JP5364401B2 - Sterilization method - Google Patents

Description

  The present invention relates to a sterilization auxiliary composition for ozone treatment and a sterilization method using the same.

Ozone has a very high standard oxidation-reduction potential at 25 ° C. of 2.07 V, and has strong oxidizing power following fluorine. For this reason, conventionally, using this oxidizing power, ozone treatment has been performed in various fields such as semiconductor cleaning, food cleaning (sterilization), and water purification.
In addition, since ozone decomposes into oxygen and has an environmentally friendly aspect, its use tends to expand in recent years.

  As ozone treatment, a method of supplying (aeration) ozone into the water to be treated containing the treatment object (ozone aeration treatment) and a method of immersing the treatment object in water (ozone water) in which ozone is dissolved (ozone water immersion) Processing) and the like are known. Among these, the ozone aeration treatment has advantages such as less ozone use, less water use, and sterilization even if the amount of organic matter to be treated is larger than the ozone water immersion treatment.

  In such an ozone treatment, a method for increasing the sterilizing effect is generally a method for increasing the amount of ozone used. However, the increase in the amount of ozone used directly increases the processing cost. Furthermore, unabsorbed ozone that has not been effectively utilized, that is, ozone that is released into the atmosphere without being absorbed by water when ozone is aerated in the water to be treated is increased. The increase in unabsorbed ozone not only increases the cost required for processing, but also raises concerns about work safety, and there is a limit to the increase in the amount of ozone used.

In order to solve such problems, a method has been proposed in which ozone is used with a compound having a specific dynamic surface tension to promote oxidation by ozone and improve the bactericidal effect (for example, Patent Documents 1 and 2).
On the other hand, food sterilizers containing chitosan have been proposed in addition to sterilization by ozone treatment (for example, Patent Documents 3 and 4).

International Publication No. 2007/040260 Pamphlet JP 2008-201992 A JP-A 63-169975 JP 2008-31059 A

  However, the bactericides such as Patent Documents 3 and 4 have applications where the bactericidal effect is insufficient. In addition, when the oxidation assistants of Patent Documents 1 and 2 are used, the ozone gas bubbles (ozone bubbles) in the water to be treated can be refined to improve the sterilization effect, but in order to obtain a sufficient sterilization effect, a large amount Therefore, there was a problem in cost. Further, ozone treatment is required to further reduce the amount of ozone used and improve the bactericidal effect.

  Then, this invention aims at the disinfection adjuvant composition which can disinfect a process target object economically and efficiently in ozone treatment, and the disinfection method using the same.

  As a result of intensive studies, the present inventors have found that the bactericidal effect can be enhanced by controlling the viscosity of the water to be treated using a water-soluble polysaccharide in the ozone treatment, leading to the present invention.

  That is, the sterilization aid composition for ozone treatment of the present invention (hereinafter sometimes simply referred to as a sterilization aid composition) contains a water-soluble polysaccharide. The water-soluble polysaccharide is preferably at least one selected from the group consisting of chitosan, xanthan gum, gellan gum, pectin, guar gum, locust bean gum, tamarind gum, carrageenan, and propylene glycol alginate, and further has 1 to 1 carbon atoms. Preferably it contains 10 fatty acid glycerides.

  The sterilization method of the present invention is characterized in that ozone is aerated in the water to be treated containing the treatment target in the presence of the sterilization aid composition.

  According to the sterilization auxiliary composition of the present invention and the sterilization method using the same, the object to be treated can be sterilized economically and efficiently in ozone treatment.

It is a schematic diagram which shows the ozone treatment apparatus used for an example of the sterilization method of this invention. It is a schematic diagram which shows the ozone treatment apparatus used for the Example.

(Sterilization aid composition for ozone treatment)
The sterilization aid composition of the present invention contains a water-soluble polysaccharide (hereinafter sometimes referred to as component (A)).

[(A) component: water-soluble polysaccharide]
The component (A) in the present invention is a water-soluble polysaccharide. The polysaccharide means a polymer by glycoside bond of sugar. Water solubility means the solubility of the solute in water, and the polysaccharide of the present application is dissolved in an aqueous solution at 100 ppm or more under the conditions of pH 2-9 and 20 ° C. For this reason, cellulose and chitin are not included in the polysaccharide of the present application.

