Laver color improver

Abstract

To provide a laver color improver and a laver color improving solution that are able to prevent laver color fading and improve the color of laver, and a method for processing cultured laver using them.SOLUTION: The laver color improver of the first invention comprises at least a water-soluble iron compound and two or more organic acid preparations selected from Group A below, and the laver color improver of the second invention comprises at least a water-soluble iron compound and three or more organic acid preparations selected from Group A and Group B below, where Group A consists of lactic acid, acetic acid and succinic acid, and Group B consists of citric acid, gluconic acid, malic acid and tartaric acid.SELECTED DRAWING: None

Description

[Technical field]

[0001] The present invention relates to an agent for improving the color tone of laver, which can prevent the color of laver from fading and improve the color tone of laver. [Background technology]

[0002] In recent years, red tides caused by the proliferation of phytoplankton have occurred in sea areas where seaweed is cultivated, such as the Ariake Sea, the Seto Inland Sea, Ise Bay, Mikawa Bay, and Tokyo Bay, causing damage to the color of seaweed, and this has become a problem. Recently, there have been cases of early and widespread color loss, and even when the amount of precipitation is about average, there has been a situation in which seaweed color loss occurs due to a lack of nutrients, etc., when there is no regular rainfall or there is little rainfall.

[0003] Examples of conventional techniques for preventing discoloration of seaweed and improving its color include: 1) A method for promoting the recovery of discolored cultured seaweed due to a lack of nitrogen and phosphorus in seawater, shortening the cultivation period of cultured seaweed and improving production efficiency, comprising immersing discolored cultured seaweed or aquaculture equipment having discolored cultured seaweed attached thereto in a treatment solution prepared by adding and dissolving 0.5 to 20% salt, 0.015 to 0.5% nitrogen, and 0.0015 to 0.15% phosphorus in seawater and adjusting the pH to 1.5 to 4.0 by adding an acid (see, for example, Patent Document 1); 2) A quality improver for seaweed cultivation, the main component of which is an iron compound, and a method for treating seaweed, which comprises immersing seaweed in the treatment agent or spraying the seaweed treatment agent on seaweed (see, for example, Patent Document 2); 3) An algicide for preventing and eradicating weeds and diseases that occur during seaweed cultivation, which is a solution containing at least one of organic and inorganic acids and ferrous sulfate, and has a specific gravity of less than 1.030 (see, for example, Patent Document 3); 4) A method for restoring or preventing discoloration of seaweed is known, which comprises soaking seaweed in seawater to which a mixture of iron oxide and / or metallic iron-containing material (including cases where the material is composed only of iron oxide and / or metallic iron) and an organic acid has been added (including seawater to which the mixture has been added, which has been left to soak for a certain period of time, and from which the solids have been removed) (see, for example, Patent Document 4).

[0004] However, although the techniques for restoring or preventing color fading of seaweed described in Patent Documents 1 to 4 above improve the color tone of seaweed compared to conventional techniques, the effect of improving the color tone of seaweed is still insufficient, and color fading of the seaweed may occur, and the quality of the seaweed may be adversely affected, so there are still issues that remain to be addressed. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] JP 2002-300819 A (Claims, Examples, etc.) [Patent Document 2] JP 2004-97167 A (Claims, Examples, etc.) [Patent Document 3] JP 2003-176204 A (claims, examples, etc.) [Patent Document 4] JP 2010-246525 A (Claims, Examples, etc.) Summary of the Invention [Problem to be solved by the invention]

[0006] The present invention is made in view of the above-mentioned conventional problems and current situation, and aims to solve these problems, and to provide a seaweed color improver and a seaweed color improver liquid that can prevent seaweed from fading and improve the color of seaweed, and a method for treating cultured seaweed using them. [Means for solving the problem]

[0007] As a result of extensive research into the above-mentioned conventional problems, the inventors discovered that the above-mentioned desired color enhancer for seaweed can be obtained by containing at least one water-soluble iron compound and two or more specific organic acid preparations, and thus completed the present invention.

