Discoloration inhibiting method of vegetable

Abstract

To provide novel means for inhibiting discoloration due to green color fading of vegetable while demonstrating superior bacteriostasis even when treating vegetables with sodium acetate.SOLUTION: A discoloration inhibiting method of vegetable includes a step of immersing vegetables into a treatment liquid containing sodium acetate, glycine, lysozyme, sucrose fatty acid ester, and at least one kind selected from a group consisting of acetic acid, malic acid, adipic acid, citric acid, fumaric acid, lactic acid, glucono delta lactone, gluconic acid, and salt thereof (excluding sodium acetate).SELECTED DRAWING: None

Description

[Technical field]

[0001] The present invention relates to a method for inhibiting discoloration of vegetables. [Background technology]

[0002] Boiled or other heat-processed vegetables are not only used as ingredients in commercial processed foods, but are also in high demand for home use due to the ease of cooking. However, after cooking, vegetables tend to fade in color and their appearance deteriorates. It is known that this type of discoloration due to green fading occurs through a mechanism different from the enzyme-induced browning of raw vegetables or the simple Maillard reaction. The mechanism of green fading has not been fully elucidated, but it is said that one of the main causes is the decomposition of chlorophyll into pheophytin due to heating during cooking or exposure to light while on store shelves.

[0003] Various means for suppressing discoloration of vegetables accompanied by green fading have been known so far. For example, Patent Document 1 discloses a means for adding 3-(4-hydroxy-3-methoxyphenyl)propionic acid obtained by culturing lactic acid bacteria in a medium containing specific components to tea, etc. Patent Document 2 discloses a means for adding a nucleic acid-related compound containing a purine skeleton to vegetables. As described in these documents, it is also known that ascorbic acid has the effect of suppressing green fading.

[0004] On the other hand, since live bacteria easily grow in vegetables after heat processing, ingredients that exert a bacteriostatic effect are often added from the viewpoint of improving the preservation quality. Such bacteriostatic ingredients include, for example, sodium acetate. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] JP 2023-056309 A [Patent Document 2] JP 2020-167970 A Summary of the Invention [Problem to be solved by the invention]

[0006] However, as shown in the test examples below, it was found that when an effective amount of sodium acetate was used as a bacteriostatic component, discoloration of vegetables was accelerated.

[0007] Therefore, an objective of the present invention is to provide a new means for suppressing discoloration of vegetables due to fading of their green color while exhibiting excellent bacteriostasis even when the vegetables are treated with sodium acetate. [Means for solving the problem]

[0008] As a result of intensive research, the inventors have found that by immersing vegetables in a treatment solution containing sodium acetate, glycine, lysozyme, sucrose fatty acid ester, and at least one organic acid or organic acid salt selected from the group consisting of acetic acid, malic acid, adipic acid, citric acid, fumaric acid, lactic acid, glucono-delta-lactone, gluconic acid, and salts thereof (excluding sodium acetate), discoloration of the vegetables can be suppressed while exhibiting excellent bacteriostatic properties, and have completed the present invention.

[0009] That is, the present invention includes the following aspects, but is not limited to these. [1] Sodium acetate, glycine, lysozyme, sucrose fatty acid esters, and At least one organic acid or organic acid salt selected from the group consisting of acetic acid, malic acid, adipic acid, citric acid, fumaric acid, lactic acid, glucono-delta-lactone, gluconic acid, and salts thereof (excluding sodium acetate). A method for inhibiting discoloration of vegetables, comprising the step of immersing vegetables in a treatment liquid containing the above-mentioned compound. [2] The method for inhibiting discoloration described in [1], wherein the vegetables have been subjected to a heating process. [3] The method for inhibiting discoloration according to [1] or [2], wherein the vegetables are green vegetables. Effect of the Invention

[0010] The method for inhibiting discoloration of vegetables of the present invention can inhibit discoloration of vegetables due to fading of their green color while exerting excellent bacteriostasis. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0011] [How to prevent discoloration] The discoloration suppression method of the present invention is, more specifically, a method for suppressing discoloration accompanied by fading of vegetables into green, and is characterized by comprising a step of soaking vegetables in a treatment solution containing sodium acetate, glycine, lysozyme, sucrose fatty acid ester, and at least one organic acid (referred to as organic acid (A)) or a salt thereof selected from the group consisting of acetic acid, malic acid, adipic acid, citric acid, fumaric acid, lactic acid, glucono-delta-lactone, gluconic acid, and salts thereof (excluding sodium acetate).

