JP2011201837A - Method for producing purified collagen hydrolyzate - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for capable of producing a sufficiently purified collagen hydrolysate excellent in production efficiency and having the less contamination of crushed materials such as microorganisms.SOLUTION: This method for producing the purified collagen hydrolysate comprising an inside pressure filtration process of passing the collagen hydrolysate-containing solution through a porous hollow fiber membrane of which tubular wall is constituted by a blended material of a hydrophobic polymer with a hydrophilic polymer, is provided with that in the case of equally dividing the tubular wall by three, into three regions in the wall thickness direction, the porous hollow fiber membrane has a higher containing ratio of the hydrophilic polymer in an outer circumferential region including an outside surface than the containing ratio of the hydrophilic polymer in an inner circumferential region including an inside surface, and the larger mean hole diameter of the inside surface than the mean hole diameter of the outside surface.

Description

  The present invention relates to a method for producing a purified collagen hydrolyzate.

  Conventionally, gel filtration, centrifugation, adsorption separation, precipitation, membrane filtration, and the like have been used as methods for removing microorganisms such as yeast from a solution. However, the gel filtration method is difficult to apply industrially because the target substance is diluted with a solvent used for gel filtration or is not suitable for mass processing. The centrifugal separation method can be applied only when the microorganism has a size of several μm or more and the viscosity of the solution is small. The adsorptive filtration method can be used to remove a specific small amount of microorganisms, but is difficult to apply to a solution in which a large variety of microorganisms are dispersed in large amounts. Although the precipitation method can be used for the treatment of a relatively large amount of solution, it is difficult to completely remove microorganisms by this method alone.

  On the other hand, a membrane filtration method using a microfiltration membrane and an ultrafiltration membrane is suitable for industrial use because it can remove all microorganisms and can perform a large amount of continuous treatment.

  However, in conventional microfiltration membranes and ultrafiltration membranes, a concentrated layer of microorganisms removed from the membrane surface or its crushed material is formed, and the membrane surface is clogged. There was a problem that a general decrease was likely to occur.

  In order to solve such problems, a filtration method using crossflow filtration or backwashing (backwashing) is used. For example, Patent Document 1 describes a method of removing components that cause turbidity while performing short-time backflushing. Further, Patent Document 2 describes a turbidity removal method combining a short-time dead-end filtration and backwashing.

Japanese Patent Laid-Open No. 7-155559 JP-A-4-260419

  Collagen hydrolyzate can be obtained by extracting from connective tissues such as animal bones, skin, ligaments or tendons, and the demand for raw materials for foods and beverages is increasing with increasing health concerns. However, microorganisms such as E. coli are mixed during extraction. Therefore, in the manufacturing method of a collagen hydrolyzate, the filtration process for fully removing these microorganisms is needed.

  However, in the conventional cross-flow filtration using a hollow fiber membrane, it is necessary to increase the flow rate of the treatment solution in order to prevent the membrane surface from being clogged. By increasing the flow rate, microorganisms are easily crushed and deformed. When microorganisms are crushed, there is a problem that the crushed material passes through the hollow fiber membrane and is mixed into the collagen hydrolyzate.

  In addition, when using a conventional hollow fiber membrane, it is necessary to flow a large amount of backwashing liquid to remove the removed matter that has been strongly adsorbed on the membrane surface when removing the removed matter accumulated on the membrane surface by backwashing. There is a problem that the processing efficiency decreases.

  Moreover, in the method of patent document 1, it cannot be said that the washing | cleaning effect is enough, and when performing a process continuously, the raise of filtration pressure occurs. Furthermore, in the method described in Patent Document 2, it is possible to increase the flow rate only by looking at the permeation flow rate during filtration. However, since switching between filtration and backwashing is frequently performed, the total efficiency of the filtration operation is low. It is not suitable for industrial use.

  An object of the present invention is to provide a production method capable of producing a collagen hydrolyzate that is excellent in production efficiency and that is sufficiently mixed with crushed materials such as microorganisms and is sufficiently purified.

That is, this invention relates to the manufacturing method of the following collagen hydrolyzate.
(1) Purified collagen hydrolysis, which includes an internal pressure filtration step of circulating a collagen hydrolyzate-containing solution through a porous hollow fiber membrane having a tube wall composed of a blend of a hydrophobic polymer and a hydrophilic polymer. A method for producing a degradation product, wherein the porous hollow fiber membrane has a hydrophilic polymer in an outer peripheral region including an outer surface when the tube wall is divided into three regions by dividing the tube wall into three equal parts. Is a porous hollow fiber membrane in which the content ratio of is larger than the content ratio of the hydrophilic polymer in the inner peripheral region including the inner surface, and the average pore diameter of the inner surface is larger than the average pore diameter of the outer surface. The production method can also be regarded as a method for purifying a collagen hydrolyzate.
(2) The porous hollow fiber membrane has an average pore diameter of 1 μm or more and 50 μm or less on the inner side surface, the outer peripheral region has a blocking pore diameter of 0.1 μm or more and less than 1 μm, and the film thickness of the tube wall Is a porous hollow fiber membrane of 300 μm or more and 1000 μm or less.
(3) The production method according to (1) or (2), wherein the hydrophilic polymer is polyvinylpyrrolidone.
(4) The porous hollow fiber membrane in which the content of the hydrophilic polymer is 0.2% by mass or more and 3% by mass or less based on the total mass of the porous hollow fiber membrane. The production method according to any one of (1) to (3).
(5) The production method according to any one of (1) to (4), wherein the porous hollow fiber membrane satisfies the following formula (I).
C _out / C _in ≧ 2 (I)
[In formula (I), C _out represents the content of the hydrophilic polymer in the outer peripheral region, and C _in represents the content of the hydrophilic polymer in the inner peripheral region. ]
(6) The manufacturing method according to any one of (1) to (5), wherein the porous hollow fiber membrane is a porous hollow fiber membrane having an inner diameter of 1000 μm or more and 2000 μm or less.
(7) The production method according to any one of (1) to (6), wherein the hydrophobic polymer is polysulfone.
(8) The internal pressure filtration is performed by cross-flow filtration, and the collagen hydrolyzate-containing solution is fed from one end of the porous hollow fiber membrane into the tube at a linear velocity of 3.0 m / sec or less. The manufacturing method according to any one of (1) to (7).
(9) The internal pressure filtration is performed by dead-end filtration, and the collagen hydrolyzate-containing solution is fed from one end of the porous hollow fiber membrane into the tube at a linear velocity of 3.0 m / sec or less. The production method according to any one of (1) to (7).
(10) The production method according to any one of (1) to (9), further including a step of back washing the porous hollow fiber membrane using the filtrate obtained in the internal pressure filtration step.

