JP2019047781A - Method for producing soy sauce using porous film - Google Patents

Abstract

To provide a method for producing a soy sauce including a filtration step of a fired soy sauce using a porous film, which is low in a change in the total nitrogen component of a fired soy sauce before and after filtration, is high in removal quality of a dregs component, and has high permeated water amount avoidance after a cleaning step of a porous fil and resistance to a cleaning liquid (medicine liquid).SOLUTION: A method for producing a soy sauce includes: a firing step of firing a soy sauce containing a dregs component to form an aggregate of the dregs component; and a filtration step of passing a fired soy sauce containing the aggregate of the dregs component through a porous film composed of formed of a resin having a three-dimensional network structure to separate a filtrate from the aggregate of the dregs component, where the total of the area of a resin part having an area of 1 μmor less is 70% or more based on the total area of the resin part, and when a dregs component ratio of the fired soy sauce before the filtration step is represented by X0, the total nitrogen component thereof is represented by N0, a dregs component ratio of the fired soy sauce after the filtration step is represented by X1 and the total nitrogen component thereof is represented by N1, the methods satisfy relationships of X1/X0×100<5% and N1/N0×100≥97%.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a method for producing soy sauce comprising the step of filtering a fired soy sauce using a porous membrane. More particularly, the present invention relates to a method for producing soy sauce comprising a filtration step using a porous membrane for removing the agglomerates from the glazed soy sauce containing the agglomerates of the sediment component, wherein total nitrogen of the cooked soy sauce before and after filtration The method relates to a method in which the change in the composition is low, the removal rate of the sediment component is high, and the water permeability recovery after the porous membrane washing step and the washing liquid (chemical solution) resistance are also high.

  Water treatment to obtain drinking water and industrial water from natural water sources such as suspended water, river water, lake water, groundwater, etc., treatment of domestic wastewater such as sewage to produce reclaimed water, clear water that can be released In the method of producing soy sauce including sewage treatment for making the waste water, and the process of removing the sediment component from the burning soy sauce, a solid-liquid separation operation (clouding operation) for separating and removing the suspension is required. In this turbidity removal operation, suspended matter (clay, colloid, bacteria, etc.) derived from natural water source water which is suspended water is removed for the treatment of fresh water, and for sewage treatment, suspended matter in the lower water, activated sludge, etc. Suspensions (sludge etc.) in treated water subjected to biological treatment (secondary treatment) are removed, and in the method of producing soy sauce, sediment component aggregates aggregated by burning are removed.

In the past, these turbidity removal operations have mainly been carried out by the pressure flotation method, sedimentation method, sand filtration method, flocculation sedimentation sand filtration method, diatomaceous earth filtration etc., but in recent years, in place of these methods, membranes Filtration methods are becoming popular. Among the advantages of the membrane filtration method are: (1) high turbidity removal level of the obtained water quality and stability (high safety of the obtained water) (2) the installation space of the filtration device is small And (3) ease of automatic operation. For example, in the pretreatment of seawater desalination reverse osmosis filtration, as an alternative means of the pressurized flotation method, or as a subsequent stage of the pressurized flotation method, a membrane filtration method to further improve the water quality of the treated water subjected to pressurized flotation treatment Is used. A flat or hollow fiber porous ultrafiltration membrane or a microfiltration membrane having an average pore diameter in the range of several nm to several hundreds nm is used for the turbidity removal operation by the membrane filtration.
Thus, since the turbidity removal operation by the membrane filtration method has many advantages which the above-mentioned conventional pressurized flotation method, sand filtration method and the like do not have, there is a desalination pretreatment for seawater as an alternative or complementary means of the conventional method. Dissemination to, etc. is progressing, and an organic film composed of a resin as described in Patent Document 1 below is widely used as a porous film.

  In addition, diatomaceous earth filtration has been mainly used to remove the sediment component of conventionally heated soy sauce, but membrane filtration has recently been used as an alternative means because disposal costs of used diatomaceous earth increase. However, it is important that the total nitrogen component of the heated soy sauce does not change before and after the membrane filtration for removing the sediment component, and 2 to 3% by weight as a washing solution (chemical solution) in the washing process after the filtration process. When using high concentration sodium hydroxide, there is a problem that chemical solution cost and wastewater treatment cost become high.

JP, 2011-168741, A

As described above, although an organic membrane composed of a resin is often used as a porous membrane, when producing a porous filtration membrane using a resin material, if the film forming method is different, the microstructure of the material constituting the membrane is used. A difference appears. Moreover, in the filtration for the removal of the sediment component of a burning soy sauce, suppressing the fall of a total nitrogen component as much as possible is required, maintaining the removal rate of a sediment component highly. Furthermore, since the membrane usually becomes clogged when the filtration operation is continued, the operation of the filtration method using a porous filtration membrane involves a washing step. On the other hand, the use of agents in the washing process induces membrane strength degradation. At this time, if there is a difference in the microstructure of the material constituting the porous filtration membrane, the degree of damage to the porous filtration membrane by the cleaning liquid (chemical solution) used in the repeated washing step is different, resulting in the filtration performance and the life. There is also the problem of influence.
In view of such problems, the problem to be solved by the present invention is a method for producing soy sauce comprising a filtration step using a porous membrane for removing the aggregate from a fired soy sauce containing an aggregate of a sediment component, wherein It is an object of the present invention to provide a method in which the change in the total nitrogen component of burned soy sauce before and after burning is low, the removal rate of the sediment component is high, and the water permeability recovery after washing the porous membrane and the washing liquid (chemical solution) resistance are high.

  The inventor of the present invention has conducted intensive studies and repeated experiments to solve the above-mentioned problems, and as a result, communication of pores from the inside of the membrane on the treated side of the porous filtration membrane to the outside of the membrane on the filtrate side In the method for producing soy sauce comprising a filtration step using a porous membrane for removing the aggregate from the fired soy sauce containing the aggregate of the sediment component by using the membrane having good conductivity, the cooked soy sauce before and after the filtration Change of total nitrogen component is low, removal rate of sediment component is high, and further, as a cleaning solution (chemical solution) used in the washing step, hot water at 50 ° C to 90 ° C, and / or 0.05% by weight or more and 0.5% or more Even when using an aqueous solution containing sodium hypochlorite in an amount of not more than% by weight or sodium hydroxide in an amount of not less than 0.4% by weight, it is expected that the deterioration of the film can be minimized. Find out and complete the present invention Those were.