[0012] (Processing solution) The solvent contained in the treatment liquid in which the vegetables are soaked is not particularly limited as long as it is food-safe, but it is preferable that the solvent contains water (for example, an aqueous solution).

[0013] There are no particular limitations on the sodium acetate and glycine, so long as they are food-safe, and they may be natural or synthetic products.

[0014] The organic acid (A), acetic acid, malic acid, adipic acid, citric acid, fumaric acid, lactic acid, glucono-delta-lactone and gluconic acid, are not particularly limited as long as they can be used in foods, and may be natural or synthetic. For acetic acid, glacial acetic acid, vinegar, etc. can be used, but glacial acetic acid is preferred from the viewpoint of suppressing the addition of unpleasant flavors to vegetables.

[0015] The salt of the organic acid (A) is a salt of acetic acid, malic acid, adipic acid, citric acid, fumaric acid, lactic acid, glucono-delta-lactone, and gluconic acid, excluding sodium acetate, and examples thereof include alkali metal salts such as sodium salts and potassium salts, alkaline earth metal salts such as magnesium and calcium, ammonium salts, etc. The salt of the organic acid (A) is not particularly limited as long as it can be used in foods, and may be a natural or synthetic product.

[0016] The sucrose fatty acid ester is an ester bond between at least one hydroxyl group of sucrose and a fatty acid, and is not particularly limited as long as it can be used in food, but a monoester is preferable, and a monoester between a hydroxyl group at the 6th position of a glucose unit of sucrose and a fatty acid is more preferable. As such a sucrose fatty acid ester, for example, one that meets the standards described in the "Sucrose Fatty Acid Ester" section of the composition standards of the 10th edition of the Japanese Standards for Food Additives can be suitably used. As the sucrose fatty acid ester, a specific compound can be used alone, or two or more different compounds can be used in combination.

[0017] The HLB (Hydrophile-lipophile balance) value of the sucrose fatty acid ester can be, for example, 1 or more, 2 or more, or 3 or more, preferably 5 or more, more preferably 9 or more, and even more preferably 15 or more. The HLB value of the sucrose fatty acid ester can be, for example, 20 or less, 18 or less, or 16 or less.

[0018] In this specification, the HLB value of sucrose fatty acid ester is the value listed in the catalog, quality specification, etc. of the manufacturer or distributor, and in the case of a non-commercial product or a product without a standard value, the value calculated by the Griffin formula is used.

[0019] The number of carbon atoms of the fatty acid in the sucrose fatty acid ester is preferably 10 to 22, more preferably 12 to 18. A preferred specific example of the sucrose fatty acid ester is at least one selected from the group consisting of sucrose laurate, sucrose myristic acid ester, sucrose palmitate, sucrose stearate, sucrose oleate, sucrose behenic acid ester, and sucrose erucic acid ester. From the viewpoint of suppressing the influence on the flavor of the combined composition during storage, saturated fatty acid esters are preferred, and among them, sucrose palmitate or sucrose stearate are more preferred.

[0020] Lysozyme is an enzyme that hydrolyzes mucopolysaccharides that constitute bacterial cell walls, and is not particularly limited as long as it is usable in food. For example, egg white lysozyme, which is described in the "Lysozyme" section of the ingredient specifications of the 10th edition of the Japanese Standards for Food Additives, is preferably used.

[0021] The content of sodium acetate in the treatment solution is preferably 0.38 mass% or more, more preferably 0.5 mass% or more, and even more preferably 0.6 mass% or more, based on the total amount of the treatment solution, from the viewpoint of improving bacteriostasis, and is preferably 2.5 mass% or less, more preferably 2.2 mass% or less, and even more preferably 2 mass% or less, from the viewpoint of suppressing the effect of its characteristic bitter taste.