[0008] That is, the color improver for seaweed of the first invention is characterized by comprising at least a water-soluble iron compound and two or more organic acid preparations selected from Group A below. In addition, the color improver for seaweed of the second invention is characterized by comprising at least a water-soluble iron compound and three or more organic acid preparations selected from the following groups A and B: Group A: Lactic acid, acetic acid, succinic acid Group B: Citric acid, gluconic acid, malic acid, tartaric acid In addition, it is preferable that the color improver for laver of the first or second invention further contains at least one component selected from the following Group C. Group C: Amino acids or their salts, inorganic salts, sugars

[0009] The seaweed color improving liquid of the present invention is characterized by being obtained by diluting the seaweed color improving agent of the first or second invention described above with water or seawater. In addition, the method for treating cultured seaweed of the present invention is characterized in that the seaweed color enhancer of the first or second invention described above is diluted with water or seawater to obtain a treatment solution having a pH of 1.0 to 6.0, with the water-soluble iron compound being 0.003 to 0.6 mass% in total, the organic acid preparation of group A being 0.005 to 0.7 mass% in total in the first invention described above, and the organic acid preparations of groups A and B being 0.005 to 0.7 mass% in total in the second invention described above, and the seaweed is treated with the seaweed color improving treatment solution by immersing the seaweed or aquaculture equipment such as a seaweed net with seaweed attached thereto in the treatment solution or by passing the seaweed through the treatment solution. The treatment time of the above-mentioned method for treating cultured seaweed is preferably 10 seconds to 10 minutes. Effect of the Invention

[0010] According to the present invention, there are provided a seaweed color improver and a seaweed color improver liquid capable of preventing discoloration of seaweed and improving the color of seaweed, and a method for treating cultured seaweed using these. The objects and advantages of the invention will be realized and obtained by means of the elements and combinations particularly pointed out in the claims. Both the foregoing general description and the following detailed description are exemplary and explanatory but are not restrictive of the invention as claimed. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0011] The following describes in detail the embodiments of the present invention. However, it should be noted that the technical scope of the present invention is not limited to the embodiments described in detail below, but extends to the inventions described in the claims and their equivalents. The present invention can be implemented based on the contents disclosed in this specification and common technical knowledge in the relevant field (including design matters and obvious matters).

[0012] In the first invention, the color enhancer for seaweed of the present invention is characterized by comprising at least a water-soluble iron compound and two or more organic acid preparations selected from Group A below, and in the second invention, the color enhancer for seaweed is characterized by comprising at least a water-soluble iron compound and three or more organic acid preparations selected from Groups A and B below. Group A: Lactic acid, acetic acid, succinic acid Group B: Citric acid, gluconic acid, malic acid, tartaric acid In the present specification, the term "the present invention" hereinafter includes both the first and second inventions.

[0013] The water-soluble iron compound used in the present invention (first or second invention, the same applies below) is a substance that is easily soluble in water and dissolves in water to produce iron ions (including complex ions). Examples of water-soluble iron compounds that can be used include ferrous sulfate, ferric sulfate, ferrous chloride, ferric chloride, ferrous nitrate, ferric nitrate, ferrous phosphate, ferric phosphate, sodium ferrous citrate, ferric hexacyanidate (II) ion, ferric hexacyanidate (III) ion, and at least one selected from these (each alone or in combination of two or more, the same applies below). In particular, it is preferable to use at least one of ferrous sulfate, ferric sulfate, ferrous chloride, ferric chloride, ferrous nitrate, ferric nitrate, ferrous phosphate, and ferric phosphate. These water-soluble iron compounds are the essential iron components when producing chlorophyll, which functions in photosynthesis in seaweed, from nitrogen nutrients. These iron compounds produce stronger chlorophyll, promote photosynthesis, and provide easily absorbed iron, which helps restore the seaweed's vitality, prevents discoloration, and improves its color. In addition to synthesizing chlorophyll in seaweed, these water-soluble iron compounds also play a role in the production of energy in mitochondria and in converting nitrogen fertilizer into amino acids.

