Method for sterilizing and maintaining the freshness of cut vegetables
The method using peracetic acid and alternative solutions effectively sterilizes and preserves cut vegetables, addressing bacterial growth and freshness issues, with electrical conductivity monitoring for optimal storage.
Patent Information
- Authority / Receiving Office
- JP · JP
- Patent Type
- Patents
- Current Assignee / Owner
- MITSUBISHI GAS CHEM CO INC
- Filing Date
- 2020-11-02
- Publication Date
- 2026-06-02
AI Technical Summary
Cut vegetables face issues with bacterial growth and decreased freshness after cutting, necessitating effective sterilization and preservation methods.
A method involving treatment with an aqueous peracetic acid solution followed by an alternative aqueous solution, such as hypochlorous acid, sodium hypochlorite, or sodium acetate, to sterilize and maintain freshness, with optional electrical conductivity monitoring for freshness management.
The method effectively sterilizes and retains freshness in cut vegetables, extending their shelf life and reducing cell damage.
Smart Images
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Abstract
Description
Technical Field
[0001] The present invention relates to a method for sterilizing cut vegetables and maintaining freshness.
Background Art
[0002] In recent years, cut vegetables that have been cut into a predetermined size in advance have been circulated in the market. Cut vegetables can be cooked without cutting the vegetables, can also be provided as a salad, and can save the trouble of cooking, so the demand is large. By the way, for example, vegetables with a high sugar content such as green onions are likely to have problems such as the leachate coming out from the cut surface after cutting adhering to the surface of the vegetables and bacteria growing. In order to suppress the growth of such bacteria, vegetables are often sterilized. For example, Patent Document 1 discloses an invention related to a method for producing cut green onions, which includes a sterilization step of bringing green onions into contact with an aqueous solution at 45 to 60 °C of any one of an aqueous sodium hypochlorite solution, an aqueous organic acid solution, an aqueous percarboxylic acid solution, and an aqueous calcined calcium solution having a predetermined concentration and / or a predetermined pH before performing a cutting step of making the green onions into cut green onions.
Prior Art Documents
Patent Documents
[0003]
Patent Document 1
Summary of the Invention
Problems to be Solved by the Invention
[0004] In addition, cut vegetables also have the problem that their freshness is likely to decrease, so a method for sterilizing cut vegetables and maintaining freshness is required.
Means for Solving the Problems
[0005] The present invention provides a method for sterilizing and maintaining the freshness of cut vegetables, comprising the steps of treating the cut vegetables with an aqueous peracetic acid solution, and treating the cut vegetables that have undergone the first step with water or an aqueous solution other than the aqueous peracetic acid solution. Specifically, the present invention provides, for example, the following embodiments [1] to
[12] . [1] A method for sterilizing and maintaining the freshness of cut vegetables, comprising the following steps (1) to (2). Step (1): A step of treating the cut vegetables with an aqueous peracetic acid solution. Step (2): A step of treating the cut vegetables that have gone through step (1) with water or an aqueous solution (excluding peracetic acid aqueous solution). [2] The method according to [1], wherein the peracetic acid concentration of the peracetic acid aqueous solution used in step (1) is 10 to 250 ppm by mass. [3] The method according to [1] or [2] above, wherein the temperature of the peracetic acid aqueous solution used in step (1) is 1 to 70°C. [4] The method according to any one of the above [1] to [3], wherein the treatment in step (1) is an immersion treatment in which the cut vegetables are immersed in an aqueous peracetic acid solution. [5] The method according to [4] above, wherein the immersion time of the immersion treatment is 5 to 600 seconds. [6] The method according to any one of the above [1] to [5], wherein the aqueous solution used in step (2) is an aqueous solution containing at least one selected from hypochlorous acid, sodium hypochlorite, acetic acid, and sodium acetate. [7] The method according to any one of the above [1] to [6], wherein the concentration of the active ingredient in the aqueous solution used in step (2) is 5 to 1000 ppm by mass. [8] The method according to any one of the above [1] to [7], wherein the treatment in step (2) is the treatment of pouring water or the aqueous solution over the cut vegetables. [9] The method according to any one of the above [1] to [7], wherein the process in step (2) is to immerse the cut vegetables in water or the aqueous solution.