[0022] The content of glycine in the treatment solution is preferably 0.0086 mass% or more, more preferably 0.05 mass% or more, and even more preferably 0.1 mass% or more, based on the total amount of the treatment solution, from the viewpoint of achieving good bacteriostasis, and from the viewpoint of suppressing the effect of its unique sweetness, it is preferably 3 mass% or less, more preferably 2.5 mass% or less, and even more preferably 2 mass% or less.

[0023] The content of lysozyme in the treatment solution is preferably 0.0021% by mass or more, more preferably 0.005% by mass or more, and even more preferably 0.01% by mass or more, based on the total amount of the treatment solution, from the viewpoint of achieving good bacteriostasis, and is preferably 0.1% by mass or less, more preferably 0.05% by mass or less, and even more preferably 0.02% by mass or less, from the viewpoint of suppressing the effect of its unique astringent taste.

[0024] The content of sucrose fatty acid ester in the treatment solution is preferably 0.0021 mass% or more, more preferably 0.005 mass% or more, and even more preferably 0.01 mass% or more, based on the total amount of the treatment solution, from the viewpoint of improving bacteriostasis, and is preferably 0.1 mass% or less, more preferably 0.05 mass% or less, and even more preferably 0.02 mass% or less, from the viewpoint of suppressing turbidity of the treatment solution.

[0025] The total content of the organic acid (A) or a salt thereof in the treatment solution is preferably 0.022 mass% or more, more preferably 0.03 mass% or more, and even more preferably 0.04 mass% or more, based on the total amount of the treatment solution, from the viewpoint of improving bacteriostasis, and is preferably 0.5 mass% or less, more preferably 0.2 mass% or less, and even more preferably 0.1 mass% or less, from the viewpoint of suppressing the characteristic sourness.

[0026] The content of glycine per 1 part by mass of sodium acetate in the processing solution is preferably 0.034 to 7.9 parts by mass, more preferably 0.1 to 3 parts by mass, even more preferably 0.15 to 2 parts by mass, and even more preferably 0.22 to 1.2 parts by mass, from the viewpoints of more significantly exhibiting the effects of the present invention and improving the flavor. The content of lysozyme per 1 part by mass of sodium acetate in the treatment liquid is preferably 0.00085 to 0.27 parts by mass, more preferably 0.001 to 0.2 parts by mass, even more preferably 0.002 to 0.1 parts by mass, and even more preferably 0.0055 to 0.04 parts by mass, from the viewpoints of more pronounced effects of the present invention and good flavor. The content of sucrose fatty acid ester per 1 part by mass of sodium acetate in the treatment liquid is preferably 0.00085 to 0.27 parts by mass, more preferably 0.001 to 0.2 parts by mass, even more preferably 0.002 to 0.1 parts by mass, and even more preferably 0.0055 to 0.04 parts by mass, from the viewpoints of more prominently exhibiting the effects of the present invention and suppressing turbidity of the treatment liquid. The total content of the organic acid (A) or a salt thereof per 1 part by mass of sodium acetate in the treatment liquid is preferably 0.0088 to 1.4 parts by mass, more preferably 0.01 to 1 part by mass, even more preferably 0.03 to 0.5 parts by mass, and still more preferably 0.057 to 0.2 parts by mass, from the viewpoints of more significantly exhibiting the effects of the present invention and improving the flavor.

[0027] In order to more significantly exhibit the effects of the present invention, the content of sucrose fatty acid ester per 1 part by mass of lysozyme in the treatment solution is preferably 0.02 to 50 parts by mass, more preferably 0.1 to 10 parts by mass, even more preferably 0.2 to 5 parts by mass, and even more preferably 0.5 to 2 parts by mass.

[0028] In order to more significantly exhibit the effects of the present invention, the content of sucrose fatty acid ester per 1 part by mass of glycine in the treatment liquid is preferably 0.0001 to 1.2 parts by mass, more preferably 0.001 to 1 part by mass, even more preferably 0.002 to 0.8 parts by mass, and even more preferably 0.03 to 0.5 parts by mass.