[0014] The ferrous sulfate used (iron(II) sulfate) has the formula FeSO 4 or FeSO 4 7H 2 Ferrous sulfate (iron(III) sulfate) is a compound of ferric sulfate, which is soluble in water and approved as a food additive. The formula is Fe 2 (SO 4 ) 3 It exists in anhydrous and several hydrated forms, but is usually used as an aqueous solution. The ferrous chloride used (iron(II) chloride) has the formula FeCl 2 It is a compound that is easily soluble in water, and ferric chloride [iron(III) chloride] has the formula FeCl 3 When dissolved in water, it forms a reddish-brown solution. The ferrous nitrate used is iron(II) nitrate, which has the chemical formula Fe(NO 3 )2 Ferric nitrate (iron(III) nitrate) is a compound of the formula Fe(NO 3 ) 3 It is a compound of the formula (I), the most common of which is the nonahydrate, and is readily soluble in water. The ferrous phosphate used is iron(II) phosphate, which has the chemical formula Fe 3 (PO 4 ) 2 Ferric phosphate (iron(III) phosphate) is a type of iron phosphate with the formula FePO 4 It is a compound used as a food additive. The sodium ferrous citrate used has the formula C 12 H 10 Na 4 O, a soluble non-ionic iron preparation. The hexacyanidoferrate(II) ion has the formula [Fe(CN) 6 ] 4- is a soluble ionic iron preparation, and the hexacyanidoferrate(III) ion has the formula [Fe(CN) 6 ] 3- It is a soluble ionic iron preparation. Of these water-soluble iron compounds, it is preferable to use ferrous sulfate and ferric chloride from the standpoints of biological safety and water solubility.

[0015] The content of these water-soluble iron compounds (iron content) is preferably 0.30 to 10 mass% and more preferably 1.0 to 7.0 mass% based on the total amount of the seaweed color enhancer (undiluted solution: 100 times diluted or 200 times diluted) from the standpoint of formulation stability such as precipitation, turbidity, and color tone, and ease of dilution with water or seawater.

[0016] In the first invention, the organic acid preparation used in the color enhancer for laver of the present invention is a combination of two or more acids selected from group A, namely, lactic acid, acetic acid, and succinic acid. The reason why the combination of two or more acids selected from group A, namely, lactic acid, acetic acid, and succinic acid, is limited in the first invention is based on the fact that the color recovery effect, which is thought to be related to the uptake of the iron chelate complex into laver cells, when multiple organic acids are combined is unexpectedly and significantly improved compared to the combination of two other organic acids, which was revealed for the first time through extensive verification, etc. These points will be described in more detail in the examples and comparative examples described below.

[0017] In the second invention, a combination of three or more acids from among citric acid, gluconic acid, malic acid, and tartaric acid, which are group B used in combination with the above group A, is used. In the second invention, the above group A and group B, lactic acid, citric acid, gluconic acid, succinic acid, malic acid, acetic acid, and tartaric acid, are selected from among many organic acids because they are useful as ingredients for improving the color of seaweed due to their permeability to cells and their excellent ligands involved in the formation of a chelate complex with iron, and the reason for limiting the combination to three or more acids is that it has been revealed for the first time through extensive testing that the color recovery effect, which is thought to be related to the uptake of the chelate complex with iron into seaweed cells, is unexpectedly and significantly improved compared to the combination of two organic acids. These points will be described in more detail in the examples and comparative examples described below.

[0018] The organic acid preparations used in the present invention (Invention 1 and Invention 2) are those consisting of a combination of two or more acids belonging to Group A above, and those consisting of a combination of three or more acids belonging to Group A and Group B above. Therefore, for example, acids consisting of a combination of two acids, such as lactic acid and citric acid, gluconic acid and succinic acid, malic acid and acetic acid, or gluconic acid and citric acid, cannot achieve the effects of the present invention, as shown in the comparative examples described below.

[0019] The mechanism of action of the combination of specific organic acid preparations in the present invention to improve the color tone of the seaweed of the present invention is unclear, but lactic acid, acetic acid, and succinic acid in group A are organic acids with a relatively high proportion of undissociated molecules in the weak acidic range, while citric acid, gluconic acid, malic acid, and tartaric acid in group B are organic acids that have multiple functional groups such as hydroxyl and carboxyl groups and have a relatively low proportion of undissociated molecules in the weak acidic range, and it is thought that the formation of various chelate complexes due to the characteristics of each acid has an effect.