  According to the present invention, it is possible to maintain a high filtration rate for a long period of time as compared with a conventional filtration method using a porous hollow fiber membrane, there is little destruction and deformation of microorganisms, and the membrane can be easily washed and processed. It is possible to provide a production method including a highly efficient internal pressure filtration step, which is excellent in production efficiency and can produce a sufficiently purified collagen hydrolyzate with less contamination by microorganisms and the like.

  Hereinafter, a preferred embodiment of the present invention will be described in detail.

  In the method for producing a collagen hydrolyzate according to the present embodiment, a collagen hydrolyzate-containing solution is circulated through a porous hollow fiber membrane in which a tube wall is composed of a blend of a hydrophobic polymer and a hydrophilic polymer. Includes an internal pressure filtration step.

  Here, when the porous hollow fiber membrane is divided into three regions by dividing the tube wall into three in the film thickness direction, the content of the hydrophilic polymer in the outer peripheral region including the outer surface includes the inner surface. The porous hollow fiber membrane is larger than the content ratio of the hydrophilic polymer in the inner peripheral region, and the average pore diameter on the inner side surface is larger than the average pore size on the outer side surface.

  In order to divide the tube wall into three regions by dividing the tube wall into three equal parts, for example, a tube wall of a porous hollow fiber membrane (referred to as a side wall constituting a hollow annular porous hollow fiber membrane). What is necessary is just to cut out a part and obtain a film-form tube wall, and to slice it into 3 equal parts in a film thickness direction. In this case, a region having a thickness of 1/3 including the outer surface is referred to as an “outer peripheral region”, and a region having a thickness of 1/3 including the inner surface is referred to as an “inner peripheral region”. The central portion can be referred to as a “central region”.

  The hydrophobic polymer means a polymer having a critical surface tension (γc) at 20 ° C. of 50 nN / m or more, and the hydrophilic polymer means a critical surface tension (γc) at 20 ° C. of 50 nN / m. Represents a polymer that is less than. In addition, the average pore diameter was determined by observing the inner surface or the outer surface with an electron microscope at a magnification capable of observing 10 or more holes in one field of view, and subjecting the pores in the obtained micrograph to a circular approximation process, It can be calculated by obtaining the diameter from the area average value. A blend of a hydrophobic polymer and a hydrophilic polymer means a mixture containing both a hydrophobic polymer and a hydrophilic polymer, regardless of the phase structure (for example, a compatible system or a phase-separated system). It does not matter, but it is preferable that the system is not completely compatible.)

  The porous hollow fiber membrane is a membrane having a hollow annular shape, and the membrane area per module unit volume can be increased compared to a planar membrane by having such a shape.

  In the porous hollow fiber membrane, the content ratio of the hydrophilic polymer in the outer peripheral region including the outer surface is larger than the content ratio of the hydrophilic polymer in the inner peripheral region including the inner surface, and the average pore diameter of the inner surface is equal to the outer surface. Is larger than the average pore diameter. By having the above configuration, the porous hollow fiber membrane has higher strength to withstand temperature changes and pressure changes than conventional porous hollow fiber membranes, and is compatible with both filtration speed and fractionation. Yes, it is difficult for the removed matter to accumulate on the membrane surface and inside the membrane, the membrane pores are not easily blocked, a high filtration rate can be maintained for a long time, and it can be easily washed by a known hollow fiber membrane washing method Become. Examples of the cleaning method include back-flow cleaning in which a cleaning liquid is introduced from the outer surface, and air scrubbing in which a film is shaken to remove deposits by introducing bubbles into the module.

  Since the porous hollow fiber membrane has the above-described configuration, the effect of depth filtration that holds and removes particles smaller than the membrane pores inside the membrane can be sufficiently exhibited in the inner peripheral region. On the other hand, in the outer peripheral region, since the content ratio of the hydrophilic polymer is large and the adsorbing force between the particles and the film is low, blockage of the membrane hole due to the adsorption of the particles can be prevented. A high filtration rate can be maintained for a long time by preventing clogging of the membrane pores due to adsorption of particles in the outer peripheral region having a small pore diameter. Moreover, since the effect of depth filtration can be fully demonstrated in the inner peripheral area | region with a large hole diameter, it is excellent in filtration performance, such as a fractionation property.

  Examples of the hydrophilic polymer include polyvinyl pyrrolidone, polyethylene glycol, polyvinyl alcohol, cellulose, and derivatives derived therefrom. Of these, polyvinylpyrrolidone is preferred as the hydrophilic polymer. These hydrophilic polymers can be used alone or in combination of two or more. With these hydrophilic polymers, the compatibility with the hydrophobic polymer is excellent, and the porous hollow fiber membrane is uniform and excellent in mechanical strength. In addition, it is possible to further prevent the removal material from adsorbing on the film surface and inside the film, and cleaning becomes easy.

