JP2009298750A - Method for sterilizing sprout vegetable seed and method for cultivating sprout vegetable - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a sterilization method that sterilizes putrefactive bacteria to cause putrefaction in cultivation of sprout vegetable, completely sterilizes food poisoning bacteria such as pathogenic Escherichia coli O157, Salmonella, Listeria etc., and produces a sprout vegetable seed for growing a sprout vegetable eatable without anxiety. <P>SOLUTION: The method for sterilizing a sprout vegetable seed comprises immersing a sprout vegetable seed in high-temperature hot water at 80-90°C for 10-50 seconds in a sterilization water tank 2, immersing the sprout vegetable seed in cold water in a cooling water tank 4 and quenching the sprout vegetable seed to carry out sterilization treatment of putrefactive bacteria, subsequently, immersing the sprout vegetable seed in an aqueous solution of hypochlorous acid having a chlorine content of ≥1,500 ppm for ≥2 hours so as to completely sterilize food poisoning bacteria. The sprout vegetable seed after the sterilization treatment is cultivated to carry out cultivation of eatable sprout vegetable seed. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention is a method for sterilizing raw seeds before growing, in order to prevent food poisoning, which has recently become a problem with black mung bean sprouts, mung bean sprouts, soybean sprouts, alfalfa sprouts and other bean sprouts, squid radishes and other sprout vegetables. The present invention relates to a method for cultivating sprout vegetables without fear of food poisoning.

  Various bean sprouts, sprout vegetables typified by radish have spread worldwide from Asia to Europe due to their high nutritional value, but in recent years food poisoning by Salmonella and pathogenic E. coli O157 has become a problem . In the United States, consumers are weak in the gastrointestinal system, such as children and the elderly, and are cautioning them to eat sprouts. As a countermeasure, the US FDA recommended bean sprouts producers to inspect salmonella and pathogenic E. coli O157 for sterilization of seeds and microbiological examination of sprinkling wastewater during cultivation (US Food and Drug Administration 1999, Docket Nos. 99D-4488 and 99D-4489). As a seed sterilization method for preventing food poisoning caused by such bud vegetables, sterilization with hypochlorous acid having an effective chlorine concentration of 20,000 ppm is recommended. Since chlorous acid is used, it is not only a dangerous work for an operator, but also an effective sterilizing effect is not necessarily obtained.

  On the other hand, it is important how to promote the growth of so-called sprout vegetables, such as various sprouts, that are edible when seeds are germinated and grown a little. Therefore, sprout vegetables are cultivated at a temperature and humidity suitable for germination and growth, but such a growth environment is also suitable for propagation for various microorganisms and bacteria. In general, seeds are contaminated not only with the outer surface of the seed coat but also with the inner surface in some cases, and such microorganisms cause spoilage of sprouts during cultivation. In particular, in the case of bean sprouts, it is extremely difficult to suppress microbial growth because germination and growth are performed in a high temperature and high humidity environment while supplying water.

  Under such circumstances, the present applicant has previously described that as a physical method that does not use dangerous drugs for sterilization of bud vegetable seeds, shoot vegetable seeds in high-temperature water at 70 ° C. or higher are 10 to 30 ° C. A sterilization method using hot water, which consists of immersing for a second and then rapidly cooling, has been proposed (Patent Document 1). In this sterilization method, the seeds of sprout vegetables are soaked in high-temperature water at 70 ° C. or higher for 10 to 30 seconds, so that they are accurately exposed to a predetermined high temperature for a predetermined time without impairing the function of the seeds as an organism. Can be sterilized. According to this sterilization method for bud vegetable seeds, it is possible to cultivate by sterilizing spoilage bacteria adhering to the seeds of bud vegetable and suppressing spoilage of the bud vegetable.

