In recent years, food poisoning caused by enterohemorrhagic Escherichia coli O-157 and Salmonella has attracted attention worldwide, not just in Japan, raising significant concerns about food hygiene internationally. One important point that food manufacturers need to be aware of is that these foodborne illnesses are different from previous knowledge, as even a small number of bacteria can pose a risk of illness. It is not simply a matter of preventing pathogenic bacteria from growing at the time of consumption, but rather a need for hygienic management where pathogenic bacteria are not allowed to exist in the food. To ensure food quality, the Hazard Analysis and Critical Control Points (HACCP) system has been introduced. However, the first step is to achieve complete sterilization, which involves thorough sterilization and disinfection of ingredients, packaging containers, processing machinery, work environments (floors, walls, air, etc.), and hands, as well as implementing measures to prevent microbial contamination.
In the food industry, sterilization primarily relies on methods such as heat sterilization and disinfection. Common sterilizing agents include chlorine-based agents like sodium hypochlorite, enzymatic agents like hydrogen peroxide and ozone, and alcohol. However, none of these methods are universally applicable, and they require attention to factors such as energy costs, drug residue in products, and their impact on personnel and the environment. Additionally, their usage methods and application areas are subject to various limitations, so it is necessary to incorporate a TPO (Time, Place, Occasion) approach and use them according to their specific characteristics.
Among them, electrolytically activated water, also known by various names such as "electrolyzed disinfection water," "super-oxidized water," "strongly acidic electrolyzed water," and "weakly acidic electrolyzed water," has attracted attention. In this article, it will be referred to as "electrolyzed functional water." The introduction of electrolyzed functional water generating devices for the purpose of sterilization began about ten years ago, initially gaining attention in the medical field for preventing MRSA infections (devices permitted for disinfecting medical instruments). In the food industry, the occurrence of foodborne illnesses caused by O-157 became an opportunity to rapidly popularize research on the effectiveness and convenience of electrolyzed functional water.
Our company conducted research with the aim of providing durable equipment for the dairy industry's strict hygiene management methods. Eventually, we developed a new type of electrolyzed functional water generating device that differs from conventional methods and began selling it under the name "purester" from April 2006.
This article mainly discusses the features and effects of electrolyzed functional water and the "purester" device, as well as addressing the issues related to the widespread use of electrolyzed functional water in the food industry.
1) The Essence Of Electrolyzed Functional Water
Due to the different production methods and properties, the electrolyzed functional water is named by various names by the manufacturers, but any of the names explains "the prepared water obtained by electrolyzing the chloride ion solution", and almost all of them have confirmed the sterilization of bacteria and viruses force.
Regarding the bactericidal power of electrolyzed functional water, it was said that it was caused by high oxidation reduction potential (ORP), but according to recent research, it is found that the main body of its bactericidal power is hypochlorous acid (free form). That is, the electrolyzed functional water is a chlorine-based sterilizing solution similar to hypochlorous acid soda.
One of the characteristics of electrolyzed functional water, the low chlorine concentration of 1/10 of hypochlorous soda can also achieve the same bactericidal effect. It is known that the bactericidal power of free hypochlorous acid is stronger than that of hypochlorous acid ions. The ratio of the free and ionic forms of this hypochlorous acid depends on the change in pH. If it is alkaline, there will be more ionic forms, and if it is neutral or weakly acidic, there will be more free forms. If it is acidic, it is easy to become chlorine gas and diffuse from the solution. Please refer to Figure 12 for this relationship diagram). Hypochlorite soda is generally used at a high concentration of 100-200ppm, but since the pH value is 8-9, the ratio of hypochlorite ions present is relatively high. On the other hand, the pH of the electrolytic functional water is around 2 to 6, and the ratio of hypochlorous acid (free type) and chlorine gas is high. From this point, it can be seen that the concentration of hypochlorous acid soda is lower than that of I can show a high effect, too.
2) Electrolyzed Functional Water Generating Device
There are more than 20 manufacturers of electrolytic functional water generators, but these generators are mainly divided into 3 types according to the different generation methods and raw materials. Please refer to Table 1.
The pioneers of the device still use this method today. The flowchart is shown in Figure 2.