  Examples of the hydrophobic polymer include polysulfone, polyvinylidene fluoride, polyvinylidene chloride, and polyvinyl chloride. Of these, as the hydrophobic polymer, polysulfone and polyvinylidene fluoride are preferable. These hydrophobic polymers can be used alone or in combination of two or more. With these hydrophobic polymers, the porous hollow fiber membrane is more excellent in strength against temperature change and pressure change, and can exhibit high filtration performance.

  The average pore diameter of the inner surface is preferably 1 μm or more and 50 μm or less, more preferably 5 μm or more and 40 μm or less, and further preferably 10 μm or more and 30 μm or less. When the average pore diameter on the inner surface is less than 1 μm, the effect of depth filtration that holds the removed matter inside the membrane cannot be obtained sufficiently, and the membrane pores are likely to be clogged due to the deposit of the removed matter on the membrane surface. There is a case. In addition, when the average pore diameter on the inner surface is larger than 50 μm, the ratio of the pores on the membrane surface increases, so the strength of the porous hollow fiber membrane tends to decrease. In order to make the average pore diameter of the inner surface within the above range, for example, in the production method described below, the good solvent concentration of the internal coagulating liquid may be 85% by mass or more.

  The average pore diameter of the outer surface is preferably 0.1 μm or more and 20 μm or less, more preferably 0.2 μm or more and 15 μm or less, and further preferably 0.3 μm or more and 10 μm or less. In order to make the average pore diameter of the outer surface within the above range, in the manufacturing method described below, for example, the temperature of the external coagulation liquid may be set to 50 ° C. or higher and 90 ° C. or lower.

  The outer peripheral region preferably has a blocking hole diameter of 0.05 μm or more and less than 1 μm, more preferably has a blocking hole diameter of 0.1 μm or more and less than 1 μm, and has a blocking hole diameter of 0.2 μm or more and 0.8 μm or less. More preferred. When the blocking hole diameter is less than 0.05 μm, the permeation resistance increases, the pressure required for filtration increases, and membrane destruction, deformation, membrane surface blockage due to deformation, and reduction in filtration efficiency may occur. Moreover, when it is 1 μm or more, sufficient fractionation properties tend not to be obtained. In order to set the blocking hole diameter in the outer peripheral region within the above range, for example, the temperature of the external coagulation liquid may be set to 50 ° C. or more and 90 ° C. or less in the manufacturing method described below.

  Here, the blocking pore diameter means the pore diameter of a particle when the permeation blocking ratio of the particle is 90% when a particle dispersion liquid in which particles of a certain pore diameter are dispersed is filtered using a porous hollow fiber membrane. To do. Specifically, for example, the particle dispersion is filtered, and the change in the concentration of the particles before and after filtration is measured. This measurement is performed while changing the particle diameter from 0.1 μm to about 0.1 μm to create a particle inhibition curve. The particle diameter capable of 90% inhibition can be read from this inhibition curve, and the diameter can be defined as the inhibition pore diameter.

  The porous hollow fiber membrane preferably includes a minimum pore diameter layer in the outer peripheral region. The presence of the minimum pore diameter layer in the outer peripheral region where the content ratio of the hydrophilic polymer is large can prevent the blockage of the membrane pores due to the adsorption of particles more reliably. Here, the minimum pore diameter layer refers to a layer including the smallest pore diameter when the cross section of the film is observed with an electron microscope. The hole diameter of the minimum hole diameter layer is almost equal to the blocking hole diameter, and the hole diameter of the minimum hole diameter layer can be obtained by measuring the blocking hole diameter. The pore diameter of the minimum pore diameter layer is preferably 0.05 μm or more and less than 1 μm, more preferably 0.1 μm or more and less than 1 μm, and further preferably 0.2 μm or more and 0.8 μm or less. In order to include the minimum pore diameter layer in the outer peripheral region, in the manufacturing method described below, for example, the good solvent concentration of the internal coagulating liquid is 85% by mass or more and the good solvent concentration of the external coagulating liquid is 50% by mass. % Or less.

  The porous hollow fiber membrane preferably has a pore size that is continuously reduced from the inner surface to the minimum pore size layer. By having such a configuration, it is possible to further obtain the effect of depth filtration that holds the removed substance inside the membrane and to maintain a high filtration rate for a longer time. In order to continuously reduce the pore diameter from the inner surface to the minimum pore diameter layer, in the manufacturing method described below, for example, the good solvent concentration of the internal coagulating liquid is 85% by mass or more, and the external coagulating liquid The good solvent concentration may be 50% by mass or less.

  The porous hollow fiber membrane preferably has a film thickness of 300 μm or more and 1000 μm or less, and more preferably 350 μm or more and 800 μm or less. In a porous hollow fiber membrane having a film thickness of less than 300 μm, the range in which the removed matter inside the membrane can be retained is limited, so that the effect of depth filtration may not be sufficiently obtained, and the filtration rate may decrease. It tends to occur easily. In the case of a porous hollow fiber membrane having a film thickness of more than 1000 μm, it becomes difficult to wash the removed matter deposited inside the membrane, and the filtration performance may not be sufficiently recovered after washing. In order to make the film thickness within the above range, in the manufacturing method described below, for example, the outer flow path of the double tubular nozzle may be 200 μm to 1200 μm (preferably 300 μm to 1000 μm).