In addition, as a research at the laboratory level after that, the sterilization conditions by hot water treatment of mung bean seeds against dangerous pathogens Salmonella and pathogenic E. coli O157 were presented (Journal of Food Protection Vol. 71, No.4. 2008, Pages 830-834).
However, in actual bean sprouts cultivation, a larger amount of raw material seeds must be sterilized continuously, and it has not been confirmed whether the seeds after the sterilization treatment are normally sprouts.
Therefore, microorganisms that cause food poisoning, including pathogenic E. coli O157, Salmonella, Listeria, etc., can be completely killed and eaten live without sacrificing the vital activity of germination and growth of seeds as organisms. There is a need for a method of sterilizing sprout vegetable seeds that can grow safe sprout vegetables.
Japanese Patent No. 3225474

  The present invention sterilizes spoilage bacteria that cause spoilage in cultivation of sprout vegetables, and also disinfects food poisoning bacteria such as pathogenic Escherichia coli O157, Salmonella, Listeria, etc. It is an object to provide an effective method of sterilizing bud vegetable seeds that can be cultivated. In particular, an object of the present invention is to provide a method for sterilizing sprouts and vegetable seeds that can kill both spoilage bacteria and food poisoning bacteria without using strong chemicals or the like that would impede raw eating. . Another object of the present invention is to provide a method for cultivating sprout vegetables that can cultivate sprout vegetables that can be eaten raw without fear of food poisoning by food poisoning bacteria while suppressing the occurrence of spoilage due to microbial propagation.

  The present invention solves the above-mentioned problems in the sterilization treatment of bud vegetable seeds, and does not impair the vital functions of seed embryos, but invades from the seed surface and, in some cases, from seed trauma or cracks, present in seeds. It is immersed in high-temperature hot water of 80-90 ° C effective for sterilization of living microorganisms for 10-50 seconds and then rapidly cooled to bring it into contact with each other accurately for an appropriate time, and subsequently hypochlorous acid having a chlorine concentration of 1500 ppm or more. A method for sterilizing sprout vegetable seeds comprising completely sterilizing remaining food poisoning bacteria by soaking in an acid aqueous solution for 2 hours or more is employed.

  According to the present invention, the specific temperature of 80-90 ° C. hot water that exposes the bud vegetable seeds and the specific time of 10-50 seconds are selected according to the target bud vegetable seeds. In addition, the seeds are rapidly exposed after being immersed in hot water so that the seeds are exposed accurately to an optimal temperature of 80-90 ° C. for a predetermined period of time, and the seeds as living organisms are not damaged by heat. It is also effective to pre-heat the seeds before soaking them in a predetermined high temperature hot water for the purpose of accurately exposing the bud vegetable seeds for a predetermined time at an optimal temperature of 80-90 ° C. .

  Moreover, in order to solve the said subject about cultivation of sprout vegetables, this invention continues after the sterilization process which immerses the sprout vegetable seed before growing for 10-50 second in 80-90 degreeC hot water, and quenches rapidly. Then, a method of cultivating bud vegetable seeds that have been sterilized so as to completely sterilize food poisoning bacteria by immersing them in a hypochlorous acid aqueous solution having a chlorine concentration of 1500 ppm or more for 2 hours or more is adopted. The method of immersing seeds in high-temperature hot water at 80 to 90 ° C. and setting the soaking time in hypochlorous acid aqueous solution are selected according to the target bud vegetable seeds.

  In the method for sterilizing sprout vegetable seeds of the present invention, as described above, the sprout vegetable seeds are immersed in high-temperature hot water at 80 to 90 ° C. for 10 to 50 seconds, and then rapidly cooled, whereby the sprout vegetable seeds as life forms are obtained. Bacteria adhering to vegetable seeds exposed to high temperatures that can sterilize bacteria without causing damage to the seeds are sterilized, and subsequently immersed in hypochlorous acid aqueous solution having a chlorine concentration of 1500 ppm or more for 2 hours or more Thus, the remaining food poisoning bacteria are completely sterilized. By applying two-stage sterilization treatment to the bud vegetable seeds, it is possible to grow without spoilage due to microbial propagation, and to cultivate bud vegetables that are safe even if eaten raw without food poisoning bacteria. it can. Further, in the method according to the present invention, by immersing in high-temperature hot water of 80 to 90 ° C. and then rapidly cooling, it is precisely exposed to a predetermined high temperature for a predetermined time without affecting the life activity of the seed, and subsequently chlorine By immersing in a hypochlorous acid aqueous solution with a concentration of 1500 ppm or more for 2 hours or more, the remaining food poisoning bacteria are completely sterilized, and the sterilization treatment does not have a negative effect. When growing sprout vegetables using the applied seeds, the resulting sprout vegetables have almost no problems due to these sterilization treatments, and even if the sprout vegetables after cultivation are eaten raw It is safe. Thus, the bud vegetable seeds sterilized by the present invention germinate without decreasing the germination rate and grow without causing spoilage, and a safe bud vegetable can be obtained even when raw.