That is, the present invention is as follows.
[1] The following steps:
A firing step of burning soy sauce containing a precipitate component to form an aggregate of the precipitate component; and a cooked soy sauce containing an aggregate of the precipitate component in a porous membrane composed of a resin of a three-dimensional network structure. Filtration to separate the filtrate from aggregates of the sediment component by passing through
A method of producing soy sauce containing
A field of view including the inner surface, a field of view including the outer surface of the film, and an equal distance between the fields of the SEM image of the cross section in the film thickness direction orthogonal to the inner surface of the porous membrane 2 The total area of the resin part having an area of 1 μm ² or less is 70% or more with respect to the total area of the resin part in each area of a total of four visual fields.
When the sediment component ratio of the fired soy sauce before the filtration step is X0, the total nitrogen component is N0, the sediment component ratio of the fired soy sauce after the filtration step is X1, and the total nitrogen component is N1, X1 / X0 × 100 <5 % And N1 / N0 × 100 ≧ 97%
The manufacturing method of the said soy sauce characterized by the above-mentioned.
[2] the following steps:
A firing step of burning soy sauce containing a precipitate component to form an aggregate of the precipitate component; and a cooked soy sauce containing an aggregate of the precipitate component in a porous membrane composed of a resin of a three-dimensional network structure. Filtration to separate the filtrate from aggregates of the sediment component by passing through
A method of producing soy sauce containing
A field of view including the inner surface, a field of view including the outer surface of the film, and an equal distance between the fields of the SEM image of the cross section in the film thickness direction orthogonal to the inner surface of the porous membrane 2 The total area of the resin part having an area of 10 μm ² or more is 15% or less of the total area of the resin part in each area of a total of four visual fields of visual field, and
When the sediment component ratio of the fired soy sauce before the filtration step is X0, the total nitrogen component is N0, the sediment component ratio of the fired soy sauce after the filtration step is X1, and the total nitrogen component is N1, X1 / X0 × 100 <5 % And N1 / N0 × 100 ≧ 97%
The manufacturing method of the said soy sauce characterized by the above-mentioned.
[3] The following steps:
A firing step of burning soy sauce containing a precipitate component to form an aggregate of the precipitate component; and a cooked soy sauce containing an aggregate of the precipitate component in a porous membrane composed of a resin of a three-dimensional network structure. Filtration to separate the filtrate from aggregates of the sediment component by passing through
A method of producing soy sauce containing
A field of view including the inner surface, a field of view including the outer surface of the film, and an equal distance between the fields of the SEM image of the cross section in the film thickness direction orthogonal to the inner surface of the porous membrane 2 The total area of the resin part having an area of 1 μm ² or less is 70% or more with respect to the total area of the resin part in each area of a total of four visual fields, and a resin having an area of 10 μm ² or more The total area of the part is 15% or less of the total area of the resin part, and
When the sediment component ratio of the fired soy sauce before the filtration step is X0, the total nitrogen component is N0, the sediment component ratio of the fired soy sauce after the filtration step is X1, and the total nitrogen component is N1, X1 / X0 × 100 <5 % And N1 / N0 × 100 ≧ 97%
The manufacturing method of the said soy sauce characterized by the above-mentioned.
[4] The porous film is a SEM image of a film cross section in a film thickness direction orthogonal to the inner surface of the porous film, a field of view including the inner surface, a field of view including the outer surface of the film, and these fields of view in 2 field each region a total of four field of between was taken at regular intervals of, 1 [mu] m ² total area of the resin portion having an area of less than super 10 [mu] m ² is at most 15% of the total area of the resin portion The method according to any one of the above [1] to [3].
[5] The method according to any one of the above [1] to [4], wherein the surface open area ratio of the porous membrane is 25 to 60%.
[6] The method according to any one of the above [1] to [5], wherein the porous membrane is a hollow fiber membrane.
[7] The method according to any one of the above [1] to [6], wherein the resin constituting the porous membrane is a thermoplastic resin.
[8] The method according to [7] above, wherein the thermoplastic resin is a fluorine resin.
[9] The fluorine resin is vinylidene fluoride resin (PVDF), chlorotrifluoroethylene resin, tetrafluoroethylene resin, ethylene-tetrafluoroethylene copolymer (ETFE), ethylene-monochlorotrifluoroethylene copolymer (ECTFE) The method according to [8] above, which is selected from the group consisting of hexafluoropropylene resins, and mixtures of these resins.
[10] The method according to [7] above, wherein the thermoplastic resin is polyethylene (PE).
[11] The method further comprises a washing step of washing the inside of the porous membrane by passing or immersing a washing liquid in the porous membrane after the filtration step, wherein the washing liquid is hot water at 50 ° C. to 90 ° C. The method according to any one of the above [1] to [10].
[12] The method further includes a washing step of washing the inside of the porous membrane by passing or immersing a washing liquid in the porous membrane after the filtration step, wherein the washing liquid is 0.05 wt% or more and 0.5 wt%. The method according to any one of the above [1] to [10], which is an aqueous solution containing at most% sodium hypochlorite or at least 0.4 wt% and at most 4 wt% sodium hydroxide.
[13] The relationship between the tensile breaking elongation E0 of the porous membrane before the washing step and the tensile breaking elongation E1 of the porous membrane after the washing step is E1 / E0 × 100 ≧ 80% , The method as described in said [11] or [12].
[14] Tensile elongation at break E0 of the porous membrane before the washing step, and the porous membrane after repeating the washing step X times (here, X is an integer of 2 to 100) The method according to the above [11] or [12], wherein the relationship with the tensile elongation at break EX is EX / E0 × 100 ≧ 70%.
[15] The above [11] or the relation between the flux L0 of the porous membrane before the filtration step and the flux L1 of the porous membrane after the cleaning step is L1 / L0 × 100 ≧ 95%, [11] or The method described in [12].
[16] The flux L0 of the porous membrane before the filtration step, and the flux LX of the porous membrane after repeating the cleaning step X times (here, X is an integer of 2 to 100) The method according to the above [11] or [12], wherein the relationship of is X / L0 × 1009090%.
[17] The washing step includes the washing step of washing with the washing liquid and the rinsing step of rinsing with rinse water for removing the remaining washing liquid component thereafter. The method described in either.
[18] The method according to [17], wherein the amount of rinse water used in the rinse step is 100 L / m ² or less per unit area of the porous membrane.
[19] The above [17] or [17], wherein the chlorine concentration in the filtrate after restarting the filtration step after the rinse step is 0.1 ppm or less and the pH of the filtrate is 8.6 or less 18].

  The filtration step in the method for producing soy sauce according to the present invention uses a membrane having good communication of pores extending from the inside of the membrane on the treated liquid side of the porous filtration membrane to the outside of the membrane on the filtrate side. Therefore, the change in the total nitrogen component of the heated soy sauce before and after filtration is low, the removal rate of the sediment component is high, and furthermore, 50 ° C. to 90 ° C. hot water and / or 0. 2 as a cleaning solution (chemical solution) used in the washing step. Even when using an aqueous solution containing at least 05 wt% but not more than 0.5 wt% sodium hypochlorite or at least 0.4 wt% but not more than 4 wt% sodium hydroxide, the deterioration of the film is minimized. Can be reduced to Therefore, the method for producing soy sauce according to the present invention is a method which is excellent in filtration performance, its recoverability, chemical resistance, and has a long life. Conditionally, the porous membrane used in the filtration step in the method for producing soy sauce according to the present invention has high porosity communication, so adsorption of all nitrogen components of the burned soy sauce to the membrane is small, and total nitrogen before and after filtration The change of the component is 3% or less, and the removal rate of the sediment component is more than 95%. Furthermore, even when a sodium hydroxide aqueous solution having a relatively low concentration of 1% by weight is used as the washing solution in the washing step, the water permeability of the porous membrane can be sufficiently recovered.

It is an example of the SEM image of the cross section of the porous membrane used for the filtration process in the manufacturing method of the soy sauce of this embodiment (a black part shows resin and a white part shows a pore (open hole)). A field of view including the inner surface, a field of view including the outer surface of the film, and the like between the fields of view in a SEM image of a film cross section in a film thickness direction orthogonal to the inner surface of the porous film used in Example 1. It is a histogram which shows the ratio (%) of the total of the area of the resin part which has a predetermined area with respect to the total area of the resin part in each area | region (circle 1-circle 4) of a total of four visual fields of 2 visual fields image | photographed by space | interval. A field of view including the inner surface, a field of view including the outer surface of the film, and the like between the fields of view in a SEM image of a film cross section in a film thickness direction orthogonal to the inner surface of the porous film used in Example 2. It is a histogram which shows the ratio (%) of the total of the area of the resin part which has a predetermined area with respect to the total area of the resin part in each area | region (circle 1-circle 4) of a total of four visual fields of 2 visual fields image | photographed by space | interval. A field of view including the inner surface, a field of view including the outer surface of the film, and the like between the fields of view in a SEM image of a film cross section in a film thickness direction orthogonal to the inner surface of the porous film used in Example 3. It is a histogram which shows the ratio (%) of the total of the area of the resin part which has a predetermined area with respect to the total area of the resin part in each area | region (circle 1-circle 4) of a total of four visual fields of 2 visual fields image | photographed by space | interval. A field of view including the inner surface, a field of view including the outer surface of the film, and a field between the fields of view in a SEM image of a film cross section in a film thickness direction orthogonal to the inner surface of the porous film used in Comparative Example 2. It is a histogram which shows the ratio (%) of the total of the area of the resin part which has a predetermined area with respect to the total area of the resin part in each area | region (circle 1-circle 4) of a total of four visual fields of 2 visual fields image | photographed by space | interval.

  Hereinafter, an embodiment of the present invention (hereinafter, also referred to as the present embodiment) will be described in detail. The present invention is not limited to the present embodiment.

