JP4629149B2 - How to recover or prevent discoloration of seaweed - Google Patents

Description

  The present invention relates to a method for recovering or preventing discoloration of seaweed.

In nori culture, laver spores are attached to a laver net spread on the surface of shallow water, and the seedlings are grown and grown until they become mature, and then harvested when the mature sprout has grown to an appropriate size. .
Color is one of the important factors determining the quality of seaweed, and it is not evaluated as a luxury product unless it is dry and deep black. However, in the cultivation of seaweed, there is a phenomenon called so-called “color loss” in which the color of the seaweed is brown or yellowish. In recent years, this phenomenon has frequently occurred. Has had a great impact on the production of. Such discoloration of seaweed is said to be caused by an abnormal decrease in the content of nitrogen and phosphorus in seawater necessary for the growth of seaweed. For this reason, conventionally, in order to recover the fading of the laver, the nutrient salts containing nitrogen and phosphorus have been sprayed in the water area of the laver farm, but no great results have been obtained.

On the other hand, in Patent Document 1, in order to suppress the growth of plankton that ingests nitrogen in seawater, and as a result, to secure a nitrogen content that can be ingested by laver, A method of spraying a color fading preventive such as is shown.
Further, in Patent Document 2, in order to recover the color fading of seaweed, an aquaculture of fading is added to a treatment liquid in which inorganic salts are added / dissolved in seawater at a predetermined concentration and the pH is adjusted by adding an acid. A method of immersing nori is shown.

JP 2003-265058 A JP 2002-300819 A

  However, the methods of Patent Documents 1 and 2 described above cannot be expected to have both effects of preventing laver color fading and restoring laver color fading. That is, it is considered that the method of Patent Document 1 does not have an effect of recovering the color loss of seaweed, while the method of Patent Document 2 is not effective in preventing the color loss of seaweed. In addition, the method of Patent Document 2 has a drawback that it takes time and cost to adjust the components and pH of the treatment liquid, and is unsuitable for treating a large amount of discolored seaweed.

  Accordingly, an object of the present invention is to provide a method that can effectively recover or prevent the color loss of seaweed and that can be easily prepared at low cost.

As a result of investigating and examining a color fading recovery / inhibitor that can effectively recover or prevent the color fading of seaweed to solve the above-mentioned problems, the present inventors have found that iron oxide and / or metal Treatment agents combining iron-containing substances and organic acids (for example, mixtures obtained by mixing organic acids with iron oxide and / or metallic iron-containing substances) have excellent performance as color fading recovery / prevention agents I found out. Moreover, it turned out that the especially outstanding effect is acquired by using steelmaking slag as an iron oxide and / or metallic iron containing substance.
The present invention has been made on the basis of such findings and has the following gist.

[1] Seawater to which a mixture of iron oxide and / or metallic iron-containing substance (including a substance composed only of iron oxide and / or metallic iron) and an organic acid is added (however, the above mixture is added and constant) (Including seawater after removing the solid content after immersion for a period of time) , wherein at least a part of the iron oxide and / or metal iron-containing substance is steel slag. A method for recovering or preventing discoloration of seaweed.
[2] Iron oxide and / or metallic iron-containing substances (including those containing only iron oxide and / or metallic iron) and seawater to which an organic acid is added (provided that the iron oxide and / or metallic iron are contained) And a method of immersing laver in seawater after adding a substance and an organic acid and immersing for a certain period of time and then removing the solid content thereof, and at least part of the iron oxide and / or metal iron-containing substance Is a method for recovering or preventing discoloration of seaweed, characterized by being steel slag .

[3] After adhering seawater to which organic acid is added to the laver, the laver is added with iron oxide and / or metal iron-containing substances (however, including the case of a substance consisting only of iron oxide and / or metal iron). It is a method of immersing in the added seawater (however, including the seawater after adding the iron oxide and / or metal iron-containing substance and immersing for a certain period of time and then removing the solid content thereof), A method for recovering or preventing discoloration of seaweed , wherein at least a part of the metallic iron-containing substance is steel slag .
[4] A mixture of iron oxide and / or metal iron-containing substances (including substances consisting only of iron oxide and / or metal iron) and organic acids is installed in the seawater of the sea area where the laver farm is located A method for recovering or preventing color loss of seaweed , wherein at least a part of the iron oxide and / or metal iron-containing substance is steel slag .