[0020] In the first invention, preferred combinations of two or more acids in group A include a combination of lactic acid and acetic acid, and a combination of lactic acid and succinic acid. In the second invention, the preferred combination of three or more of the organic acids in group A and group B is a combination of three or more of two or more organic acids selected from group A and one or more organic acids selected from group B. In the second invention, particularly preferred are combinations of lactic acid, acetic acid, citric acid and / or gluconic acid and / or malic acid, combinations of lactic acid, succinic acid, citric acid and / or gluconic acid and / or malic acid, and combinations of lactic acid, acetic acid, succinic acid, citric acid and / or gluconic acid and / or malic acid.

[0021] The total content of these organic acid preparations of Group A of the first invention, or Groups A and B of the second invention, is preferably 20 to 60 mass% based on the total amount of the seaweed color enhancer (undiluted solution: 100 times diluted or 200 times diluted), from the standpoint of preparation stability such as precipitation / sedimentation, turbidity, and color tone, and ease of dilution with water or seawater, and is more preferably 20 to 55 mass%.

[0022] In the present invention, in order to achieve a high degree of color tone improvement effect in a short treatment period, it is preferable to further contain at least one component selected from amino acids or salts thereof of group C, inorganic salts, and sugars. Examples of amino acids that can be used include at least one of glycine, alanine, valine, leucine, isoleucine, phenylalanine, tryptophan, proline, methionine, serine, threonine, cysteine, tyrosine, asparagine, glutamine, histidine, lysine, arginine, aspartic acid, glutamic acid, etc. Furthermore, examples of amino acid salts that can be used include sodium salts, potassium salts, magnesium salts, calcium salts, and ammonium salts of amino acids. In particular, it is preferable to use at least one of glycine, sodium aspartate, alanine, glutamic acid, sodium glutamate, potassium glutamate, calcium glutamate, magnesium glutamate, theanine, valine, methionine, and isoleucine.

[0023] Examples of inorganic salts that can be used include sodium chloride, potassium chloride, magnesium chloride, ammonium chloride, calcium chloride, sodium nitrate, potassium nitrate, magnesium nitrate, ammonium nitrate, calcium nitrate, ammonium aluminum sulfate, potassium aluminum sulfate, sodium sulfate, potassium sulfate, magnesium sulfate, ammonium sulfate, calcium sulfate, sodium phosphate, potassium phosphate, magnesium phosphate, ammonium phosphate, calcium phosphate, sodium carbonate, potassium carbonate, magnesium carbonate, ammonium carbonate, and calcium carbonate. At least one selected from these can be used.

[0024] Examples of sugars that can be used include glucose, galactose, fructose, xylose, mannose, ribose, maltose, sucrose, lactose, cellobiose, trehalose, galactooligosaccharides, fructooligosaccharides, maltooligosaccharides, mannan oligosaccharides, lactose fructose oligosaccharides, xylooligosaccharides, soybean oligosaccharides, sugar alcohols, and caramel, and at least one selected from these can be used.

[0025] The total content of these components of Group C is preferably 0.05 to 5.0 mass% based on the total amount of the seaweed color enhancer (undiluted solution: 100 times diluted or 200 times diluted) from the standpoint of formulation stability such as precipitation, turbidity, and color tone, and ease of dilution with water or seawater, and is more preferably 0.1 to 2.0 mass%.

[0026] In the first invention, the color enhancer for seaweed of the present invention contains at least a water-soluble iron compound and two or more organic acid preparations selected from the above group A, and in the second invention, it contains at least a water-soluble iron compound and three or more organic acid preparations selected from the above group A and group B, and preferably further contains at least one component selected from amino acids or their salts, inorganic salts, and sugars, which are group C. The content of each component is such that the water-soluble iron compound is 0.30 to 10 mass% in total, the two or more organic acid preparations selected from the above group A or the three or more organic acid preparations of the above group A and group B are 20 to 60 mass% in total, and further, the group C is 0 to 5.0 mass%, and the remainder is prepared with water (purified water, ion-exchanged water, etc.) to prepare the formulation.