[10] The method according to any one of the above [1] to [9], wherein the cut vegetables that have gone through step (2) are placed in a bag or container and sealed for storage.
[11] The method according to any one of the above [1] to
[10] , further comprising step (3) below. • Step (3): A step to manage the freshness of the cut vegetables after step (2) by measuring their electrical conductivity.
[12] The method according to
[11] , wherein the freshness of the cut vegetables in step (3) is controlled so that the electrical conductivity is below a predetermined value. [Effects of the Invention]
[0006] According to a preferred embodiment of the present invention, it is possible to provide sterilized cut vegetables with improved freshness retention. [Modes for carrying out the invention]
[0007] [Method for sterilizing and preserving the freshness of cut vegetables according to the present invention] The present invention relates to a method for sterilizing and maintaining the freshness of cut vegetables, comprising the following steps (1) to (2). Step (1): A step of treating the cut vegetables with an aqueous peracetic acid solution. Step (2): A step of treating the cut vegetables that have gone through step (1) with water or an aqueous solution (excluding peracetic acid aqueous solution). Furthermore, a method according to one aspect of the present invention may further include the following step (3). • Step (3): A step to manage the freshness of the cut vegetables after step (2) by measuring their electrical conductivity.
[0008] In one embodiment of the present invention, there are no particular restrictions on the vegetables that are to be sterilized and have their freshness preserved, but examples include watermelon, melon, bitter melon, winter melon, pumpkin, lettuce, cabbage, komatsuna, spinach, garland chrysanthemum, mugwort, Chinese cabbage, bell pepper, green pepper, eggplant, cucumber, green beans, snow peas, garlic, onion, celery, tomato, bok choy, radish, turnip, carrot, broccoli, cauliflower, corn, perilla, parsley, ginger, asparagus, leek, beetroot, burdock, molokhia, yuzu, yam, sweet potato, potato, and the like.
[0009] In one embodiment of the present invention, the cut vegetables obtained by cutting the vegetables may be any vegetables having a cut surface on at least a part of their surface. For example, they may be cut vegetables from which parts unsuitable for consumption have been removed. Furthermore, they may be cut vegetables that can be directly used for various cooking methods or consumption without further cutting, and there are no particular restrictions on the cut form of the cut vegetables, and examples include julienne, thin slices, round slices, half-moon slices, thin strips, minced, ginkgo leaf slices, rectangular slices, irregular slices, batonnet slices, chunks, small pieces, rough chops, and shaved pieces. The details of each step in the method of the present invention will be described below.
[0010] <Process (1)> Step (1) is a process in which the cut vegetables are treated with a peracetic acid solution. In this process, the cut vegetables can be sterilized by treating them with a peracetic acid solution. Furthermore, the freshness retention of the cut vegetables can be improved. This is because the peracetic acid solution causes minimal damage to the cells of the cut vegetables, and the treatment with the peracetic acid solution enables effective sterilization, suppressing bacterial growth over time.
[0011] The method for preparing the peracetic acid aqueous solution used in this process is not particularly limited. It may be prepared by adding peracetic acid to water, or by adding a peracetic acid preparation containing peracetic acid to water. In addition, it is preferable that the peracetic acid preparation contains hydrogen peroxide together with peracetic acid. Examples of the water used for preparing the peracetic acid aqueous solution include tap water, pure water, ultrapure water, sterilized ultrapure water, ion-exchanged water, distilled water, etc., and sterilized ultrapure water is preferable.
[0012] From the viewpoint of sufficiently sterilizing cut vegetables and improving the freshness retention of cut vegetables, the peracetic acid concentration of the peracetic acid aqueous solution used in this process is preferably 10 to 250 ppm by mass, more preferably 12 to 200 ppm by mass, more preferably 15 to 150 ppm by mass, still more preferably 17 to 100 ppm by mass, even more preferably 19 to 70 ppm by mass, and particularly preferably 22 to 40 ppm by mass. In addition, in this specification, the peracetic acid concentration can be measured by Hiranuma Peracetic Acid Counter PA-300 (manufactured by Hiranuma Sangyo Co., Ltd., product name).