[5] In the method according to any one of [1] to [4], the organic acid is at least one selected from gluconic acid, citric acid, and nitrogen-containing oxyacids How to recover or prevent discoloration.
[6] A method for recovering or preventing color loss of seaweed, wherein the nitrogen-containing oxyacid is one or more selected from glutamic acid, humic acid, and fulvic acid.

[7] In any one of the above methods [1] to [6], the iron oxide and / or metallic iron-containing material is steel slag, non-ferrous smelting slag, refuse molten slag, dust, scale, iron powder, iron oxide A method for recovering or preventing discoloration of laver characterized by being at least one selected from powder, iron sand and iron ore .

  According to the present invention, discoloration of seaweed can be effectively recovered or prevented, and a mixture of iron oxide and / or a metal iron-containing substance and an organic acid is added to seawater, installed in the sea, or oxidized. Since it is only necessary to add iron and / or metal iron-containing substances and organic acids to seawater, it can be carried out at low cost with little effort, especially when processing a large amount of laver or in a wide water area of laver farms. Even when it is targeted, it can be carried out at low cost. In particular, in a method in which a mixture of iron oxide and / or metal iron-containing material and organic acid is added to seawater or installed in the sea, iron oxide and / or metal iron-containing material and organic acid exist in close proximity. It is advantageous for the formation of iron chelate, and for this reason, the effect of recovering and preventing the discoloration of seaweed can be further enhanced and sustained for a long time.

  In addition, when steelmaking slag is used as the iron oxide and / or metallic iron-containing material, the steelmaking slag has stable components and has a moderate elution of iron ions. Therefore, the present invention can be implemented at a lower cost because the material is inexpensive and can be obtained in large quantities.

The graph which shows the time-dependent change of the SPAD value (chlorophyll density | concentration), L ^* value (lightness), and a ^* value (redness degree) of the laver leaf body which served for Example 1. The graph which shows the time-dependent change of the SPAD value (chlorophyll density | concentration), L ^* value (lightness), and a ^* value (redness degree) of the laver leaf body used for Example 2.

In the method of the present invention, iron oxide and / or metal iron-containing substances and organic acids, or a mixture thereof are used as a noble color recovery or prevention agent.
The iron oxide and / or metal iron-containing substance (hereinafter simply referred to as “iron source (x)” for convenience of description) may be any material containing iron oxide and / or metal iron. And / or the substance which consists only of metallic iron may be sufficient.
Examples of the iron source (x) include steel slag, non-ferrous smelted slag, refuse molten slag, dust, scale, iron powder, iron oxide powder, iron sand, iron ore, and the like. Can do.

Steel slag (slag generated in the steel manufacturing process) includes blast furnace slag, steelmaking slag, ore reduction slag, and the like. Blast furnace slag includes blast furnace slow cooling slag and blast furnace granulated slag.
Steelmaking slag is slag generated in the steelmaking process of the steelmaking process. Examples of such steelmaking slag include converter slag (decarburization slag), hot metal pretreatment slag (dephosphorization slag, desulfurization slag, desiliconization slag, etc.), ingot slag, electric furnace slag, etc. It is not limited to these.

Examples of non-ferrous smelting slag include copper smelting slag and various alloyed iron slags. Examples of the garbage melting slag include garbage incineration ash melting slag, garbage direct melting slag, and the like. These slags include a slowly cooled crystalline one and a rapidly cooled glass cullet-like one.
The particle size of the slag described above is not particularly limited, but from the viewpoint of the elution efficiency of the active ingredient, a particle size of 25 mm or less, more preferably 10 mm or less, particularly preferably 5 mm or less is desirable.
Typical examples of the dust include dust generated in the steel manufacturing process (for example, converter dust, blast furnace dust, etc.). As a scale, the scale (for example, mill scale etc.) which generate | occur | produces in a steel manufacturing process is mentioned as a typical thing.

As the iron source (x), a material containing iron oxide as a solid solution, such as slag, is preferable to pure iron oxide because it has high reactivity with an organic acid and high iron ion elution ability.
Table 1 shows the results of examining the elution of iron ions in seawater when gluconic acid and humic acid are applied to various iron sources. The test for gluconic acid was performed under the following conditions.

