JP2010057442A - Method for removing heavy metal from fish and shellfish containing harmful heavy metal in short time, and manufacturing method of foodstuff obtained by the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a technique for removing in a short time a heavy metal from fishes and shellfishes or the like without adding water and an acid thereto while maintaining freshness and qualities thereof, considering that some fishes and shellfishes contain a harmful heavy metal in their internal organ and that therefore processed foodstuffs, fodder and fertilizers obtained utilizing the fishes and shellfishes inevitably contain the heavy metal. <P>SOLUTION: The method for removing a heavy metal includes crushing fishes and shellfishes containing the heavy metal and mixing it with a heavy metal-absorbing material with agitation under heating. Thus, the heavy metal can be removed from the fishes and shellfishes in a short time without adding water and an acid thereto while maintaining freshness and qualities thereof. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

The present invention relates to a method for removing heavy metals without adding water and acid while maintaining quality from fish and shellfish containing heavy metals, and further relates to a technique for using fish and shellfishes from which heavy metals have been removed as food.

When processing fish with low freshness and low quality that are not suitable for fresh foods, use them as feed or fertilizer after removing heavy metals.

Methods for removing heavy metals from organic materials containing heavy metals include methods in which organic materials are immersed in a strongly acidic aqueous solution (pH 1) such as sulfuric acid to dissociate heavy metals and then deposited on electrodes (Patent Document 1). A method of adsorbing and removing the heavy metal in the liquid phase after dissociating the heavy metal into the liquid phase (Patent Document 2), using a microorganism such as lactic acid bacteria or yeast to dissociate the heavy metal into the liquid phase and then removing the heavy metal in the liquid phase Method of adsorbing and removing (Patent Document 3), Method of removing heavy metal with chelate fiber from liquid phase after scallop viscera is immersed in pH 1-2 solution such as hydrochloric acid to dissociate heavy metal into liquid phase (Patent Document 4) and so on.

However, the method of precipitating an organic substance in a strongly acidic aqueous solution (pH 1) such as sulfuric acid to dissociate heavy metals and then depositing it on the electrode uses a denatured useful component (protein, lipid, etc.) in the organic substance and uses an alkali such as lime. Neutralization does not return. In addition, it is difficult to use organic substances in which lime added in a large amount to neutralize strongly acidic aqueous solution remains in the form of gypsum, and there are problems such as high processing costs and long processing days. is there.

In addition, with regard to the method of adsorbing and removing heavy metal in the liquid phase after dissociating heavy metal into the liquid phase using self-digesting enzymes, it is difficult to suppress contamination by bacteria because the heavy metal is adsorbed in the neutral range, and organic matter is likely to decay. In addition, the generation of a wide variety of degradation products due to other enzymes is a major problem when used as food.

Furthermore, with respect to a method of adsorbing and removing heavy metal in the liquid phase after dissociating the heavy metal into the liquid phase using microorganisms such as lactic acid bacteria and yeast, dissociation of the heavy metal into the liquid phase, solid-liquid separation of the organic substance and the liquid phase, and Since a series of steps of heavy metal adsorption removal from the liquid phase takes a long time and quality such as taste and smell is lowered, it can be used as feed and fertilizer, but it is difficult to use as food.

The method of immersing in a pH 1-2 solution such as hydrochloric acid to dissociate heavy metals into the liquid phase reduces the value by diluting amino acids in the visceral fluid by hydration, and the amount of wastewater treated is several There is a problem to double.