[0029] From the viewpoints of more significantly exhibiting the effects of the present invention and improving the flavor, the pH of the treatment liquid is preferably 4 or more, more preferably 4.2 or more, even more preferably 4.5 or more, even more preferably 4.8 or more, and particularly preferably 5 or more, and from the viewpoint of improving bacteriostasis, the pH of the treatment liquid is preferably 7 or less, more preferably 6.5 or less. The pH of the treatment liquid may be, for example, 6.4 or less, 6.3 or less, 6.2 or less, 6.1 or less, 6 or less, or less than 6.

[0030] In addition to the above-mentioned components and vegetables, the treatment liquid may contain at least one of other food ingredients (meat, marine products, mushrooms, fruits, etc., or processed products thereof); various additives (solvents (water, ethanol, etc.), thickening polysaccharides, organic acids other than organic acid (A) or their salts, emulsifiers, chelating agents (phytic acid, phosphates, etc.), sugars, sugar alcohols, oligosaccharides, sweeteners, flavorings, coloring agents, edible metal salts, excipients (dextrin, lactose, sugar alcohols, etc.), amino acids, vitamins, minerals, preservatives, shelf life enhancers, antibacterial agents, bacteriostatic agents, antioxidants (vitamin C, vitamin E, etc.), etc.).

[0031] In one embodiment, the treatment liquid may be a broth, a seasoning liquid such as stock or sauce, or cooking water (hot water).

[0032] The above-mentioned various additives are not particularly limited as long as they are used in foods and do not impair the effects of the present invention. For example, thickening polysaccharides include xanthan gum, galactomannan (e.g., locust bean gum, guar gum, tara gum, etc.), deacylated gellan gum, native gellan gum, carrageenan (e.g., kappa type, iota type, lambda type, etc.), tamarind seed gum, glucomannan, psyllium seed gum, macrophomopsis gum, agar, gelatin, pectin (e.g., HM pectin, LM pectin, etc.), alginic acid, alginates (e.g., sodium alginate, potassium alginate, calcium alginate, etc.), pullulan, curdlan, tragacanth gum, ghatti gum, gum arabic, arabinogalactan, karaya gum, furcellaran, chitin, succinoglycan, celluloses (e.g., carbo Examples of suitable cellulose acetate preparations include cellulose acetate esters (e.g., cellulose acetate esters ...

[0033] Examples of the organic acid or a salt thereof other than the organic acid (A) include tartaric acid, sorbic acid, benzoic acid, propionic acid, itaconic acid, and salts thereof.

[0034] Examples of the emulsifier include glycerin fatty acid esters (e.g., distilled monoglyceride, reactive monoglyceride, di- or triglyceride, organic acid monoglyceride, polyglycerin fatty acid ester, polyglycerin condensed ricinoleic acid ester, etc.), sorbitan fatty acid ester, propylene glycol fatty acid ester, yucca extract, saponin, stearoyl lactylate (e.g., sodium salt, calcium salt, etc.), polysorbate, soybean lecithin, egg yolk lecithin, and enzyme-treated lecithin.

[0035] Examples of preservatives, shelf life enhancers, antibacterial agents or bacteriostatic agents include nisin, sorbates (such as potassium sorbate), polylysine, protamine, and ethanol.

[0036] From the viewpoint of further enhancing the effects of the present invention, the treatment liquid may contain ascorbic acid or a salt thereof.

[0037] (Vegetables) Examples of vegetables that are the subject of the present invention for preventing discoloration include leafy vegetables (e.g., spinach, Chinese cabbage, cabbage, lettuce, mizuna, chrysanthemum, celery, onion, Chinese chive, green onion, komatsuna, bok choy, takana, rapeseed, nozawana, broccoli, asparagus, udo, fern, bracken, water shield, molokheiya, myoga, etc.); beans (soybeans (including edamame, etc.), adzuki beans, kidney beans, peas (including green peas, snow peas, etc.), cowpeas, broad beans, sword beans, peanuts, chickpeas, etc.); fruits. Vegetables (pumpkin, eggplant, tomato, bell pepper, cucumber, zucchini, wax gourd, bitter melon, okra, chili pepper, shishito pepper, avocado, corn, etc.); root vegetables (for example, radish, carrot, potato, burdock, lotus root, taro, sweet potato, turnip, bamboo shoots, beets, arrowhead, lily root, Chinese burdock, yacon, ginger, wasabi, scallion, etc.); seaweed (wakame, kelp, green laver, asakusa nori, kasanori, sea lettuce, hijiki, mozuku, sea grapes, etc.), tea, etc.