(1) Various iron sources were put in a plastic bag with a chuck, 0.15 mass% gluconic acid of the iron source amount was added and mixed, and then allowed to stand overnight to prepare a sample.
(2) After putting 10 g of a sample into a 250 mL plastic bottle and injecting 200 mL of artificial seawater, continuous shaking was performed at 200 rpm for 24 hours with a shaking device.
(3) The contents of the plastic bottle after shaking were filtered with a 0.45 μm filter, and the Fe concentration of the liquid after filtration was measured. The analysis of the Fe concentration in the liquid was performed using ICP-AES (inductively coupled plasma emission spectrometer).

Moreover, the test regarding humic acid was performed under the following conditions.
(1) A humic acid reagent was added to artificial seawater to prepare 0.05 mass% humic acid artificial seawater. The pH of the solution at this time was about 8.
(2) 10 g of various iron sources were put in a 250 mL plastic bottle and 200 mL of 0.05 mass% humic acid artificial seawater was injected, followed by continuous shaking at 200 rpm for 24 hours with a shaking device.
(3) The contents of the plastic bottle after shaking were filtered with a 0.45 μm filter, and the Fe concentration of the liquid after filtration was measured. The analysis of the Fe concentration in the liquid was performed using ICP-AES (inductively coupled plasma emission spectrometer).

  As shown in Table 1, the amount of iron ions eluted from the iron oxide reagent is small. On the other hand, non-ferrous slag such as copper smelting slag and refuse melting slag has a large amount of iron ion elution, but lacks long-term elution sustainability due to its high elution ability. On the other hand, steelmaking slag has a moderate elution ability of iron ions (elution ability higher than that of reagent iron oxide and lower than that of non-ferrous slag), and thus has a long-term elution durability. Steelmaking slag also has the advantage of being inexpensive and available in large quantities.

  In addition, when gluconic acid is used, metallic iron and iron oxide other than the reagent have higher elution ability of iron ions than steelmaking slag, but have moderate elution ability compared to the iron oxide and non-ferrous slag of the reagent. It can be said that. However, since these metallic iron and iron oxide have considerably higher elution ability of iron ions than steelmaking slag, long-term elution sustainability is inferior to steelmaking slag. Furthermore, it is more expensive than steelmaking slag and is difficult to obtain in large quantities. On the other hand, when humic acid is used, the elution ability of metallic iron other than the reagent and iron ions of iron oxide is much smaller than that of steel slag.

In view of the above, as the iron source (x), steel slag, non-ferrous smelting slag, and municipal waste molten slag are particularly preferable, and an iron source (x) composed of one or more of these or mainly composed of one or more of these. ) (Including the case where the iron source (x) consists only of slag such as steel slag, and the same applies hereinafter). Among steel slags, steelmaking slag, in particular, has moderate elution ability as described above, has long-term elution durability, has stable components, contains a lot of iron, Therefore, an iron source (x) containing steelmaking slag or containing steelmaking slag as a main component (including the case where the iron source (x) consists only of steelmaking slag, the same applies hereinafter) is preferable. Incidentally, slag because low pH is desirable, the CaO contained in slag may be used one obtained by carbonation to CaCO _3.

Examples of the organic acid include glutamic acid, citric acid, humic acid, acetic acid, fulvic acid, gluconic acid, and the like, and one or more selected from these can be used. Among these, gluconic acid, citric acid, and nitrogen-containing oxyacids (for example, glutamic acid, humic acid, fulvic acid, etc.) are preferable, and it is preferable to use one or more selected from these.
The organic acid source may be any of organic acid powders, organic acid salts, organic acid-containing substances (including organic acid-containing solutions), and the like. For example, fulvic acid may be contained in clay, and such clay may be used as the organic acid-containing substance. Therefore, when an organic acid is mixed with the iron source (x), the organic acid itself may be added and mixed, or a substance containing the organic acid may be added and mixed. For example, when fulvic acid is contained in the clay, the clay containing such fulvic acid may be added to an iron source (x) such as steelmaking slag.

