JP3268657B2 - How to remove heavy metals from amino acid solution of fish and shellfish - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for removing heavy metals from an amino acid solution of fish and shellfish, and more particularly to a method for removing harmful substances from the mid-gut line of scallops, which is one of the processing residues of fish and shellfish. The present invention relates to a method for removing heavy metals from fish and shellfish amino acid liquids, which removes heavy metals such as cadmium, and makes it possible to expand the use of fish and shellfish containing harmful metals as resources and to reduce pollution sources.

[0002]

2. Description of the Related Art Conventionally, seafood products that effectively utilize processed residues of fish and shellfish include concentrated soups and steamed drip by-products when producing canned, dried and boiled products and fish cake meal. , This concentrate is digested with an enzyme preparation,
Inedible parts such as the head, skin, bones, and internal organs that are by-produced when processing fish and shellfish are digested with organic, inorganic acids, or enzyme agents.
And umami seasonings which have been self-digested over a long period of time using salt for meat and internal organs of fish and shellfish.

[0003] By the way, in fish and shellfish, heavy metals attributed to the food chain are accumulated to some extent, and particularly, among the internal organs, a large amount is accumulated in the liver, kidney or organs corresponding to these functions. In particular, heavy metals such as cadmium are accumulated in the midgut glands of scallop, and are buried in soil or incinerated without being used as resources.

[0004]

However, the disposal method of scallop midgut glands and fish and shellfish containing cadmium and other heavy metals at high concentration by burial in the soil is not suitable for odor from landfill sites. It becomes a source of pollution, such as the occurrence of flies and flies, and a source of crows. It also pollutes rivers and other vegetation due to decayed decay juice, and makes it difficult to secure landfill sites.

[0005] In view of the difficulty in securing this landfill, various measures have been taken to incinerate it.
It is incinerated at 00 to 800 ° C. If heated above the melting point and the boiling point of cadmium, it may be scattered in the air, and it presents a problem as a new pollution source, such as generating a peculiar odor due to burning of the protein. I have.

The present invention has been made in view of such circumstances, and transfers heavy metals such as cadmium accumulated in proteins of fish and shellfish to a produced amino acid solution and dissolves in the amino acid solution. It is an object to provide a method for removing heavy metals such as cadmium.

[0007]

Means for Solving the Problems The present inventors have made intensive studies to solve the above-mentioned problems, and as a result, dissolved heavy metals binding to proteins of fish and shellfish in acids, and hydrolyzed the dissolved heavy metals by acids. Transfer to the generated amino acid solution, succeeded in selectively separating and removing heavy metals dissolved in this amino acid only under predetermined conditions, and not only can reduce the source of pollution, but also expand its use as a resource The present inventors have also found that the method for removing heavy metals from the amino acid solution of fish and shellfish according to the present invention has been completed.

That is, in the method for removing heavy metals from the amino acid solution of fish and shellfish according to the present invention, a chelating agent is added to the amino acid solution of fish and shellfish whose pH is adjusted to 8 to 9 to cause the chelating agent to act. The solution is to adsorb heavy metals contained in the shellfish amino acid solution.

The method for removing heavy metals from the amino acid solution of fish and shellfish according to the present invention is characterized in that the pH is 4 or less and the pH is 20 to 50.
The fish and shellfish protein is decomposed into an amino acid solution by self-digestion of the fish and shellfish protein in a fermenter adjusted to a temperature of ° C. and, if necessary, by the action of a protease, and then the fish is adjusted to pH 8 to 9. The solution is to add a chelating agent to the shellfish amino acid solution to cause the chelating agent to adsorb heavy metals contained in the fish and shellfish amino acid solution.

Further, the method for removing heavy metals from the amino acid solution of fish and shellfish according to the present invention is characterized in that the pH of the crushed fish and shellfish is 4 or less.
The fish and shellfish protein is hydrolyzed by the action of acids under the following conditions, and then the fish and shellfish protein is autolyzed in a fermenter prepared at a temperature of 20 to 50 ° C., and the protease is allowed to act as necessary. To decompose the fish and shellfish protein into an amino acid solution, and further add a chelating agent to the fish and shellfish amino acid solution adjusted to pH 8 to 9 to cause the chelating agent to remove heavy metals contained in the fish and shellfish amino acid solution. Adsorption is the solution.