  Furthermore, since the sprout vegetables grown by the cultivation method according to the present invention are in a state of less microbial propagation, the sprout vegetables with good shelf life can be harvested according to the present invention. Moreover, according to the cultivation method of the sprout vegetables by this invention, it immerses in the hypochlorous acid aqueous solution with a chlorine concentration of 1500 ppm or more continuously for 2 hours or more with respect to the seed after immersing in the hot water of 80-90 degreeC. Because it is cultivated using bud vegetable seeds that have been treated to completely sterilize the food poisoning bacteria, the two-stage pickling helps the sterilization effect and grows safe bud vegetables without spoilage. Let them eat raw and harvest safe bud vegetables.

The present inventor has further developed research on sterilization of vegetable seeds with high temperature hot water, and obtained the present invention by searching for the effect of sterilization treatment against food poisoning bacteria in consideration of practical application in actual bean sprouts cultivation plant. is there. Tests dealing with dangerous food poisoning bacteria can only be handled within a specific experimental facility (P2, P3 level) by law, so the actual test machine (1/10 size) reduced to be usable in that experimental facility And searched for sterilization conditions.
Moreover, the seeds after the treatment were germinated normally and compared with the treatment conditions that can be produced as normal bean sprouts. The high-temperature hot water treatment condition according to the present invention is approximately 80 to 90 ° C. and 10 to 50 seconds in terms of the condition that food poisoning bacteria can be safely sterilized. This hot water treatment with high-temperature hot water needs to be performed within a predetermined number of seconds with an accurate hot water temperature so as not to impair the vitality of seed germination and subsequent growth on bean sprouts. Moreover, it is necessary to cool as soon as possible after the high-temperature hot water treatment. Also, in order to maintain reproducibility as sterilization conditions, it is necessary to repeat accurate processing temperature and time.

  From the above, and considering that a large amount of seeds are treated every day, sterilization with high-temperature hot water requires processing by a machine. The present applicant has developed a hot water sterilizer for bud vegetable seeds by the method described in Patent Document 1 previously invented, and verified the effect by performing these treatments with a test machine in which the actual machine was reduced. In addition, a cultivation test was actually conducted, and it was confirmed that the processing conditions were not problematic as long as production was not hindered in bean sprouts production. FIG. 1 shows the configuration of an actual sterilizer using high-temperature hot water, and FIG. 2 shows the configuration of a reduced sterilization tester. As shown in FIG. 1, the actual machine has a mesh basket 3 for immersing bud vegetable seeds in hot water at a predetermined temperature in a raw material hopper 1, a sterilized water tank 2, and a sterilized water tank 2 for a predetermined time in a sterilized water tank 2. The cooling water tank 4 for rapidly cooling the vegetable seeds of the sprout which finished the sterilization processing is provided. The seeds after the sterilized vegetable seeds having a predetermined weight (3-5 kg) to be sterilized are received from the raw material hopper 1 into the basket 3 and immersed in the sterilized water tank 2 to finish the sterilization, Thus, it is configured to be quickly transferred into the cooling water tank 4. The actual machine also includes an exhaust hood 5 and a control panel 6 that cover the upper part of the sterilizing water tank 2.

  As shown in FIG. 2, the test machine has a mesh basket 11 for storing bud vegetable seeds (300-500 g) to be sterilized, and a support portion 12 that supports the basket 11, and is supported by the support portion. An actuator 13 is provided that moves the basket 11 up and down relative to the sterilized water tank 10 and immerses the bud vegetable seeds in the basket 11 in high-temperature hot water in the sterilized water tank 10 for a predetermined time. 14 is a heater that heats the water in the sterilizing water tank 2 to a predetermined high temperature, and 15 is a thermometer that measures the temperature of the hot water in the sterilizing water tank 10. Reference numeral 16 denotes a drain valve for draining the water in the sterilizing water tank 10. Reference numeral 17 denotes a control panel, 18 is a start button, and 19 is an automatic control monitor.