[0038] Among the vegetables, green vegetables having chlorophyll in the edible part are preferable from the viewpoint of more prominently exerting the effect of the present invention. Examples of such green vegetables include spinach, Chinese cabbage, cabbage, lettuce, mizuna, chrysanthemum, celery, onion, Chinese chive, green onion, komatsuna, bok choy, takana, rapeseed, nozawana, broccoli, asparagus, udo, osmanthus, bracken, water shield, mulukhiyah, soybean, kidney bean, pea, broad bean, sword bean, pumpkin, bell pepper, cucumber, zucchini, bitter melon, okra, shishito pepper, avocado, wasabi, etc.

[0039] The vegetables may be ones that have been previously processed, such as cut, peeled, seasoned, skewered, etc.

[0040] The vegetables may have been subjected to a heating process in advance. As shown in the following examples, the discoloration suppression method of the present invention can suppress discoloration even when a treatment liquid is applied after heat processing. In addition, heat processing can be performed simultaneously with treatment with the treatment liquid, for example, by using the broth from boiling as the composition of the treatment liquid. Alternatively, the treatment liquid can be applied before the vegetables are heat processed. From the viewpoint of allowing the treatment liquid to remain on the vegetables for a long time and act, it is preferable to immerse the vegetables in the treatment liquid simultaneously with or after the heat processing.

[0041] Examples of the heat processing of the above vegetables include boiling, steam heating, microwave heating, stir-frying, deep-frying, oven heating, etc. The temperature during the heat processing is, for example, 50° C. or more, 60° C. or more, 70° C. or more, 80° C. or more, 90° C. or more, or 95° C. or more, and, for example, 120° C. or less or 100° C. or less. The heat processing time is, for example, 5 minutes or more, 10 minutes or more, 20 minutes or more, or 30 minutes or more, and, for example, 6 hours or less, 2 hours or less, or 1 hour or less.

[0042] (Immersion in processing solution) The amount of the processing liquid can be appropriately changed depending on the type and processing state of the vegetables, the amounts of the components of the processing liquid, the temperature, etc. The amount of the processing liquid can be, for example, 0.05 to 20 parts by mass, 0.1 to 10 parts by mass, 0.2 to 5 parts by mass, or 0.5 to 2 parts by mass per part by mass of the vegetables.

[0043] The time for immersing the vegetables in the processing solution can be appropriately changed depending on the type and processing state of the target vegetables, the component amounts of the processing solution, the temperature, etc., but is, for example, 1 second or more, 10 seconds or more, 30 seconds or more, 1 minute or more, 2 minutes or more, 5 minutes or more, 10 minutes or more, 20 minutes or more, 30 minutes or more, and for example, 6 hours or less, 2 hours or less, or 1 hour or less. From the viewpoint of sufficient immersion, the immersion time is preferably 2 minutes or more.

[0044] In one embodiment, the temperature of the treatment liquid when soaking the vegetables is, for example, 50° C. or more, 60° C. or more, 70° C. or more, 80° C. or more, 90° C. or more, or 95° C. or more, and, for example, 120° C. or less, or 100° C. or less. For example, these temperatures can be used when soaking the vegetables simultaneously with heat processing or when soaking the vegetables after heat processing.

[0045] In one embodiment, the temperature of the treatment liquid when the vegetables are soaked may be, for example, 90° C. or less, 70° C. or less, 50° C. or less, 30° C. or less, 20° C. or less, 10° C. or less, or 4° C. or less. For example, when the vegetables are soaked in the treatment liquid after heat processing, the temperature may be one of these.