As the component (A), water-soluble hemicellulose, gum arabic, tragacanth gum, carrageenan, xanthan gum, guar gum, tara gum, cloth nori, agar, fur celerin, tamarind seed polysaccharide, karaya gum, troarooi, pectin, sodium alginate, pullulan, gellan gum, locust bean gum , Various starches, carboxymethylcellulose (CMC), methylcellulose (MC), ethylcellulose (EC), hydroxymethylcellulose (HMC), hydroxyethylcellulose (HEC), hydroxypropylcellulose (HPC), hydroxyethylmethylcellulose (HEMC), hydroxyethylethylcellulose (HEEC), hydroxypropylmethylcellulose (HPMC), hydroxypropylethylcellulose (HPEC), hydroxyethylhydroxypropylcellulose (HEHPC), sulfoethylcellulose, dihydroxypropylcellulose (DHPC), propylene glycol alginate, glycogen, hyaluronic acid, heparin, chitosan and modified starches such as soluble starch .
Among these, chitosan, xanthan gum, gellan gum, pectin, guar gum, locust bean gum, tamarind gum, carrageenan, and propylene glycol alginate that can increase viscosity under pH 5 or less are preferable. In particular, chitosan is most preferred because its radical scavenger function is known. Such (A) component can be used individually by 1 type or in combination of 2 or more types as appropriate.
Since the component (A) described above exhibits a thickening effect, by adding to the water to be treated, the rising of bubbles of ozone-containing gas (ozone gas bubbles) in the water to be treated is suppressed, and the bactericidal effect by the ozone aeration method Can be improved. In addition, the component (A) having radical scavenger ability is considered to work to stabilize ozone and improve the bactericidal effect by ozone.

The molecular weight of the component (A) can be determined in consideration of the type of the component (A), the concentration of the component (A) in the water to be treated, the viscosity required for the water to be treated, and the weight average molecular weight is 500, for example. It is preferable that it is -10,000,000, and it is more preferable that it is 10,000-10,000,000.
In general, the higher the molecular weight, the more limited the movement of the molecules, so the various reaction rates are generally slower. Oxidation reaction by ozone is also included in the reaction, and those having a high molecular weight are also suppressed. In that sense, the addition of a polymer compound is presumed to have little adverse effect on the bactericidal effect in ozone treatment. On the other hand, when the molecular weight increases, the viscosity of the water to be treated tends to increase. If the viscosity of the water to be treated increases too much, it is difficult to make the ozone gas bubbles fine, and the sterilization effect in the ozone treatment tends to be reduced. For this reason, if the weight average molecular weight of (A) component is in the range of 10,000 to 10,000,000, the bactericidal effect can be improved in the ozone treatment.
Here, the weight average molecular weight can be measured by a method of analyzing with a gel filtration chromatography (GPC) -differential refractive index detector (RI) system using polyethylene glycol (PEG) as a standard substance. The measurement of the weight average molecular weight is an operation of eluent: 0.1 M NaNO ₃ , flow rate: 1 ml / min, sample: 0.02 to 0.3% by mass, solvent: 0.1 M NaNO ₃ , injection amount: 200 μL. In the conditions, the weight average molecular weight is a value calculated as a numerical value in terms of PEG. In addition, for the above measurement, as an apparatus, for example, a liquid feed pump: Shodex DS-4 (manufactured by Showa Denko KK), a degasser: ERC3115 (manufactured by RC Co., Ltd.), a column: Shodex SB-806MHQ (Showa Denko KK) Manufactured), differential refractive index detector: Shodex RI-71 (manufactured by Showa Denko KK) and the like can be used.

  In the sterilization auxiliary composition, the proportion of the component (A) is preferably in the range of 0.1 to 99% by mass with respect to the total mass solid content (total amount of components other than moisture) of the sterilization auxiliary composition. 10 to 99% by mass is more preferable. This is because the sterilization effect in the ozone treatment can be improved within the above range.