In addition, it is effective to immerse in an aqueous solution containing a sterilizing agent after high-temperature hydrothermal treatment from the enrichment test performed on seeds sterilized by high-temperature hydrothermal treatment or after germination. As a processing condition, it was found that the effective chlorine concentration by hypochlorous acid is preferably 1500 ppm or more and 2 hours or more.
In the process of acquiring knowledge of the present invention, chlorous acid, chlorous acid, chlorine gas, and the like were used as a sterilizing agent as well as sodium hypochlorite and calcium hypochlorite. In addition, it has been found that as a safer drug, sterilization treatment is also performed using electrolyzed water and ozone water to have a sterilizing effect. Soaking with these chemicals may be incorporated into the seed soaking process in normal bean sprouts cultivation. Also, from the viewpoint of preventing secondary contamination in the soaking process, it is recommended to use a drug at an acceptable concentration in consideration of safety.

As described above, by the immersion treatment in high-temperature hot water according to the present invention and subsequent immersion in a hypochlorous acid aqueous solution, spoilage bacteria and food poisoning bacteria that are problematic in bean sprouts are completely sterilized, and food poisoning brought from raw materials There is no risk of contamination of the bean sprouts. The present invention is proposed as one of effective means that can be used practically as a method for sterilizing raw seeds of sprout vegetables recommended by the US FDA.
Since the water tank which performs the immersion process by the hypochlorous acid aqueous solution performed after the heat sterilization process by the processing apparatus by the high temperature hot water shown in FIG. 1, FIG. 2 may be an appropriate water tank, the illustration is abbreviate | omitted.

[Experiment 1]
The rate of germination rate and normal growth rate when mung bean seeds were processed at the temperature and time shown in Table 1 using the actual reduction test machine shown in Fig. 2 developed for hot water treatment of sprout vegetable seeds. I confirmed. Hot water treatment was performed automatically for each time by a test machine set with water temperature (accuracy: ± 0.5 ° C.). Raw material seeds (300 g) are put in the basket 11 of the machine, and the switch is automatically lowered to the sterilized water tank 2 containing hot water. After the seeds were sterilized with hot water for each treatment time, the basket 11 automatically rose again, so that the basket 11 was quickly immersed in tap water in the cooling tank 3 to cool the seeds. A part of the result of this experiment is shown in Table 1. It was found that sterilization treatment with almost no problem in growth was performed at 85 ° C. for up to 40 seconds and at 88 ° C. for up to 20 seconds.

[Example 1]
Mung bean seeds (500 g) inoculated with food poisoning bacteria (E. coli O157: H7) were treated with hot hot water and further immersed in an aqueous solution of sodium hypochlorite. That is, first, seeds previously inoculated with Escherichia coli O157 are sterilized with high-temperature hot water under the following conditions, and then immersed in an aqueous sodium hypochlorite solution to inspect the number of remaining Escherichia coli O157 in the seeds after sterilization treatment. did. Further, some of the remaining seeds were enriched overnight in peptone water and examined for the presence of the inoculated E. coli O157. In addition, after the other remaining seeds were cultivated at room temperature (about 20 ° C.) for 72 hours, the presence or absence of the inoculated E. coli O157 was also examined. All of these tests were conducted in a facility of P2 level or higher.
The treatment with high-temperature hot water was performed at 85 ° C. for 40 seconds and at 88 ° C. for 20 seconds.
Hot water treatment was automatically performed for each time by a test machine set to a water temperature (accuracy ± 0.5 ° C.). By injecting the seed material that has been inoculated into the basket 11 and pressing the switch, the basket 11 is automatically lowered into the sterilizing water tank 2 and sterilized with high-temperature hot water for each treatment time. Since the basket 11 ascends, the basket 11 was quickly immersed in the cooling water in the cooling tank 3 containing cold water (about 0 ° C.) to cool the seeds.
The soaking treatment with hypochlorous acid was carried out at an effective chlorine concentration of 2,000 ppm for 2 hours (room temperature of about 20 ° C.) with an aqueous solution about twice the amount of seeds. A part of the result of this experiment is shown in Table 2. Inoculated Escherichia coli O157 was not detected after either hot water treatment, but in the test for enrichment with peptone water or the test after germination for 72 hours, the presence of the bacteria was observed. After high-temperature hydrothermal treatment at 85 ° C for 40 seconds, when immersed in an aqueous sodium hypochlorite solution with a chlorine concentration of 2,000 ppm for 2 hours, residual bacteria were observed both after enrichment and after germination. I couldn't. In this treatment, it was determined that the inoculated E. coli O157 was completely sterilized.