On the other hand, the inventor announced a method of adsorbing and removing cadmium by determining the number of cadmium binding sites and binding constants of scallopuro and mixing and stirring with scallopuro in nitric acid solution using insolubilized humic acid as an adsorbent. (Non-Patent Document 1). Furthermore, the heavy metal removal method from the organic substance using the heavy metal adsorbent at low temperature is developed (patent document 5). However, according to the above method, cadmium adsorption / removal required 24 hours under weakly acidic conditions, and it was necessary to add some acid and neutralizer.
JP 07-203036 A JP 06-106155 A Japanese Patent No. 3174825 Japanese Patent No. 4092252 Hideshi S.H. , Akira S. (1997) A new method for the removal of toxic metal ions from acid-sensitive biomaterial. Journal of colloid and interface science 190, pp. 206-211. Japanese Patent No. 4000346

This invention makes it a subject to isolate | separate a heavy metal economically in a short time, and to use as a foodstuff, without adding water and an acid, keeping quality from the fish and shellfish containing a heavy metal.

The heavy metal removal method of the present invention is capable of removing heavy metals from seafood by crushing seafood containing heavy metals and stirring and mixing the heavy metal adsorbent while heating at 40 ° C to 70 ° C, preferably 60 ° C. By carrying out this method, propagation of various bacteria can be suppressed, and heavy metals can be removed without adding water and acid while maintaining the quality of seafood in a short time.

In addition, the heavy metal removal method of the present invention uses a competitive adsorption equilibrium of the seafood and the adsorbent for heavy metal ions, and the heavy metal adsorption capacity of the adsorbent becomes excessive with respect to the heavy metal adsorption capacity of the seafood. Thus, by adding the adsorbent, heavy metals can be more efficiently adsorbed and removed from seafood.

Furthermore, the seafood obtained by the heavy metal removal method of the present invention can be used as food, beverages, etc., with cadmium removed by 95.0% or more.

According to the present invention, since heavy metals can be removed from fish and shellfish containing heavy metals at pH 5.0 to pH 7.0 in a short time without adding water and acid, economically without losing quality from fish and shellfish containing heavy metals such as cadmium. Heavy metals can be separated, and it can be used not only as feed and fertilizer but also as food.

The “heavy metal” in the present invention refers to cadmium, lead, arsenic, mercury and the like, and means at least containing cadmium and binding to proteins or existing in an ionic form.

In the present invention, fish and shellfish containing heavy metals are targeted. “Seafood” in the present invention includes fish, shellfish and their internal organs, and includes not only natural products but also processed products. Therefore, it is obvious to those skilled in the art that scallop viscera and squid viscera are included in seafood. The “scallop viscera” refers to various organs other than scallops, and includes the midgut gland, gonads, sputum, mantle, and the like. In addition, the “squid viscera” generally refers to the viscera of a bandit and sometimes only the liver.

The “heavy metal adsorbent” in the present invention refers to a resin, fiber, natural material or the like having a chelating action or an ion exchange action, and includes those inexpensive natural materials such as corrosive substances, algae and clay minerals for those skilled in the art. It is self-explanatory.

In the present invention, “acid” refers to organic acids such as formic acid, lactic acid, acetic acid and citric acid, or inorganic acids such as hydrochloric acid, sulfuric acid and phosphoric acid, and “acidic” generally refers to a pH of less than 6.0. The “acidic aqueous solution” refers to a liquid in which an acid is dissolved in water and is acidic.

`` Mixing and stirring '' in the present invention refers to mixing and stirring the seafood containing heavy metal and the heavy metal adsorbent, but may be stirred after combining the seafood containing heavy metal and the heavy metal adsorbent, You may add the other to the place which is stirring either one.

“Adsorption” in the present invention means that heavy metal is captured by the heavy metal adsorbent, and includes not only positive adsorption but also negative adsorption. Further, “adsorption removal” means removal of a heavy metal adsorbent on which heavy metals have been adsorbed, and removal of only heavy metals from a heavy metal adsorbent on which heavy metals have been adsorbed.

Competitive adsorption equilibrium in the present invention means that when a heavy metal adsorbent is added to a ground product of seafood containing heavy metals, a phenomenon occurs in which cadmium is competing competitively between the seafood and the adsorbent. By adding the adsorbent so that the adsorption capacity of the material is excessive with respect to the adsorption capacity of the fish and shellfish, it means that the previous phenomenon reaches an equilibrium state, that is, the mutual adsorption action reaches an equilibrium state. In the state of competitive adsorption equilibrium, the adsorbent adsorbs more heavy metals than the seafood.