[0013] In addition, the peracetic acid aqueous solution used in this process may contain other solutes other than peracetic acid. The content of other solutes other than peracetic acid may be 0 to 50 parts by mass, 0 to 30 parts by mass, 0 to 20 parts by mass, 0 to 10 parts by mass, 0 to 5 parts by mass, 0 to 1 part by mass, 0 to 0.1 part by mass, 0 to 0.01 part by mass, or 0 to 0.001 part by mass with respect to 100 parts by mass of the total amount of peracetic acid contained in the peracetic acid aqueous solution.
[0014] From the viewpoint of sufficiently sterilizing cut vegetables and improving the freshness retention of cut vegetables, the temperature of the peracetic acid aqueous solution used in this process is preferably 1°C or higher, more preferably 3°C or higher, still more preferably 5°C or higher, even more preferably 7°C or higher, and particularly preferably 8°C or higher. Also, it is preferably 70°C or lower, more preferably 65°C or lower, more preferably 60°C or lower, still more preferably 50°C or lower, still more preferably 40°C or lower, even more preferably 30°C or lower, and particularly preferably 20°C or lower.
[0015] The treatment using an aqueous peracetic acid solution in this process may be a process of pouring the aqueous peracetic acid solution over the cut vegetables, or may be an immersion treatment of immersing the cut vegetables in the aqueous peracetic acid solution. However, from the viewpoint of sufficiently sterilizing the cut vegetables and improving the freshness retention of the cut vegetables, it is preferable that the cut vegetables be subjected to an immersion treatment of immersing them in the aqueous peracetic acid solution.
[0016] In addition, when performing the process of pouring the aqueous peracetic acid solution over the cut vegetables, the mass ratio [aqueous peracetic acid solution / cut vegetables] of the poured aqueous peracetic acid solution to the cut vegetables is preferably 0.5 to 20.0, more preferably 1.0 to 16.0, still more preferably 2.0 to 12.0, even more preferably 2.5 to 10.0, and particularly preferably 3.0 to 7.5 from the above viewpoints.
[0017] Also, when performing the immersion treatment of immersing the cut vegetables in the aqueous peracetic acid solution, the immersion time of the immersion treatment is preferably 5 to 600 seconds, more preferably 10 to 500 seconds, still more preferably 15 to 400 seconds, even more preferably 20 to 350 seconds, and particularly preferably 30 to 300 seconds from the above viewpoints. In addition, the mass ratio [aqueous peracetic acid solution / cut vegetables] of the aqueous peracetic acid solution used in the immersion treatment to the cut vegetables is preferably 1.0 to 20.0, more preferably 1.5 to 16.0, still more preferably 2.0 to 12.0, even more preferably 2.5 to 10.0, and particularly preferably 3.0 to 7.5 from the above viewpoints.
[0018] After the treatment in step (1) is completed, when the immersion treatment is being performed, it is preferable to take out the cut vegetables from the aqueous peracetic acid solution and perform the treatment in the next step (2) without performing another treatment.
[0019] <Step (2)> Step (2) is a step of performing a treatment on the cut vegetables that have undergone step (1) using water or an aqueous solution (excluding the aqueous peracetic acid solution). By passing through this step, the freshness retention of the cut vegetables can also be improved. The reason is considered to be that the damage to the cells of the cut vegetables during storage can be suppressed through this step.
[0020] Examples of water used in this process include tap water, pure water, ultrapure water, sterilized ultrapure water, ion-exchanged water, and distilled water, with sterilized ultrapure water being preferred.