Hereinafter, the method for removing heavy metals from the amino acid solution of fish and shellfish according to the present invention will be described in more detail.

Although the present invention is not particularly limited to the theory, the present invention pays attention to the property that cadmium bound to fish and shellfish proteins dissolves in acids, and firstly, dissolves the dissolved cadmium into an amino acid solution produced by acids. To
Next, a chelating agent is added to the fish and shellfish amino acid solution adjusted to pH 8 to 9 to act thereon, and the chelating agent is allowed to adsorb heavy metals contained in the fish and shellfish amino acid solution to selectively separate and extract heavy metals. Based on first finding that it can be removed.

By the way, cadmium is known to be bound to a protein called metallothionein containing a metal and sulfur and having a molecular weight of about 6000, and is dissolved acidicly and precipitates as cadmium hydroxide on the alkaline side.

In the present invention, utilizing such properties of cadmium, first, fish or shellfish, which is a raw material crushed by a meat chopper or the like, is converted into an inorganic or organic acid such as hydrochloric acid.
The pH is adjusted to 4 or less with acetic acid, and the fish and shellfish proteins are hydrolyzed to an amino acid solution. Here, the pH is set to “4 or less” because the action of acids can dissolve and release cadmium, and can inhibit the activity of bacteria involved in spoilage in the hydrolysis and fermentation of fish and shellfish proteins. . As a result, heavy metals such as cadmium bound to the fish and shellfish proteins migrate to the amino acid solution and can be present in a dissolved state.

This condition can be more effectively achieved by the action of the autolyzing enzyme contained in the raw material in addition to the acids and the action of the protease if necessary, and the application of mechanical shearing by stirring. it can. That is, the action of the acids on the raw material to adjust the pH value to 4 or less and the hydrolysis of the fermenter prepared at a temperature of 20 to 50 ° C. by the action of the autolyzing enzyme and the mechanical shearing by stirring more effectively proceed,
The reaction proceeds more effectively by acting a protease as necessary. The reason why the temperature was limited to “20 to 50 ° C.” is that the enzyme works most effectively within this range.

Since the amino acid solution thus obtained is a viscous suspended liquefied product, the solid content and the fat content are removed and purified by solid-liquid separation and oil / fat separation, respectively. These steps are desirable as a pretreatment step for allowing the chelating agent to act.

After the purified amino acid solution is adjusted to pH 8 to 9 with caustic soda, ammonia or the like, a chelating agent such as methyl isobutyl ketone (hereinafter referred to as MIBK)
Cadmium is adsorbed by reacting, for example, diethyldithiocarbamic acid (hereinafter referred to as DDTC) as a solvent corresponding thereto. There are several other chelating agents having this effect, and it goes without saying that the chelating agents are not limited to those exemplified in the examples.

A stirring type, a centrifugal type and a vibration type are used for mixing and coalescing of a solvent, a solvent and a solute, and among them, a vortex type is most effective. The mixed and unified liquid mixture is separated into a solvent, a solvent and a solute by a separation tank such as a tower, and the solvent and the solvent are extracted. Then, the separated liquid is concentrated under reduced pressure or the like to obtain a product.

In carrying out the present invention, anaerobic fermentation and decomposition in the treatment step must be particularly emphasized. The visceral mass, including the midgut gland, excluding the scallop of the fresh scallop, usually contains a lot of sand and shell pieces, which sediment and deposit in the fermentation process, forming a dead space. It becomes fermentation. Anaerobic fermentation degrades the product and, in some cases, has to dump the entire work in process. Most of the shell pieces are stabbed in the raw meat, and it is desirable to remove the shell pieces in advance by primary washing and secondary washing. The equipment used for the primary washing and the secondary washing is specially prepared for the treatment of the internal organs of scallops.