  The porous hollow fiber membrane preferably has a hydrophilic polymer content of 0.2% by mass or more and 3% by mass or less, based on the total mass of the porous hollow fiber membrane, and 0.5% by mass or more. It is more preferable that it is 2 mass% or less. In the case of a porous hollow fiber membrane having a hydrophilic polymer content of less than 0.2% by mass, the removed product is likely to be adsorbed on the membrane surface and inside the membrane, and the membrane pores are easily clogged and washing is difficult. Tend to be. In a porous hollow fiber membrane having a hydrophilic polymer content of more than 3% by mass, the membrane pores may be blocked by the swelling of the hydrophilic polymer, and the permeation resistance may increase. Moreover, it is excellent in detergency because content of a hydrophilic polymer is the said range, and when filtration and washing | cleaning are repeated, high filtration performance can be maintained. In order to make the content of the hydrophilic polymer within the above range, in the production method described below, for example, in the blend of the hydrophobic polymer and the hydrophilic polymer, the hydrophobic polymer and the hydrophilic polymer are used. Of the former: the latter = (1) :( 0.1 to 1.5) (preferably, the former: the latter = (1) :( 0.5 to 1.3)).

The porous hollow fiber membrane preferably satisfies the following formula (I).
C _out / C _in ≧ 2 (I)

In the above formula (I), C _out indicates the content ratio in the outer peripheral region of the hydrophilic polymer, and C _in indicates the content ratio in the inner peripheral region of the hydrophilic polymer. The porous hollow fiber membrane in which the hydrophilic polymer exhibits such a distribution is further excellent in the effect of depth filtration in the inner peripheral region and the effect of preventing the clogging of membrane pores due to adsorption of removed substances in the outer peripheral region. Moreover, it is excellent in detergency and can maintain high filtration performance even when filtration and washing are repeated. In order to satisfy the following formula (I), in the production method described below, for example, the ratio of the hydrophobic polymer to the hydrophilic polymer in the blend of the hydrophobic polymer and the hydrophilic polymer. The former: latter = (1) :( 0.1-1.5) (preferably, the former: latter = (1) :( 0.3-1.2)).

  The porous hollow fiber membrane preferably has an inner diameter of 1000 μm or more and 2000 μm or less. When the internal diameter is less than 1000 μm, when filtering suspended substances such as microorganisms that tend to aggregate, the inlet of the hollow fiber may be clogged with the aggregated suspended substances and filtration may not be continued. On the other hand, when the inner diameter is larger than 2000 μm, one porous hollow fiber membrane is thickened, the effective membrane area per module is reduced, and the filtration performance tends to be lowered. In order to make the film thickness within the above range, in the manufacturing method described below, for example, the diameter of the inner flow path of the double tubular nozzle may be 500 μm to 2500 μm (preferably 600 μm to 2200 μm).

The porous hollow fiber membrane may be sterilized by autoclaving. By sterilizing by autoclaving, the porous hollow fiber membrane can be suitably used for filtration of collagen hydrolyzate. When the autoclave treatment is performed, it is preferable that the hydrophobic polymer has a small change in water permeability before and after the autoclave treatment. Specifically, the water permeability change rate (F _AC / F ₀ ) before and after the autoclave treatment, which is obtained from the pure water permeability (F ₀ ) before the autoclave treatment and the pure water permeability (F _AC ) after the treatment, is 0. It is preferable that it is 0.9 or more and less than 1.1. Examples of such a hydrophobic polymer include polysulfone.

  Hereinafter, the manufacturing method of a porous hollow fiber membrane is demonstrated in detail.

The method for producing a porous hollow fiber membrane includes a coagulation step in which the following (1) and (2) are simultaneously discharged (extruded) and coagulated in an external coagulation liquid.
(1) Outflow of the internal coagulation liquid from the inner channel of the double tubular nozzle (2) Good for hydrophobic polymer, hydrophilic polymer and both of these polymers from the outer channel of the double tubular nozzle Outflow of production stock solution containing solvent and non-solvent for the hydrophobic polymer

  According to such a production method, a porous hollow fiber membrane can be easily obtained. In addition, after the outflow (extrusion) of (1) and (2), it is preferable to pass the idle running portion before solidification in the external coagulation liquid. Here, “passing through the idling portion” means once in the air (or in a gas such as an inert gas) so that the production stock solution flowing out from the double tubular nozzle does not immediately contact the external coagulation liquid. To pass through.

  Here, the double tubular nozzle refers to a nozzle in which an inner flow path is formed in the central portion of the nozzle, an outer flow path is formed so as to surround it, and a partition wall is formed between both flow paths. . The inner flow path of the double tubular nozzle preferably has a circular cross section perpendicular to the longitudinal direction of the nozzle, and the outer flow path of the double tubular nozzle preferably has a cross section perpendicular to the longitudinal direction of the nozzle. Are preferably circular, and both flow paths are preferably concentric (the center is common).

  As the internal coagulation liquid, an aqueous solution containing a good solvent of a hydrophobic polymer, which is 80% by mass or more and less than 100% by mass, based on the total mass of the internal coagulation liquid is preferable. Further, from the viewpoint of obtaining a porous hollow fiber membrane having a pore diameter of 5 μm or more on the inner surface, an aqueous solution containing 85% by mass or more and less than 98% by mass is preferable.

  As the external coagulation liquid, a coagulation liquid containing water as a main component and having a higher coagulation power with respect to the production stock solution than the internal coagulation liquid is preferable. By using such an external coagulation liquid, it is possible to obtain a porous hollow fiber membrane in which the inner surface pore diameter is larger than the outer surface pore diameter and the pore diameter continuously decreases from the inner surface to the minimum pore diameter layer. The coagulation force can be measured by the rate at which turbidity occurs when a transparent film-forming stock solution is cast thinly on glass and each coagulation solution is dropped on it. A strong coagulation liquid is shown.

  The good solvent for both the hydrophobic polymer and the hydrophilic polymer refers to a solvent in which insoluble components are not observed when 30 g of the hydrophobic polymer or hydrophilic polymer is dissolved in 100 g of the solvent. As a good solvent for dissolving both polymers, one or a mixture of two or more selected from N-methylpyrrolidone (NMP), dimethylformamide (DMF) and dimethylacetamide (DMAC) is used from the viewpoint of the stability of the stock solution. A solvent containing 80% or more of the solvent is preferable, and a solvent containing 90% or more is more preferable. Further, from the viewpoint of easy handling and high water permeability, the good solvent preferably contains N-methylpyrrolidone.