<Method for producing soy sauce>
The method for producing soy sauce of this embodiment comprises the following steps:
A firing step of burning soy sauce containing a precipitate component to form an aggregate of the precipitate component; and a cooked soy sauce containing an aggregate of the precipitate component in a porous membrane composed of a resin of a three-dimensional network structure. Filtration to separate the filtrate from aggregates of the sediment component by passing through
A method for producing soy sauce containing the following components, wherein the sediment component ratio of the cooked soy sauce before the filtration step is X0, the total nitrogen component is N0, the sediment component ratio of the cooked soy sauce after the filtration step is X1, Satisfy the relationship of X1 / X0 × 100 <5% and N1 / N0 × 100 ≧ 97%,
It is characterized by
Preferably, X1 / X0 × 100 <0.5%, and more preferably, X1 / X0 × 100 <0.3%.
Further, it is preferable that N1 / N0 × 10010098%, and more preferably N1 / N0 × 100 ≧ 99.5%.
The shape of the porous membrane is not particularly limited, and may be a flat membrane, a tubular membrane, or a hollow fiber membrane, but from the viewpoint of space saving of the filtration device, that is, the membrane area per unit volume of membrane module is large. Hollow fiber membranes are preferred because they can be

As a filtration step in the method for producing soy sauce according to the present embodiment, for example, a burned soy sauce (liquid to be treated) containing an aggregate of a sediment component coagulated by burning in a hollow portion (inner surface) of a porous hollow fiber membrane is supplied A so-called internal pressure type filtration step which passes the membrane thickness (thickness) portion of the porous hollow fiber membrane and takes out the liquid exuded from the outer surface of the porous hollow fiber membrane as a filtrate. A so-called external pressure type filtration process may be used, in which the liquid to be treated is supplied from the outer surface of the porous hollow fiber membrane and the filtrate exuded from the inner surface of the porous hollow fiber membrane is taken out through the hollow portion. .
As used herein, the term "inside of the porous membrane" refers to a portion of a film thickness (thickness) in which a large number of pores are formed.

Preferably, the method for producing soy sauce of the present embodiment further comprises a washing step of washing the inside of the porous membrane by passing or immersing the porous membrane with a washing liquid after the filtration step, the washing liquid It may be hot water at 50 ° C. to 90 ° C. (hereinafter, also referred to as hot water).
More preferably, the method for producing soy sauce of the present embodiment further comprises a washing step of washing the inside of the porous membrane by passing or immersing a washing liquid in the porous membrane after the filtration step, the washing liquid The aqueous solution containing 0.05% by weight or more and 0.5% by weight or less of sodium hypochlorite or 0.4% by weight or more and 4% by weight or less of sodium hydroxide (hereinafter also referred to as a chemical solution) it can. In the cleaning step, it is preferable to perform chemical solution cleaning after the hot water cleaning.
The washing step may include a washing step of washing with the washing solution and a rinsing step of rinsing with rinse water to remove the remaining washing component. When the cleaning liquid is hot water, the temperature of the hot water can be preferably 55 ° C. or more and 85 ° C. or less, more preferably 60 ° C. or more and 80 ° C. or less. When the cleaning liquid is the chemical solution, the temperature of the chemical solution may be preferably 15 ° C. or more and 35 ° C. or less, more preferably 20 ° C. or more and 35 ° C. or less. The concentration of sodium hydroxide in the chemical solution is more preferably 0.7% by weight or more and 4% by weight or less, and still more preferably 1% by weight or more and 4% by weight or less. The concentration of sodium hypochlorite in the chemical solution is more preferably 0.1% by weight or more and 0.5% by weight or less, and still more preferably 0.2% by weight or more and 0.5% by weight or less. As the washing step, for example, from the filtration side of the porous membrane by passing the washing solution from the filtrate side to the burning soy sauce side in the opposite direction to the flow direction of the burning soy sauce in the filtering step Examples of the method include reverse pressure water washing to separate and remove attached matter (insoluble component), and air scrubbing to shake the porous film with air to shake the insoluble component attached to the porous film. The amount of rinsing water used in the rinsing step, it is preferable that the porous film per unit area 100L / m ² or less of, and more preferably at 50L / m ² or less. Moreover, it is preferable that chlorine concentration in the filtrate after restarting the said filtration process after the said rinse process is 0.1 ppm or less, and pH of this filtrate is 8.6 or less.
The structure, raw material (material) and manufacturing method of the porous membrane used for the filtration process in the manufacturing method of soy sauce of this embodiment are explained in full detail below.

<Porous membrane>
The porous membrane is a field of view including the inner surface, a field of view including the outer surface of the membrane, and the like between the fields of view in the SEM image of the membrane cross section in the film thickness direction orthogonal to the inner surface of the porous membrane The total area of the resin part having an area of 1 μm ² or less is 70% or more with respect to the total area of the resin part in each area of a total of four visual fields of two visual fields photographed at a distance; The total area of the resin part having an area of 10 μm ² or more is 15% or less with respect to the total area of the resin part; the total area of the resin part having an area of 1 μm ² or less in each region But the total area of the resin part having an area of 70 μm or more and 10 μm ² or more with respect to the total area of the resin part is 15% or less with respect to the total area of the resin part; It is either. Preferred porous membranes in the respective regions, the total area of the resin portion having an area of 1 [mu] m ² or less, is 70% or more of the total area of the resin portion, an area of less than 1 [mu] m ² Ultra 10 [mu] m ² The total area of the resin part is 15% or less of the total area of the resin part, and the total area of the resin part having an area of 10 μm ² or more is the total area of the resin part It is 15% or less.

FIG. 1: is an example of the SEM image of the cross section of the porous membrane used for the filtration process in the manufacturing method of the soy sauce of this embodiment. Such an SEM image is a SEM image of a cross section of the membrane in the film thickness direction orthogonal to the inner surface of the hollow fiber porous membrane, a field of view including the inner surface, a field of view including the outer surface of the membrane, and a field of view Among the areas of the total of four visual fields of two visual fields photographed at equal intervals, among the areas closest to the inner side, the SEM image obtained by photographing the predetermined visual field in the area closest to the inner side is a binarized image is there.
In each of the regions, the difference in the presence distribution of the resin portion, ie, the pores, between the cross section in the thickness direction orthogonal to the inner surface of the hollow fiber porous membrane and the cross section parallel to the inner surface. The communication anisotropy of can be virtually ignored.
In the present specification, the term "resin part" is a dendritic skeleton part of a three-dimensional network structure composed of a resin, which forms a large number of pores in a porous membrane. The portions shown in black in FIG. 1 are resin portions, and the white portions are holes.
Inside the porous membrane, there are formed communicating holes which are communicated while being bent from the inside to the outside of the membrane, and the inside of the SEM image of the membrane cross section in the film thickness direction orthogonal to the inside surface of the porous membrane The total area of the resin part having an area of 1 μm ² or less in each field of a total of four fields of view including the surface, the field of view including the outer surface of the film, and two fields captured at equal intervals between these fields However, if the total area of the resin portion is 70% or more, the communication of the holes is high (that is, the existence ratio of the communication holes in the membrane is high), and the flux of the liquid to be treated (water permeability, Permeability), retention of water permeability after cleaning is high, and damage to the membrane after chemical solution cleaning indicated by tensile breaking elongation is also alleviated. However, when the ratio of the total area of the resin part having an area of 1 μm ² or less to the total area of the resin part is too high, a tree of a three-dimensional network structure made of resin forms many pores in the porous membrane. to become as Jo skeletal portion is too thin, the total area of the resin portion having an area of 1 [mu] m ² or less, while maintaining 70% or more relative to the total area of the resin portion, 1 [mu] m ² greater than The total area of the resin part having an area is preferably 2% to 30% of the total area of the resin part, and the total area of the resin part having an area of 10 μm ² or more is the resin The total area of the resin part having an area of more than 1 μm ^{2 and} less than 10 μm ² is more preferably 15% or less with respect to the total area of the resin part. , and, 10μm ² or more Total area of the resin portion having a product is, those present at less than 15% 2% relative to the total area of the resin portion are more preferable. If the total area of the resin part having an area of more than 1 μm ² is present at 2% or more and 30% or less with respect to the total area of the resin part, the dendritic skeleton part having a three-dimensional network structure composed of resin Since it is not too thin, the strength and tensile elongation at break of the porous membrane can be maintained properly.