[(B) component: C1-C10 fatty acid glyceride]
The bactericidal aid composition of the present invention can contain a fatty acid glyceride having 1 to 10 carbon atoms as the component (B) as necessary. Examples of the component (B) include water-soluble triacetin, diacetin, monoacetin, caprylic acid glyceride such as monocaprylin, capric acid glyceride such as monocaprin, etc. Among them, triacetin, diacetin, and monoacetin increased the aeration amount. Even in this case, it is preferable that bubbles do not accumulate in the water to be treated. (B) By mix | blending a component, ozone-containing gas can be refined | miniaturized and the bactericidal effect can be improved.
Various microbubble generators can be used to refine the ozone-containing gas, but by using chemicals such as salts, surfactants, solvents, etc., it is possible to refine them with a lower mechanical force. In addition, when bubbles are accumulated in the water to be treated, the sterilizing effect is reduced due to overflow. Further, the wettability is improved by reducing the surface tension of the water to be treated, and the cleaning property of the object to be treated can be improved.
Such (B) component can be used individually by 1 type or in combination of 2 or more types as appropriate.

  When (B) component is mix | blended with a disinfection adjuvant composition, it is preferable that the ratio of (B) component is the range of 0.01-50 mass% with respect to the total mass solid content of a disinfection adjuvant composition. The range of 0.1 to 30% by mass is more preferable. This is because the sterilization effect in the ozone treatment can be further improved within the above range.

[Optional ingredients]
In addition to the component (A) and the component (B), the bactericidal aid composition of the present invention can be used as an optional component in order not to inhibit the ozone oxidation reaction. A surfactant, a fragrance, an enzyme, an inorganic salt, a pH adjuster, a solvent and the like may be contained.
There is no restriction | limiting in particular as surfactant, According to the objective, it can select suitably from conventionally well-known surfactant, For example, following (1)-(4) etc. are mentioned.

(1) alkylbenzene sulfonic acid, alkyl sulfuric acid, alkyl phenyl ether sulfuric acid, polyoxyethylene alkyl ether sulfuric acid, acylamido alkyl sulfuric acid, alkyl phosphoric acid, polyoxyethylene alkyl ether carboxylic acid, paraffin sulfonic acid, α-olefin sulfonic acid, α- Water-soluble salts such as sulfocarboxylic acids and their esters, and anionic surfactants such as soap.
(2) ethoxylated nonions such as polyoxyalkyl ether and polyoxyalkylphenyl ether, polyglycerin fatty acid ester, glycerin fatty acid ester, propylene glycol fatty acid ester, sorbitan fatty acid ester, polyoxyethylene sorbitan fatty acid ester, glucoside ester, sugar ester, Nonionic surfactants such as sugar active agents such as methyl glucoside ester, ethyl glucoside ester and alkylpolyglucoxide, amide active agents such as alkylamine oxide, alkyldiethanolamide and fatty acid N-alkylglucamide, and alkylamine oxide.
(3) Amphoteric surfactants such as aminocarboxylates such as alkylcarboxybetaines, alkylsulfoxybetaines, alkylamidopropylbetaines, and alkylalaninates, imidazoline derivatives, and alkylamine oxides.
(4) Cationic surfactants such as alkyltrimethylammonium salts and dialkyldimethylammonium salts.
Surfactant can be used individually by 1 type or in combination of 2 or more types as appropriate.

  By the way, if the ozone-containing gas is aerated in the water to be treated containing a high concentration surfactant, the water surface may be foamed and an undesirable phenomenon may occur in the process such as overflow. Therefore, it is preferable to consider the concentration of the surfactant in the water to be treated as the content of the surfactant in the sterilization aid composition. In this invention, it is preferable that content of surfactant is the range of 0-10 mass% with respect to the total mass solid content of a disinfection adjuvant composition, and it is the range of 0-5 mass%. More preferred.

  The form of the sterilization aid composition is not particularly limited as long as it contains the component (A), and may be in the form of an aqueous solution obtained by mixing the component (A) and water. It may be a solid containing. In addition, when the component (B) and the optional component are blended, an aqueous solution in which the component (A), the component (B), and the optional component are dissolved in water may be used. It may be a thing. Alternatively, the solid component (A), the component (B), and the optional component are prepared separately, and when the ozone treatment is performed, the component (A) and the component (B) and / or the optional component are dissolved in water. In addition, water to be treated may be prepared.