[0046] The temperature of the treatment liquid does not need to be constant, and may be varied. For example, vegetables may be immersed in the treatment liquid during heat processing, and then the immersion may be continued while cooling.

[0047] The method of the present invention may further include steps such as a heat processing step for the vegetables, a draining step, other cooking steps, a sterilization step, a cooling / freezing step, and a packaging step, depending on the type of vegetables and the manner of processing.

[0048] (Effects, uses, etc.) In the discoloration suppression method of the present invention, the discoloration of vegetables, particularly fading to green, is suppressed by the treatment liquid. When vegetables are prone to fading to green by heating, the effect of the present invention is more pronounced. In addition, the treatment liquid exhibits excellent bacteriostatic properties and suppresses the harsh taste peculiar to sodium acetate. In addition, there is no need to remove the treatment liquid by washing or the like after application to vegetables, and the process of contamination with various bacteria can be reduced, thereby improving the shelf life.

[0049] Vegetables to which the discoloration suppression method of the present invention has been applied can be eaten directly or after removing the treatment solution by washing or the like. Vegetables that have been treated by the method of the present invention are particularly suitable for long-term storage foods such as frozen foods, chilled foods, canned foods, bottled foods, retort foods, tube foods, and dressings, or foods that are poorly sealed during distribution and sales or foods that are easily deteriorated when exposed to temperatures above room temperature, such as cooked foods and side dishes. Vegetables to which the discoloration suppression method of the present invention has been applied can be used in, for example, simmered dishes such as boiled vegetables, oden, and simmered kelp; soups such as soups and miso soup; curry, stew, sauces, etc. containing vegetables; tsukudani; salads; grilled dishes; boiled dishes; steamed dishes; salads, etc. EXAMPLES

[0050] The present invention will be described in more detail below using examples. However, these examples do not limit the present invention. In the examples, "parts" and "%" mean "parts by mass" and "% by mass", respectively.

[0051] [Test Example 1. Discoloration prevention test for heat-processed vegetables] (Preparation of test formulations and treatment solutions) To prepare the treatment liquid for cooked vegetables, first, preparations A to D in Table 1 below were prepared by a conventional method. Sucrose fatty acid esters with HLB values ​​in the range of 9 to 16 were used. Preparation A was dissolved at 2.0%, preparation B at 1.0%, preparation C at 0.5%, and preparation D at 2.0% in water to prepare aqueous solutions, which were then used as treatment liquids for vegetables (the compositions of the treatment liquids are shown in Table 2).

[0052] [Table 1]

[0053] [Table 2]

[0054] (Vegetable heat processing, preservation testing and bacterial count testing) The following three types of vegetables were heat-processed and divided into five test groups (soaked in additive-free water, soaked in the four types of treatment liquids shown in Table 2 above). The number of bacteria was confirmed by culturing the samples on standard agar medium at 35°C for 48 hours, and the general viable bacteria count (cfu / g) per 1g of sample was measured by colony counting method. <Green peas, spinach> (1) Frozen green peas or frozen spinach were placed in five times the amount of boiling water, and then heated for 30 seconds after re-boiling. (2) The green peas or spinach were drained through a sieve and placed in twice the amount of processing solution and soaked at 10°C for 30 minutes. (3) Drain the processing liquid through a sieve and then place the vegetables in a sterilized container. (4) Samples for confirming the initial bacterial count were taken and then stored at 25°C for 24 or 48 hours. (5) The number of bacteria after storage was confirmed. <Boiled kidney beans> (1) 1 part by mass of frozen kidney beans and 2 parts by mass of a seasoning liquid having the formulation shown in Table 3, which contains one of the treatment liquid preparations shown in Table 1, were combined and simmered for 2 minutes. (2) The resulting stew was placed in a sterilized container. (3) Samples for confirming the initial bacterial count were taken and then stored at 25°C for 24 or 48 hours. (4) The number of bacteria after storage was confirmed.