Among the stirring temperatures in the present invention, the pasteurization effect at 60 ° C. to 70 ° C. provides a pasteurization effect and has the effect of sterilizing various pathogens and preventing spoilage.

In general, heavy metals are bound to specific proteins (metallothionein) in organic matter. In order to completely dissociate heavy metals bound to metallothionein (99.5% or more) by acid treatment, a strong acid at pH 1.0 is used. (Patent Document 1). According to the heavy metal adsorption / removal method of the present invention, water and acid can be obtained by mixing and stirring a heavy metal-containing marine product and a heavy metal adsorbent combining a H-type and Na-type resin or fiber having chelating and ion-exchange effects. In addition, heavy metals can be separated from marine products under neutral conditions.

According to the heavy metal adsorption removal method of the present invention, water and acid are not added to fish and shellfish, and the heavy metal adsorption capacity is about 40 times that of fish and shellfish (about 10.0 times that of fish and shellfish on a dry weight basis). Separation of heavy metals from fish and shellfish in a short time by adding heavy metal adsorbent that combines H type and Na type of resin or fiber having chelating action and ion exchange action so that Is possible.

In the conventional acid treatment method, heavy metals in organic matter are dissociated by using substitution reaction of hydrogen ions in liquid phase, and the concentration of hydrogen ions in liquid phase is the driving force for substitution reaction, so acidic or strongly acidic aqueous solution It was necessary to use. In the method for removing heavy metals according to the present invention, seafood is heated to 40 ° C. to 70 ° C., preferably 60 ° C. without adding water and acid, and trace amounts of heavy metals dissociated in the water are immediately adsorbed. The concentration of heavy metals in the water is always kept at a low level by removing them, and the heavy metals are dissociated from the seafood with the difference in the concentration of heavy metals in the seafood and the water as a driving force. 95.0% or more of heavy metals can be removed.

In the conventional method, it took 4 to 7 days to reduce organic heavy metals (Patent Document 3). On the other hand, the present inventor has developed a method of removing 99.0% or more of heavy metals in weakly acidic, low temperature conditions in about 24 hours (Patent Document 5), but it requires addition of an acid and a neutralizing agent. It was. According to the heavy metal removal method of the present invention, it becomes possible to remove heavy metals from fish and shellfish without adding acid in a short time, and since no acid or neutralizing agent is added, the food can be used in a wider range. Can be used.

According to the present invention, heavy metals contained in fish and shellfish can be removed until the water content becomes 0.1 to 1.0 mg / kg or less. In addition, heavy metals can be removed in a short time under neutral conditions without adding water and acid, so that work safety is high and processing costs are low.

According to the method of the present invention, the processing time and the amount of chemicals used can be significantly reduced compared to the existing technology, which is inherently low cost, but cheap natural materials such as corrosive substances, algae and clay minerals are used as the adsorbent. By doing so, the cost of the heavy metal adsorbent can be greatly reduced, which is suitable for the production of feed and fertilizer from low freshness and low quality marine products that cannot be used as food.

EXAMPLES Hereinafter, although an Example demonstrates this invention more concretely, this invention is not limited at all by these Examples.

In this example, a freshly scallop (Hokkaido Tomakomai) visceral viscera containing cadmium was used as the treatment target seafood.

As the chelating resin, commercially available Diaion CR11 (Na type) manufactured by Mitsubishi Chemical Corporation and an H type resin prepared from Na type resin with 1N hydrochloric acid aqueous solution were used. A combination of these two types of resins was used so that the pH during stirring was about 7.0.

100 g of homogenized scallop viscera was placed in a beaker, placed in a thermostatic bath at each temperature of 40 ° C., 50 ° C., 60 ° C., and 70 ° C., and stirred at 100 rpm using a stirrer (MAZERA Z-1200 manufactured by EYELA).