In the concentrated product obtained through the above-mentioned steps, the content of heavy metals such as cadmium is greatly reduced from the regulation standard value for ensuring safety, so that the source of pollution can be simply suppressed. It can be used as a resource for fertilizers such as agricultural products.

[0021]

EXAMPLES Hereinafter, the method for removing heavy metals from the amino acid solution of fish and shellfish according to the present invention will be described in detail with reference to examples, but the present invention is not limited to these examples.

Example 1 Weight of fish and shellfish from amino acid solution
The following method for removing metals, the method for removing heavy metals from acid solutions of fish and shellfish, the respective steps will be described.

(1) First Step (First Washing) After removing the scallops of the scallop, which is a raw material, about 40 to 40-minutes are obtained by an improved fish washer incorporating a specially prepared rotating sieve of a strainer structure type. Sand was passed through the raw material at 45 ° C. for 3 to 4 minutes to remove sand, shell pieces and attached dirt. By this step, sand and shell pieces can be removed from the visceral mass including the midgut gland of the scallop.

(2) Second Step (Second Washing) An improved cooker with a built-in strainer-structured endless track specially prepared for sand and shell pieces that cannot be completely removed by the first washing. While passing through hot water of about 40 to 45 ° C. for about 10 minutes while washing with hot water. In removing the sand and shell pieces, the sand and shell pieces were removed from the back side of the compare on which the raw materials were placed while operating the raw materials in hot water with compressed air so as to dance. By this step, sand and shell pieces are removed, and a visceral mass of scallops washed at a temperature of 40 ° C. or higher is obtained.

(3) Third Step (Crushing) The raw material washed in the washing step was crushed by a meat chopper.

(4) Fourth Step (Preparation of pH) The raw material crushed by the meat chopper was placed in a strong acid-resistant container, and hydrochloric acid was added to adjust the pH to about 4 to 3.8.

(5) Fifth Step (Fermentation) After the pH-adjusted raw material is stored in a constant temperature fermentation tank,
For 14 hours or more to ferment and digest.

(6) Sixth Step (Solid-Liquid Separation) The fermentation digest was heated to 85 to 90 ° C., and the solid was separated by a screw type decanter to obtain a separated liquid. The amount of cadmium detected in the residue by solid-liquid separation was 0.8 ppm.

(7) Seventh Step (Oil Separation) Oils and fats suspended in the separated liquid separated by solid-liquid separation were separated by a disk type decanter. The amount of cadmium detected in the separated solution after the separation of the oil and fat was 14 ppm.

(8) Eighth Step (pH Adjustment) The separated liquid after the separation of the oil and fat was adjusted to pH 8 to 9 using caustic soda. By shifting the pH of the separated solution from the acidic region to the alkaline region, the reaction between cadmium and the chelating agent becomes easy.

(9) Ninth Step (Extraction) MIBK as a chelating agent and DDTC as a corresponding solvent were added to the prepared solution in which the pH was adjusted to an alkaline region, and the mixture was extracted using a vortex stirring tank. According to this method,
Since the structure is such that a vortex is generated in the stirring blade provided in the stirring tank, the solvent, the solvent, and the solute can be uniformly and quickly mixed. This tank needs to be kept at a temperature of 40 ° C. or more to prevent invasion and prevention of various bacteria. After stirring and mixing for about 15 to 20 minutes, the mixture was transferred to a separation tank.

(10) Tenth Step (Separation) The solvent floating in the separation tank mounted on the tank and the solvent were separated by suction. The amount of cadmium detected in the separated solution after the extraction and separation was 0.15 ppm. This result is far below the regulatory standards for ensuring the safety of fertilizers.

(11) Eleventh Step (Concentration) The separated liquid was concentrated by heating under reduced pressure to obtain a product.

