JP5013878B2 - Treatment of organic matter containing chitin - Google Patents

Description

  The present invention relates to a method for efficiently treating and effectively using an organic substance containing chitin. Specifically, the present invention relates to a method for efficiently obtaining high-purity chitin and useful substances by treating an organic substance containing chitin in a subcritical or supercritical state.

  The demand for chitin and chitosan is increasing as natural substances having various interesting functions. On the other hand, a large amount of organic waste containing chitin and chitosan such as crab shell and shrimp shell is discharged from the fish market and processing plant, and an effective treatment method of the waste is a serious issue. Therefore, methods for producing chitin and chitosan from waste such as crab shell and shrimp shell have been studied. However, in order to isolate and purify chitin and chitosan from these organic wastes, it is necessary to separate ash, proteins, lipids and pigments from chitin.

  The conventional method requires a multi-step process, a schedule of several days, a large amount of reagent and water, and a large amount of wastewater treatment, which is a heavy burden in terms of cost. Therefore, the utilization of the waste containing chitin or chitosan has been hardly performed.

  On the other hand, methods using subcritical water or supercritical water have been reported as methods for treating organic substances and polymer compounds (see JP-A Nos. 05-031000 and 11-342379).

  However, it was difficult to obtain chitin and chitosan with high purity.

  The main object of the present invention is to provide a method for obtaining high-purity chitin from an organic substance containing chitin by a small number of processes in a short time and at a low cost. Furthermore, the main object is to provide a method for obtaining a useful substance from an organic substance containing chitin.

  As a result of intensive studies aimed at solving the above-mentioned problems, the present inventors have efficiently treated chitin by treating an organic substance containing chitin in an acidic aqueous solution in a subcritical or supercritical state. The present inventors have found that it can be purified with high purity, and have further studied to complete the present invention.

  That is, the present invention relates to the following purification method and production method.

  Item 1: A method for purifying chitin, comprising treating an organic substance containing chitin in an acidic aqueous solution in a subcritical state or a supercritical state.

  Preferably, chitin-containing organic matter is treated in a subcritical or supercritical acidic aqueous solution to separate ash, protein, lipid, and pigment from the chitin, thereby purifying chitin Method.

  Preferably, an organic substance containing chitin is treated in an acidic aqueous solution in a subcritical state or a supercritical state to thereby separate ash, protein, lipid and pigment from the chitin in one step. Purification method.

  In addition, the “purification method of chitin” in this specification can also be referred to as “a method for producing high-purity chitin”.

  Item 2: The purification method according to Item 1, wherein an organic substance containing chitin is treated in an acidic aqueous solution in a subcritical state.

  Preferably, a method for purifying chitin, comprising a step of separating ash, protein, lipid, and pigment from chitin in one step by treating an organic substance containing chitin in an acidic aqueous solution in a subcritical state.

  Item 3: The purification method according to Item 1 or Item 2, wherein an organic substance containing chitin is treated in an acidic aqueous solution in a subcritical state of less than 493K.

  Preferably, purification of chitin, comprising a step of separating ash, protein, lipid and pigment from chitin in a single step by treating an organic substance containing chitin in a subcritical acid aqueous solution of less than 493K Method.

  Item 4: The purification method according to any one of Items 1 to 3, wherein the acidic aqueous solution is an organic acid aqueous solution.

  The purification method according to any one of Items 1 to 3, wherein the acidic aqueous solution is an aqueous acetic acid solution.

  Item 5: A method for producing chitosan, comprising treating an organic substance containing chitin in an acidic aqueous solution in a subcritical state or a supercritical state, and deacetylating the treated chitin.

  The embodiment of Item 5 includes a method for producing chitosan characterized by purifying chitin by the method according to any one of Items 1 to 4 and deacetylating the purified chitin obtained. A specific embodiment includes a method for producing chitosan characterized by treating an organic substance containing chitin in an acidic aqueous solution in a subcritical state and deacetylating the treated chitin.

  Further, in a specific embodiment, (1) by treating an organic substance containing chitin in an acidic aqueous solution in a subcritical state or a supercritical state, decomposition of ash, protein, lipid and pigment in the organic substance in one step. A method for producing high-purity chitosan having a step of obtaining chitin by performing and a step of deacetylating the chitin obtained in (2) and (1) is also included.

  Item 6: A method for producing a low-molecular chitin and / or chitin oligosaccharide, comprising treating an organic substance containing chitin in an acidic aqueous solution in a subcritical state or a supercritical state.