[0021] Furthermore, the aqueous solution used in this process may be any aqueous solution other than a peracetic acid aqueous solution, and examples include aqueous solutions containing at least one selected from hypochlorous acid, sodium hypochlorite, acetic acid, sodium acetate, calcium nitrate, calcium hydroxide, pernitric acid, and ozone. Among these, from the viewpoint of improving the freshness retention of cut vegetables, the aqueous solution used in this process is preferably an aqueous solution containing at least one selected from hypochlorous acid, sodium hypochlorite, acetic acid, and sodium acetate, more preferably an aqueous solution containing at least one selected from hypochlorous acid, sodium hypochlorite, and sodium acetate, and even more preferably an aqueous solution of hypochlorous acid.
[0022] The method for preparing the aqueous solution used in this process is not particularly limited; it may be prepared by adding a solute to water, or by adding a formulation containing a solute to water. The above-mentioned hypochlorous acid aqueous solution may also be prepared by adding sodium hypochlorite or a preparation containing sodium hypochlorite to water to prepare a sodium hypochlorite aqueous solution, and then bubbling carbon dioxide gas through the sodium hypochlorite aqueous solution. Examples of water used in preparing the aqueous solution include tap water, pure water, ultrapure water, sterile ultrapure water, ion-exchanged water, and distilled water, with sterile ultrapure water being preferred.
[0023] The concentration of the active ingredient in the aqueous solution used in this process is preferably 5 ppm by mass or more, more preferably 7 ppm by mass or more, more preferably 10 ppm by mass or more, even more preferably 12 ppm by mass or more, even more preferably 15 ppm by mass or more, and particularly preferably 17 ppm by mass or more, and also preferably 1000 ppm by mass or less, more preferably 900 ppm by mass or less, more preferably 800 ppm by mass or less, even more preferably 700 ppm by mass or less, even more preferably 600 ppm by mass or less, and particularly preferably 550 ppm by mass or less. In this specification, the concentration of the active ingredient refers to the concentration of components other than water. Hypochlorous acid and sodium hypochlorite can be measured by sodium thiosulfate titration (Reference: Ministry of Health, Labour and Welfare Notification No. 318, September 29, 2003). Sodium acetate can be measured by perchloric acid titration (Reference: JIS K8371).
[0024] The effective chlorine concentration of the hypochlorous acid solution used in this process should be set as described above for both the lower and upper limits, from the viewpoint of improving the freshness preservation of cut vegetables. However, it may also be set to 500 ppm by mass or less, 400 ppm by mass or less, 300 ppm by mass or less, 200 ppm by mass or less, 150 ppm by mass or less, 100 ppm by mass or less, 90 ppm by mass or less, 80 ppm by mass or less, 70 ppm by mass or less, or 60 ppm by mass or less.
[0025] The effective chlorine concentration of the hypochlorous acid aqueous solution used in this process is set as described above for the lower and upper limits, from the viewpoint of improving the freshness preservation of cut vegetables. However, it may also be 20 ppm or more, 30 ppm or more, 40 ppm or more, 60 ppm or more, 80 ppm or more, 100 ppm or more, 120 ppm or more, 140 ppm or more, 160 ppm or more, or 180 ppm or more. Alternatively, it may be 500 ppm or less, 450 ppm or less, 400 ppm or less, 350 ppm or less, 300 ppm or less, or 250 ppm or less.
[0026] The concentration of the active ingredient (sodium acetate) in the aqueous sodium acetate solution used in this process should have the lower and upper limits set as described above, from the viewpoint of improving the freshness retention of cut vegetables. However, it may also be set to 20 ppm or more, 50 ppm or more, 70 ppm or more, 100 ppm or more, 150 ppm or more, 200 ppm or more, 250 ppm or more, 300 ppm or more, 350 ppm or more, or 400 ppm or more.
[0027] The temperature of the aqueous solution used in this process is preferably 1 to 70°C, more preferably 1 to 50°C, even more preferably 1 to 30°C, even more preferably 1 to 20°C, and particularly preferably 1 to 10°C, from the viewpoint of improving the freshness preservation of the cut vegetables.