[Example 2]
The same test as in Example 1 was performed using Salmonella as a food poisoning inoculum. The results are shown in Table 3. In the case of Salmonella as well, as in the case of Escherichia coli O157, the appearance of bacteria was not observed in the test after the high-temperature hot water treatment, but the residual was observed in the test after the enrichment or after the germination treatment. After treatment with hot water at 85 ° C for 40 seconds, when immersed in an aqueous solution of sodium hypochlorite with a chlorine concentration of 2,000 ppm for 2 hours, no bacteria remained after the germination or germination treatment, and it was completely sterilized. It was judged that it was done.

[Example 3]
The decrease in germination rate of mung bean seeds by hot water treatment was investigated. Seed Table 4 shows the germination rate and normal growth rate when non-inoculated seeds are treated with high-temperature hydrothermal treatment and further immersed in an aqueous sodium hypochlorite solution having a chlorine concentration of 2,000 ppm. there were. As in Experimental Example 1, even when the hot water treatment was performed, the germination rate was hardly decreased, but the growth rate was slightly decreased. There was almost no effect on the germination rate and growth rate by soaking with sodium hypochlorite after high-temperature hydrothermal treatment.

[Example 4]
In order to examine the concentration of the sodium hypochlorite aqueous solution used in the sterilization treatment performed after high-temperature heat treatment immersed in hot water at 85 ° C. for 40 seconds, the same test as in Examples 1 and 2 was conducted for the sodium hypochlorite aqueous solution. The concentration was changed. The results are shown in Table 5. At an effective chlorine concentration of 1500 ppm or more, it was judged that the inoculated E. coli O157 and Salmonella were completely sterilized.

[Example 5]
After the high-temperature hot water treatment of immersing in hot water at 85 ° C. for 40 seconds, the immersion time with an aqueous sodium hypochlorite solution having a chlorine concentration of 2,000 ppm was examined. Tests similar to those of Examples 1 and 2 were performed by changing the time of immersion in the aqueous sodium hypochlorite solution. The results are shown in Table 6. In the 90 minute immersion treatment, Escherichia coli O157 was sterilized, but Salmonella seemed to remain. It was judged that it was completely sterilized by the immersion treatment for 120 minutes (2 hours).

[Example 6]
Under the same treatment conditions as in Example 3, the seeds were sterilized and then sprouts were cultivated normally. The hot water treatment was performed with 1.5 kg of raw material seeds using an actual machine. The results are shown in Table 7. The weight and magnification of sprouts after harvest were compared. A slight decrease in yield (about 5%) was observed compared to the case of cultivation with untreated raw materials. This was thought to be due to ungerminated or poorly germinated by hot water treatment, but other normally germinated seeds grew to normal sprouts and were considered to have no problem as a product.

  As seen in the above examples, it was shown that even the seeds artificially inoculated with food poisoning bacteria can be completely sterilized by the present invention. Even in actual bean sprouts cultivation, it can be seen that the raw material seeds are effectively sterilized by the method of the present invention, and the risk of food poisoning, which is a problem in bean sprouts cultivation, can be suppressed to a very low level.

The perspective view which shows the whole structure of the real machine developed for the hot water sterilization of the bud vegetable seed. The perspective view which shows the structure of the test machine used in order to verify the sterilization method of the sprout vegetable seed by this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Raw material hopper 2 Sterilization water tank 3 Basket 4 Cooling water tank 5 Exhaust hood 6 Control panel 10 Sterilization water tank 11 Basket 12 Support part 13 Actuator 14 Heater 15 Thermometer 16 Drain valve 17 Control panel 18 Start button 19 Automatic control monitor

Claims (2)

  Sterilize the bud vegetable seeds by immersing them in high-temperature hot water at 80-90 ° C. for 10-50 seconds, followed by rapid cooling, and then immersing in a hypochlorous acid aqueous solution with a chlorine concentration of 1500 ppm or more for 2 hours or more. A sterilization method for bud vegetable seeds characterized in that the remaining food poisoning bacteria are completely sterilized.   A method for cultivating sprout vegetables characterized by cultivating the sprout vegetable seeds subjected to the sterilization treatment according to claim 1.