[0027] When used, i.e., when treating cultured seaweed, the obtained seaweed color improver of the present invention is diluted with water or seawater, etc., as necessary, and used as a seaweed color improver. When diluting the seaweed color enhancer of the present invention, the agent is diluted with water or seawater so that the water-soluble iron compounds of group A are present in a total amount of 0.003 to 0.6% by mass, the organic acid preparations of group A are present in a total amount of 0.005 to 0.7% by mass in the first invention, and the organic acid preparations of groups A and B are present in a total amount of 0.005 to 0.7% by mass in the second invention, and more preferably, the organic acid preparations of group C are present in a total amount of 0.0001 to 0.01% by mass, and the agent is diluted with water or seawater to a pH of 1.0 to 6.0 to obtain a seaweed color enhancer (treatment liquid). The pH of the treatment liquid is adjusted to 1.0 to 6.0 from the viewpoints of the stability of the iron component as an aqueous solution and the degree of improvement in the color tone of the seaweed. The pH is preferably 1.5 to 3.5, and more preferably 2.0 to 3.5. In order to keep the pH within this range, if necessary, it can be adjusted using a pH adjuster such as an organic acid (or its salt) or an inorganic acid (or its salt) other than the composition of the present invention.

[0028] The method for treating cultured seaweed of the present invention involves treating the cultured seaweed with a seaweed color improving liquid (treatment liquid) by immersing the cultured seaweed or culture equipment such as seaweed nets to which the cultured seaweed is attached in the treatment liquid in which each of the above-mentioned components falls within a predetermined concentration range or by passing the cultured seaweed through the treatment liquid. Furthermore, in the case of actually processing cultured seaweed, the processing method when using the above-mentioned seaweed color enhancer as a seaweed color enhancer diluted with seawater or water is not particularly limited. For example, in the immersion processing method, the seaweed color enhancer is placed in a container such as a processing liquid tank on board a ship, and seaweed pulled out of the sea or culture equipment with seaweed attached thereto is immersed in the seaweed color enhancer. The treatment (immersion) time of the nori in the color improving solution varies depending on the growth condition of the nori, the nutrient salt condition of the sea area, the specific gravity of the seawater, the type of acid and its concentration, the pH of the treatment solution, and even the temperature during treatment, but in normal cases, the treatment time of the above-mentioned cultured nori treatment method is preferably 10 seconds to 10 minutes, and more preferably 10 seconds to 7 minutes.

[0029] It is also possible to treat the seaweed in a relatively short time by using a boat under the seaweed cultivation net and passing the net through the treatment solution, as in the case of a non-fishing boat. In the case of a short-time treatment using a non-fishing boat, the concentration of the treatment solution can be set higher than in the case of the immersion treatment. The treatment time using a non-fishing boat is about 30 seconds to 2 minutes, and usually about 40 seconds to 1 minute.

[0030] In the method for treating cultured seaweed of the present invention, the color tone improver of the seaweed as described above is diluted with water or seawater to obtain a treatment solution containing 0.003-0.6% by mass of water-soluble iron compounds in total, 0.005-0.7% by mass of two or more organic acids of the above group A or 0.0001-0.01% by mass of the above group C components in total, and a pH of 1.0-6.0. The seaweed or the seaweed culturing equipment such as a seaweed net with the seaweed attached thereto is immersed in the treatment solution or passed through the treatment solution to treat the seaweed with the treatment solution for improving the color tone of the seaweed, thereby preventing discoloration of the seaweed and improving the color tone of the seaweed. Furthermore, when the pH of the treatment solution is set to 1.8-2.5, the color tone of the seaweed is improved and diseases of the seaweed (diatoms, red rot bacteria, etc.) can be eradicated.

[0031] In a particularly preferred embodiment of the first invention of the method for treating cultured seaweed, after dilution, the solution contains a total of 0.003 to 0.3 mass% water-soluble iron compounds (0.001 to 0.11 mass% iron), and from the above group A, 0.005 to 0.69 mass% lactic acid, 0.0005 to 0.4 mass% acetic acid and / or 0.001 to 0.5 mass% succinic acid, as well as 0.0005 to 0.01 mass% of an amino acid or a salt thereof from the above group C, if necessary, thereby further preventing discoloration of the seaweed and improving the color tone of the seaweed. The most preferred embodiment of the first invention is a method for treating cultured seaweed which, after dilution, contains a total of 0.01 to 0.1% by mass of water-soluble iron compounds (0.004 to 0.04% by mass of iron), and, from the above group B, 0.01 to 0.5% by mass of lactic acid, 0.001 to 0.3% by mass of acetic acid and / or 0.005 to 0.1% by mass of succinic acid, as well as 0.001 to 0.01% by mass of an amino acid or a salt thereof from the above group C, as necessary.