  Preferably, the manufacturing method of claim | item 6 which processes the organic substance containing a chitin in the acidic aqueous solution of a subcritical state.

  A specific embodiment includes the production method according to Item 6, wherein the acidic aqueous solution is an organic acid aqueous solution, particularly an acetic acid aqueous solution.

  Item 7: An organic substance containing chitin is treated in an acidic aqueous solution in a subcritical state or a supercritical state, and the low molecular chitin and / or chitin oligosaccharide obtained is deacetylated, and / or Or the manufacturing method of chitosan oligosaccharide.

  The embodiment of Item 7 includes a method for producing a low-molecular chitosan and / or chitosan oligosaccharide characterized by deacetylating the low-molecular chitin and / or chitin oligosaccharide obtained by the method of Item 6. .

  Item 8: A method for producing a chitin degradation product and / or a protein degradation product, wherein an organic substance containing chitin is treated in an acidic aqueous solution in a subcritical state or a supercritical state.

  Preferably, the chitin degradation product and / or the protein degradation product is one or more compounds selected from the group consisting of amino acids, organic acids, low molecular sugars, peptides, and low molecular weight water-soluble proteins.

  The present invention includes a case where a plurality of one or more methods selected from items 1 to 8 are performed in parallel.

  For example, examples of specific embodiments of the present invention include the following methods.

Item 9: Purification of chitin and production of low-molecular chitin and / or chitin oligosaccharide, characterized by treating an organic substance containing chitin in an acidic aqueous solution in a subcritical or supercritical state, preferably in one step And how to do it,
Item 10: Purification of chitin, low molecular chitin, chitin oligosaccharide, chitin degradation product and / or proteolysis characterized by treating an organic substance containing chitin in an acidic aqueous solution in a subcritical or supercritical state A method for producing a product, preferably in one step.

  Hereinafter, the present invention will be described in detail.

Organic matter containing chitin The organic matter targeted by the present invention is not particularly limited as long as it contains chitin, and includes, for example, a biological component itself containing chitin or a processed product thereof, or organic waste.

  Organic waste includes, for example, food processing waste from fish markets and fish processing plants, food waste such as garbage and food residues from homes and schools, and the like.

  Specifically, organic matter containing chitin includes crab and / or shrimp shells, insect shells and legs, mollusc organs such as squid shells and shellfish, diatoms, fungi, microorganisms that produce chitin or chitosan, Bacteria or processed products thereof are included.

  These organic materials may be used as they are, or may be pulverized to an appropriate size. Further, a pretreatment such as drying may be performed in advance.

Treatment of Subcritical State or Supercritical State The present invention includes a step of treating an organic substance containing chitin in an acidic aqueous solution in a subcritical state or supercritical state.

  By treating an organic substance containing chitin in an acidic aqueous solution in a subcritical state or a supercritical state, separation of ash (specifically, calcium carbonate), protein, lipid and pigment from chitin, in other words, chitin in the organic substance It is possible to remove ash, proteins, lipids and pigments adhering to the chitin in a single step, making it unnecessary to consume a large amount of reagents and water and to treat a large amount of waste water. In addition, the cost required for processing can be significantly reduced.

In the present invention, the subcritical state means that the temperature of the solvent is about 433 to 647 K, especially about 433 to 523 K, particularly about 433 to 493 K, and the pressure is about 0.62 to 22.1 MPa, It means that it is in a state of about 0.62 to 4.0 MPa, particularly about 0.62 to 2.32 MPa.
In the present invention, the supercritical state means that the temperature of the solvent is 647 K or higher, particularly about 647 K to 673 K, and the pressure is 22.1 MPa or higher, particularly about 22.1 to 30.0 MPa. Means.

  In the present invention, it is particularly preferable to perform the treatment in a subcritical state. Processing in the subcritical state increases the yield of chitin, in other words, the chitin remaining rate, compared to processing in the supercritical state. In particular, the residual ratio of high molecular weight chitin increases.

  Even in the subcritical state, the yield of high molecular weight chitin can be further improved by processing in a relatively low temperature range, preferably a subcritical state of less than 493 K (220 ° C.). The treatment in the subcritical state at a relatively low temperature causes less thermal decomposition of chitin than the treatment in a higher temperature region, and increases the residual ratio of the original molecular weight or high molecular weight chitin.

  On the other hand, the yield of low-molecular chitin, chitin oligosaccharide, chitin degradation product and / or protein degradation product can be improved by processing in a subcritical state in a relatively high temperature region.

