JP6858516B2 - Liquid food concentration method - Google Patents

Description

The present invention relates to a method for concentrating a liquid food, particularly a coffee liquor. More specifically, the present invention relates to a method for producing concentrated coffee having a large amount of aroma by minimizing the loss of aroma components in the process of producing concentrated coffee from, for example, a coffee extract.

In general, it is important that foods having a flavor (aroma and / or taste) component contain the component appropriately. Consumers are sensitive to aroma as well as taste of the product, and lack of this adversely affects the sense of the product.
The content of aroma components is likely to decrease, especially during concentrated processing of liquid foods. In the fields of various juices, dairy products such as lactic acid bacteria beverages, soup stock, coffee, etc., maintaining the aroma component during concentration processing is an important problem. Especially in the field of coffee, maintaining the freshly brewed aroma when preparing soluble powdered coffee is the biggest challenge.

When the water content of the coffee extract is simply heated and evaporated to concentrate, the aroma component of the coffee evaporates and is lost, and only concentrated coffee with a reduced flavor can be obtained.
In order to produce concentrated coffee with excellent aroma, a method of collecting the aroma component of the dissipated coffee and mixing it with the concentrated coffee, or taking out the coffee aroma component directly from the crushed coffee beans and mixing it with the concentrated coffee extract. Methods are being considered.

For example, a method of recovering an aroma component by stripping an aqueous slurry of crushed coffee beans with gas is disclosed (Patent Document 1). In this method, the stripped aroma components are condensed and recovered at a low temperature. However, it is difficult to completely remove the aroma component by the stripping operation, and it is difficult to completely recover the aroma component even in the condensation process. As a result, the recovery rate of the aroma component becomes insufficient. In addition, the thermal history of the stripping gas may degrade the aroma components.
Further, a method of humidifying, heating, and depressurizing a crushed coffee bean product to take out an aroma component and recovering it by low-temperature condensation is also disclosed (Patent Document 2). Even with this method, it is difficult to take out the aroma component and completely recover it by condensing. Similar to Patent Document 1, there is a concern that the aroma component may be deteriorated by heat.

Furthermore, a method of separating and recovering aroma components using a filtration membrane has also been proposed. In Patent Document 3, the coffee extract is concentrated by a reverse osmosis membrane. However, according to this method, since the removed water contains an aroma component, a step of evaporating the concentrated removal liquid under reduced pressure to condense the evaporated aroma component at a low temperature and recover it is required. Even with this method, it is difficult to completely recover the evaporated aroma components by condensing them. Concentration of coffee extract with a reverse osmosis membrane also has a problem that the solid component of coffee causes clogging of the membrane and a sufficient concentration ratio cannot be obtained.
Patent Document 4 discloses a method of concentrating an aroma component without missing it by subjecting a concentrated removal liquid obtained by a reverse osmosis membrane to a reverse osmosis membrane treatment with a low operating pressure. However, even in this case, there is a problem that the solid component of coffee causes clogging of the membrane by the first concentration by the reverse osmosis membrane, and a sufficient concentration ratio cannot be obtained.

International Publication No. 99/5237 Japanese Unexamined Patent Publication No. 2011-217756 Japanese Unexamined Patent Publication No. 2003-319794 Japanese Unexamined Patent Publication No. 2003-204757

An object of the present invention is to provide a method for producing concentrated coffee having a large amount of aroma by minimizing the loss of the aroma component in the process of producing concentrated coffee from a liquid food having an aroma component, particularly a coffee extract. is there.

The present inventors have completed the present invention by proceeding with diligent studies in order to solve the above-mentioned problems.
The present invention is as follows.
[1] A method for concentrating liquid foods, which comprises concentrating by a forward osmosis process.
[2] The concentration method according to [1], wherein the liquid food is a coffee extract.
[3] The concentration method according to [1] or [2], wherein the amount of water permeation in the forward osmosis process is ^{controlled in the range of 0.1 kg / (m 2} × hr) or more and 20 kg / (m ^{2 × hr) or less.} ..
[4] The concentration method according to [3], wherein the water permeation amount is ^{controlled in the range of 0.5 kg / (m 2} x hr) or more and 10 kg / (m ^{2 x hr) or less.}

According to the method of the present invention, it is possible to minimize the loss of aroma components when concentrating a liquid food and to produce a liquid food concentrate having an excellent aroma amount.
The method of the present invention is particularly suitable for concentrating coffee extracts. By concentrating the coffee extract by the method of the present invention, it is possible to produce concentrated coffee having the same aroma as freshly brewed.