The mixing ratio of the iron source (x) and the organic acid (in the case of mixing the iron source (x) and the organic acid) is 0.5% by mass or more of the organic acid with respect to the iron source (x). Preferably it is 5 mass% or more. On the other hand, if the organic acid exceeds 50% by mass, the effect of recovery or prevention of discoloration of seaweed is saturated.
The treatment agent comprising a combination of an iron source (x) and an organic acid (particularly preferably one or more of glutamic acid, citric acid, humic acid, fulvic acid, and gluconic acid) has an effect of recovering or preventing the color loss of laver. It is considered that the organic acid has a chelating effect capable of holding iron contained in the iron source (x) as dissolved iron, and the dissolved iron contributes to recovery or prevention of discoloration of laver.

  In addition, as in the first and fourth methods of the present invention described later, in a method of using a mixture of an iron source (x) and an organic acid and adding the mixture to seawater or installing it in the sea, an iron source ( Since x) and the organic acid are present in close proximity, it is advantageous for the formation of iron chelate, and the concentration of iron chelate eluted in seawater can be increased and the elution persistence can also be increased. For this reason, the color fading recovery / prevention effect of seaweed can be further enhanced and sustained for a long time.

  In the first method of the present invention, laver is immersed in seawater to which the above-mentioned mixture of the iron source (x) and the organic acid (hereinafter referred to as “mixture A” for convenience) is added. Here, the seawater in which the seaweed is immersed includes seawater after the mixture A is added and immersed for a certain period of time, and then the solid content is removed. This method is usually performed for the purpose of recovering the color fading of the laver (the laver having the color fading), but may be performed for the purpose of preventing the laver from fading.

Usually, in this method, the mixture A is added (charged) to a water tank containing seawater, and the seaweed is added to the seawater (or the seawater after the solids are removed after the mixture A is immersed for a certain period of time). Is immersed. In this case, only the seaweed may be dipped, or the whole nori net for aquaculture may be dipped.
Although there is no special condition for the dipping period of the seaweed, it is generally preferably 24 hours or longer in order to sufficiently recover the color fading.

In the second method of the present invention, laver is immersed in seawater to which the iron source (x) and the organic acid described above are added. That is, the iron source (x) and the organic acid are added to seawater without being mixed in advance, and the seaweed is immersed in the seawater. The seawater in which the seaweed is immersed includes seawater after the solid content is removed after the iron source (x) and the organic acid are added and immersed for a certain period of time. This method is usually performed for the purpose of recovering the color fading of the laver (the laver having the color fading), but may be performed for the purpose of preventing the laver from fading.
Usually, in this method, an iron source (x) and an organic acid are added (charged) to a water tank containing seawater, and the seawater (or the iron source (x) and the organic acid are immersed for a certain period of time, The seaweed is immersed in the seawater after removing the solid content.
Other conditions are the same as in the first method.

In the third method of the present invention, the seawater added with the organic acid described above is attached to the seaweed, and then the seaweed is immersed in the seawater added with the iron source (x) described above. Although the method of adhering the seawater to which the organic acid is added to the seaweed is arbitrary, the seaweed is usually immersed in seawater to which the organic acid has been added.
The seawater to which the organic acid is added is attached to the seaweed, and the seawater in which the seaweed is immersed also includes seawater after the solid content is removed after the iron source (x) is added and immersed for a certain period of time. . This method is usually performed for the purpose of recovering the color fading of the laver (the laver having the color fading), but may be performed for the purpose of preventing the laver from fading.

In this method, for example, an organic acid is added (charged) to the first aquarium containing seawater, and an iron source (x) is added to the second aquarium. The laver is added to the seawater in the first aquarium. After being immersed, it is immersed in the seawater of the second tank (or in the seawater after the solid content is removed after being immersed in the iron source (x) for a certain period of time).
Other conditions are the same as in the first method.

In the fourth method of the present invention, the mixture A is installed in seawater in a water area where a laver farm is located. This method is usually performed for the purpose of preventing the color loss of the seaweed, but may be performed for the purpose of recovering the color loss of the seaweed (the seaweed in which color loss has occurred).
As a form in which the mixture A is installed in seawater, it may be installed on the seabed, or may be suspended in the sea using a laver net or other holding means.