Purification of Chitin The present invention provides a method for purifying chitin, comprising a step of treating an organic substance containing chitin in an acidic aqueous solution in a subcritical state or a supercritical state. By treating in an acidic aqueous solution in a subcritical state or a supercritical state, chitin is efficiently purified, and high-purity chitin can be produced.

  The ratio between the amount of the organic substance and the amount of the acidic aqueous solution in the treatment of the present invention can be appropriately set according to the treatment conditions and the like, but usually the organic matter / acidic aqueous solution is about 0.05 to 0.2 by weight.

  The acidic aqueous solution used in the present invention can be obtained by adding an acid component to the aqueous solution.

  The kind of acid component is not particularly limited, and a strong acid or a weak acid can be used.

  Strong acids include hydrochloric acid, nitric acid, sulfuric acid and the like. In addition, the weak acid includes organic acids such as acetic acid, lactic acid, succinic acid, malic acid, formic acid, pyroglutamic acid, glycolic acid and citric acid, and inorganic acids such as phosphoric acid.

  Of these, organic acids such as acetic acid and lactic acid are preferred because they do not corrode the reactor and can be reused by decomposition of proteins during processing.

  Specifically, the treatment by recycling the acid can be performed as follows.

By treating an organic substance containing chitin in an acidic aqueous solution in a subcritical or supercritical state, ash, protein, lipid and pigment are separated from the chitin,
In the treatment, an acidic aqueous solution is prepared using an organic acid produced by protein degradation,
In the prepared acidic aqueous solution, the organic substance containing chitin is treated in a subcritical state or a supercritical state.

  Thereby, chitin can be refine | purified continuously and a highly purified chitin can be manufactured continuously.

  The concentration of the acidic aqueous solution can be appropriately set according to the processing conditions and the like. For example, in the case of an acetic acid aqueous solution, it may be about 1 to 2 or more, which is the stoichiometric molar ratio of the reaction between calcium carbonate and acetic acid usually contained in an organic substance, and is usually about 1 to 2 to 1: 4. In particular, a stoichiometric molar ratio as close to 1 to 2 as possible is suitable.

  The processing procedure is not particularly limited, and can be set as appropriate. For example, an organic substance containing chitin may be added to an acidic aqueous solution, and the resulting solution may be prepared and reacted under subcritical or supercritical conditions.

  The treatment time is not particularly limited, but is usually about 1 to 30 minutes, preferably about 1 to 10 minutes.

  After the treatment, separation and purification can be appropriately performed. For example, the treated organic substance is separated by filtration into a solid phase containing chitin and an aqueous phase containing degradation products such as amino acids, organic acids, and sugars, and further purified as necessary to obtain chitin. Can be isolated.

Production of chitosan High-purity chitosan can be obtained by deacetylating chitin obtained by treating an organic substance containing chitin in an acidic aqueous solution in a subcritical or supercritical state as described above.

  The method for the deacetylation treatment is not particularly limited, and a known method can be appropriately used.

  For example, a method of treating chitin with an alkali or an enzyme can be used. More specifically, the obtained chitin is deacetylated by treating it with 30-60% high-concentration molten sodium hydroxide solution under a heating and stirring condition of 353-393K for 30 minutes to 5 hours. It can be performed.

  The degree of deacetylation is not particularly limited, and can be set as appropriate for the purpose of obtaining chitosan having desired physical properties.

  By this method, waste containing chitin can be used effectively, and high-purity chitosan can be produced in a short time, efficiently, and at a low cost with fewer processes than conventional methods.

Production of low-molecular chitin and / or chitin oligosaccharide By treating an organic substance containing chitin in an acidic aqueous solution in a subcritical or supercritical state as described above, low-molecular chitin and / or chitin oligosaccharide can be efficiently produced. It can also be manufactured.

  In the present specification, the low molecular chitin means chitin that has been decomposed into chitin contained in an organic substance to have a lower molecular weight. Moreover, chitin oligosaccharide means the oligosaccharide produced | generated by decomposition | disassembly of chitin.

  The low-molecular chitin and / or chitin degradation product can be isolated by appropriately separating and purifying after the treatment. For example, the organic substance after the treatment is separated by filtration into a solid phase containing chitin and an aqueous phase containing chitin or chitin oligosaccharide which has become low molecular weight and becomes soluble, and further purified as necessary. Thus, a desired substance can be isolated.