[0055] [Table 3]

[0056] (Evaluation of discoloration prevention effect) (1) Measurement sample Measurement samples were prepared by carrying out the following treatment on the vegetables of the non-additive group before the storage test (i.e., immediately after heat processing) and the vegetables of the Examples and Comparative Examples after the above-mentioned 24-hour or 48-hour storage. Five grams of green peas were filtered through a 60 mesh filter and used as the measurement sample. First, the leaves of spinach were mixed with the same mass of ion-exchanged water and crushed in a mixer. The crushed material was centrifuged at 3000 rpm, and 5 g of solids were used as a measurement sample. For boiled kidney beans, the same mass of ion-exchanged water was added to the boiled beans and crushed in a mixer. The crushed beans were centrifuged at 3000 rpm, and 5 g of solid content was used as a measurement sample. (2)L * a * b * Measurement of values After storing the food for 24 or 48 hours, the food was measured using a Nippon Denshoku Industries Co., Ltd. SE2000 spectrophotometer according to the CIE Lab color system (L * a * b * System) L * Value, a * Value, b * The color difference (ΔE = {(ΔL * ) 2 +(Δa * ) 2 +(Δb * ) 2} 1 / 2 ) was sought. (3) Judgment criteria If the ΔE of the food after 48 hours of storage was less than 3.2, it was judged as good (◯) with no significant discoloration, and if it was 3.2 or more, it was judged as poor (×) with significant discoloration.

[0057] (Bacteriostatic evaluation) The bacteriostatic property was evaluated by confirming that the initial number of bacteria before storage was less than 10 cfu / g, and then verifying that the general viable bacteria count after 48 hours obtained by the above-mentioned bacterial count measurement was 10 3 Less than cfu / g indicates strong bacteriostatic activity (◎), 103 CFU > 10 5 Less than cfu / g indicates bacteriostatic (〇), 10 5 cfu / g or more was evaluated as not bacteriostatic (×).

[0058] (Sensory evaluation of the bitter taste peculiar to sodium acetate) A sensory evaluation panel consisting of 10 panelists engaged in research and development of food ingredients and skilled in sensory evaluation conducted a sensory evaluation of the bitter taste characteristic of sodium acetate in vegetables after treatment with the treatment solution, according to predetermined evaluation criteria. (1) Evaluation samples and sample consumption method The green peas and spinach were used for evaluation after soaking in the treatment liquid and draining the soaking liquid with a sieve. The boiled kidney beans were used for evaluation after being removed from the boiling liquid. The samples were eaten in the usual way for vegetables. (2) Evaluation criteria Separately, each vegetable was treated with 0%, 2%, 4%, 6%, 8%, and 10% aqueous sodium acetate solutions instead of the above treatment solutions. A sensory evaluation panel tasted these and was trained to evaluate the harshness peculiar to sodium acetate according to the following criteria. 0% sodium acetate treatment: 5 points 2% sodium acetate treatment: 4 points 4% sodium acetate treatment: 3 points 6% sodium acetate treatment: 2 points 8% sodium acetate treatment: 1 point 10% sodium acetate treatment: 0 points (3) Judgment criteria The evaluation was based on the simple average of the scores of each panelist for each sample. A higher score indicates less of the harsh taste peculiar to sodium acetate. Based on the panel's prior evaluation, it was found that the desirability of flavor changes significantly at the average score border of 3.75 points, so a simple average score of 3.75 or more was judged to have a good taste (◯), and a score below 3.75 was judged to have a bad taste (×).

[0059] (result) The results of the sensory evaluation of the discoloration inhibitory effect, bacteriostasis, and harshness of boiled green peas, spinach, and kidney beans treated with the treatment solution containing Preparations A to D are shown in Table 4. The standard deviation of the scores of the 10 panelists in the sensory evaluation was less than 1 point, and the convergence was high.

[0060] [Table 4]

[0061] In Example 1, which used Preparation A, a good discoloration suppression effect was observed regardless of the type of vegetables, and the bacteriostasis was also the best. On the other hand, in the Comparative Example, the discoloration suppression was insufficient, and the bacteriostasis was also insufficient depending on the target vegetables. Although Example 1 used a treatment solution containing the most sodium acetate, the flavor was good. On the other hand, in the Comparative Example, it was incompatible with some vegetables, and the bitter taste peculiar to sodium acetate was strongly felt.