  2 to 5 respectively show SEM images of the cross section of the membrane in the thickness direction orthogonal to the inner surface of the porous membrane used in Example 1, Example 2, Example 3 and Comparative Example 2. In each of the four fields of view (circles 1 to 4) of 2 fields of view including 2 fields of view including the field of view including the outer surface of the film and the fields of view including the outer surface of the film It is a histogram which shows the ratio (%) of the sum total of the area of the resin part which has an area. In FIG. 1, the resin part appears in a granular form. 2 to 5 measure the area of each of the granular resin parts, and for each of the areas of the granular resin parts, the ratio of the area to the total area of all the resin parts in the field of a predetermined size in each region is a histogram It shows. The circle 1 in FIGS. 2 to 5 is a field of view including the inner surface, a field of view including the outer surface of the film, and a field of view in the SEM image of the film cross section in the film thickness direction orthogonal to the inner surface of the porous film. Of the total of four visual field areas of two visual fields photographed at regular intervals, it is the number of the area closest to the inner side, and the circle 4 is the number of the area closest to the inner side. For example, Example 1 circle 1 is a histogram when a visual field of a predetermined size in the innermost region of the porous hollow fiber membrane of Example 1 is photographed. The measuring method of the area distribution of the resin part in each area | region of a porous hollow fiber membrane is mentioned later.

  The surface open area ratio of the porous membrane is preferably 25 to 60%, more preferably 25 to 50%, and still more preferably 25 to 45%. If the surface opening ratio on the side to be in contact with the liquid to be treated is 25% or more, the clogging and the deterioration of the water permeability due to abrasion of the membrane surface are reduced, so that the filtration stability can be enhanced. On the other hand, if the surface open area ratio is high and the pore diameter is too large, the required separation performance may not be exhibited. Therefore, the average pore diameter of the porous membrane is preferably 100 to 700 nm, and more preferably 100 to 600 nm. When the average pore diameter is 100 to 700 nm, the separation performance is sufficient, and the connectivity of the pores can be secured. The method of measuring the surface aperture ratio and the average pore diameter will be described later, respectively.

  The thickness of the porous membrane is preferably 80 to 1,000 μm, more preferably 100 to 300 μm. If the film thickness is 80 μm or more, the strength of the film can be secured, and if it is 1000 μm or less, the pressure loss due to the film resistance will be small.

  The shape of the porous hollow fiber membrane may be an annular single layer membrane, but it may be a multilayer membrane having different pore sizes in the separation layer and the support layer supporting the separation layer. In addition, the inner and outer surfaces of the membrane may have an irregular cross-sectional structure such as having projections.

(Material of porous membrane (material))
The resin constituting the porous membrane is preferably a thermoplastic resin, and more preferably a fluorine resin. As a fluorine resin, vinylidene fluoride resin (PVDF), chlorotrifluoroethylene resin, tetrafluoroethylene resin, ethylene-tetrafluoroethylene copolymer (ETFE), ethylene-monochlorotrifluoroethylene copolymer (ECTFE), hexameric resin Those selected from the group consisting of fluoropropylene resins, and mixtures of these resins.
Thermoplastic resins include polyolefins, copolymers of olefins and halogenated olefins, halogenated polyolefins, and mixtures thereof. As a thermoplastic resin, for example, polyethylene (PE), polypropylene, polyvinyl alcohol, ethylene-vinyl alcohol copolymer, ethylene-tetrafluoroethylene copolymer, polyvinylidene fluoride (which may contain a domain of hexafluoropropylene), these A mixture of These resins are excellent as a membrane material because they are thermoplastic and have excellent handleability and toughness. Among these, vinylidene fluoride resin, tetrafluoroethylene resin, hexafluoropropylene resin or mixtures thereof, ethylene, tetrafluoroethylene, homopolymers or copolymers of chlorotrifluoroethylene, or mixtures of homopolymers and copolymers are mechanical. It is preferable because it has excellent strength and chemical strength (chemical resistance) and good moldability. More specifically, fluorine resin such as polyvinylidene fluoride, vinylidene fluoride-hexafluoropropylene copolymer, ethylene-tetrafluoroethylene copolymer, ethylene-chlorotrifluoroethylene copolymer and the like can be mentioned.

  The porous membrane can contain components (impurity and the like) other than the thermoplastic resin up to about 5% by mass. For example, the solvent used at the time of porous membrane manufacture is included. As described later, it contains the first solvent (hereinafter also referred to as non-solvent), the second solvent (hereinafter also referred to as good solvent or poor solvent), or both used as the solvent at the time of production of the porous membrane. . These solvents can be detected by pyrolysis GC-MS (gas chromatography mass spectrometry).

The first solvent is sebacic acid ester, citric acid ester, acetyl citric acid ester, adipic acid ester, trimellitic acid ester, oleic acid ester, palmitic acid ester, stearic acid ester, phosphoric acid ester, having 6 to 30 carbon atoms And at least one selected from the group consisting of epoxidized vegetable oils.
In addition, the second solvent is different from the first solvent in sebacic acid ester, citric acid ester, acetyl citric acid ester, adipic acid ester, trimellitic acid ester, oleic acid ester, palmitic acid ester, stearic acid ester, phosphorus It may be at least one selected from the group consisting of an acid ester, a fatty acid having 6 to 30 carbon atoms, and an epoxidized vegetable oil. Examples of fatty acids having 6 to 30 carbon atoms include capric acid, lauric acid and oleic acid. Moreover, as epoxidized vegetable oil, epoxy soybean oil, epoxidized linseed oil and the like can be mentioned.
The first solvent is thermoplastic even if the temperature of the first mixed solution is raised to the boiling point of the first solvent in the first mixed solution in which the ratio of the thermoplastic resin to the first solvent is 20:80. It is preferable that the resin be a non-solvent which does not dissolve uniformly in the first solvent.
The second solvent is a second mixture having a ratio of the thermoplastic resin to the second solvent of 20:80, and the temperature of the second mixture is higher than 25 ° C. and not more than the boiling point of the second solvent. It is preferable that the thermoplastic resin is a good solvent which is uniformly dissolved in the second solvent at a certain temperature.
The second solvent is a second mixed solution in which the ratio of the thermoplastic resin and the second solvent is 20:80, and the temperature of the second mixed solution is 25 ° C., and the thermoplastic resin is uniformly mixed in the second solvent. The thermoplastic resin is a poor solvent which is uniformly dissolved in the second solvent at any temperature which is higher than 100.degree. C. and not higher than the boiling point of the second solvent. preferable.

In the filtration step of the method for producing soy sauce of this embodiment, a porous hollow fiber membrane using polyvinylidene fluoride (PVDF) as a thermoplastic resin, which contains a first solvent (non-solvent) It can be used.
In this case, the first solvent is sebacic acid ester, citric acid ester, acetyl citric acid ester, adipic acid ester, trimellitic acid ester, oleic acid ester, palmitic acid ester, stearic acid ester, phosphoric acid ester, carbon number 6 At least one selected from the group consisting of fatty acids of 30 or less and epoxidized vegetable oil, wherein the ratio of polyvinylidene fluoride to the first solvent is 20:80 in the first mixed solution; The polyvinylidene fluoride can be a non-solvent which does not dissolve uniformly in the first solvent even if the temperature of the liquid is raised to the boiling point of the first solvent. As a non-solvent, bis 2-ethylhexyl adipate (DOA) is preferred.
Also, the porous hollow fiber membrane may contain a second solvent different from the first solvent. In this case, the second solvent is sebacic acid ester, citric acid ester, acetyl citric acid ester, adipic acid ester, trimellitic acid ester, oleic acid ester, palmitic acid ester, stearic acid ester, phosphoric acid ester, carbon number 6 At least one selected from the group consisting of fatty acids of 30 or less and epoxidized vegetable oil, wherein the ratio of polyvinylidene fluoride to the second solvent is 20:80; It is preferable that polyvinylidene fluoride be a good solvent which is uniformly dissolved in the second solvent at any temperature which is higher than 25 ° C. and not higher than the boiling point of the second solvent. In the second solvent, polyvinylidene fluoride is not uniformly dissolved in the second solvent when the temperature of the second mixed solution is 25 ° C., and the temperature of the second mixed solution is higher than 100 ° C. It is more preferable that polyvinylidene fluoride is a poor solvent which is uniformly dissolved in the second solvent at any temperature below the boiling point of the above. As a poor solvent, tributyl acetyl citrate (ATBC) is preferred.