The cadmium contained in the used scallop viscera was measured using an atomic absorption device (AAnalyst100 manufactured by PerkinElmer), and the initial concentration was 3.73 mg / kg (actual).

After 15 minutes, 20% of the prepared chelate resin (mixed Na type and H type, pH 7) was added to the scallop viscera, and cadmium in the scallop viscera was adsorbed and removed at each temperature.

As a result, it was confirmed that the adsorption rate of cadmium in the scallop viscera with an initial concentration of 3.73 mg / kg increased as the temperature increased. At 40 ° C., it took 7 hours for Cd in the scallop viscera to drop to 0.21 mg / kg (actual), but at 50 ° C., it took 4 hours to decrease to 0.21 mg / kg (actual). The temperature dropped to 0.20 mg / kg (actual) at 0 ° C. for 3 hours and at 170 ° C. for 3 hours to 0.14 mg / kg (actual) (FIG. 1).

In this example, a fresh squid (produced in Hakodate, Hokkaido) viscera containing cadmium was sufficiently homogenized as the seafood to be treated.

As the chelating resin, commercially available Diaion CR11 (Na type) manufactured by Mitsubishi Chemical Corporation and an H type resin prepared from Na type resin with 1N hydrochloric acid aqueous solution were used. A combination of these two types of resins was used so that the pH during stirring was about 7.0.

100 g of homogenized squid viscera was placed in a beaker, placed in a thermostatic bath at each temperature of 40 ° C., 50 ° C., 60 ° C., and 70 ° C., and stirred at 100 rpm using a stirrer (MAZERA Z-1200 manufactured by EYELA).

The cadmium contained in the squid viscera used was measured using an atomic absorption device (AAnalyst 100 manufactured by PerkinElmer), and the initial concentration was 56.81 mg / kg (actual).

After 15 minutes, 20% of the prepared chelate resin (mixed Na type and H type, pH 7) was added to the squid viscera, and cadmium in the squid viscera was adsorbed and removed at each temperature.

As a result, it was confirmed that the adsorption rate of cadmium in the squid viscera having an initial concentration of 56.81 mg / kg increased as the temperature increased. Cd in the squid viscera decreased only to 3.23 mg / kg (actual) at 40 ° C. in 4 hours, but decreased to 0.81 mg / kg (actual) in 70 hours at 4 ° C. (FIG. 2).

After the adsorption and removal of cadmium was completed, the chelate resin dispersed in the squid viscera was quickly separated by filter filtration and solid-liquid separation.

In general, the service temperature of chelate resins is from 80 ° C. to 100 ° C. or around 120 ° C., and use at higher temperatures is likely to damage the resin. In actual use, use at lower temperatures is encouraged. From the results of Example 1 and Example 2, the temperature at which cadmium can be efficiently adsorbed and removed from fish and shellfish in a short time is 40 ° C to 70 ° C, preferably 60 ° C. For this reason, it is not efficient, and a temperature higher than that is not preferable because the resin may be damaged.

In this example, fresh scallops (produced in Tomakomai, Hokkaido) that contained cadmium as the treatment target seafood were sufficiently homogenized.

As the chelating resin, commercially available Diaion CR11 (Na type) manufactured by Mitsubishi Chemical Corporation and an H type resin prepared from Na type resin with 1N hydrochloric acid aqueous solution were used. A combination of these two types of resins was used so that the pH during stirring was about 7.0.

100 g of homogenized scallop viscera was placed in a beaker and adjusted to pH 5.0, 6.0, 7.0 using concentrated hydrochloric acid, and then placed in a constant temperature bath at 60 ° C., respectively, and a stirrer (MAZERA made by EYELA). Z-1200) and stirred at 100 rpm.

The cadmium contained in the used scallop viscera was measured using an atomic absorption device (AAnalyst100 manufactured by PerkinElmer), and the initial concentration was 3.73 mg / kg (actual).