  The content of the good solvent for both the hydrophobic polymer and the hydrophilic polymer in the production stock solution is preferably 40% by mass or more and 75% by mass or less, based on the total mass of the production stock solution, and 50% by mass. % To 70% by mass is more preferable.

  The non-solvent for the hydrophobic polymer refers to a solvent in which insoluble components are observed when 5 g of the hydrophobic polymer is dissolved in 100 g of a solvent. Examples of the non-solvent for the hydrophobic polymer include water and alcohol compounds. Of these, glycerin is preferred from the viewpoints of ease of preparation of the film-forming stock solution, difficulty of composition change during storage, ease of handling, and the like.

  The content of the non-solvent in the production stock solution is preferably 0.5% by mass or more and 15% by mass or less, preferably 1% by mass or more and 10% by mass or less, based on the total mass of the production stock solution. More preferred.

  The production stock solution preferably has a solution viscosity of 30 Pa · sec or more and 200 Pa · sec or less, more preferably 40 Pa · sec or more and 150 Pa · sec or less, at a temperature of flowing out from the double tubular nozzle. When the solution viscosity is less than 30 Pa · sec, the film-forming stock solution that has flowed out from the outer flow path of the double tubular nozzle drips by its own weight, making it difficult to take a long run time and the film thickness is 300 μm or more. And it becomes difficult to produce a porous hollow fiber membrane having a pore diameter of 0.1 μm or more. On the other hand, when the solution viscosity is larger than 200 Pa · sec, it is difficult to stably extrude from the double tubular nozzle, and the film performance may vary.

  In the above production method, the hydrophilic polymer is preferably polyvinylpyrrolidone having a weight average molecular weight of 400,000 or more and 800,000 or less. By using such a hydrophilic polymer, it is possible to easily adjust a production stock solution having a solution viscosity within the above preferred range.

  The content of the hydrophilic polymer in the production stock solution is preferably 8% by mass or more and 30% by mass or less, and preferably 10% by mass or more and 25% by mass or less, based on the total mass of the production stock solution. More preferred. The content of the hydrophobic polymer in the production stock solution is preferably 15% by mass or more and 30% by mass or less, and more preferably 18% by mass or more and 25% by mass or more, based on the total mass of the production stock solution. It is more preferable. When the content of the hydrophilic polymer and the hydrophobic polymer is in the above range, the production stock solution having a solution viscosity within the above preferable range can be easily adjusted, and the content of the hydrophilic polymer is the above. A porous hollow fiber membrane within a suitable range can be obtained.

  As said manufacturing method, it is preferable to remove a part of hydrophilic polymer using an oxidizing agent containing aqueous solution simultaneously with the coagulation | solidification process or after that (preferably after a coagulation process). Examples of the oxidizing agent-containing aqueous solution include a sodium hypochlorite aqueous solution and a hydrogen peroxide aqueous solution. According to such a production method, it is possible to obtain a porous hollow fiber membrane in which the content of the hydrophilic polymer is within the above preferred range, and the filtration performance and the washability are further improved.

  The “collagen hydrolyzate” in this embodiment is a general term for substances obtained by hydrolyzing collagen obtained from connective tissues such as bones, skin, ligaments or tendons of animals, For example, gelatin, glue, collagen peptide and the like can be mentioned.

  Examples of the “collagen hydrolyzate-containing solution” in the present embodiment include an aqueous solution in which a collagen hydrolyzate is dissolved, an aqueous solution in which a collagen hydrolyzate is dispersed, and the like.

  In the method for producing a collagen hydrolyzate according to the present embodiment, a collagen hydrolyzate-containing solution containing a removed product such as a microorganism is circulated through the porous hollow fiber membrane. Thereby, a removal thing is removed by a porous hollow fiber membrane, and a collagen hydrolyzate containing solution is clarified. Then, a purified collagen hydrolyzate can be obtained from the clarified collagen hydrolyzate-containing solution.

  Examples of the collagen hydrolyzate-containing solution include a solution obtained by immersing connective tissue such as animal bone, skin, ligament or tendon in warm water for several hours and eluting the collagen hydrolyzate in the warm water. It is done.

  Examples of the collagen hydrolyzate-containing solution include a solution having a bacterial cell concentration of less than 100,000 cells / g (food sanitation inspection guidelines). When the cell concentration of the collagen hydrolyzate-containing solution is less than 100,000 cells / g, a collagen hydrolyzate with less contamination of crushed materials such as microorganisms can be obtained.

  The pH of the collagen hydrolyzate-containing solution is preferably 3.0 or more and 8.0 or less, and more preferably 4.0 or more and 7.0 or less. When the pH is within the above range, a collagen hydrolyzate having a good taste can be obtained when used in a final product such as a beverage.

  When the collagen hydrolyzate is gelatin, the collagen hydrolyzate-containing solution is preferably a solution having a gelatin concentration of 5% by mass to 70% by mass, more preferably a solution having a mass of 20% by mass to 50% by mass. preferable. When the collagen hydrolyzate is gelatin, the collagen hydrolyzate can be obtained with good productivity when the concentration in the collagen hydrolyzate-containing solution is 5% by weight or more. Moreover, when the density | concentration in a collagen hydrolyzate containing solution is 70 mass% or less, the fall of the filtrate flow rate resulting from the viscosity raise of a collagen hydrolyzate containing solution does not occur easily, and stable filtration processing is attained.