(Sterilization method)
In the sterilization method of the present invention, ozone is aerated in the water to be treated containing the object to be treated in the presence of the sterilization aid composition of the present invention. Below, the sterilization method of this invention is demonstrated using FIG. FIG. 1 is a schematic view of an ozone treatment apparatus 10 used in an example of the sterilization method of the present invention.
As shown in FIG. 1, the ozone treatment apparatus 10 includes a water tank 12, an aeration unit 14, and a stirring unit 18. The aeration means 14 includes a supply pipe 15 and an air diffuser 16 provided at the tip of the supply pipe 15. The air diffuser 16 is immersed in the water stored in the water tank 12, and the supply pipe 15 is connected to the ozone-containing gas supply means 13. The stirring means 18 is provided in the water tank 12.

The material of the water tank 12 is not particularly limited, but because the oxidizing power of ozone is strong, for example, glass, Teflon (registered trademark) (polytetrafluoroethylene), titanium, ozone treatment (a strong oxide film formation by high-concentration ozone) It is preferable to use aluminum or stainless steel. When using a material such as nitrile rubber or urethane having low resistance to ozone, it is necessary to pay sufficient attention to deterioration of the water tank 12.
Further, the size of the water tank 12 can be determined in consideration of the processing amount of the processing object to be cleaned and the ability of the stirring means 18.

The ozone-containing gas supply means 13 only needs to be able to supply ozone-containing gas containing ozone, and examples thereof include an ozone generator and a cylinder filled with ozone-containing gas. Moreover, for example, a device that generates ozone with an ozone generator, sends the generated ozone to a mass flow controller via a regulator, and supplies ozone into the water to be treated while adjusting the flow rate with the mass flow controller.
The ozone generator is not particularly limited, and examples thereof include a method of irradiating oxygen with high energy light such as an electron beam, radiation, and ultraviolet rays, a chemical method, an electrolytic method, a discharge method, and the like. Industrially, the silent discharge method is often used because of generation cost and generation amount. As such a commercially available ozone generator, for example, YGR-50 (trade name) manufactured by Lacey Co., Ltd. is commercially available as a low concentration ozone generator, and ED- manufactured by Ecodesign Co., Ltd. is used as a high concentration ozone generator. OG-PSA1 (trade name) and the like are commercially available.

  The aeration means 14 is not particularly limited as long as the ozone-containing gas can be supplied to the water to be treated as fine bubbles, and for example, known devices such as a diffuser plate, a diffuser cylinder, a diffuser, and an ejector can be used. By using such an apparatus and generating as fine bubbles as possible, the sterilization efficiency of the object to be processed can be increased.

  The stirring means 18 may be anything that can stir the water to be treated in the water tank 12, may be one using a stirring blade, or may be one that generates a water flow with a pump or the like.

A sterilization method using the ozone treatment apparatus 10 will be described.
First, an arbitrary amount of water to be treated is stored in the water tank 12, and a treatment object 19 to be cleaned is placed therein. Next, ozone-containing gas is circulated from the ozone-containing gas supply means 13 to the supply pipe 15, and ozone-containing gas bubbles 17 are generated from the diffuser 16 in the water to be treated. Then, a water flow is generated in the water to be treated in the water tank 12 by the stirring means 18. Thereafter, the ozone-containing gas bubble 17 is generated for an arbitrary time, and the processing object 19 is cleaned.

  There is no restriction | limiting in particular as a process target object as the process target object 19, Generally the sterilization process may be performed. For example, kitchen utensils such as kitchen knives, cutting boards, tableware, sponges, toilet articles such as toilet seats, bath utensils such as bags and bathtubs, cloth products such as clothes, sheets, and futons, medical instruments such as endoscopes and scalpels, vegetables, Examples include fresh foods such as fruits, meat, fish, shellfish and eggs, processed foods thereof, bodies such as the oral cavity and fingers, factory production lines, packaging containers, walls, floors, piping and other equipment, and sludge.