[0032] In a particularly preferred embodiment of the second invention of the method for treating cultured seaweed, after dilution, the solution contains a total of 0.003 to 0.3 mass% water-soluble iron compounds (0.001 to 0.11 in terms of iron content), and a combination of two or more of the above Group A and Group B, namely 0.005 to 0.69 mass% lactic acid, 0.0005 to 0.4 mass% acetic acid, and 0.001 to 0.5 mass% succinic acid, as well as one or more of 0.001 to 0.5 mass% citric acid, 0.001 to 0.5 mass% gluconic acid, 0.001 to 0.5 mass% malic acid, and 0.001 to 0.5 mass% tartaric acid, and, if necessary, 0.0005 to 0.01 mass% of an amino acid or a salt thereof in the above Group C, thereby further preventing discoloration of the seaweed and improving the color tone of the seaweed. And the most preferred embodiment of the second invention is a method for treating cultured seaweed which, after dilution, contains a total of 0.01 to 0.1 mass% water-soluble iron compounds (0.004 to 0.04 in terms of iron content), and a combination of two or more of the above-mentioned Groups A and B, namely 0.01 to 0.5 mass% lactic acid, 0.001 to 0.3 mass% acetic acid, and 0.005 to 0.1 mass% succinic acid, as well as one or more of 0.002 to 0.3 mass% citric acid, 0.001 to 0.3 mass% gluconic acid, 0.002 to 0.3 mass% malic acid, and 0.001 to 0.3 mass% tartaric acid, and, if necessary, 0.001 to 0.01 mass% of an amino acid or a salt thereof of the above-mentioned Group C. EXAMPLES

[0033] The present invention will now be described in more detail with reference to examples and comparative examples of the color tone improver for laver according to the present invention, but the present invention is not limited to the following examples.

[0034] [Examples 1 to 80 and Comparative Examples 1 to 32] We prepared seaweed color improving solutions with the compositions shown in Tables 1 to 6 below (treatment solution, the remainder being a pH adjuster (hydrochloric acid, sodium hydroxide aqueous solution) mixed to set the pH and adjusted with seawater, total amount 100% by mass). The resulting seaweed color improving liquids (treatment liquids) from Examples 1 to 80 and Comparative Examples 1 to 32 were used to evaluate the pH of the treatment liquid, the seaweed color improvement, damage, and liquid stability by the following evaluation methods, etc. The evaluation results are shown in Tables 1 to 6 below.

[0035] Table 1 below shows the seaweed color improving solutions of Examples 1 to 8 and Comparative Examples 1 to 12, which used ferrous sulfate as a water-soluble iron compound and lactic acid, acetic acid, succinic acid, citric acid, gluconic acid, malic acid, tartaric acid, and adipic acid (not used, combination of two acids) as organic acid preparations (Group A and others), and the evaluation results of each. Tables 2 and 3 below show seaweed color-improving solutions of Examples 9 to 45 and Comparative Examples 13 to 20, which used ferrous sulfate as a water-soluble iron compound, lactic acid, acetic acid, and succinic acid as organic acid preparations (Group A), and citric acid, malic acid, gluconic acid, tartaric acid, and other adipic acids (combinations of three types) in Group B, and the results of their evaluation. Table 4 below shows the seaweed color improving solutions and the evaluation results of each of the solutions in Examples 46 to 62 and Comparative Examples 21 to 29, in which the concentration of ferrous sulfate as a water-soluble iron compound was varied from 0.001 to 0.8% by mass, and the organic acid preparations were not used (not used), or lactic acid, citric acid, gluconic acid, succinic acid, malic acid, acetic acid, tartaric acid and adipic acid (combinations of three or four types) were used, and amino acids, inorganic salts and sugars were used as group C. Table 5 below shows the seaweed color improving solutions of Examples 63 to 74 and Comparative Example 30, which used ferrous sulfate, ferric sulfate, ferrous chloride, ferric chloride, ferrous nitrate, ferric nitrate, ferrous phosphate, and ferric phosphate as the water-soluble iron compound, and used lactic acid, citric acid, and gluconic acid (a combination of three) as the organic acid preparations (Group A and Group B), and varied the pH of the treatment solution from 1.0 to 7.0, and the evaluation results of each. Table 6 below shows the evaluation results of the seaweed color improvement solutions of Examples 75 to 80 and Comparative Examples 31 and 32, which used ferrous sulfate as the iron compound preparation, lactic acid and succinic acid as the organic acid preparations (Group A), and citric acid, gluconic acid, and malic acid (none and a combination of three) as Group B, and the treatment times were either 10 minutes or 10 seconds.