[0028] The treatment using water or the aqueous solution in this process may be a treatment in which water or the aqueous solution is poured over the cut vegetables, or it may be a treatment in which the cut vegetables are immersed in water or the aqueous solution. In this process, when using water, it is preferable to run water over the cut vegetables. Furthermore, when using an aqueous solution, it is preferable to immerse the cut vegetables in the aqueous solution.
[0029] Furthermore, when the cut vegetables are subjected to a treatment involving rinsing with water or the aqueous solution, the mass ratio of the rinsing water or aqueous solution to the cut vegetables [water or aqueous solution / cut vegetables] is preferably 0.5 to 20.0, more preferably 1.0 to 16.0, even more preferably 2.0 to 12.0, even more preferably 2.5 to 10.0, and particularly preferably 3.0 to 7.5, from the viewpoint of improving the freshness retention of the cut vegetables.
[0030] Furthermore, when immersing cut vegetables in water or the aforementioned aqueous solution, the immersion time is preferably 5 to 600 seconds, more preferably 10 to 480 seconds, even more preferably 15 to 300 seconds, even more preferably 20 to 180 seconds, and particularly preferably 25 to 120 seconds, from the viewpoint of improving the freshness retention of the cut vegetables.
[0031] The cut vegetables that have undergone this process may be stored in a sealed bag or container. The bags mentioned above may be paper bags, or plastic bags such as polyethylene bags or polypropylene bags. Examples of the above-mentioned containers include plastic containers made from resins such as polyethylene and polypropylene, ceramic containers, and metal containers. There are no particular restrictions on the method of sealing; for example, for a bag, one method is to close the opening with a rubber band or a zipper. For a container, one method is to put a lid over the opening, or to close the opening with food wrap made of polyethylene film, polypropylene film, polyvinyl chloride, etc.
[0032] <Process (3)> The method of the present invention may include a step (3) in which the freshness of the cut vegetables after step (2) is managed by measuring their electrical conductivity. One method for measuring electrical conductivity is to immerse the cut vegetables that have undergone step (2) in water and measure the electrical conductivity of the extracted water after immersion using a commercially available measuring device. The water used here is preferably pure water, ultrapure water, sterilized ultrapure water, ion-exchanged water, distilled water, etc., with sterilized ultrapure water being more preferable.
[0033] The higher the measured electrical conductivity, the more damaged the cells of the cut vegetables are considered to be, and the more electrolytic substances (sodium ions, calcium ions, etc.) are leaching out from within the cells. Therefore, the freshness of cut vegetables can be managed by measuring their electrical conductivity. One method for managing the freshness of the cut vegetables in this process is to control the electrical conductivity so that it is below a predetermined value. The threshold for electrical conductivity is predetermined, and if it exceeds this threshold, it can be determined that electrolytes from within the cells are leaching out and the freshness of the cut vegetables has deteriorated. Therefore, by controlling the electrical conductivity to be below a predetermined value, the freshness of the cut vegetables can be managed. [Examples]
[0034] The present invention will be described below with reference to examples, but the present invention is not limited in any way to these examples. The measurements in the examples were taken using the following methods or apparatus. Please note that Examples 1, 2, 4-6, 11, 12, 15, 17, 19, 20, and 23 below are for reference only.
[0035] Preparation Example 1 (Preparation of peracetic acid aqueous solution) A peracetic acid preparation (manufactured by Mitsubishi Gas Chemical Company, trade name "Dia Power FP", food-grade peracetic acid, 14% peracetic acid, 5.6% hydrogen peroxide) was dissolved in sterile ultrapure water to prepare peracetic acid aqueous solutions with peracetic acid concentrations of 10 ppm, 20 ppm, 30 ppm, 50 ppm, 80 ppm, and 300 ppm.
[0036] Preparation Example 2 (Preparation of sodium hypochlorite aqueous solution) Sodium hypochlorite (manufactured by AS ONE Corporation, product name "Sani-Clear Commercial Disinfectant and Bleach," with an effective chlorine concentration of 6.0-7.0% by mass (at the time of factory shipment)) was dissolved in sterile ultrapure water to prepare an aqueous sodium hypochlorite solution with an effective chlorine concentration of 200 ppm by mass.