Production of low molecular chitosan and / or chitosan oligosaccharide Deacetylation treatment of low molecular chitin and chitin oligosaccharide obtained by treating an organic substance containing chitin in a subcritical or supercritical acidic aqueous solution as described above By doing so, a low molecular chitosan and / or chitosan oligosaccharide can be obtained.

  The method for the deacetylation treatment is not particularly limited, and a known method can be appropriately used as described above.

  For example, a method of treating low molecular chitin or chitin oligosaccharide with an alkali or an enzyme can be used. More specifically, the obtained low-molecular chitin or chitin oligosaccharide is treated with a high concentration molten sodium hydroxide solution of 30 to 60% under a heating and stirring condition of 353 to 393 K for 30 minutes to 5 hours. Thus, deacetylation can be performed.

  The degree of deacetylation is not particularly limited, and can be appropriately set for the purpose of obtaining low-molecular chitosan or chitosan oligosaccharide having desired physical properties.

  By this method, waste containing chitin can be effectively used to produce low-molecular chitosan and chitosan oligosaccharide in a short time, efficiently, and at low cost.

Manufacture of chitin degradation product and / or proteolysis product A useful substance is obtained by treating an organic substance containing chitin in an acidic aqueous solution in a subcritical state or a supercritical state, so that part of the chitin and / or protein is degraded. Can be manufactured.

  The chitin degradation product and / or protein degradation product means a compound produced by the degradation of chitin, a compound produced by the degradation of protein, and / or a mixture thereof.

  An example of a specific embodiment of the chitin degradation product and / or proteolysis product is one or more compounds selected from the group consisting of amino acids, organic acids, low molecular sugars, peptides, and low molecular weight water-soluble proteins.

  Examples of amino acids generated by decomposition include cystine, serine, valine, threonine, glycine, proline, alanine, methionine, histidine, arginine, leucine, isoleucine, tyrosine, lysine, phenylalanine, aspartic acid, glutamic acid and the like.

  Examples of the organic acid generated by decomposition include malic acid, succinic acid, lactic acid, formic acid, acetic acid, pyroglutamic acid and the like.

  Examples of low molecular weight saccharides produced by decomposition include low molecular weight chitin, chitin oligosaccharides, glucosamine, erythrose and the like.

  Examples of other decomposition products include phosphoric acid.

  These decomposition products can be recovered as resources and reused effectively. For example, it can be used as a component of pharmaceuticals, seasonings, health drinks, additives and the like.

  Conventionally, in the treatment of organic matter containing chitin, deproteinization processing has been expensive, and the protein has been disposed of as it is. However, according to this method, high-purity chitin can be obtained by a simple and efficient process. As well as useful substances such as amino acids, organic acids, and low-molecular sugars.

Effective use of organic matter In the method of the present invention, the organic matter containing chitin is treated in a subcritical state or a supercritical state, whereby the above one or two or more embodiments are carried out in parallel or in one step. be able to.

  For example, by treating an organic substance containing chitin in an acidic aqueous solution in a subcritical state or supercritical state, production of high-purity chitin and production of low-molecular chitin and / or chitin oligosaccharide are preferably performed in one step. ,It can be carried out.

  In addition, by treating an organic substance containing chitin in an acidic aqueous solution in a subcritical state or a supercritical state, production of high-purity chitin and low molecular chitin, chitin oligosaccharides, chitin degradation products and / or protein degradation products The production can also be carried out preferably in one step.

  Furthermore, the process residue after collect | recovering them can also be utilized for energy recovery as raw materials, such as methane fermentation.

  As described above, the method for treating an organic substance of the present invention has an excellent advantage that other useful substances can be recovered and used together with the acquisition of purified high-purity chitin.

  In addition, in the processing method in this invention, the various well-known techniques regarding the manufacturing process of chitin and chitosan can be added as needed.

  INDUSTRIAL APPLICABILITY The present invention has an exceptional effect that it can efficiently purify chitin and obtain high-purity chitin from an organic substance containing chitin in a short time and at a low cost with fewer processes than before. .

  According to the conventional method, when isolating chitin from an organic substance containing chitin, a multi-step process and a schedule of several days are required for the decalcification process, the deproteinization process, and the like. In addition, a large amount of reagent is consumed, and a large amount of wastewater treatment is required.

  On the other hand, according to the present invention, it is possible to efficiently separate ash, protein, lipid, and pigment from chitin in a short time in an organic substance containing chitin. In addition, the burden on the use of a large amount of reagent and water and the treatment of a large amount of wastewater can be greatly reduced. Therefore, according to this invention, the cost accompanying the process of the organic substance containing chitin can be reduced significantly.