  When the collagen hydrolyzate is gelatin, the viscosity of the collagen hydrolyzate-containing solution (viscosity measured according to JIS K6503: 2001) is preferably 1.1 mPa · sec to 13 mPa · sec. When the viscosity of the collagen hydrolyzate-containing solution is 1.1 mPa or more, the gelatin content is appropriate and the energy required for solidification is reduced. Therefore, solidified gelatin can be easily obtained from the solution that has passed through the porous hollow fiber membrane. On the other hand, when the viscosity of the collagen hydrolyzate-containing solution is 13 mPa · sec or less, the viscosity is not too high and the membrane easily passes through the porous hollow fiber membrane, so that the treatment speed is further improved. The viscosity is more preferably 1.5 mPa · sec or more and 6 mPa · sec or less.

  When the collagen hydrolyzate is a collagen peptide, the collagen hydrolyzate-containing solution is preferably a solution having a collagen peptide concentration of 5% by mass to 70% by mass, preferably 30% by mass to 60% by mass. Is more preferable. When the collagen hydrolyzate is a collagen peptide, if the concentration in the collagen hydrolyzate-containing solution is within the above range, an effect of obtaining an efficient filtration flow rate while maintaining productivity can be obtained. The

  When the collagen hydrolyzate is a collagen peptide, the viscosity of the collagen hydrolyzate-containing solution (measured according to the method of measuring the concentration of “Niwa” in JIS K6503: 2001) is 0.5 mPa · sec to 3.2 mPa · It is preferable that it is sec or less. When the viscosity of the collagen hydrolyzate-containing solution is 0.5 mPa · sec or more, the collagen peptide content is appropriate and the energy required for solidification is reduced. Therefore, the solidified collagen peptide can be easily obtained from the solution that has passed through the porous hollow fiber membrane. On the other hand, when the viscosity of the collagen hydrolyzate-containing solution is 3.2 mPa · sec or less, the viscosity is not too high and the membrane easily passes through the porous hollow fiber membrane, so that the processing speed is further improved. The viscosity is more preferably 0.6 mPa · sec or more and 2 mPa · sec or less.

  The method for producing a collagen hydrolyzate according to the present embodiment includes an internal pressure filtration step in which a collagen hydrolyzate-containing solution is circulated through the porous hollow fiber membrane. The internal pressure filtration step includes a conventional hollow fiber membrane. Compared with the method used, a high filtration rate can be maintained for a long time, there is little destruction and deformation of microorganisms, membrane cleaning is easy, and processing efficiency is excellent.

  The internal pressure filtration in the internal pressure filtration step is preferably performed by cross flow filtration from the viewpoint that a high filtration rate can be maintained for a long time. Cross-flow filtration is a method of introducing a collagen hydrolyzate-containing solution from one end of a porous hollow fiber membrane into the inside of the tube and feeding it along the tube wall. It refers to a filtration method in which a collagen hydrolyzate-containing solution is discharged and the collagen hydrolyzate-containing solution concentrated by filtration is extracted from the other end of the porous hollow fiber membrane.

  The feeding speed of the collagen hydrolyzate-containing solution in the crossflow filtration is preferably 3.0 m / sec or less, more preferably 2.0 m / sec or less, in terms of linear velocity. When the liquid feeding speed is 3.0 m / sec or less, the energy load applied to the porous hollow fiber membrane is small, and the porous hollow fiber membrane can be used for a long time. Further, when it is 0.2 m / sec or more and 1.5 m / sec or less, the porous hollow fiber membrane can be used for a longer period while maintaining a sufficiently high processing speed.

  The internal pressure filtration in the internal pressure filtration step can also be performed by dead end filtration from the viewpoint that the internal pressure filtration step can be performed with high energy efficiency. Dead end filtration means closing the end of the porous hollow fiber membrane, introducing a collagen hydrolyzate-containing solution into the tube from the other end, filtering the tube wall, and clarifying it from the pores. It refers to a filtration method in which the contained solution is allowed to flow out and accumulated removed substances such as microorganisms are accumulated on the membrane surface and inside the membrane.

  Even if the manufacturing method of the collagen hydrolyzate which concerns on this embodiment includes the solidification process of obtaining the solidified collagen hydrolyzate from the clarified collagen hydrolyzate containing solution obtained by an internal pressure filtration process Good.

  In the solidification step, for example, the clarified collagen hydrolyzate-containing solution is placed in a dryer and solidified.

  According to such a solidification process, a collagen hydrolyzate can be easily obtained from a clarified collagen hydrolyzate-containing solution. Since a clarified collagen hydrolyzate-containing solution is used, the purified collagen hydrolyzate can be obtained with a low content of microorganisms and crushed materials thereof.

  The method for producing a collagen hydrolyzate according to this embodiment may include an extraction step of obtaining an extract containing collagen and / or collagen hydrolyzate from connective tissue such as bone, skin, ligament or tendon of an animal. Good.

  The method for producing a collagen hydrolyzate according to the present embodiment may also include a hydrolysis step of hydrolyzing collagen in the extract obtained in the extraction step.

  The extraction step can be performed, for example, by immersing connective tissue such as bone, skin, ligament or tendon of an animal in warm water for several hours and eluting collagen and / or collagen hydrolyzate in warm water.

  Examples of the hydrolysis in the hydrolysis step include thermal hydrolysis in warm water, hydrolysis by enzyme treatment, and the like.

  The method for producing a collagen hydrolyzate according to the present embodiment further comprises a step of back-washing the porous hollow fiber membrane using the filtrate obtained in the internal pressure filtration step (clarified collagen hydrolyzate-containing solution). Furthermore, it is preferable to include. The filtration performance of the porous hollow fiber membrane can be maintained for a long period of time by periodically removing the membrane surface of the porous hollow fiber membrane and deposits inside the membrane by backwashing. In addition, since a sufficient filtration rate can be maintained for a long time at a low pressure and a low liquid feeding rate, it is possible to further prevent crushing of microorganisms and the like contained in the collagen hydrolyzate-containing solution.