[0037] Preparation Example 3 (Preparation of hypochlorous acid solution) Sodium hypochlorite (manufactured by AS ONE Corporation, product name "Sani-Clear Commercial Disinfectant and Bleach") with an effective chlorine concentration of 6.0-7.0% by mass (at the time of factory shipment) was dissolved in sterile ultrapure water, and then carbon dioxide was bubbled through the solution to adjust the pH to 5.5, thereby preparing hypochlorous acid aqueous solutions with effective chlorine concentrations of 20 ppm by mass, 30 ppm by mass, and 50 ppm by mass.
[0038] Preparation Example 4 (Preparation of sodium acetate aqueous solution) Sodium acetate (manufactured by Fujifilm Wako Pure Chemical Industries, Ltd., trade name "Sodium Acetate", 98.5% sodium acetate by mass) was dissolved in sterile ultrapure water to prepare an aqueous sodium acetate solution with a sodium acetate concentration of 500 ppm by mass.
[0039] The cut vegetables used in the following examples and comparative examples are as follows. In all cases, any parts of the cut vegetables that showed signs of spoilage, discoloration, insect damage, etc., were removed. • "Leaf lettuce": Cut leaf lettuce, roughly chopped into approximately 5cm squares using a stainless steel knife, was used as the test sample. • "Cucumber": The test sample was a cucumber thinly sliced to a thickness of approximately 2 mm using a stainless steel slicer. • "Paprika": The test sample was cut paprika, thinly sliced to a thickness of approximately 2 mm using a stainless steel slicer. • "Carrots": Cut carrots, which were thinly sliced with a stainless steel knife into pieces approximately 5 cm long and 3 mm wide, were used as the test sample. • "Daikon radish": Cut daikon radish, which was cut into strips approximately 5 cm long and 3 mm wide using a stainless steel knife, was used as the test sample.
[0040] Examples 1-11, Comparative Examples 1-9 The above-mentioned cut leaf lettuce was used as a test sample. As step (1), the test sample was immersed in a peracetic acid aqueous solution with a peracetic acid concentration of five times its mass as shown in Table 1, for the immersion time and temperature (temperature of the peracetic acid aqueous solution) as shown in Table 1. Next, as step (2), the test samples removed from the peracetic acid aqueous solution after the immersion treatment were subjected to the following treatments: in Examples 1-7 and 10, the test samples were immersed in sterilized ultrapure water at 2°C in an amount five times the mass of the test sample; and in Examples 8-10, the test samples were immersed in an aqueous solution with a solute concentration listed in Table 1, in an amount five times the mass of the test sample, for the immersion time and temperature (temperature of the aqueous solution) listed in Table 1. After the immersion treatment, the test samples were removed from the aqueous solution. For Comparative Examples 1 to 9, the samples were removed from the peracetic acid solution after the immersion treatment, and the process was completed without going through step (2).
[0041] Examples 12-23 One of the above-mentioned cut cucumbers, cut bell peppers, or cut carrots was used as a test sample. As step (1), the test samples of cut vegetables listed in Table 2 were immersed in a peracetic acid aqueous solution with a peracetic acid concentration listed in Table 2, at a concentration five times their mass. The immersion time and immersion temperature (temperature of the peracetic acid aqueous solution) are as shown in Table 2. Next, as step (2), the test samples removed from the peracetic acid solution after the immersion treatment were subjected to a treatment in which sterilized ultrapure water at 2°C was poured over them in an amount five times the mass of the test samples.
[0042] Examples 24-30 The above-mentioned cut radish was used as a test sample. As step (1), the test sample was subjected to an immersion treatment in a peracetic acid aqueous solution with a peracetic acid concentration of five times its mass as shown in Table 2, for the immersion time and temperature (temperature of the peracetic acid aqueous solution) as shown in Table 2. Next, as step (2), the test samples removed from the peracetic acid aqueous solution after the immersion treatment were subjected to the following treatments: in Examples 21 and 25, the test samples were immersed in sterilized ultrapure water at 2°C in an amount five times the mass of the test sample; and in Examples 22-24 and 26-27, the test samples were immersed in a hypochlorous acid aqueous solution with an effective chlorine concentration as shown in Table 2, in an amount five times the mass of the test sample, for the immersion time and temperature (temperature of the aqueous solution) as shown in Table 2. After the immersion treatment, the test samples were removed from the aqueous solution.