The water to be treated is an aqueous solution containing the sterilization aid composition of the present invention.
The water used for to-be-processed water is not specifically limited. Ozone reacts with dissolved metals, chlorine, organic substances, etc. because of its strong oxidizing power, and therefore, the water to be treated is preferably water having a low content (high purity) of these impurities. Examples of such water include ultrapure water having a resistivity of preferably 0.00001 MΩ · cm or more, more preferably 0.001 MΩ · cm or more, and further preferably 1 MΩ · cm or more.

The concentration of the sterilization aid composition in the water to be treated takes into consideration the concentration of the component (A) in the sterilization aid composition, the type of the component (A) in the sterilization aid composition, the ability of the aeration means 14, and the like. Can be determined.
Here, the viscosity of pure water at 25 ° C. is 0.89 m (mm) Pa · s. In contrast, the chitosan aqueous solution (pH 3.5) has a viscosity of 1.13 mPa · s at a chitosan concentration of 100 ppm, 2.36 mPa · s at 200 ppm, and 10.5 mPa · s at 1000 ppm. . Thus, the viscosity increases as the concentration of the component (A) in the water to be treated increases. And if the to-be-processed water has a viscosity of 1.01 mPa · s or more, the rising of the ozone gas bubble 17 can be suppressed. And the ozone gas bubble 17 can exhibit a high sterilization effect because contact time with a process target object becomes long. In addition, since many of the polysaccharides are weak but exhibit surface adsorption, not only the effect of increasing the viscosity of the water to be treated, but the component (A) stabilizes the bubbles by increasing the viscosity of the surface of the ozone gas bubble 17. It is thought that it contributes to the improvement of the bactericidal effect.

When the chitosan concentration in the water to be treated is 2000 ppm by mass, the viscosity reaches 25.4 mPa · s. When the viscosity of the water to be treated exceeds 25.0 mPa · s, it becomes difficult to obtain fine ozone gas bubbles 17 in the water to be treated. When the ozone gas bubble 17 in the water to be treated increases, the sterilizing effect tends to decrease. For this reason, it is not preferable that the viscosity of the water to be treated becomes too high.
For example, in the miniaturization of the ozone gas bubble 17 using an injector as the aeration means 14, if the viscosity of the water to be treated is too high, the flow of the water to be treated becomes slow and the shearing force becomes weak so that the ozone gas bubble 17 becomes large. End up. Further, when a device that generates ozone gas bubbles 17 from a porous material such as an air diffuser is used as the aeration means 14, if the viscosity of the water to be treated is too high, the ozone gas bubbles 17 may be detached from the air diffuser 16. Slow down and bubbles grow.
For this reason, the density | concentration in the to-be-processed water of (A) component becomes like this. Preferably the viscosity in 25 degreeC of concentration to-be-processed water is 1.01-25.0 mPa * s, More preferably, it is 1.03-10.5 mPa * s. Can be determined. For example, when (A) component is chitosan, 10 mass ppm or more and less than 2000 mass ppm are preferable, and 50-500 mass ppm is more preferable. If it is within the above range, the viscosity of the water to be treated is set to an appropriate range, the ozone gas bubbles 17 are kept fine in the water to be treated, and a high sterilizing effect is obtained.

  When mix | blending (B) component with a disinfection adjuvant composition, the density | concentration of (B) component in to-be-processed water is although it does not specifically limit, 1-5000 mass ppm is preferable and 10-1000 mass ppm is more preferable. If it is 1 mass ppm or more, the sterilizing effect is further improved, and if it is 5000 mass ppm or less, the consumption of ozone due to the reaction between ozone and the ozone oxidation promoter in the water to be treated is suppressed. Processing efficiency is improved.

  As the ozone-containing gas, ozone generated by an ozone generator may be used as it is, or a gas diluted with a dilution gas may be used. As the dilution gas, a gas inert to ozone or poor in reactivity is preferable, and examples thereof include helium, argon, carbon dioxide, oxygen, air, and nitrogen. Since ozone is self-degrading, it is desirable to use it immediately after it is prepared with an ozone generator.

  The concentration of ozone in the ozone-containing gas is not particularly limited, but is preferably 5000 ppm by volume or less and more preferably 1000 ppm by volume or less in consideration of work safety. The lower limit is not particularly limited, but is preferably 1 ppm by volume or more and more preferably 10 ppm by volume or more in consideration of the efficiency of ozone treatment. The present invention is particularly useful when the concentration of ozone is low, for example, in the range of 50 to 5000 ppm by volume, which effectively provides a bactericidal effect.