(Physical properties of porous membrane)
The initial value of the tensile elongation at break of the porous membrane is preferably 60% or more, more preferably 80% or more, still more preferably 100% or more, and particularly preferably 120% or more. The measuring method of tensile elongation at break will be described later.

  Moreover, from a practical viewpoint, the compressive strength of the porous membrane is preferably 0.2 MPa or more, more preferably 0.3 to 1.0 MPa, and still more preferably 0.4 to 1.0 MPa.

<Method of producing porous membrane>
Hereinafter, the manufacturing method of a porous hollow fiber membrane is demonstrated. However, the method for producing the porous hollow fiber membrane used in the filtration method of the present embodiment is not limited to the following production method.
The method for producing a porous hollow fiber membrane used in the filtration step in the method for producing soy sauce according to the present embodiment includes (a) preparing a melt-kneaded product, and (b) supplying the melt-kneaded product to a spinning nozzle having a multiple structure. The method may include the steps of: obtaining a hollow fiber membrane by extruding the melt-kneaded product from a spinning nozzle; and (c) extracting the plasticizer from the hollow fiber membrane. When the melt-kneaded product contains an additive, the method may further include the step (d) of extracting the additive from the hollow fiber membrane after the step (c).

The concentration of the thermoplastic resin of the melt-kneaded product is preferably 20 to 60% by mass, more preferably 25 to 45% by mass, and still more preferably 30 to 45% by mass. If this value is 20 mass% or more, mechanical strength can be increased, and if it is 60 mass% or less, water permeability can be increased. The melt-kneaded product may contain an additive.
The melt-kneaded product may be composed of two components of a thermoplastic resin and a solvent, or may be composed of three components of a thermoplastic resin, an additive and a solvent. The solvent contains at least a non-solvent as described later.
As the extractant used in step (c), it is preferable to use a liquid such as methylene chloride or various alcohols which does not dissolve the thermoplastic resin but which has a high affinity for the plasticizer.
When a melt-kneaded product containing no additive is used, the hollow fiber membrane obtained through the step (c) may be used as a porous hollow fiber membrane. When a porous hollow fiber membrane is produced using a melt-kneaded product containing additives, after step (c), the additive (d) is extracted and removed from the hollow fiber membrane to obtain a porous hollow fiber membrane It is preferable to go through the process further. As the extractant in the step (d), it is preferable to use a liquid which can dissolve the used additives such as hot water or an acid or an alkali but not the thermoplastic resin.

An inorganic substance may be used as an additive. The inorganic substance is preferably an inorganic fine powder. The primary particle diameter of the inorganic fine powder contained in the melt-kneaded product is preferably 50 nm or less, and more preferably 5 nm or more and less than 30 nm. Specific examples of the inorganic fine powder include silica (including fine powder silica), titanium oxide, lithium chloride, calcium chloride, organic clay and the like, and among these, fine powder silica is preferable from the viewpoint of cost. The above-mentioned "primary particle size of inorganic fine powder" means a value determined from analysis of an electron micrograph. That is, first, a group of inorganic fine powders is pretreated by the method of ASTM D3849. Thereafter, the particle diameters of 3000 to 5000 particles photographed in the transmission electron micrograph are measured, and the primary particle diameter of the inorganic fine powder can be calculated by arithmetically averaging these values.
About the inorganic fine powder inside a porous hollow fiber membrane, the raw material (material) of the inorganic fine powder which exists can be identified by identifying the element which exists by a fluorescent X ray etc.
When an organic substance is used as the additive, the hollow fiber membrane can be rendered hydrophilic by using a hydrophilic polymer such as polyvinyl pyrrolidone or polyethylene glycol. In addition, the viscosity of the melt-kneaded product can be controlled by using an additive having high viscosity such as glycerin and ethylene glycol.

Next, the step of preparing (a) the melt-kneaded product in the method for producing a porous hollow fiber membrane of the present embodiment will be described in detail.
In the method of manufacturing the porous hollow fiber membrane of the present embodiment, the non-solvent of the thermoplastic resin is mixed with the good solvent or the poor solvent. The mixed solvent after mixing is a non-solvent of the thermoplastic resin used. Thus, when a non-solvent is used as a raw material of the membrane, a porous hollow fiber membrane having a three-dimensional network structure can be obtained. The mechanism of action is not necessarily clear, but it is thought that crystallization of the polymer is appropriately inhibited and a three-dimensional network structure is more likely to be obtained if a solvent having a lower solubility is used by mixing a non-solvent. . For example, non-solvent and poor solvent or good solvent are phthalic acid ester, sebacic acid ester, citric acid ester, acetyl citric acid ester, adipic acid ester, trimellitic acid ester, oleic acid ester, palmitic acid ester, stearic acid ester It is selected from the group consisting of phosphate esters, fatty acids having 6 to 30 carbon atoms, and various esters such as epoxidized vegetable oil.
The solvent which can dissolve the thermoplastic resin at normal temperature is a good solvent. The solvent which can not dissolve at normal temperature but can be dissolved at high temperature can be a poor solvent of the thermoplastic resin. The solvent which can not dissolve even at high temperature. Although called non-solvent, good solvent, poor solvent, and non-solvent can be determined as follows.
Add about 2 g of thermoplastic resin and about 8 g of solvent in a test tube, heat to the boiling point of the solvent in 10 ° C increments with a test tube block heater, mix the inside of the test tube with a spatula, etc. What dissolves is a good solvent or a poor solvent, and what does not dissolve is a non-solvent. Those which are soluble at relatively low temperatures of 100 ° C. or less are judged as good solvents, and those which do not dissolve unless they are heated to a temperature of 100 ° C. or more and boiling points or less are judged as poor solvents.
For example, using polyvinylidene fluoride (PVDF) as a thermoplastic resin and tributyl acetyl citrate (ATBC), dibutyl sebacate or dibutyl adipate as a solvent, PVDF is uniformly mixed with these solvents at about 200 ° C. Dissolve. On the other hand, using bis (2-ethylhexyl) adipate (DOA), diisononyl adipate, or bis (2-ethylhexyl) sebacate as the solvent, PVDF does not dissolve in these solvents even if the temperature is raised to 250 ° C.
When ethylene-tetrafluoroethylene copolymer (ETFE) is used as the thermoplastic resin and diethyl adipate is used as the solvent, ETFE is uniformly mixed and dissolved at about 200 ° C. On the other hand, it does not dissolve when bis 2-ethylhexyl adipate (DIBA) is used as a solvent.
Also, when ethylene-monochlorotrifluoroethylene copolymer (ECTFE) is used as a thermoplastic resin and triethyl citrate is used as a solvent, it dissolves uniformly at about 200 ° C. When triphenylphosphorous acid (TPP) is used, it dissolves do not do.

  EXAMPLES Hereinafter, the present invention will be specifically described by way of examples, but the present invention is not limited thereto. Each physical property value in an Example and a comparative example was calculated by the following methods, respectively.

(1) Outer diameter and inner diameter of porous hollow fiber membrane The porous hollow fiber membrane was thinly sliced using a razor in a cross section orthogonal to the length direction, and the outer diameter and inner diameter were measured with a 100-fold magnifying glass. . For one sample, measurement was performed on 60 cross sections at intervals of 30 mm in the length method, and the average value was taken as the outer diameter and the inner diameter of the hollow fiber membrane.