  According to the method for producing a collagen hydrolyzate according to the present embodiment, it is possible to maintain a high filtration rate for a long period of time as compared with a conventional filtration method using a porous hollow fiber membrane, and there is less destruction and deformation of microorganisms. In addition, it is possible to produce a collagen hydrolyzate that is excellent in production efficiency and includes a pulverized product such as microorganisms and that is sufficiently purified, including an internal pressure filtration step that facilitates membrane cleaning and high processing efficiency.

  The preferred embodiment of the present invention has been described above, but the present invention is not limited to the above embodiment. For example, in the above embodiment, the method for producing a collagen hydrolyzate has been described. However, the present invention may be a method for clarifying a collagen hydrolyzate-containing solution, and manufacturing a clarified collagen hydrolyzate-containing solution. It may be a method.

  EXAMPLES Hereinafter, although this invention is demonstrated more concretely based on an Example and a comparative example, this invention is not limited to a following example.

  For the porous hollow fiber membranes of the following examples and comparative examples, the measurement of the position of the inner surface pore diameter and the minimum pore diameter layer, the measurement of the pore diameter of the minimum pore diameter layer, the measurement of the inner diameter, the outer diameter and the film thickness, the content ratio of polyvinylpyrrolidone Measurement, measurement of the distribution of polyvinyl pyrrolidone, measurement of the solution viscosity of the film forming stock solution, and measurement of the weight average molecular weight of polyvinyl pyrrolidone were performed by the following methods.

(1) Measurement of position of inner side surface pore diameter and minimum pore diameter layer The inner side surface of the freeze-dried porous hollow fiber membrane was observed with an electron microscope at a magnification capable of observing 10 or more pores in one field of view. The pores in the obtained micrograph were subjected to circular approximation processing, and the diameter obtained from the area average value was defined as the inner side surface pore diameter. The cross section of the freeze-dried porous membrane was continuously observed from the inner side to the outer side, and the position of the layer having the smallest cross-sectional pore diameter was confirmed.

(2) Pore size determination method of minimum pore size layer Polystyrene latex particles were dispersed in a 0.5 wt% sodium dodecyl sulfate aqueous solution so that the particle concentration was 0.01 wt% to prepare a latex particle dispersion. The latex particle dispersion was filtered using a porous hollow fiber membrane, and the change in latex particle concentration before and after filtration was measured. This measurement was performed while changing the latex particle diameter in steps of 0.1 μm to about 0.1 μm, and a latex particle inhibition curve was prepared. From this blocking curve, the particle diameter capable of blocking 90% permeation was read, and the diameter was taken as the pore diameter of the minimum pore diameter layer.

(3) Measurement of the inner diameter, outer diameter and film thickness of the porous hollow fiber membrane The porous hollow fiber membrane is cut into a thin tube and observed with a measuring microscope to determine the inner diameter (μm) and outer diameter of the porous hollow fiber membrane. (Μm) was measured. The film thickness was calculated from the obtained inner and outer diameters using the following formula (II).
Film thickness (μm) = (outer diameter−inner diameter) / 2 (II)

(4) Measurement of polyvinylpyrrolidone content (in the case of polysulfone membrane)
1H-NMR measurement of the porous hollow fiber membrane was carried out under the following conditions, and the integrated value (I _PVP ) of the signal derived from polyvinylpyrrolidone (4H min) appearing in the vicinity of 1.85 to 2.5 ppm in the obtained spectrum It was calculated by the following formula (III) from the integrated value (I _PSf ) of the signal derived from polysulfone (4H min) appearing in the vicinity of 7.3 ppm.

[Measurement condition]
Device: JNM-LA400 (JEOL Ltd.)
Resonance frequency: 400.05 MHz
Solvent: deuterated DMF
Sample concentration: 5% by mass
Integration count: 256 times

[Formula (III)]
Polyvinylpyrrolidone content ratio (% by mass) = 111 (I _PVP / 4) / {442 (I _PSf / 4) +111 (I _PVP / 4)} × 100

(5) Measurement of polyvinylpyrrolidone distribution When the tube wall of the porous hollow fiber membrane is divided into three regions by dividing the tube wall into three equal parts in the film thickness direction, the outer peripheral region including the outer surface and the inner surface are included. The portion of the inner peripheral region was sampled, and the content ratio of polyvinyl pyrrolidone contained in the porous hollow fiber membrane was determined by NMR measurement in the same manner as the above measurement. The distribution of polyvinyl pyrrolidone was determined from the content (C _out ) of polyvinyl pyrrolidone in the outer peripheral region and the content (C _in ) in the inner peripheral region according to the following formula (IV).
Distribution of polyvinyl pyrrolidone = C _out / C _in (IV)

(6) Measurement of solution viscosity of membrane-forming stock solution The membrane-forming stock solution placed in a wide-mouth bottle was placed in a thermostatic bath, and the temperature of the solution was set to be a temperature extruded from a double tube nozzle. Viscosity was measured using a B-type viscometer.

(7) Weight average molecular weight measurement of polyvinyl pyrrolidone A sample solution in which polyvinyl pyrrolidone was dissolved in DMF at a concentration of 1.0 mg / ml was prepared, and GPC measurement was performed under the following conditions to determine its weight average molecular weight (PMMA conversion). .
Equipment: HLC-8220GPC (Tosoh Corporation)
Column: Shodex KF-606M, KF-601
Oven: 40 ° C
Mobile phase: 0.6 ml / min DMF
Detector: Differential refractive index detector

Example 1
[Production of porous hollow fiber membrane]
Polysulfone (SOLVAY ADVANCED POLYMERS, Udel P3500) 18% by mass and polyvinylpyrrolidone (BASF, Luvitec k80) 15% by mass were dissolved in N-methyl-2-pyrrolidone 62% by mass at 70 ° C., and glycerin 5 Mass% was added and further stirred to prepare a film-forming stock solution. This film-forming stock solution was fed from a double ring spinning nozzle (outer diameter 2.4 mm, intermediate diameter 1.2 mm, inner diameter 0.6 mm, the same in the following examples) to 90 mass% NMP of the internal coagulation liquid. It was extruded with an aqueous solution and allowed to solidify in water at 80 ° C. through a 50 mm free running distance. After removing the solvent in water, the PVP treatment was performed in a 2000 ppm sodium hypochlorite aqueous solution, followed by washing with water to obtain a porous hollow fiber membrane. The evaluation results of the obtained porous hollow fiber membrane are shown in Table 1.