The supply amount of the ozone-containing gas to the water to be treated can be determined according to the purpose of cleaning and the type and amount of the object to be treated.
The bubble diameter of the ozone-containing gas when aerated to the water to be treated is not particularly limited, but the bubble diameter is preferably as small as possible from the viewpoint of improving the sterilization efficiency.

The pH of the water to be treated can be determined in consideration of the properties of the object to be treated 19. For example, the pH is preferably 5 or less, and more preferably 3 to 5 while the ozone-containing gas is aerated on the water to be treated. preferable. In cleaning using ozone, decomposition of dissolved ozone can be suppressed by lowering the pH. It is known that the decomposition of ozone is suppressed by self-decomposition by hydroxy radicals generated from ozone, and the lower the pH, the less likely the hydroxyl radicals are generated and the higher the stability of ozone. Here, since the hydroxy radical is a substance having higher reactivity than ozone, generation of the hydroxy radical is not preferable because it causes decomposition of the component (A). For this reason, by making it pH 5 or less, further efficient sterilization can be performed, preventing decomposition | disassembly of (A) component.
The lower limit value of the pH of the water to be treated can be determined in consideration of the type of the processing object 19 and the like. For example, when processing fresh food, the pH is set to 3 or more to prevent the deterioration of the fresh food. can do.

The pH indicates the pH value of the water to be treated itself measured using a hydrogen electrode or the like.
The pH of the water to be treated can be adjusted by adding an alkali agent such as sodium hydroxide or potassium hydroxide; an acid such as hydrochloric acid, sulfuric acid, phosphoric acid, acetic acid, or citric acid.

  The time for aeration of ozone-containing gas to the water to be treated (aeration time) can be determined in consideration of the degree of sterilization to be obtained, the amount of the treatment target 19 in the water to be treated, the temperature of the water to be treated, etc. It is preferable to determine in the range of 1 to 10 minutes. This is because within the above range, the influence on the processing object 19 is extremely small.

  The temperature of the treated water during aeration with ozone-containing gas (aeration temperature) takes into consideration the degree of sterilization to be obtained, the type of treatment object 19 in the treatment water, the amount of treatment object 19 in the treatment water, the aeration time, etc. For example, it is preferable to determine in the range of 0 to 55 ° C. This is because ozone is relatively stable within the above range.

As described above, the sterilization aid composition contains the component (A), thereby increasing the viscosity of the water to be treated and controlling the rising speed of the ozone gas bubble, so that the treatment target in the water to be treated has a relatively low concentration. A high bactericidal effect is obtained by aeration of the ozone-containing gas in the presence of the component (A). For this reason, the processing object can be sterilized economically and efficiently.
In addition, the sterilization efficiency can be further improved by using the component (B) in combination.

(Raw materials used)
[(A) component: water-soluble polysaccharide]
-Chitosan: Koyo Chitosan FH-80 (acetylation degree 80% or more), manufactured by Koyo Chemical Co., Ltd.-Carrageenan: NEWGELIN SV-80 (Lambda type), manufactured by Mitsubishi Corporation Foodtech Co., Ltd.

[(B) component: C1-C10 fatty acid glyceride]
・ Triacetin: Special grade reagent, manufactured by Kanto Chemical Co., Inc.

[Others]
-Malic acid: manufactured by Kanto Chemical Co., Ltd.-Sodium hypochlorite: New Bleach food additive (12%), manufactured by Lion Hygene Co., Ltd.