(2) Electron Microscopy The porous hollow fiber membrane was cut in an annular shape in a cross section orthogonal to the length direction, 10% phosphotungstic acid + osmium tetraoxide staining was performed, and embedded in an epoxy resin. Then, after trimming, the sample cross section was subjected to BIB processing to produce a smooth cross section, and a conductive processing was performed to produce a speculum sample. Using the electron microscope SU8000 series manufactured by HITACHI, the produced microscope sample is an electron microscope (SEM) image of a cross section of the film at an acceleration voltage of 1 kV at 5,000 to 30,000 times a thickness (thick portion) cross section Within each of the four fields of view (circles 1 to 4 in FIGS. 2 to 5), the field of view including the inner surface of the field of view, the field of view including the outer surface of the film, and two fields of view taken at equal intervals between these fields of view. Taken with a given field of view. Depending on the average pore size, the magnification can be changed, and specifically, when the average pore size is 0.1 μm or more, 5000 times, and when the average pore size is 0.05 μm or more and less than 0.1 μm. And 10,000 times, and when the average pore diameter is less than 0.05 μm, 30,000 times. The size of the field of view was 2560 × 1920 pixels.
For image processing, ImageJ was used, and threshold processing (Image-Adjust-Treshold: Otsu method (select Otsu)) was performed on the photographed SEM image to binarize the hole portion and the resin portion. .
Surface aperture ratio: The surface aperture ratio was measured by calculating the ratio of the resin part and the hole part of the binarized image.
Area distribution of resin part: The size of the binarized granular resin part included in the photographed SEM image was measured using the "Analyze Particle" command (Analyse Particle: Size 0.10-Infinity) of ImageJ. . Assuming that the total area of all the resin parts contained in the SEM image is ΣS and the area of the resin part of 1 μm ² or less is ΣS (<1 μm ² ), 1 μm is calculated by calculating ΣS (<1 μm ² ) / ΣS. The area ratio of the resin part having an area of ² or less was calculated. Similarly, the area ratio of the resin part having an area in a predetermined range was calculated.
In addition, about the noise removal at the time of performing a binarization process, the resin part of the area less than 0.1 micrometer ² was removed as a noise, and the resin part of the area 0.1 micrometer ² or more was made into analysis object. Also, noise removal was performed by applying median filtering (Process-Filters-Median: Radius: 3.0 pixels).
In addition, the granular resin portion cut at the end of the SEM image was also measured. In addition, "Incude Holes" was not processed. In addition, no process was performed to correct the shape of the "snowman" type into a "flat" type or the like.
Average pore size: Measured using ImageJ's "Plugins-Bone J-Thickness" command. In addition, space size was defined as the largest circle size which enters an air gap.

(3) Flux (water permeability, initial pure water flux)
After immersing the porous hollow fiber membrane in ethanol, the pure water immersion is repeated several times, and then one end of the wet hollow fiber membrane of about 10 cm length is sealed, and the injection needle is inserted into the hollow portion at the other end, 25 Pure water of 25 ° C. is injected from the injection needle at a pressure of 0.1 MPa in an environment of 0 ° C., and the amount of pure water transmitted from the outer surface of the membrane is measured, and the following formula:
Initial pure water flux [L / m ² / h] = 60 × (permeate flow rate [L]) / {π × (outer membrane diameter [m]) × (effective membrane length [m]) × (measurement time [min] )}
The pure water flux was determined by the following equation to evaluate the water permeability.
The "membrane effective length" refers to the net length of the membrane excluding the portion where the injection needle is inserted.

(4) Permeability retention rate at the time of real liquid filtration First, heat was applied to fresh fried soy sauce at 70 ° C. for 60 minutes, and the mixture was burned to prepare a seasoned soy sauce stock solution.
Next, (i) pure water was introduced into the circulation tank, circulation filtration was performed so as to obtain a transmembrane pressure difference of 0.05 MPa, and permeated water was collected for 1 minute to obtain an initial water permeability.
Next, (ii) after draining the water in the pipe, a firewood soy sauce stock solution was put into a circulation tank, and circulation filtration was performed so as to obtain an inter-membrane differential pressure = 0.15 MPa.
Then, after (iii) removing the burned soy sauce residual solution in the piping, pure water was introduced into the circulation tank, and circulation filtration was performed so that the pressure difference between the membranes was 0.05 MPa, and the water was washed.
Next, (iv) after draining the water in the piping, the prepared chemical solution was charged into the circulation container, and membrane circulation filtration was performed to perform chemical solution cleaning for 30 minutes. As a chemical solution, an aqueous solution in which 0.2% by weight of sodium hypochlorite and 1% by weight of caustic soda were mixed was used.
Next, after (v) chemical solution cleaning, after removing the chemical solution in the pipe, pure water is put into the circulation tank, circulation filtration is performed so that the pressure difference between the membranes = 0.05 MPa, and the permeated water comes out The water was repeatedly collected at a timing of 10 L / m ² , and when the chlorine concentration of the permeate water was 0.1 ppm or less and the pH became 8.6 or less, the water washing was ended, and the amount of water in the rinse was recorded. In addition, circulation filtration was performed with the same transmembrane differential pressure to collect the permeated water for 1 minute, and the water permeability was determined and compared with the initial water permeability.
Each parameter was calculated by the following equation:
Transmembrane differential pressure = {(input pressure) + (output pressure)} / 2
Intra-membrane surface area [m ² ] = π × (hollow fiber membrane inner diameter [m]) × (hollow fiber membrane effective length [m])
Membrane surface linear velocity [m / s] = 4 × (circulating water amount [m ³ / s]) / {π × (inner diameter of membrane [m]) ² }. Moreover, all the operations were performed at 25 ° C. and a film surface linear velocity of 1.0 m / sec.

(5) Tensile elongation at break (%)
The porous hollow fiber membrane was used as a sample as it was, and the tensile elongation at break was calculated according to JIS K7161. The load and displacement at tensile failure were measured under the following conditions.
Measuring equipment: Instron type tensile tester (AGS-5D manufactured by Shimadzu Corporation)
Chuck distance: 5 cm
Tension speed: 20 cm / min

(8) Stirred component ratio (X0, X1) before and after filtration of roasted soy sauce Add 20 mL of soy sauce to be treated into a measuring cylinder and heat it for 90 minutes in a thermostatic bath set at 85 ° C, then for 5 days at room temperature After standing, the height of the precipitated component was measured, and the height of the precipitated component before and after filtration was compared and evaluated. The ratio of the sediment component present in the soy sauce unit volume can be determined by comparing the height of the sediment component after standing.

(9) Measurement of total nitrogen content (N0, N1) A soy sauce sample was burned in a stream of pure oxygen and further reduced to determine the total nitrogen content in the sample as nitrogen gas. The total nitrogen content was calculated as a percentage of the sample volume. The measuring apparatus used SUMIGRAPH NC-220F by Sumika analysis center company, the measuring method set METHOD "LxM", sample volume to 500 microliters, reactor temperature: 870 degreeC, and reduction furnace temperature: 600 degreeC. The quantification was calculated from the calibration curve of aspartic acid.

Example 1
40% by mass of PVDF resin (Kureha KF-W # 1000) as a thermoplastic resin, 23% by mass of finely powdered silica (primary particle diameter: 16 nm), and bis 2-ethylhexyl adipate (DOA) as a non-solvent. A melt-kneaded product was prepared using 9% by mass and tributyl acetyl citrate (ATBC, boiling point 343 ° C.) 4.1% by mass as a poor solvent. The temperature of the obtained molten mixture was 240.degree. The resulting melt-blended material is passed through a free running distance of 120 mm using a double tube structure spinning nozzle, and then solidified in water at 30 ° C., and a porous structure is obtained by heat induced phase separation method. Developed. The resulting hollow fiber extrudates were pulled at a speed of 5 m / min and wound on a skein. The wound hollow fiber extrudate is immersed in isopropyl alcohol to extract and remove DOA and ATBC, and then immersed in water for 30 minutes to replace the hollow fiber membrane with water, and then to 70% in a 20 mass% aqueous NaOH solution. C. for 1 hour, and then repeated washing with water to extract and remove finely divided silica, thereby producing a porous hollow fiber membrane.
Table 1 below shows the composition and manufacturing conditions of the obtained porous membrane and various physical properties. The obtained porous hollow fiber membrane had a three-dimensional network structure. Moreover, it was a film with high flux (water permeability) and high communication. The burning process was carried out. After adding 20 mL of soy sauce after burning in a graduated cylinder and heating it for 90 minutes in a thermostatic bath set at 85 ° C, let stand at room temperature for 5 days, and precipitate sediment of 110 mm against a liquid level of 138 mm. Was formed. On the other hand, when 20 mL of the filtrate obtained by filtering the soy sauce after the burning step through the porous membrane was treated in the same manner, a sediment of 1 mm was formed at a liquid level of 138 mm. That is, the removal rate of the sediment component by the filtration was over 99%. Also, the total nitrogen content of the cooked soy sauce before filtration was 1.77% by weight, while the total nitrogen content after filtration was 1.78%, a change of less than 2%.