[0062] [Test Example 2. Examination of the amount of each component added] (Preparation of test formulations and treatment solutions) Preparations E to I were prepared to prepare the treatment solutions for vegetables so that the compositions of the treatment solutions were as shown in Table 5 below. The pH was adjusted to 5.7 using hydrochloric acid and sodium hydroxide. Sucrose fatty acid esters with an HLB value in the range of 9 to 16 were used.

[0063] [Table 5]

[0064] Using each treatment solution, frozen green peas were treated according to the method described above in (Heat processing of vegetables, storage test and bacterial count measurement), and evaluated based on the above descriptions in (Evaluation of discoloration inhibition effect) and (Evaluation of bacteriostasis). The results are shown in Table 6.

[0065] [Table 6]

[0066] In Examples 2 to 4, in which Preparations F to H were used, a good discoloration suppression effect was observed, and the bacteriostasis was also good. The bacteriostasis was particularly good in Examples 3 and 4. On the other hand, the bacteriostasis was insufficient in Comparative Example 4, and the discoloration suppression was insufficient in Comparative Example 5.

[0067] [Test Example 3. Examination of various organic acids] (Preparation of test formulations and treatment solutions) The following formulations A and J to M in Table 7 were prepared by conventional methods. Sucrose fatty acid esters with HLB values ​​in the range of 9 to 16 were used. Each formulation was dissolved in water at 2.0%, and the solution was adjusted to pH 5.7 using hydrochloric acid and sodium hydroxide, and used as a treatment solution for vegetables (the composition of the treatment solution is shown in Table 8).

[0068] [Table 7]

[0069] [Table 8]

[0070] Using each treatment solution, frozen green peas were treated according to the method described above in (Heat processing of vegetables, storage test and bacterial count measurement), and evaluated based on the above descriptions in (Evaluation of discoloration inhibition effect) and (Evaluation of bacteriostasis). The results are shown in Table 9.

[0071] [Table 9]

[0072] In all of Examples 5 to 9, which used Preparations A, J to M, a good discoloration inhibiting effect was observed, and the bacteriostasis was also good. Example 5 showed particularly good bacteriostasis.

[0073] [Test Example 4. Examination of various components] (Preparation of test formulations and treatment solutions) Preparations A and N to Q in Table 10 below were prepared by conventional methods. Sucrose fatty acid esters with HLB values ​​in the range of 9 to 16 were used. Each preparation was dissolved in water at 2.0%, and the solution was adjusted to pH 5.7 using hydrochloric acid and sodium hydroxide, and used as a treatment solution for vegetables (the composition of the treatment solution is shown in Table 11).

[0074] [Table 10]

[0075] [Table 11]

[0076] Using each treatment solution, frozen green peas were treated according to the method described above in (Heat processing of vegetables, storage test and bacterial count measurement), and evaluated based on the above descriptions in (Evaluation of discoloration inhibition effect) and (Evaluation of bacteriostasis). The results are shown in Table 12.

[0077] [Table 12]

[0078] In all of Comparative Examples 6 to 9, in which each component was removed from Preparation A one by one, discoloration inhibition was insufficient. It was confirmed that sodium acetate, glycine, lysozyme, sucrose fatty acid ester, and organic acid were essential.

Claims

1. Sodium acetate, glycine, lysozyme, sucrose fatty acid esters, and At least one organic acid or organic acid salt selected from the group consisting of acetic acid, malic acid, adipic acid, citric acid, fumaric acid, lactic acid, glucono-delta-lactone, gluconic acid, and salts thereof (excluding sodium acetate). A method for inhibiting discoloration of vegetables, comprising the step of immersing vegetables in a treatment liquid containing the above-mentioned compound.

2. The method for inhibiting discoloration according to claim 1 , wherein the vegetables have been subjected to a heating process.

3. The method for inhibiting discoloration according to claim 1 or 2, wherein the vegetables are green vegetables.

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