(Examples 1-8, Comparative Examples 1, 3)
<Cleaning by ozone treatment>
With reference to the ozone treatment of a general fresh food factory, the food (lettuce) is washed according to the following treatment order, and the bactericidal power is evaluated using the washed lettuce. The results are shown in Table 1. .
(Pre-washing process) → (Washing process) → (First rinsing process) → (Second rinsing process) → (Dehydration process)

In the pre-washing process, 500 g of lettuce cut to 1/8 (about 5 cm square) is put into an electric bucket (product name: N-Bk2, manufactured by Panasonic Corporation) in which 7 L of tap water is stored, and washing is performed for 2 minutes. Went.
In the washing process, lettuce was sterilized and washed by ozone treatment. The washing process uses a washing machine (product name: CW-C30A1, manufactured by Mitsubishi Electric Corporation; 2-tank washing machine), stores 40 L of tap water in the washing tub, and contains (A) component and (B ) Component was added according to the formulation shown in Table 1 to prepare treated water. Vegetables (lettuce) were added to the prepared water to be treated, and the mixture was stirred by stirring for 5 to 10 minutes under the ozone aeration conditions described below. The pH of the water to be treated was adjusted using malic acid. The viscosity of the water to be treated was measured and listed in Table 1.

The first rinsing step was performed by storing 40 L of tap water in the two-tub washing machine and stirring for 1 minute.
In the second rinsing step, 20 L of water was stored in a bucket, and lightly stirred using a sterilized stainless steel colander (diameter 15 cm, mesh 2 mm).
In the dehydration step, dehydration was performed for 1 minute in the dewatering tank of the 2-tank washing machine.
For the movement of the lettuce between each operation, a stainless colander sterilized with ethanol was used.

≪Ozone aeration conditions≫
The cleaning process in the above “<cleaning by ozone treatment>” is an ozone treatment device 100 shown in FIG. 2 that is self-made using a washing machine (product name: CW-C30A1, manufactured by Mitsubishi Electric Corporation; 2-tank washing machine). Was treated with ozone.
The ozone treatment apparatus 100 includes a two-tank washing machine 110 having a washing tub 111 and a dehydration tub 112, ozone-containing gas supply means 120, and water to be treated sucked from the washing tub 111. And a circulation system 140 that circulates while supplying ozone-containing gas from 120.
The washing machine 110 has a pulsator 113 as a stirring means at the bottom of the washing tub 111.
The ozone-containing gas supply means 120 includes an air cylinder 121 that sends out air, a regulator 122 that controls the flow rate (ozone concentration) of air, and an ozone generator 123 that generates ozone in the sent-out air to prepare an ozone-containing gas. (Product name: OZSD-3000A, manufactured by Sugawara Jitsugyo Co., Ltd.) and a mass flow controller 124 (Product name: MODEL5100, manufactured by Coflock Co., Ltd.) for controlling the flow rate of ozone-containing gas. The air cylinder 121 is connected to an ozone generator 123 via a regulator 122, and the ozone generator 123 is connected to a mass flow controller 124. The ozone generator 123 includes an ozone monitor (product name: EG-600, manufactured by Sugawara Jitsugyo Co., Ltd.) not shown.

The mass flow controller 124 is connected to a circulation pump 134, the pump 134 is connected to a pipe 132, and the pipe 132 is connected to a turning accelerator 135 that mixes gas and liquid by a spiral flow. The turning accelerator 135 is connected to a pipe 133, and the pipe 133 is connected to an air diffuser 137 provided in the washing tub 111. In this way, the aeration means 130 is configured by the pump 134, the turning accelerator 135, the air diffuser 137, and the pipes 132, 133.
The pump 134 is connected to a pipe 131, and the pipe 131 is connected to a strainer 136 (made of Teflon (registered trademark), mesh having a diameter of 1 mm) provided near the bottom of the washing tub 111. Thus, the aeration means 130, the pipe 131, and the strainer 136 constitute a circulation system 140 that circulates the water to be treated.
In addition, all the piping used for the ozone treatment apparatus 100 was made from vinyl chloride.

In the ozone treatment of this example, the water to be treated was circulated by the pump 134 at 10 L / min. The flow rate was as follows.
The ozone-containing gas was prepared by adjusting the amount of air sent out from the air cylinder 121 by a regulator 122 so that the ozone concentration was 5000 ppm by volume.
Supply of the ozone-containing gas to the water to be circulated is performed through the aeration means 130, and the flow rate of the ozone-containing gas is set to 0.4 L / min. The ozone-containing gas was supplied (aerated) to the water to be treated in the washing tub 111. The bubbles of ozone-containing gas generated in the water to be treated had an average bubble diameter of 50 μm.