[Example 1]
In order to verify the color fading recovery effect of seaweed according to the present invention, the following test was conducted.
Add the additive to 1 L of seawater (however, the test solution (5) has no additive), and after stirring for 24 hours, remove the solid with filter paper, adjust the filtrate to pH 8 with hydrochloric acid or sodium hydroxide, Test solutions (1) to (5) were prepared. As seawater, seawater was cultured in natural seawater and depleted of dissolved inorganic nitrogen (DIN). As the steelmaking slag, dephosphorization slag (particle size of 0.6 mm or less) was used.

Of the following test solutions, the test solutions (2), (3), and (4) are used as examples of the present invention, and the test solutions (1) and (5) are used as comparative examples.
(1) Test solution to which steelmaking slag (10 g) was added (2) Test solution to which a mixture of steelmaking slag (10 g) and fulvic acid-containing clay (90 g) was added (3) Steelmaking slag (10 g) and glutamic acid (0.5 g) (4) Test solution with steelmaking slag (10 g) and humic acid (3 g) added (5) Test solution without additive

One piece of nori leaf was prepared to 10 mm (diameter), and two pieces of this nori leaf were immersed in each test solution, and a color fading recovery evaluation test was conducted. The immersion conditions were seawater temperature: 15 (13-17) ° C., salinity: 33 PSU, light / dark cycle: 12 hours / 12 hours, and light intensity: 8000 LUX. In this test, the SPAD value (chlorophyll concentration), L ^* value (lightness), and a ^* value (redness) of the laver leaf bodies were measured at the start of immersion, 24 hours after immersion, and 48 hours after immersion, The degree of color fading recovery was evaluated. The result is shown in FIG.
(1) SPAD value Using Konica Minolta Sensing Co., Ltd.'s “Chlorophyll Meter SPAD-502” (trade name), measure the SPAD value (chlorophyll concentration) of the two laver leaf bodies, and calculate the average of these measured values. SPAD value was used.

(2) L ^* value Using Konica Minolta Sensing Co., Ltd. “Color Difference Meter CR-400” (trade name), we measured the L ^* value (lightness) of the two laver leaves and measured these values. Was the L ^* value. Higher values are whitish and lower values are darker. Therefore, the faded seaweed has a high value, and if the L ^* value is 79 or more, it is determined that the color is severely discolored.
(3) a ^* value Using a “color difference meter CR-400” (trade name) manufactured by Konica Minolta Sensing Co., Ltd., measured the a ^* value (redness) of the two laver leaves. The average of the measured values was defined as a ^* value. When this value goes in the positive direction, the redness is strong, and when it goes in the negative direction, the green becomes strong.

According to FIG. 1, the SPAD value hardly changes even after 48 hours of immersion in the comparative example, whereas the SPAD value greatly increases after 48 hours of immersion in the example of the present invention. Also, it can be seen from the L ^* value and the a ^* value that the color loss of the present invention is greatly recovered compared to the comparative example. Further, among the examples of the present invention, the one using the test solution (4) exhibits the most remarkable color fading recovery.

[Example 2]
In order to verify the effect of preventing discoloration of seaweed according to the present invention, the following test was conducted.
Add the additive to 1 L of seawater (however, the test solution (5) has no additive), and after stirring for 24 hours, remove the solid with filter paper, adjust the filtrate to pH 8 with hydrochloric acid or sodium hydroxide, Test solutions (1) to (5) were prepared. As seawater, seawater was cultured in natural seawater and depleted of dissolved inorganic nitrogen (DIN). As the steelmaking slag, dephosphorization slag (particle size of 0.6 mm or less) was used.

Of the following test solutions, the test solutions (1) and (2) are used as examples of the present invention, and the test solutions (3), (4) and (5) are used as comparative examples.
(1) Test solution to which a mixture of steelmaking slag (10 g) and glutamic acid (0.5 g) was added (2) Test solution to which a mixture of steelmaking slag (10 g) and humic acid (3 g) was added (3) Glutamic acid (0.5 g) (4) Test solution with humic acid (3 g) added (5) Test solution without additive

One piece of nori leaf was prepared to 10 mm (diameter), and two pieces of this nori leaf were immersed in each test solution, and an evaluation test for color fading prevention of nori was conducted. The immersion conditions were seawater temperature: 15 (13-17) ° C., salinity: 33 PSU, light / dark cycle: 12 hours / 12 hours, and light intensity: 8000 LUX. In this test, the SPAD value (chlorophyll concentration), L ^* value (lightness), and a ^* value (redness) of the laver leaf bodies were measured at the start of immersion, 24 hours after immersion, and 48 hours after immersion, respectively. The degree of color fading prevention was evaluated. The result is shown in FIG.