  Moreover, according to the present invention, high-purity chitin with a high degree of purification can be efficiently produced.

  In particular, high-molecular-weight chitin can be obtained with high purity by processing in a subcritical state at a relatively low temperature. Moreover, the yield of low molecular weight chitin and chitin oligosaccharide can also be improved by processing in a relatively high temperature subcritical state.

  Furthermore, by using the method of the present invention, it is possible to efficiently obtain chitosan, low-molecular chitosan and chitosan oligosaccharide from an organic substance containing chitin.

  In the treatment in the subcritical state or supercritical state in the present invention, useful substances such as amino acids and organic acids are produced by the decomposition of proteins and the like, and these can be recovered and used. Furthermore, it is possible to continuously carry out purification of chitin and production of the useful substance using the recovered organic acid.

  Furthermore, according to the method of the present invention, by treating an organic substance containing chitin in a subcritical state or a supercritical state, purification of chitin and production of a useful substance can be performed in parallel or in one step. It can be carried out. Furthermore, energy can be used for the residue after the treatment.

  As described above, the present invention has an excellent advantage that both high-purity chitin can be obtained and useful resources can be recovered and used.

  According to the present invention, useful compounds such as chitin, chitosan, chitin oligosaccharide, chitosan oligosaccharide, various amino acids, organic acids, and glucosamine can be produced efficiently and at low cost from waste organic substances. In addition, the present invention can greatly promote the use of organic substances containing chitin.

  As described above, the present invention can be effectively used as an effective processing technique for organic substances and an efficient production technique for useful substances.

It is the figure which showed the relationship between the solid-phase residual rate at the time of processing crab shell in the aqueous solvent of a subcritical state, and reaction time. It is the figure which showed the relationship between calcium carbonate residual rate and reaction temperature at the time of processing calcium carbonate in the aqueous solvent of a subcritical state. It is the figure which showed the relationship between the chitin residual rate and reaction temperature at the time of processing chitin in the water solvent of a subcritical state. It is the figure which showed the relationship between calcium carbonate residual rate and reaction time at the time of processing calcium carbonate in the acetic acid aqueous solution of a subcritical state. It is the figure which showed the relationship between chitin residual rate at the time of processing chitin in the acetic acid aqueous solution of a subcritical state, and reaction time. It is the figure which showed the relationship between calcium carbonate residual rate and reaction time at the time of processing calcium carbonate in the acetic acid aqueous solution of a subcritical state of a comparatively low temperature. It is the figure which showed the relationship between chitin residual rate and reaction time at the time of processing chitin in the acetic acid aqueous solution of a comparatively low temperature subcritical state. It is the figure which showed the relationship between the calcium carbonate collection | recovery rate at the time of processing crab shell in the acetic acid aqueous solution of a subcritical state, and reaction temperature. It is the figure which showed the relationship between the solid-phase residual rate at the time of processing crab shell in the acetic acid aqueous solution of a subcritical state, and reaction temperature.

  EXAMPLES Hereinafter, although this invention is demonstrated further in detail using an Example and an experiment example, this invention is not limited to these Examples and an experiment example. This method can also be applied to crustaceans such as crabs and shrimps other than snow crab, and it is possible to continuously purify chitin using a subcritical continuous processing apparatus or the like.

Experimental example 1
First, for comparison, crab shells were treated according to a conventional method.

  As the crab shell, a frozen and dried product of a snow crab shell was crushed with a mini blender as a sample.

  First, the crab shell was immersed in a 2 mol / l hydrochloric acid aqueous solution for 1 day. Thereafter, the aqueous solution of hydrochloric acid was replaced, and the deashing treatment was performed by immersing for another day. This removed about 40% of the calcium carbonate initial weight of the crab shell.

  Next, the protein was boiled for 6 hours in a 1 mol / l aqueous sodium hydroxide solution, and the solution was changed and boiled for 30 hours to perform deproteinization treatment. This removed about 25% of the initial weight of the crab shell.

  Furthermore, the remaining lipid and pigment were removed by heating at ethanol reflux for 6 hours.

  These multi-step operations ultimately left a solid phase corresponding to about 35% of the initial weight of the crab shell. This remaining solid phase was regarded as chitin produced by the conventional method.

Experimental example 2
Next, the crab shell was treated in a subcritical water solvent according to the following procedure while appropriately changing the reaction conditions.

(procedure)
As the crab shell, a frozen and dried product of a snow crab shell was crushed with a mini blender as a sample. As the water, ultrapure water produced by an ultrapure water production apparatus (Minipure TW-250RU manufactured by Nomura Micro Science Co., Ltd.) was used.

