2O2+hv→2OH.
The hydroxyl radical generated in such a pathway reacts with a water-soluble organic substance (R) in water in the following manner and a radical reaction starts in such a manner that hydrogen is drawn out from the water-soluble organic substance.
RH+OH.→R.+H2O
Further, a generated a carbon radical R. reacts with other water-soluble organic substance (R′) in water, and a carbon radical or a hydrogen radical is generated in a chain reaction in the following manner.
R.+R′H→RH+R′.
R.+R′H→RR′+H.
When water containing a hydrogen radical and/or a carbon radical is produced by causing generation of a hydroxyl radical in water containing a water-soluble organic substance, a preferred concentration of the water-soluble organic substance in water varies depending on a kind of the water-soluble organic substance, and an object to be processed by the radical water, and is not particularly limited, however, TOC (total organic carbon) is preferably within a range of 0.01 to 20 mg/L, and more preferably within a range of 0.1 to 10 mg/L.
The radical water in the present invention may be such that a hydrogen radical and a carbon radical are caused to generate by mixing gas containing a hydrogen atom and/or a carbon atom such as hydrogen gas or carbon dioxide gas into water (preferably, tap water, pure water or ultrapure water) and causing generation of a hydroxyl radical in the water into which the gas is mixed. Water in which a hydrogen radical or a carbon radical is caused to generate by such dissolved gas in ultrapure water is also encompassed in the radical water in the present invention.
When the radical water in the present invention is produced by mixing gas containing a hydrogen atom and/or a carbon atom with water, and causing generation of a hydroxyl radical in the water, preferred concentration of gas containing a hydrogen atom and/or a carbon atom in water varies depending on a kind of gas, and the object to be processed by the radical water and is not particularly limited, however, it is preferably within a range of 1 to 50 ppm, and more preferably within a range of 1 to 20 ppm.
In the washing method of the present invention using the radical water, a method of bringing the radical water into contact with an object to be processed is not particularly limited, however, the contact is preferably achieved in a dipping mode or a shower mode. Among these, it is preferred to bring radical water in the present invention into contact with an object to be processed in a shower mode capable of conducting efficient washing in a short time while its washing effect is less likely to be inhibited even when the object to be processed is cut vegetable from which a liquid (leaching liquid) is leached such as cabbage cut into strips. The radical water in the present invention is able to exert the washing effect satisfactorily even when it is taken out of the system for generating the radical water after generation and brought into contact with an object to be processed in a dipping mode or in a shower mode because sequential radical generation is continued by the chain reaction as described above, and it may be preferably applied particularly in a shower mode.
In the washing method of the present invention, when the shower mode is applied, it is particularly preferred to wash an object to be processed by supplying radical water in a shower mode from above a processing bath so that the radical water is pooled in the processing bath in such an amount that the object to be processed is dipped, in a condition that the radical water after process is discharged from the bottom of the processing bath.
In the apparatus of the present invention, the means for supplying radical water preferably has a means for supplying water containing a water-soluble organic substance and a means for causing generation of a hydroxyl radical in the water containing a water-soluble organic substance. By further having these means, the radical water in the present invention can be preferably produced by, as described above, causing a hydroxyl radical to generate in water containing a water-soluble organic substance, and causing a hydrogen radical and a carbon radical to generate in water by a chain reaction with a water-soluble organic substance originally from the a hydroxyl radical. In the apparatus of the present invention, the means for supplying radical water may have a means for mixing gas containing a hydrogen atom and/or a carbon atom (for example, hydrogen gas or carbon dioxide gas) into water, in place of the means for supplying water containing a water-soluble organic substance, and even with such a configuration, the radical water containing a hydrogen radical and/or a carbon radical in the present invention can be preferably produced.