Example 2
40% by mass of ETFE resin (manufactured by Asahi Glass Co., Ltd., TL-081) as a thermoplastic resin, 23% by mass of finely powdered silica (primary particle diameter: 16 nm), 32.9% by mass of bis-2-ethylhexyl adipate (DOA) as a non-solvent A melt-kneaded product was prepared using% and 4.1% by mass of diisobutyl adipate (DIBA) as a poor solvent. The temperature of the obtained molten mixture was 240.degree. The resulting melt-blended material is passed through a free running distance of 120 mm using a double tube structure spinning nozzle, and then solidified in water at 30 ° C., and a porous structure is obtained by heat induced phase separation method. Developed. The resulting hollow fiber extrudates were pulled at a speed of 5 m / min and wound on a skein. The wound hollow fiber extrudate is immersed in isopropyl alcohol to extract and remove DOA and DIBA, and then immersed in water for 30 minutes to replace the hollow fiber membrane with water, and then to 70% in a 20 mass% aqueous NaOH solution. C. for 1 hour, and then repeated washing with water to extract and remove finely divided silica, thereby producing a porous hollow fiber membrane.
Table 1 below shows the composition and manufacturing conditions of the obtained porous membrane and various physical properties. The obtained porous hollow fiber membrane had a three-dimensional network structure. Moreover, it was a film with high flux (water permeability) and high communication.
The burning process was carried out. After adding 20 mL of soy sauce after burning in a graduated cylinder and heating it for 90 minutes in a thermostatic bath set at 85 ° C, let stand at room temperature for 5 days, and precipitate sediment of 110 mm against a liquid level of 138 mm. Was formed. On the other hand, when 20 mL of the filtrate obtained by filtering the soy sauce after the burning step through the porous membrane was treated in the same manner, a sediment of 1 mm was formed at a liquid level of 138 mm. That is, the removal rate of the sediment component by the filtration was over 99%. Also, the total nitrogen content of the cooked soy sauce before filtration was 1.77% by weight, while the total nitrogen content after filtration was 1.77%, a change of less than 2%.

[Example 3]
40% by mass of ECTFE resin (manufactured by Solvay Specialty Polymers, Halar 901) as thermoplastic resin and 23% by mass of finely divided silica (primary particle diameter: 16 nm) and triphenylphosphorous acid (TPP) 32 as non-solvent A melt-kneaded product was prepared using 9% by mass and bis-2-ethylhexyl adipate (DOA) 4.1% by mass as a poor solvent. The temperature of the obtained molten mixture was 240.degree. The resulting melt-blended material is passed through a free running distance of 120 mm using a double tube structure spinning nozzle, and then solidified in water at 30 ° C., and a porous structure is obtained by heat induced phase separation method. Developed. The resulting hollow fiber extrudates were pulled at a speed of 5 m / min and wound on a skein. The wound hollow fiber extrudate is immersed in isopropyl alcohol to extract and remove TPP and DOA, and then immersed in water for 30 minutes to replace the hollow fiber membrane with water, and then to 70% in 20% by weight aqueous NaOH solution. C. for 1 hour, and then repeated washing with water to extract and remove finely divided silica, thereby producing a porous hollow fiber membrane.
Table 1 below shows the composition and manufacturing conditions of the obtained porous membrane and various physical properties. The obtained porous hollow fiber membrane had a three-dimensional network structure. Moreover, it was a film with high flux (water permeability) and high communication.
The burning process was carried out. After adding 20 mL of soy sauce after burning in a graduated cylinder and heating it for 90 minutes in a thermostatic bath set at 85 ° C, let stand at room temperature for 5 days, and precipitate sediment of 110 mm against a liquid level of 138 mm. Was formed. On the other hand, when 20 mL of the filtrate obtained by filtering the soy sauce after the burning step through the porous membrane was treated in the same manner, a sediment of 1 mm was formed at a liquid level of 138 mm. That is, the removal rate of the sediment component by the filtration was over 99%. Also, the total nitrogen content of the cooked soy sauce before filtration was 1.77% by weight, while the total nitrogen content after filtration was 1.71%, a change of about 3%.

Comparative Example 1
A hollow fiber membrane of Comparative Example 1 was obtained in the same manner as in Example 1 except that the solvent was changed to ATBC only. Table 1 below shows the composition and manufacturing conditions of the obtained porous membrane and various physical properties. The obtained porous hollow fiber membrane had a spherulite structure. Moreover, it was a film with low flux and low communication.
The burning process was carried out. After adding 20 mL of soy sauce after burning in a graduated cylinder and heating it for 90 minutes in a thermostatic bath set at 85 ° C, let stand at room temperature for 5 days, and precipitate sediment of 110 mm against a liquid level of 138 mm. Was formed. On the other hand, when 20 mL of the filtrate obtained by filtering the soy sauce after the burning step through the porous membrane was treated in the same manner, a sediment of 1 mm was formed at a liquid level of 138 mm. That is, the removal rate of the sediment component by the filtration was over 99%. Also, the total nitrogen content of the cooked soy sauce before filtration was 1.77 wt%, while the total nitrogen content after filtration was 1.2%, a change of about 32%.

Comparative Example 2
A hollow fiber membrane of Comparative Example 2 was obtained in the same manner as in Example 1 except that the amount of finely divided silica was 0% and the solvent was only γ-butyrolactone. Table 1 below shows the composition and manufacturing conditions of the obtained porous membrane and various physical properties. The obtained porous hollow fiber membrane had a spherulite structure. Also, the flux was low and the membrane was low in communication.
The burning process was carried out. After adding 20 mL of soy sauce after burning in a graduated cylinder and heating it for 90 minutes in a thermostatic bath set at 85 ° C, let stand at room temperature for 5 days, and precipitate sediment of 110 mm against a liquid level of 138 mm. Was formed. On the other hand, when 20 mL of the filtrate obtained by filtering the soy sauce after the burning step through the porous membrane was treated in the same manner, a sediment of 1 mm was formed at a liquid level of 138 mm. That is, the removal rate of the sediment component by the filtration was over 99%. Also, the total nitrogen content of the cooked soy sauce before filtration was 1.77% by weight, while the total nitrogen content after filtration was 1.3%, a change of about 27%.

Comparative Example 3
A hollow fiber membrane of Comparative Example 3 was obtained in the same manner as in Example 3 except that the solvent was changed to DOA only. Table 1 below shows the composition and manufacturing conditions of the obtained porous membrane and various physical properties. The obtained porous hollow fiber membrane had a spherulite structure. Also, the flux was low and the membrane was low in communication.
The burning process was carried out. After adding 20 mL of soy sauce after burning in a graduated cylinder and heating it for 90 minutes in a thermostatic bath set at 85 ° C, let stand at room temperature for 5 days, and precipitate sediment of 110 mm against a liquid level of 138 mm. Was formed. On the other hand, when 20 mL of the filtrate obtained by filtering the soy sauce after the burning step through the porous membrane was treated in the same manner, a sediment of 1 mm was formed at a liquid level of 138 mm. That is, the removal rate of the sediment component by the filtration was over 99%. Also, the total nitrogen content of the cooked soy sauce before filtration was 1.77% by weight, while the total nitrogen content after filtration was 1.25%, a change of about 29%.