[Production of collagen hydrolyzate]
A porous hollow fiber membrane obtained so as to have a membrane area of 1200 cm ² was put in a module case having an effective length of 20 cm to produce a cross-flow type mini-module. Unfiltered collagen peptide was fed to the module at a filtration pressure of 60 kPa and a linear velocity of 0.5 m / sec, and the average permeation rate was measured. The measurement results are shown in Table 1. Moreover, in the present Example, the high filtration rate was able to be maintained for 1 hour or more.

  The unfiltered collagen peptide had a concentration of 52%, a value measured by the method for measuring the concentration of glue in JIS K6503: 2001, 1.6 mPa · sec, a pH of 6.0, and a bacterial cell concentration of 100,000 cells / g. It was. On the other hand, the collagen peptide after filtration has a microbial cell concentration of 500 cells / g or less, and it was confirmed that microorganisms and their crushed materials were sufficiently removed.

  The collagen peptide after filtration was dried with a dryer to obtain a solidified collagen peptide. It was confirmed that the obtained collagen peptide was purified by removing the content of microorganisms and crushed materials thereof.

(Example 2)
[Production of collagen hydrolyzate]
A valve was attached to one end of the same minimodule as in Example 1 and closed, and one end of the porous hollow fiber membrane was closed. An unfiltered collagen peptide was fed to the module at a filtration pressure of 60 kPa, filtered at the dead end, and the average permeation rate was measured. The measurement results are shown in Table 1. Moreover, in the present Example, the high filtration rate was able to be maintained for 1 hour or more.

  The unfiltered collagen peptide had a concentration of 52%, a value measured by the method for measuring the concentration of glue in JIS K6503: 2001, 1.6 mPa · sec, a pH of 6.0, and a bacterial cell concentration of 100,000 cells / g. It was. Further, the collagen peptide after filtration had a microbial cell concentration of 500 cells / g or less, and it was confirmed that microorganisms and their crushed materials were sufficiently removed.

  The collagen peptide after filtration was dried with a drier to obtain a solidified collagen peptide. It was confirmed that the obtained collagen peptide was purified by removing the content of microorganisms and crushed materials thereof.

(Comparative Example 1)
[Production of collagen hydrolyzate]
The collagen hydrolyzate was purified by the same method as in Example 1 except that a polyvinylidene fluoride homogeneous membrane having an average pore diameter of 0.45 μm was used instead of the porous hollow fiber membrane of Example 1. The measurement results are shown in Table 1. When the hollow fiber membrane was used, the membrane was clogged, and as a result, the filtration rate was significantly reduced.

Claims (10)

A purified collagen hydrolyzate comprising an internal pressure filtration process in which a collagen hydrolyzate-containing solution is circulated through a porous hollow fiber membrane in which a tube wall is composed of a blend of a hydrophobic polymer and a hydrophilic polymer. A manufacturing method comprising:
In the porous hollow fiber membrane, when the tube wall is equally divided into three regions in the film thickness direction and divided into three regions, the content of the hydrophilic polymer in the outer peripheral region including the outer surface includes the inner surface. A production method, wherein the porous hollow fiber membrane is larger than the content ratio of the hydrophilic polymer in the inner peripheral region and the average pore diameter on the inner surface is larger than the average pore size on the outer surface.   The porous hollow fiber membrane has an average pore diameter of 1 μm or more and 50 μm or less on the inner surface, the outer peripheral region has a blocking pore diameter of 0.1 μm or more and less than 1 μm, and the film thickness of the tube wall is 300 μm or more. The manufacturing method of Claim 1 which is a porous hollow fiber membrane of 1000 micrometers or less.   The production method according to claim 1 or 2, wherein the hydrophilic polymer is polyvinylpyrrolidone.   The porous hollow fiber membrane is a porous hollow fiber membrane in which the content of the hydrophilic polymer is 0.2% by mass or more and 3% by mass or less based on the total mass of the porous hollow fiber membrane. The manufacturing method of any one of Claims 1-3. The manufacturing method of any one of Claims 1-4 with which the said porous hollow fiber membrane satisfy | fills following formula (I).
C _out / C _in ≧ 2 (I)
[In formula (I), C _out represents the content of the hydrophilic polymer in the outer peripheral region, and C _in represents the content of the hydrophilic polymer in the inner peripheral region. ]   The manufacturing method according to any one of claims 1 to 5, wherein the porous hollow fiber membrane is a porous hollow fiber membrane having an inner diameter of 1000 µm or more and 2000 µm or less.   The manufacturing method according to claim 1, wherein the hydrophobic polymer is polysulfone. The internal pressure filtration is performed by cross flow filtration,
The collagen hydrolyzate-containing solution is fed from one end of the porous hollow fiber membrane into the tube at a linear velocity of 3.0 m / sec or less, according to any one of claims 1 to 7. Production method.   The said internal pressure filtration is a manufacturing method as described in any one of Claims 1-7 performed by dead end filtration.   The manufacturing method of any one of Claims 1-9 which further includes the process of backwashing the said porous hollow fiber membrane using the filtrate obtained at the said internal pressure filtration process.