The salt solution is electrolyzed in a diaphragm electrolyzer, the anode mainly produces chlorine gas, and the cathode produces caustic soda and hydrogen gas. Chlorine gas at the anode immediately reacts with water to form hypochlorous acid and hydrochloric acid. When separated from the cathode by a diaphragm, the anode water must be acidic and have a low pH. Generally, it is used when the pH is lower than 3. The pH value of hypochlorous acid is unstable, but it will diffuse into chlorine gas in a short period of time in the open state, which will also reduce the concentration of effective chlorine. Therefore, it is best to prepare it before use, and the diffused chlorine gas should also be considered. The liquid containing caustic soda obtained in the cathode chamber is called "alkaline ionized water". Because this method electrolyzes all the relatively weak solutions and needs to increase the electrolysis voltage, it consumes more power than other methods. When the amount of chlorine gas produced is the same, the power consumption is dozens of times that of (B) and (C) dilution methods. At the same time, we do not think it is suitable for high-capacity installations requiring large electrolyzers due to too much power consumption.
The "weakly acidic and neutral type" in (B) uses an electrolytic cell without a diaphragm. This way there is no separation of the anode and cathode waters, so the anode and cathode liquids will mix. After electrolysis of the salt solution, the hypochlorous acid and hydrochloric acid produced in the anode will be completely neutralized with the caustic soda produced in the cathode to become table salt and hypochlorous soda. In order to obtain free hypochlorous acid solution, it is necessary to add acid to the salt solution raw material in advance, or to neutralize the resulting liquid. In this method, the preparation solution is obtained by electrolyzing a relatively concentrated salt solution and diluting the decomposed product with water. Therefore, the electricity consumed when generating chlorine is not as high as that of the strongly acidic diaphragm electrolysis method. And because alkaline ionized water will not be produced, water will not be wasted.
"QINHUANG" (C) is a kind of non-diaphragm type, weakly acidic and neutral type electrolytic functional water generating device, and its main feature is that only hydrochloric acid is used as the source of chloride ions. The flowchart of "QINHUANG" is shown in Figure 3. In the electrolytic cell, according to the following reaction formula, 2 mol of hydrochloric acid generates 1 mol of hypochlorous acid and 1 mol of hydrochloric acid.
By repeating the above reaction, hypochlorous acid can be continuously generated from hydrochloric acid. The concentration of hydrochloric acid in the stock solution and the degree of electrolysis determine the pH of the resulting solution (also affected by the hardness of the water), so that weakly acidic and neutral electrolytic functional water can be easily obtained. The main feature of this method is that hydrochloric acid is used as an ion source, which can improve the electrolysis efficiency. Compared with table salt with the same concentration of chloride ions, the chlorine produced per unit of electrolytic power is about 1.5 times. Moreover, this method does not use salt, and the generated electrolytic functional water does not contain salt. At the same time, there is no adverse situation when salt is contained, such as side effects of salt on plants, and crystallization may occur when repeated spraying in indoor and other places, etc., and it is safe to use.
In addition, a device (hypochlorous soda type) that electrolyzes salt solution in an electrolytic cell without a diaphragm to prepare alkaline hypochlorous soda is also sold on the market. This is a method for producing hypochlorous soda by electrolysis. The main component of water is hypochlorite ion.
Fungicides, which have been conveniently used for a long time, have begun to be pointed out their harm in recent years. This harm mainly refers to the direct impact of the use of fungicides, but the environmental pollution caused by exhaust gas is also an important issue. Moreover, food safety issues such as the prevention and control of food poisoning caused by pathogenic microorganisms are also top priorities for the food industry. Unfortunately, there is no epoch-making method to solve the above two problems at the same time, but it is necessary to make a choice that best suits the object.
Therefore, we are convinced that one of the options is to popularize electrolytic functional water with various characteristics that previous fungicides did not have in the food field. I believe this also has great social significance.
Further popularizing the use in the food industry and solving the problem of food additives is also an important issue. Fortunately, the "Functional Water Research Promotion Group" under the Ministry of Health, Welfare and Drug Administration was officially established in 1993 to conduct research on functional water such as electrolyzed functional water. Dissemination activities such as research grants, research promotion, and research presentations. It is hoped that the consortium-based production science will work together to determine the position of electrolyzed functional water in the Food Sanitation Law as soon as possible.
In addition, slightly acidic water can also be used in a wide range of fields besides the food field. For example, it can be used for cleaning of breeding rooms in livestock, for feed water, etc., because there is no salt damage, it can also be used for watering plants and soil in gardening, and spraying in greenhouses. Dilute the electrolyzed product of hydrochloric acid into seawater instead of fresh water to obtain purester water with the same composition as seawater, which can also be used in fishery. In addition, it can be used for cleaning and deodorization of hotels, restaurants, and rooms in public facilities because it has little impact on the surroundings.
It is necessary to care about food hygiene. Therefore, seeking new sterilization methods in the medical and agricultural fields is a common demand not only in Japan, but also in the world. I hope that the electrolyzed functional water developed in Japan can be widely used in the world.