[0043] After draining any moisture from the test samples processed as described above, the test samples were placed in sterilized sample bags (NASCO Whirl-Pak, manufactured by NASCO Corporation, product name "NASCO Whirl-Pak," polyethylene film bags with a resealable opening), the openings were sealed, and the samples were stored refrigerated at 10°C. Changes in appearance, texture, and the presence or absence of odor were checked daily, and the number of days until a predetermined deterioration state was reached was defined as the "freshness retention period." The freshness retention performance was then evaluated according to the following criteria. These results are shown in Tables 1 and 2. [Evaluation Criteria for Freshness Preservation] A+: The product has a shelf life of 6 days or more. A: The shelf life is between 4 and 5 days. B: The shelf life is 3 days. • C: The shelf life is 2 days or less.
[0044] [Table 1]
[0045] [Table 2]
[0046] Tables 1 and 2 show that the cut vegetables processed through steps (1) and (2) of Examples 1 to 30 had a freshness retention period of 4 days or more, indicating good freshness retention. On the other hand, Table 1 shows that the cut vegetables processed only through step (1) of Comparative Examples 1 to 9 had a freshness retention period of 3 days or less, indicating inferior freshness retention compared to the examples.
[0047] In Examples 1, 3, 4, and 24-30, the electrical conductivity of the test sample removed after step (2) was measured in step (3) using the following procedure. First, 10g of the test sample was immersed in 40g of sterile ultrapure water (the extraction water) for 30 minutes. The electrical conductivity of the extracted water after immersion was measured using a pH / EC tester (GroLine Combo (H198131)). The measurement was performed twice, and the average values are shown in Table 3.
[0048] [Table 3]
[0049] As shown in Table 3, in all of the examples, the electrical conductivity of the water extracted from the cut vegetables in the test samples was less than 0.20 mS / cm, and the evaluation of freshness preservation was also good.
Claims
1. A method for sterilizing and maintaining the freshness of cut vegetables, comprising the following steps (1) to (2). Step (1): A step of treating the cut vegetables with an aqueous peracetic acid solution having a peracetic acid concentration of 20 to 30 ppm by mass, wherein the temperature of the aqueous peracetic acid solution is 1 to 10°C. Step (2): A step of treating the cut vegetables that have gone through step (1) with water or an aqueous solution (excluding peracetic acid aqueous solution).
2. The method according to claim 1, wherein the treatment in step (1) is an immersion treatment in which the cut vegetables are immersed in an aqueous peracetic acid solution.
3. The method according to claim 2, wherein the immersion time for the immersion treatment is 5 to 600 seconds.
4. The method according to any one of claims 1 to 3, wherein the aqueous solution used in step (2) is an aqueous solution containing at least one selected from hypochlorous acid, sodium hypochlorite, acetic acid, and sodium acetate.
5. The method according to any one of claims 1 to 4, wherein the concentration of the active ingredient in the aqueous solution used in step (2) is 5 to 1000 ppm by mass.
6. The method according to any one of claims 1 to 5, wherein the process in step (2) is the process of pouring water or the aqueous solution over the cut vegetables.
7. The method according to any one of claims 1 to 5, wherein the process in step (2) is a process of immersing the cut vegetables in water or the aqueous solution.
8. The method according to any one of claims 1 to 7, wherein the cut vegetables that have gone through step (2) are placed in a bag or container, sealed, and stored.
9. The method according to any one of claims 1 to 8, further comprising the following step (3). Step (3): A step to manage the freshness of the cut vegetables after step (2) by measuring their electrical conductivity.
10. The method according to claim 9, wherein the freshness of the cut vegetables in step (3) is controlled so that the electrical conductivity is below a predetermined value.