Comparative Example 4
The soy sauce stock solution after burning was mixed with diatomaceous earth of a standard super cell (made by Celite), and filtration was carried out with a filter press made by Oita Keiki Co., Ltd. so that the pressure was 1.0 MPa. After adding 20 mL of soy sauce after burning in a graduated cylinder and heating it for 90 minutes in a thermostatic bath set at 85 ° C, let stand at room temperature for 5 days, and precipitate sediment of 110 mm against a liquid level of 138 mm. Was formed. On the other hand, when 20 mL of the filtrate obtained by filtering the soy sauce after the burning step with diatomaceous earth was treated in the same manner, a sediment of 5 mm was formed at a liquid level of 138 mm. That is, the removal rate of the sediment component by the diatomaceous earth filtration was about 95%. Also, the total nitrogen component of the cooked soy sauce before filtration was 1.77% by weight, while the total nitrogen component after filtration was 1.74%, a change of about 2%.

  From the above results, it was found that the membrane having good communication was excellent in filtration performance and chemical solution resistance, and had a long life.

  The filtration step in the method for producing soy sauce according to the present invention uses a membrane having good communication of pores extending from the inside of the membrane on the liquid side to the outside of the membrane on the filtrate side of the porous filtration membrane Therefore, the change in the total nitrogen component of the fired soy sauce before and after filtration is low, the removal rate of the sediment component is high, and furthermore, 50 ° C to 90 ° C hot water and / or 0 as a washing solution (chemical solution) used in the washing step. Even when an aqueous solution containing not less than .05 wt% and not more than 0.5 wt% sodium hypochlorite or not less than 0.4 wt% and not more than 4 wt% sodium hydroxide is used, the deterioration of the film is minimized. Therefore, the method for producing soy sauce according to the present invention is a method having excellent filtration performance and chemical resistance and a long life.

Claims (19)

The following steps:
A firing step of burning soy sauce containing a precipitate component to form an aggregate of the precipitate component; and a cooked soy sauce containing an aggregate of the precipitate component in a porous membrane composed of a resin of a three-dimensional network structure. Filtration to separate the filtrate from aggregates of the sediment component by passing through
A method of producing soy sauce containing
A field of view including the inner surface, a field of view including the outer surface of the film, and an equal distance between the fields of the SEM image of the cross section in the film thickness direction orthogonal to the inner surface of the porous membrane 2 The total area of the resin part having an area of 1 μm ² or less is 70% or more with respect to the total area of the resin part in each area of a total of four visual fields.
When the sediment component ratio of the fired soy sauce before the filtration step is X0, the total nitrogen component is N0, the sediment component ratio of the fired soy sauce after the filtration step is X1, and the total nitrogen component is N1, X1 / X0 × 100 <5 % And N1 / N0 × 100 ≧ 97%
The manufacturing method of the said soy sauce characterized by the above-mentioned. The following steps:
A firing step of burning soy sauce containing a precipitate component to form an aggregate of the precipitate component; and a cooked soy sauce containing an aggregate of the precipitate component in a porous membrane composed of a resin of a three-dimensional network structure. Filtration to separate the filtrate from aggregates of the sediment component by passing through
A method of producing soy sauce containing
A field of view including the inner surface, a field of view including the outer surface of the film, and an equal distance between the fields of the SEM image of the cross section in the film thickness direction orthogonal to the inner surface of the porous membrane 2 The total area of the resin part having an area of 10 μm ² or more is 15% or less of the total area of the resin part in each area of a total of four visual fields of visual field, and
When the sediment component ratio of the fired soy sauce before the filtration step is X0, the total nitrogen component is N0, the sediment component ratio of the fired soy sauce after the filtration step is X1, and the total nitrogen component is N1, X1 / X0 × 100 <5 % And N1 / N0 × 100 ≧ 97%
The manufacturing method of the said soy sauce characterized by the above-mentioned. The following steps:
A firing step of burning soy sauce containing a precipitate component to form an aggregate of the precipitate component; and a cooked soy sauce containing an aggregate of the precipitate component in a porous membrane composed of a resin of a three-dimensional network structure. Filtration to separate the filtrate from aggregates of the sediment component by passing through
A method of producing soy sauce containing
A field of view including the inner surface, a field of view including the outer surface of the film, and an equal distance between the fields of the SEM image of the cross section in the film thickness direction orthogonal to the inner surface of the porous membrane 2 The total area of the resin part having an area of 1 μm ² or less is 70% or more with respect to the total area of the resin part in each area of a total of four visual fields, and a resin having an area of 10 μm ² or more The total area of the part is 15% or less of the total area of the resin part, and
When the sediment component ratio of the fired soy sauce before the filtration step is X0, the total nitrogen component is N0, the sediment component ratio of the fired soy sauce after the filtration step is X1, and the total nitrogen component is N1, X1 / X0 × 100 <5 % And N1 / N0 × 100 ≧ 97%
The manufacturing method of the said soy sauce characterized by the above-mentioned. The porous membrane is a field of view including the inner surface, a field of view including the outer surface of the membrane, and a field of view in the SEM image of the cross section of the membrane in the thickness direction orthogonal to the inner surface of the porous membrane. in each area of a total of four field of 2 field taken at regular intervals, the total area of the resin portion having an area of less than 1 [mu] m ² ultra 10 [mu] m ² is 15% or less relative to the total area of the resin portion, wherein The method according to any one of Items 1 to 3.   The method according to any one of claims 1 to 4, wherein the surface open area ratio of the porous membrane is 25 to 60%.   The method according to any one of claims 1 to 5, wherein the porous membrane is a hollow fiber membrane.   The method according to any one of claims 1 to 6, wherein the resin constituting the porous membrane is a thermoplastic resin.   The method according to claim 7, wherein the thermoplastic resin is a fluorocarbon resin.   The fluorine resin is vinylidene fluoride resin (PVDF), chlorotrifluoroethylene resin, tetrafluoroethylene resin, ethylene-tetrafluoroethylene copolymer (ETFE), ethylene-monochlorotrifluoroethylene copolymer (ECTFE), hexamer 9. The method of claim 8 selected from the group consisting of fluoropropylene resins, and mixtures of these resins.   The method according to claim 7, wherein the thermoplastic resin is polyethylene (PE).   The method further comprises the step of washing the inside of the porous membrane by passing or immersing the washing liquid in the porous membrane after the filtration step, and the washing liquid is hot water at 50 ° C. to 90 ° C. 10. The method according to any one of.   After the filtration step, the method further includes a washing step of washing the inside of the porous membrane by passing or immersing a washing liquid in the porous membrane, wherein the washing liquid is 0.05% by weight or more and 0.5% by weight or less The method according to any one of claims 1 to 10, which is an aqueous solution containing sodium hypochlorite or 0.4 wt% or more and 4 wt% or less of sodium hydroxide.   The relationship between the tensile breaking elongation E0 of the porous membrane before the washing step and the tensile breaking elongation E1 of the porous membrane after the washing step is E1 / E0 × 100 ≧ 80%. The method according to 11 or 12.   Tensile breaking elongation E0 of the porous membrane before the washing step, and tensile breaking elongation of the porous membrane after repeating the washing step X times (where X is an integer of 2 to 100) The method according to claim 11 or 12, wherein the relationship with the degree EX is EX / E0 x 100 70 70%.   The relationship between the flux L0 of the porous membrane before the filtration step and the flux L1 of the porous membrane after the washing step is L1 / L0 × 100 ≧ 95%, according to claim 11 or 12, Method.   The relationship between the flux L0 of the porous membrane before the filtration step and the flux LX of the porous membrane after repeating the cleaning step X times (where X is an integer of 2 to 100) is The method according to claim 11 or 12, wherein X / L0 x 100 90 90%.   The cleaning process according to any one of claims 11 to 16, wherein the cleaning process includes a cleaning process performing the cleaning with the cleaning solution and a rinsing process performing the rinsing with rinse water to remove the remaining cleaning solution components thereafter. the method of. The method according to claim 17, wherein the amount of rinse water used in the rinse step is 100 L / m ² or less per unit area of the porous membrane.   The method according to claim 17 or 18, wherein the chlorine concentration in the filtrate after restarting the filtration step after the rinse step is 0.1 ppm or less, and the pH of the filtrate is 8.6 or less. .