After 15 minutes, 20% of the prepared chelate resin (mixed Na type and H type, pH 7) was added to the scallop viscera, and cadmium in the scallop viscera was adsorbed and removed at each temperature. The pH during cadmium removal was maintained at the initial value by adding concentrated hydrochloric acid and sodium hydroxide.

As a result, it was confirmed that the initial adsorption rate of cadmium in the scallop viscera with an initial concentration of 3.73 mg / kg increased as the pH decreased (FIG. 3). This is because the ionic dissociation of cadmium bound to a protein such as metallothionein in the scallop viscera is promoted and is easily captured by the chelate resin because the pH of the scallop viscera is lowered.

In this example, a fresh squid (produced in Hakodate, Hokkaido) viscera containing cadmium was sufficiently homogenized as the seafood to be treated.

As the chelating resin, commercially available Diaion CR11 (Na type) manufactured by Mitsubishi Chemical Corporation and an H type resin prepared from Na type resin with 1N hydrochloric acid aqueous solution were used. A combination of these two types of resins was used so that the pH during stirring was about 7.0.

100 g of homogenized squid viscera was placed in a beaker and adjusted to pH 5.0, 6.0, 7.0 using concentrated hydrochloric acid, and then placed in a constant temperature bath at 60 ° C., respectively, and a stirrer (MAZERA made by EYELA). Z-1200) and stirred at 100 rpm.

The cadmium contained in the squid viscera used was measured using an atomic absorption device (AAnalyst 100 manufactured by PerkinElmer), and the initial concentration was 56.81 mg / kg (actual).

After 15 minutes, 20% of the prepared chelate resin (Na type and H type mixed, pH 7) was added to the squid viscera, and cadmium in the scallop viscera was removed by adsorption at each temperature. The pH during cadmium removal was maintained at the initial value by adding concentrated hydrochloric acid and sodium hydroxide.

As a result, it was confirmed that the adsorption rate of cadmium in the squid viscera having an initial concentration of 56.81 mg / kg increased as the pH decreased (FIG. 4).

A comparison of the pH dependence of the Cd elution rate from the squid viscera and the Cd adsorption rate to the chelate resin is shown in FIG. At pH 7, the cadmium elution rate of scallop viscera is close to 0%, but at pH 5, it increases to 25%. This is because at pH 5, cadmium adsorption to the resin is not only due to direct contact between the cadmium bound to the protein and the resin, but also the adsorption between the eluted cadmium ions and the resin, so that pH 5 is faster than pH 7. It suggests adsorption at a rate, which is consistent with the results of Examples 3 and 4.

From the results of Examples 3 and 4, it can be said that a lower pH is preferable when cadmium is adsorbed and removed from seafood in a short time. However, the use of chemicals for lowering the pH of both scallop and squid viscera may affect the cost increase and subsequent use as food and as fertilizer and feed. It can be said that cadmium treatment at pH 7.0, preferably around pH 6 without adding chemicals is desirable.

In this example, fresh scallops (produced in Tomakomai, Hokkaido) that contained cadmium as the treatment target seafood were sufficiently homogenized.

Three types of chelate resins were used: Dia Chemical CR11 Na-type resin, Na-type and H-type mixed resin (pH 7), and H-type resin. As the Na type, a commercially available product was used as it was, and a resin (pH 7) mixed with Na type and H type was prepared in the same manner as in Example 1, and the H type resin was prepared by a predetermined method using 1N hydrochloric acid.

100 g of homogenized scallop viscera was placed in a beaker, placed in a thermostatic bath at 60 ° C., and stirred at 100 rpm using a stirrer (MAZERA Z-1200 manufactured by EYELA).

The cadmium contained in the used scallop viscera was measured using an atomic absorption device (AAnalyst100 manufactured by PerkinElmer), and the initial concentration was 3.73 mg / kg (actual).