[0036] (Method of measuring pH of treatment solution) The pH of the treatment solution (liquid temperature: 25° C.) was measured using a Toa DKK Corporation "HM-41X."

[0037] [Methods for evaluating color improvement, damage, and liquid stability of seaweed] Ten sheets of laver leaves cut into 1 cm squares were prepared for each test area. The resulting laver leaves from Examples 1-80 and Comparative Examples 1-32 were treated with the color-improving solution (treatment solution) twice, once at the start and once after 6 days, under treatment conditions of 10°C, 10 seconds, 60 seconds or 10 minutes. After treatment, the laver leaves were rinsed with seawater, and then 0.1 ml of culture nutrients was added to 500 mL of seawater and cultured at 10°C (culture conditions described below). The SPAD value (chlorophyll concentration) was measured at the start and after 6 and 12 days. The SPAD value was measured using a chlorophyll meter SPAD-502Plus (Konica Minolta), and five points were measured per sample, and the average value was used. The SPAD value after 12 days was used for comparison. Culture conditions: 10°C, with ventilation, light level 1 (1000-1500 Lux), light:dark = 10 hours:14 hours.

[0038] The relative value of the seaweed color improvement, which was the evaluation item, was calculated from the SPAD value ratio, with the SPAD value of the same concentration of iron compound only set as the standard (1.00). The improvement in color tone of the seaweed was evaluated according to the following evaluation criteria. Evaluation criteria: ◎◎: 1.50 or higher ◎: 1.25 or more and less than 1.50 ○: 1.10 or more and less than 1.25 △: 1.05 or more and less than 1.10 ×: Less than 1.05 The evaluation criteria with a relative value of "○" of 1.10 or more were judged to be sufficient for the issues of seaweed cultivation (prevention of color fading and improvement of quality). Furthermore, the evaluation criteria with a relative value of "◎: 1.25 or more" and especially the evaluation criteria with a relative value of "◎◎: 1.50 or more" were judged to be necessary and sufficient for the issues of seaweed cultivation (prevention of color fading and improvement of quality).

[0039] [Method for evaluating seaweed damage] To evaluate the degree of damage to the laver after 12 days of culture, the laver leaves after culture were observed under a light microscope at a magnification (100x or more) to check the percentage of dead cells, and evaluated according to the following criteria. Evaluation criteria: ○: 0-10% dead cells △: 10% to less than 20% dead cells ×: 20% or more dead cells

[0040] [Method for evaluating liquid stability] After preparing the seaweed color improving liquid (treatment liquid), the state of the liquid was visually observed after 1 hour at room temperature and evaluated according to the following criteria. Evaluation criteria: ○: The liquid is transparent and no precipitation occurs. △: The liquid becomes cloudy ×: Precipitation occurs in the liquid

[0041] [Table 1]

[0042] [Table 2]

[0043] [Table 3]

[0044] [Table 4]

[0045] [Table 5]

[0046] [Table 6]