When the means for supplying radical water has a means for supplying water containing a water-soluble organic substance and a means for causing generation of a hydroxyl radical in the water containing a water-soluble organic substance, the means for supplying water containing a water-soluble organic substance is preferably implemented to have, as is the example shown in
In the example shown in
In apparatus 1 having the configuration as shown in
As for the radical water after ultraviolet radiation by ultraviolet lamp 9a, a necessary amount that is at least a part thereof is supplied to processing bath 2 via a conduit 12, and the remainder is returned to tank 4 via a conduit 13. In the apparatus of the present invention, the radical water may be brought into contact with an object to be processed in processing bath 2 in any of dipping mode or shower mode.
Apparatus 1 of the present invention may be configured to circulate the radical water in processing bath 2 as is necessary.
The means for supplying radical water in washing apparatus 21 of the present invention is realized, for example, by connecting a conduit 31 for supplying radical water to shower head 24. To this conduit 31, for example, a means for supplying water containing a water-soluble organic substance and an ozone generator similarly to those of the apparatus of the example shown in
In the present invention, it is preferred that the means for supplying radical water is configured to supply radical water into processing bath 22 so that the amount of radical water capable of dipping an object to be processed is pooled in processing bath 22 in a condition that radical water after process is discharged from the bottom of processing bath 22. As a result, the washing process using washing apparatus 21 of the present invention is conducted by dipping an object to be processed in radical water 25 pooled in an internal space of bucket 23, and supplying radical water 25 into processing bath 22 in a shower mode from above processing bath 22 in the means for supplying radical water. In this manner, since radical water 25 is supplied in a shower mode, influence by eluate from an object to be processed is small, and since it is possible to bring radical water into contact with the entire object to be processed as well as with the face of the object to be processed where the shower abuts by dipping the object to be processed in radical water in processing bath 22, uniform and high washing effect can be obtained. Therefore, washing effect is dramatically improved compared to conventional washing apparatuses that conduct washing in either of a shower mode or a dipping mode. The washing apparatus of the present invention eliminates the need of stirring in contrast to a washing apparatus conducting washing only in a dipping mode, so that sufficient washing effect can be exerted even when a smaller processing bath compared with a washing apparatus conducting washing only in a dipping mode is used, and higher water-saving effect is achieved.
Preferably, the processing bath in the washing apparatus of the present invention has a pump for discharging radical water after process in its bottom.
Preferably, the washing apparatus of the present invention is able to keep water level of radical water in the processing bath constant. As a result, it is possible to conduct efficient washing while pooling radical water in an amount such that an object to be processed can be dipped in the processing bath. For example, in the case of washing apparatus 21 in the example shown in
Preferably, the processing bath in the washing apparatus of the present invention is oscillatable, or provided with a means for supplying bubbling air in its bottom. Apparatus 21 of the example shown in
In the following, the present invention will be described more in detail by way of Experimental examples, however, the present invention will not be limited thereto.
An experiment for examining a relationship between the concentration of a water-soluble organic substance in water and the generated radical species was conducted using a quartz cell for absorbance measurement. As water subjected to generation of a radical, ultrapure water, 1% ethanol aqueous solution, 5% ethanol aqueous solution, 10% ethanol aqueous solution and 20% ethanol aqueous solution were respectively used, and after blowing ozone therein in an amount exceeding solubility, radical water was caused to generate by irradiation for 10 minutes by a ultraviolet lamp. Immediately after generation, each radical water was subjected to electron spin resonance (ESR) using a free radical monitor JES-FR30 (manufactured by JEOL Ltd.), and from the obtained ESR chart, radical species and content proportions in radical water were detected.