A reaction tube with SWAGELOK caps attached to both ends of a stainless steel pipe (made of SUS316) having an inner diameter of 6.4 mm, an outer diameter of 9.5 mm, a length of 150 mm, and an internal volume of about 8.0 cm ³ was prepared. The reaction tube was filled with 0.1 or 0.2 g of crab shell and 2 g of water, and the dissolved oxygen was replaced with argon, and then the reaction tube was closed. The reaction tube was added to a salt bath in which potassium nitrate and sodium nitrate were added at a ratio of 1: 1 and preheated to a predetermined temperature (533 to 593K), and allowed to stand for a predetermined time (1 to 10 minutes). Thereafter, the reaction tube was quickly taken out from the salt bath and poured into water to quench it.

  The sample in the reaction tube was centrifuged at 2500 rpm for 10 minutes and washed with water three times, and then filtered to separate the aqueous phase and the solid phase. Subsequently, component analysis was performed about each phase.

(Measuring method)
Organic acid contained in the aqueous phase as a product is a high-performance liquid chromatographic organic acid analysis system (Shimadzu LC-10A, separation method: ion exclusion chromatography, detection method: post-column pH buffered conductivity detection method (column: Shim-pack SCR-102H in series, mobile phase: 5 mol / m ³ p-toluenesulfonic acid aqueous solution, flow rate 1.33 × 10 ^-8 m ³ / s, buffer: 5 mol / m ³ p-toluenesulfonic acid aqueous solution, 0.1 mol / m ³ EDTA, 20 mol / m ³ Bis-Tris aqueous solution, detector: Shimazu CDD-6A, column temperature: 318 K).

The amino acid concentration contained in the aqueous phase as a product is HPLC system (Shimadzu LC-10A, ISC-07 / S1504 column, mobile phase: 4 types, flow rate 8.33 × 10 ^-9 m ³ / s, temperature: 328K) and fluorescence Using a meter (Shimadzu RF-535), it was determined by a post column method (reaction reagents: 2 types, flow rate: 5 × 10 ⁻⁹ m ³ / s).

The sugar contained in the aqueous phase is a high-performance liquid chromatographic sugar analysis system HSS-1500 (column: Shodex SUGAR KS-804, mobile phase: water, flow rate 1.0 cm ³ / min, detector: differential refraction, manufactured by JASCO Corporation. MD-2010 deflection type, column temperature: 313K).

The total organic carbon content (TOC) in the aqueous phase was measured with a TOC analyzer (Shimadzu TOC-500). According to standard methods, 0.01 cm ³ of water soluble product was injected into the TOC analyzer. The measurement is performed under the condition of a high-purity air flow rate of 2.5 × 10 ⁻⁶ m ³ / s, 250 ppm potassium hydrogen phthalate as the standard solution for total carbon (TC), and 250 ppm sodium hydrogen carbonate as the standard solution for inorganic carbon (IC). And TOC was determined by subtracting IC from TC.

  Calcium ions dissolved in the aqueous phase due to the decomposition and reaction of calcium carbonate are measured using the ICP plasma emission spectrometer SPS7800 manufactured by Seiko Instruments Inc. (measurement wavelength: 393.366 nm). I went.

  In Examples 1 and 2 below, the same measurement method as in this experimental example was used.

(result)
FIG. 1 shows the results of examining the relationship between the solid phase residual rate of crab shell and the reaction time. No reaction occurs at room temperature and pressure. However, as shown in FIG. 1, by performing subcritical water treatment at a high temperature of 533 to 593K, the weight of the solid phase decreased with the reaction time. From this, it is considered that deproteinization occurs rapidly under these conditions. However, the solid phase residual ratio is 50% or more, and considering the material balance estimated from the conventional method (Experimental Example 1), it is highly likely that calcium carbonate and chitin are not decomposed.

  After the reaction was completed, the TOC, IC value, amino acid concentration, and organic acid concentration present in the aqueous phase were measured. The IC value was close to 0, and most of the degraded proteins were amino acids and organic acids. It was found that it was hydrolyzed. As amino acids, proline, alanine, methionine, histidine, arginine and the like were produced. In addition, malic acid, succinic acid, lactic acid, formic acid, acetic acid, pyroglutamic acid and the like were produced as organic acids. Moreover, it turned out that those yields become large with reaction time, and the yield of acetic acid, pyroglutamic acid, etc. is high with an amino acid, an organic acid, and an amino acid.