After 15 minutes, 20% of the three chelate resins prepared above were added to the scallop viscera, and the cadmium in the scallop viscera was removed by adsorption.

As a result, it was confirmed that cadmium in the squid viscera having an initial concentration of 3.73 mg / kg increases in the initial adsorption rate in the order of H-type resin, Na-type and H-type mixed resin, and Na-type (FIG. 3). 6). The pH of the scallop viscera after removal of cadmium was 4.13, 6.12, and 7.15, respectively.

From the results of Example 5, it can be said that when the cadmium is adsorbed and removed from the seafood in a short time, the H-type resin is preferable. In the Na type, the adsorption rate of cadmium is slow. However, when the H-type resin is used, it is necessary to use chemicals for neutralizing the lowered pH after removing cadmium in both the scallop and squid viscera. It can be said that it is optimal to use a resin (pH 7) in which Na type and H type are mixed because it increases the cost of chemicals and affects the subsequent use as food and the use as fertilizer and feed.

FIG. 1 is a graph showing a difference in cadmium concentration and treatment time due to a difference in temperature when scallop viscera containing cadmium and a chelate resin are mixed and stirred. The horizontal axis in FIG. 1 indicates the time (h) required for the treatment, and the vertical axis indicates the cadmium concentration (mg / kg actual product). FIG. 2 is a graph showing a difference in cadmium concentration and treatment time due to a difference in temperature when squid viscera containing cadmium and a chelate resin are mixed and stirred. The horizontal axis of FIG. 2 indicates the time (h) required for the treatment, and the vertical axis indicates the cadmium concentration (mg / kg actual product). FIG. 3 is a graph showing the difference in cadmium concentration and treatment time at each pH when scallop viscera containing cadmium and a chelating resin are mixed and stirred. The horizontal axis of FIG. 3 shows the time (h) required for the treatment, and the vertical axis shows the cadmium concentration (mg / kg actual product). FIG. 4 is a graph showing the difference in cadmium concentration and treatment time at each pH when squid viscera containing cadmium and a chelating resin are mixed and stirred. The horizontal axis in FIG. 4 indicates the time (h) required for the treatment, and the vertical axis indicates the cadmium concentration (mg / kg actual product). FIG. 5 is a graph showing a comparison of the pH dependence of the Cd elution rate from the squid viscera and the Cd adsorption rate to the chelate resin. The horizontal axis of FIG. 5 indicates pH, and the vertical axis indicates cadmium adsorption rate or elution rate (%). FIG. 6 is a graph showing the difference between the cadmium concentration and the treatment time when scallop viscera containing cadmium and a chelate resin are mixed and agitated and when H type, Na type and H type mixed, and Na type resin is used. The horizontal axis in FIG. 6 indicates the time (h) required for the treatment, and the vertical axis indicates the cadmium concentration (mg / kg actual product).

Claims (3)

After pulverizing fish and shellfish containing heavy metals, heat and stir at 40 ° C to 70 ° C, preferably 60 ° C, and add a heavy metal adsorbent such as a resin or fiber having a chelating action or ion exchange action to adsorb heavy metals. A method for removing heavy metals, characterized by adsorbing and removing heavy metals from seafood by mixing and stirring in addition to the warmed internal organs of the seafood. By using a combination of H type and Na type heavy metal adsorbents such as chelate and ion exchange functions for adsorbing heavy metals and fibers or the like, water and acids can be added at pH 5.0 to pH 7.0. The heavy metal removing method according to claim 1, wherein heavy metal is separated. After the food containing the heavy metal is made fine, it is stirred while heating at 40 ° C. to 70 ° C., preferably 60 ° C., and the heavy metal adsorbent such as a resin or fiber having a chelating action or an ion exchange action for adsorbing the heavy metal is heated. A method for producing a food from which heavy metals have been removed, wherein the heavy metals are adsorbed and removed from the food by adding to and mixing with the food.

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