(Comparative Example 2)
Lettuce was washed in the same manner as in Example 1 except that air was used instead of the ozone-containing gas. Bactericidal power was evaluated using lettuce after washing.

<PH measurement>
A pH meter (SevenEasy, manufactured by METTTLER TOLEDO) was used for pH measurement.

<Viscosity measurement>
The viscosity of the water to be treated was measured at 25 ° C. using an Ubbelohde viscometer (manufactured by Shibata Kagaku Co., Ltd.).

(Evaluation of sterilizing power)
Using the lettuce after washing (after the dehydration step) in “<Ozone cleaning>”, the bactericidal activity was evaluated by the following method.

<Sterilization standards>
As a sterilization standard, the lettuce was washed in the same manner as in Example 1 except that the water to be treated in the washing step was a 200 mass ppm sodium hypochlorite aqueous solution and stirred for 5 minutes without performing ozone aeration. About the lettuce after washing | cleaning, according to the following measuring method, the number of bacteria per 1g of lettuce was measured, and the measured number of bacteria was made into the sterilization reference value. In addition, the process by 200 mass ppm sodium hypochlorite aqueous solution is the sterilization method made into the standard in the industry of the cut product processing of fresh vegetables.

<Measurement method>
25 g of lettuce after washing was collected, and the lettuce was mixed with a peptone-containing buffer (3.56 g potassium dihydrogen phosphate, 18.2 g disodium hydrogen phosphate dodecahydrate, 4.3 g sodium chloride, 1.0 g peptone). It was adjusted to 1 liter of purified water and neutralized to pH 7.0). In addition to 225 mL, it was ground using a stomacher bag with a filter. This suspension was serially diluted and mixed with SCD agar medium (Nissui Pharmaceutical Co., Ltd.). This was repeated three times per sample, and after culturing at 37 ° C. for 24 hours, the number of viable bacteria was determined as the number of bacteria per gram of lettuce by counting the number of colonies.

<Evaluation method>
The number of bacteria of the lettuce after washing obtained in the washing of each example was used as a test measurement value, and the ratio represented by the test measurement value / sterilization reference value was used as an index value. The index value was defined as sterilizing power, and a value of less than 5 times corresponding to 1.0 × 10 ^0.7 was evaluated as “good”, and a value of 5 times or more was evaluated as “x”. In addition, if it is less than 1.0 * ^100.7 (less than 5 times), it can be judged that there exists a bactericidal effect substantially equivalent to the washing | cleaning using 200 mass ppm sodium hypochlorite.

As shown in Table 1, in Examples 1 to 8 using the water to be treated to which the sterilization aid composition of the present invention was added, the sterilization power evaluation was all “◯”. Among them, the highest bactericidal effect was obtained in Example 7 using the component (B). Moreover, in the comparison with Example 2 and Example 6, and the comparison with Example 4 and Example 5, when chitosan was used as (A) component, it turned out that a high bactericidal effect is acquired.
On the other hand, in Comparative Examples 1 and 3 in which the component (A) was not added, a sufficient bactericidal effect was not obtained. In addition, the bactericidal power was extremely low in Comparative Example 2 in which ozone aeration was not performed.
From these results, it was found that the bactericidal power was synergistically increased by ozone aeration in the presence of the component (A).

DESCRIPTION OF SYMBOLS 10,100 Ozone processing apparatus 12 Water tank 13,120 Ozone supply means 14,130 Aeration means 18 Stirring means 123 Ozone generator

Claims (4)

In the treated bacterium method killing it aeration ozone in water containing processed object,
The treated water contains a bactericidal aid composition containing a water-soluble polysaccharide,
The viscosity of the water to be treated is 1.01 to 25.0 mPa · s. The water-soluble polysaccharide is at least one selected from the group consisting of chitosan, xanthan gum, gellan gum, pectin, guar gum, locust bean gum, tamarind gum, carrageenan, and propylene glycol alginate. The sterilization method as described in 1 .. The sterilization method according to any one of claims 1 and 2, wherein the sterilization auxiliary composition further contains a fatty acid glyceride having 1 to 10 carbon atoms. The sterilization method according to any one of claims 1 to 3, wherein the object to be treated is a fresh food, and the water to be treated has a pH of 3 to 5.

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