[0047] From Table 1 above (Examples 1 to 8, Comparative Examples 1 to 12), it was found that among combinations of two types of organic acid preparations, only the combination of 0.005 to 0.7 mass% of Group A (lactic acid, acetic acid, succinic acid) can become a seaweed color improvement treatment solution (effect) of the present invention. From the above Tables 2 and 3 (Examples 9-45, Comparative Examples 13-20), it was found that, among the combinations of three organic acid preparations, only the combination of 0.005-0.7 mass% of Group A (lactic acid, acetic acid, succinic acid) and Group B (citric acid, gluconic acid, malic acid, tartaric acid) can be the seaweed color improvement treatment solution (effect) of the present invention. It was also found that two types from Group A and one type from Group B had a higher effect. From the above Table 4 (Examples 46 to 62, Comparative Examples 21 to 29), it was demonstrated that the appropriate range of the water-soluble iron compound according to the present invention is 0.003 to 0.6 mass%, and the effects of the present invention of three or more (four) types of organic acid preparations (Group A and Group B) were verified. It was also shown that the effect can be further improved by combining Group C of amino acids (salts), inorganic salts, and sugars. From Table 5 above (Examples 63 to 74, Comparative Example 30), it was demonstrated that ferrous sulfate, ferric sulfate, ferrous chloride, ferric chloride, ferrous nitrate, ferric nitrate, ferrous phosphate, and ferric phosphate can be appropriately used as water-soluble iron compounds in the seaweed color improvement treatment solution of the present invention, and that the treatment solution can be appropriately used within the pH range of 1.0 to 6.0. From Table 6 above (Examples 75 to 80, Comparative Examples 31 and 32), it was shown that the treatment time of 10 seconds and 10 minutes with the seaweed color improvement treatment solution of the present invention can be appropriately used. That is, looking at the compositions and evaluation results of each of the compositions in Table 1 (Examples 1-8, Comparative Examples 1-12), Tables 2 and 3 (Examples 9-45, Comparative Examples 13-20), Table 4 (Examples 46-62, Comparative Examples 21-29), Table 5 (Examples 63-74, Comparative Example 30), and Table 6 (Examples 75-80, Comparative Examples 31 and 32), it was found that Examples 1-80, which are within the scope of the present invention, are able to prevent discoloration of the seaweed and improve the color tone of the seaweed, while also causing no damage to the seaweed and having excellent liquid stability, compared to Comparative Examples 1-32, which are outside the scope of the present invention. [Industrial Applicability]

[0048] Since the color fading of the seaweed can be prevented and the color tone of the seaweed can be improved, it is possible to obtain high-quality seaweed excellent in color, luster, flavor, etc.

Claims

1. A color improver for seaweed, comprising at least a water-soluble iron compound and two or more organic acid preparations selected from Group A below. Group A: Lactic acid, acetic acid, succinic acid

2. A color improver for seaweed, comprising at least a water-soluble iron compound and three or more organic acid preparations selected from the following groups A and B: Group A: Lactic acid, acetic acid, succinic acid Group B: Citric acid, gluconic acid, malic acid, tartaric acid

3. A color improver for seaweed according to claim 1 or 2, characterized in that it contains at least one component selected from the following Group C. Group C: Amino acids or their salts, inorganic salts, sugars

4. A seaweed color improving liquid obtained by diluting the seaweed color improving agent according to claim 1 or 2 with water or seawater.

5. A method for treating cultured seaweed, comprising: diluting the seaweed color enhancer according to claim 1 with water or seawater to a total content of 0.003 to 0.6% by mass of the water-soluble iron compound, a total content of 0.005 to 0.7% by mass of the organic acid preparation of group A, and a pH of 1.0 to 6.0 to obtain a treatment solution; and immersing seaweed or aquaculture equipment such as a seaweed net having seaweed attached thereto in the treatment solution or passing the treatment solution through the treatment solution to treat the seaweed with the treatment solution for improving the color of the seaweed.

6. A method for treating cultured seaweed, comprising: diluting the seaweed color enhancer according to claim 2 with water or seawater to a total content of 0.003 to 0.6% by mass of the water-soluble iron compound, a total content of 0.005 to 0.7% by mass of the organic acid preparations of group A and group B, and a pH of 1.0 to 6.0 to obtain a treatment solution; and immersing seaweed or aquaculture equipment such as a seaweed net having seaweed attached thereto in the treatment solution or passing the treatment solution through the treatment solution to treat the seaweed with the treatment solution for improving the color of the seaweed.

7. The method for treating cultured seaweed according to claim 5 or 6, characterized in that the treatment time of the method for treating cultured seaweed is 10 seconds to 10 minutes.

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