Example 2 Weight of fish and shellfish from amino acid solution
Metal removal method Scallop amino acid solution is used in place of scallop as raw material, and first step (first washing) to seventh step (oil and fat separation)
A method for removing heavy metals from the amino acid solution of fish and shellfish was carried out in the same manner as in Example 1 except that was omitted. As a result, the detected amount of cadmium contained in the scallop amino acid solution as a raw material was 3.2 ppm, but after the method according to the present invention was carried out, the detected amount was reduced to 0.08 ppm. This result is far below the regulatory standards for ensuring the safety of fertilizers.

Example 3 Weight of Fish and Shellfish from Amino Acid Solution
A method for removing metals, wherein a visceral mass containing the midgut gland of the scallop is used in place of the scallop, and the first step (first washing) to the fourth step (p
Except for omitting H preparation), a method for removing heavy metals from the amino acid solution of fish and shellfish was carried out in the same manner as in Example 1. As a result, the detected amount of cadmium contained in the visceral mass including the midgut gland of the raw material scallop was 9.3 ppm, but after the method according to the present invention was carried out, the detected amount was reduced to 0.12 ppm. did. This result is far below the regulatory standards for ensuring the safety of fertilizers. In the examples, the amount of the chelating agent added varies depending on the amount of cadmium dissolved in the amino acid solution, and the cadmium removal rate also varies depending on the amount of the chelating agent added. Since the amount of cadmium dissolved in the amino acid solution varies depending on the sea area, season, and individual being caught, sampling is conducted in a fixed lot, and the amount of the chelating agent added is determined after preliminary tests.

[0036]

【The invention's effect】

(1) In the present invention, a heavy metal contained in a fish and shellfish amino acid solution is adsorbed to a chelating agent, and the content thereof is adjusted to 0.15 to 0.5.
It can be reduced to 08 ppm. Therefore, according to the method according to the present invention, the content of heavy metals such as cadmium contained in the midgut glands and visceral mass of scallop, which is originally a troublesome industrial waste, is regulated to ensure the safety of fertilizers and the like. Not only can the source of pollution be reduced, but also can be used as a foliar spraying agent for leafy vegetables and fruits and vegetables, as a fertilizer, to improve the sugar content of fruits, and to expand its use as a resource such as organic fertilizers. . (2) The method according to the present invention is a simple processing method that does not require advanced technology or complicated equipment because a chelating agent is used as a heavy metal adsorbent. (3) The chelating agent used in accordance with the present invention does not increase the processing cost, since heavy metals such as cadmium adsorbed by vacuum distillation are eluted and collected and can be used repeatedly. (4) Cadmium recovered by the present invention contains p
It exists in pm units and is a very small amount,
If refined, it can be expected as a useful material due to the inherent properties of heavy metals such as cadmium.

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI // A23L 1/015 A23L 1/325 A 1/325 B09B 3/00 304Z (56) References JP-A-3-47051 (JP) , A) (58) Fields investigated (Int. Cl. ⁷ , DB name) B09B 3/00 A23J 3/04 501 A23L 1/238 A23L 1/015 A23L 1/325

Claims (2)

(57) [Claims] 1. A fish and shellfish protein is decomposed into an amino acid solution by autolyzing a fish and shellfish protein in a fermenter adjusted to a temperature of 20 to 50 ° C. at a pH of 4 or less and, if necessary, by acting a protease. , Then pH 8-9
A method for removing heavy metals from a fish and shellfish amino acid solution, comprising adding a chelating agent to the fish and shellfish amino acid solution prepared in Example 1, and allowing the chelating agent to adsorb heavy metals contained in the fish and shellfish amino acid solution. . 2. The fish and shellfish protein is hydrolyzed by the action of acids under the condition that the pH of the crushed fish and shellfish is 4 or less, and then the fish and shellfish protein is prepared in a fermenter prepared at a temperature of 20 to 50 ° C. The fish and shellfish protein is decomposed into an amino acid solution by self-digestion and, if necessary, by the action of a protease, and a chelating agent is added to and acted on the fish and shellfish amino acid solution adjusted to a pH of 8 to 9, whereby the chelate is added. A method for removing heavy metals from a fish and shellfish amino acid solution, wherein the heavy metal contained in the fish and shellfish amino acid solution is adsorbed to an agent.