  Next, in order to investigate the influence of the reaction temperature and reaction time on the decomposition of calcium carbonate, the experiment was performed with the reaction temperature set to 533K or 563K and the reaction time set to 1 minute or 2 minutes. As a result, as shown in FIG. 2, the calcium carbonate was hardly decomposed by the treatment for 2 minutes in the subcritical water solvent at 563K. It is considered that the higher the temperature is, the stronger the decomposition power is. Therefore, it is considered that calcium carbonate is not decomposed by the treatment in a subcritical water solvent at 563 K or less. Similarly, in order to investigate the influence of the reaction temperature and reaction time on the degradation of chitin, the reaction temperature was set to 533 K and 563 K, and the reaction time was set to 1 minute or 2 minutes. As a result, as shown in FIG. 3, the chitin was hardly decomposed even when treated in a subcritical water solvent at 563 K for 2 minutes. However, since the color has changed to brown, it is presumed that melanoidin is partially generated by pyrolysis and saccharides Maillard reaction. In order to produce high-purity chitin, calcium carbonate and protein must be separated from chitin, but it has been found that sufficient results cannot be obtained when water is used as a solvent.

Example 1
Considering the results of Experimental Examples 1 and 2 and the fact that acetic acid is included in the product in the treatment process and that the use of a weak acid causes less corrosion of the reactor, sub-critical treatment in an acetic acid aqueous solution should be performed. Tried.

(procedure)
The crab shell was treated in a subcritical state in the same procedure as in Experimental Example 1 except that an acetic acid aqueous solution was used as the solvent.

  As the acetic acid aqueous solution, acetic acid (special grade reagent manufactured by Wako Pure Chemical Industries, Ltd.) prepared with ultrapure water produced by an ultrapure water production apparatus (Minipure TW-250RU manufactured by Nomura Micro Science Co., Ltd.) and prepared to a predetermined concentration was used.

(result)
First, in order to investigate the influence of the concentration of acetic acid aqueous solution and the reaction temperature on the decomposition of calcium carbonate, the chemical reaction stoichiometric molar ratio to calcium carbonate is about 0.03 times the concentration (0.0174 mol / l) or about 3 times the concentration ( The subcritical reaction was performed in an acetic acid aqueous solution adjusted to 1.74 mol / l) at a temperature set to 563K, 593K or 623K. The result of investigating the relationship between the residual rate of calcium carbonate and the reaction time in this case is shown in FIG.

  From the results of FIG. 4, when the acetic acid concentration is 0.0174 mol / l, that is, a concentration considerably lower than the chemical reaction stoichiometric molar ratio 1: 2, the decomposition of calcium carbonate hardly occurs, but the acetic acid concentration 1.74 mol / l, In other words, when the stoichiometric molar ratio was 1: 3, it was found that calcium carbonate was almost completely decomposed and dissolved as calcium acetate in the aqueous phase even in a very short reaction time of 1 minute.

  Next, in order to investigate the influence of the reaction temperature on chitin when an acidic aqueous solution was used as a solvent, the reaction temperature was set to 563K, 593K or 623K, and an experiment was conducted. As a result, as shown in FIG. 5, when the acetic acid concentration is 0.174 mol / l, chitin is decomposed by the treatment in an aqueous acetic acid solution in the subcritical state at a temperature of 563 to 623K. It turned out that there exists a tendency for the decomposition amount to increase, so that it is long.

  In addition, after the reaction was completed, the TOC, IC value, amino acid concentration, and organic acid concentration present in the aqueous phase were measured, and it was found that most of the degraded protein was hydrolyzed as amino acids and organic acids. .

  As amino acids, cystine, serine, valine, threonine, glycine, proline, alanine, methionine, histidine, arginine, leucine, isoleucine, tyrosine, lysine, phenylalanine, aspartic acid, glutamic acid and the like were produced.

  In addition, malic acid, succinic acid, lactic acid, formic acid, acetic acid, pyroglutamic acid and the like were produced as organic acids.

It was also found that the degradation product contained low molecular chitin, chitin oligosaccharide, glucosamine, erythrose, phosphoric acid and the like.
Thus, this method was proved to be useful as a method for producing saccharides such as amino acids, organic acids, low-molecular chitins, chitin oligosaccharides, and glucosamine.

Example 2
In order to obtain high-purity and high-molecular-weight chitin, it is necessary to decompose calcium carbonate and protein and not to decompose chitin. Therefore, the treatment was attempted in an acidic aqueous solution in a subcritical state in a relatively low temperature region.