FIG. 2 shows that the SPAD value hardly changes after 48 hours of immersion in the comparative example, whereas the SPAD value increases significantly after 48 hours of immersion in the example of the present invention. Further, even when looking at the L ^* value and the a ^* value, it can be seen that color loss is effectively prevented and further recovered in the inventive example compared to the comparative example.

[Example 3]
In order to verify the color fading recovery effect of seaweed according to the present invention, the following test was conducted.
Sodium nitrate was added to the artificial seawater so as to have a predetermined N concentration (250 μg / L). In the invention example, various organic acids and iron powder (reduced) were added to 1 L of this artificial seawater, and after stirring for 24 hours, solids were removed with filter paper, and the filtrate was adjusted to pH 8.02 with hydrochloric acid or sodium hydroxide. Moreover, in the comparative example, after adding only various organic acids to 1 L of artificial seawater, it adjusted to pH 8.02 with hydrochloric acid or sodium hydroxide.

  One piece of nori leaf was prepared to 10 mm (diameter), and two pieces of this nori leaf were immersed in each test solution, and a color fading recovery evaluation test was conducted. The immersion conditions were seawater temperature: 15 (13-17) ° C., salinity: 33 PSU, light / dark cycle: 12 hours / 12 hours, and light intensity: 8000 LUX. In this test, the SPAD value (chlorophyll concentration) of the laver leaf bodies was measured by the same method as in Example 1 at the start of immersion and 48 hours after immersion, and [SPAD value after 48 hours after immersion]-[at the start of immersion] [SPAD value of]. The results are shown in Table 2 together with the organic acid used, the Fe concentration and the N concentration of the test solution. The analysis of the Fe concentration in the liquid was performed using ICP-AES (inductively coupled plasma emission spectrometer). According to Table 2, it can be seen that in the example of the present invention, the SPAD value after 48 hours of immersion is greatly increased.

Claims (7)

Seawater to which a mixture of iron oxide and / or metallic iron-containing substance (including a substance composed only of iron oxide and / or metallic iron) and an organic acid is added (however, the mixture is added and immersed for a certain period of time) And the seaweed after the solid content is removed) , wherein at least a part of the iron oxide and / or metal iron-containing substance is steel slag. How to recover or prevent discoloration. Iron oxide and / or metallic iron-containing substances (including those containing only iron oxide and / or metallic iron) and seawater to which an organic acid is added (however, the iron oxide and / or metallic iron-containing substances and organic And after immersion for a certain period of time after adding an acid, the seaweed is then immersed in the seawater after the solid content is removed), and at least a part of the iron oxide and / or metal iron-containing substance is made of steel. A method for recovering or preventing discoloration of laver characterized by being slag . Seawater to which organic acid is added is attached to the seaweed, and then seawater to which the seaweed is added with iron oxide and / or metal iron-containing substances (however, a substance consisting of iron oxide and / or metal iron only) is added. (However, after adding the iron oxide and / or metallic iron-containing substance and immersing for a certain period of time, including seawater after removing the solid content thereof), the iron oxide and / or metal A method for recovering or preventing discoloration of seaweed , wherein at least part of the iron-containing substance is steel slag . A method of installing a mixture of iron oxide and / or metal iron-containing substances (including substances consisting only of iron oxide and / or metal iron) and organic acids in the sea water of the seaweed farm A method for recovering or preventing color loss of seaweed , wherein at least a part of the iron oxide and / or metal iron-containing substance is steel slag .   The organic acid is at least one selected from gluconic acid, citric acid, and oxyacids containing nitrogen, The method for recovering or preventing color loss of laver according to any one of claims 1 to 4 .   6. The method for recovering or preventing color loss of laver according to claim 5, wherein the oxyacid containing nitrogen is at least one selected from glutamic acid, humic acid, and fulvic acid.   The iron oxide and / or metallic iron-containing substance is at least one selected from steel slag, non-ferrous smelting slag, refuse molten slag, dust, scale, iron powder, iron oxide powder, sand iron, iron ore The method for recovering or preventing discoloration of laver according to any one of claims 1 to 6.

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