After blowing ozone of an amount exceeding solubility into tap water using the apparatus of the present invention shown in
In the ESR chart of
After blowing ozone of an amount exceeding solubility into tap water using the apparatus of the present invention shown in
An experiment for examining a relationship between oxidation-reduction potential of radical water and sterilization effect was conducted. 1 mL of bacterial liquid extracted with phosphate buffered saline from macrophyll was introduced into 100 mL of liquid medium (nutrient broth), and cultured at 37° C. for 24 hours under shaking, and 1 mL of this culture liquid and 100 mL of each sample solution were put into a sterilized bag, mixed by shaking well, and then viable cell counts were determined by a pour plate method, and thus sterilizing ability of each sample solution was examined. As sample solutions, radical waters at the points of time when oxidation-reduction potential was 700 mV, 600 mV, 450 mV, 350 mV, 300 mV and 250 mV, respectively after generating radical water by radiation of ultraviolet lamp after blowing ozone of an amount exceeding solubility into tap water using the apparatus of the present invention shown in
From Table 1, it can be found that when tap water was used as a sample solution, the viable cell counts was about 1/100 of that when the culture liquid (original liquid) alone was used by dilution as a sample solution, and sterilizing effect was not observed. In the case of radical water, viable cell counts similar to that of tap water was observed irrespective of the value of oxidation-reduction potential, and this suggests that the radical water does not have sterilizing effect unlike the ozone water and hypochlorous acid water.
An experiment for examining a relationship between oxidation-reduction potential of radical water and washing effect was conducted. Using the apparatus shown in
From Table 2, it was confirmed that the radical water having an oxidation-reduction potential of 450 mV or more exerted a washing ability substantially equal to that of hypochlorous acid.
Using the apparatus shown in
From Table 3, it was confirmed that the radical water of the present invention exerted a washing ability substantially equal to that of a hypochlorous acid aqueous solution.
Using the apparatus shown in
An experiment for comparing the effect of removing bacteria when bacteria removing process was conducted in a dipping mode and in a shower mode using cabbage cut into strips from which leaching liquid exudes abundantly as an object to be processed was conducted. The process in a dipping mode was conducted using the apparatus shown in
An experiment of evaluating a washing effect was conducted using radical water at the point of time when oxidation-reduction potential immediately after generation was 400 to 500 mV by conducting irradiation of ultraviolet lamp after blowing ozone of an amount exceeding solubility into tap water using the apparatus shown in
For cotton cloths respectively obtained in the above processes, the condition of a soiling substance was visually observed, and the washing effect was evaluated. When washed with tap water, the stain of soy sauce was removed, however, other soiling substances remained. When washed with tap water added with detergent, soiling substances were totally removed, however, stains of the substances other than soy sauce still remained. When washed with tap water added with detergent, whiteness of the entire cloth was improved due to bleaching effect. On the other hand, when washed with radical water, in addition to stain of soy sauce, stains of sauce and ketchup that were not removed even by washing with tap water added with detergent were removed.
Using the apparatus shown in
From Table 4, it was confirmed that contact angle significantly decreased in radical water, compared to the case of tap water, and hence radical water had the particle removing effect. Superior washing ability of radical water to that of tap water was clearly observed even by visual check.
After preparing 20 ppm of carbon dioxide gas using tap water, ultrapure water as raw water using the apparatus shown in
Using the washing apparatus of the example shown in
For comparison, experiments were also conducted for a case where washing was not conducted, and for a case where washing in a dipping mode was conducted. In the dipping mode, since it is necessary to make a processing bath large from the view point of stirring, a 135 L processing bath was used, and radical water was injected into the bath at 15 L/min to overflow, and 7.3 kg (about 18 L) of cucumber was put therein, and stirring was conducted by bubbling from the bottom of the processing bath. In these cases, viable cell counts (cells/g) were also calculated in a similar manner.
The result is shown in
| Number | Date | Country | Kind |
|---|---|---|---|
| 2007-125888 | May 2007 | JP | national |
This application is a Divisional of co-pending application Ser. No. 12/598,257 filed on Oct. 30, 2009 and for which priority is claimed under 35 U.S.C. §120. application Ser. No. 12/598,257 is the national phase of PCT International Application No. PCT/JP2007/071707 filed on Nov. 8, 2007 under 35 U.S.C. §371. PCT International Application No. PCT/JP2007/071707 claims the benefit of priority of JP-2007-125888 filed on May 10, 2007. The entire contents of each of the above-identified applications are hereby incorporated by reference.
| Number | Date | Country | |
|---|---|---|---|
| Parent | 12598257 | Oct 2009 | US |
| Child | 13712877 | US |