(procedure)
The measurement procedure was that except that the reaction temperature was set at a relatively low temperature in the range of 453 to 523 K, using a 1.74 mol / l aqueous acetic acid solution that had a chemical reaction stoichiometric molar ratio of about 3 times that of calcium carbonate. Subcritical processing was carried out in the same manner as in Example 1.

  First, the relationship between the decomposition of calcium carbonate and the reaction temperature was examined. The results are shown in FIG.

  As a result, it was found that at a temperature close to the lower limit of the subcritical state of 453 K, calcium carbonate was decomposed by 90% or more in a short reaction time of 1 minute.

  Furthermore, the relationship between the chitin residual rate and the reaction temperature was examined. The results are shown in FIG.

  As a result, as shown in FIG. 7, it was found that about 80% or more of chitin remained undecomposed in the subcritical state where the temperature was relatively low.

  Next, the relationship between the calcium carbonate recovery from the crab shell and the reaction temperature was examined. The results are shown in FIG. As a result, it was found that the recovery rate of calcium carbonate did not depend on the temperature when the treatment was carried out at a constant temperature of 1.453 mol / l and a reaction time of 1 minute while changing the temperature from 453 to 493K. Further, judging from the removal amount of calcium carbonate obtained by the conventional method (Experimental Example 1), the calcium carbonate contained in the crab shell is almost completely decomposed under this condition and dissolved as calcium acetate in the aqueous phase. I understood that.

  Furthermore, in order to investigate the relationship between the solid phase residual rate from the crab shell and the reaction temperature, the treatment was performed using a 1.74 mol / l aqueous acetic acid solution at a temperature set in the range of 453 to 523K. The measurement results are shown in FIG.

  As a result, when the reaction temperature was changed from 453 to 493 K under the constant conditions of acetic acid concentration of 1.74 mol / l and reaction time of 1 minute, it was judged from the amount of residual solid phase obtained by the conventional method (Experimental Example 1). In addition to calcium carbonate, it was found that proteins, lipids and pigments contained in crab shells were separated from chitin.

  The residual solid phase was about 40% of the initial weight regardless of the treatment temperature, but when the obtained solid phase was further treated with hydrochloric acid, it was found by ICP analysis to contain 3-5% calcium carbonate. This value is the same value as that of calcium carbonate contained in commercially available chitin (produced by the conventional method), and corresponds to the difference from the solid phase residual rate when no calcium carbonate is contained. From this, it was found that chitin with very high purity was obtained by the present invention.

  Further, when the reaction time was lengthened, the residual rate of calcium carbonate was further reduced, and after 10 minutes, when there was no calcium carbonate, that is, a solid phase residual rate equivalent to 100% pure chitin was obtained. Also from this fact, it was confirmed that chitin with very high purity was obtained by the present invention.

  Also, in the aqueous solution after completion of the reaction, unlike acetic acid and water, only acetic acid and glycine were detected, so some of the organic acid produced by protein hydrolysis is contained in the crab shell It is considered that a salt is formed by the reaction with calcium carbonate, and a part of the amino acid is further reacted and decomposed by calcium ions and carbon dioxide generated by the reaction of acetic acid and calcium carbonate.

  As shown from the comparison between the above Examples and Experimental Examples, by using an acidic aqueous solution activated in a subcritical state, simultaneous treatment of decalcification, decolorization, and deproteinization in an organic substance containing chitin is about 1 minute. It was found that it can be carried out easily with a short reaction time, and the treatment of organic matter containing chitin can be carried out with fewer processes and lower costs than conventional methods.

  In addition, by using acetic acid, which is a weak acid, it is possible to produce high-purity chitin without using a strong acid or strong base, and no water for neutralization required in the conventional method is required. On the contrary, it was found that acetic acid remaining after the reaction can be reused as a component of the acidic aqueous solution.

Claims (4)

(I) an organic material containing chitin, is treated with an acidic aqueous solution of subcritical state,
(Ii) separating the solid phase and aqueous phase of the treated sample;
(Iii) A method for purifying chitin, comprising obtaining a solid phase. The purification method according to claim 1, wherein an organic substance containing chitin is treated in an acidic aqueous solution in a subcritical state of 493K or less . The purification method according to claim 1 or 2 , wherein the acidic aqueous solution is an organic acid aqueous solution. A method for producing chitosan, comprising purifying an organic substance containing chitin by the purification method according to any one of claims 1 to 3 and deacetylating the purified chitin.

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