It is sectional drawing which shows an example of the hollow fiber membrane module used for the concentration method of this invention. It is a conceptual diagram of an example of the concentrator used in the concentrating method of this invention.

Hereinafter, an example of the embodiment of the present invention will be described in detail.
The flavor component in the present specification refers to a component that expresses the taste and aroma of food that consumers perceive as a taste, and in particular, a component that expresses aroma is referred to as an aroma component.
The present invention makes it possible to efficiently concentrate a liquid food, particularly a coffee extract, at a high magnification by a forward osmosis process while minimizing the loss due to deterioration and scattering of aroma components.

In the forward osmosis process, the treatment solution and the induction solution are brought into contact with each other via a forward osmosis membrane, and the osmotic pressure difference between the two solutions is driven from the treated water having a relatively low concentration to the induction solution having a relatively high concentration. Water moves as a source.
Therefore, the pressure applied to the forward osmosis membrane need only be the pressure required for liquid feeding. Therefore, compared to concentration by reverse osmosis in which a pressure equal to or greater than the osmotic pressure difference is applied to the treated water, the energy (power) required for concentration can be reduced, and the membrane is almost clogged (fouling) due to the application of high pressure. It is possible to operate for a long time with a stable amount of water permeation.
Further, as the induction solution used for concentrating the treated water, water existing in the natural world such as seawater can also be used. Therefore, the energy required to prepare the induction solution can be reduced.
Further, by using the forward osmosis process for concentration, heating in the concentration step becomes unnecessary, so that the flavor component is not deteriorated by heating the food, and the concentration with less loss of the aroma component becomes possible.

The concentration method using the normal permeation process of the present invention includes, for example, coffee extract, juices (eg, orange juice, tomato juice, etc.), dairy products (eg, lactic acid bacteria beverage, raw milk, etc.), soup stock (eg, kelp stock, etc. It is suitably used for concentrating dairy juice, etc.). In particular, it is suitable for concentrating coffee extract.

As the shape of the forward osmosis membrane used in the forward osmosis process in the present invention, for example, a flat membrane, a hollow fiber membrane, or the like can be used.

The flat membrane-like forward osmosis membrane can have, for example, a support layer and a separation active layer on the support layer.
The support layer in the flat membrane-like forward osmosis membrane is generally made of a non-woven fabric.
Examples of the material of the non-woven fabric include polyester, polyethylene, polypropylene, polyamide and the like.

As the separation active layer in the flat membrane-like forward osmosis membrane, a separation active layer composed of a support film and a polyamide is suitable.
As the material of the support film in the separation active layer, for example, it is preferable that at least one selected from polysulfone, polyethersulfone, polyacrylonitrile, polyethylene, polypropylene, polyamide, polyvinylidene fluoride, and cellulose acetate is the main component. More preferably, at least one selected from polysulfone and polyether sulfone is used as a main component, and more preferably, a polyether sulfone.
The polyamide in the separation active layer can be formed by interfacial polymerization of a polyfunctional acid halide and a polyfunctional aromatic amine.

The polyfunctional aromatic acid halide is an aromatic acid halide compound having two or more acid halide groups in one molecule. Specifically, for example, trimesic acid halide, trimellitic acid halide, isophthalic acid halide, terephthalic acid halide, pyromellitic acid halide, benzophenone tetracarboxylic acid halide, biphenyldicarboxylic acid halide, naphthalenedicarboxylic acid halide, pyridinedicarboxylic acid halide, etc. Examples thereof include benzenedisulfonic acid halide, and these alone or a mixture thereof can be used. In the present invention, particularly trimesic acid chloride alone, a mixture of trimesic acid chloride and isophthalic acid chloride, or a mixture of trimesic acid chloride and terephthalic acid chloride is preferably used.

The polyfunctional aromatic amine is an aromatic amino compound having two or more amino groups in one molecule. Specifically, for example, m-phenylenediamine, p-phenylenediamine, 3,3'-diaminodiphenylmethane, 4,4'-diaminodiphenylamine, 4,4'-diaminodiphenyl ether, 3,4'-diaminodiphenyl ether, 3 , 3'-diaminodiphenylamine, 3,5-diaminobenzoic acid, 4,4'-diaminodiphenylsulfone, 3,3'-diaminodiphenylsulfone, 3,4'-diaminodiphenylsulfone, 1,3,5-tri Aminobenzene, 1,5-diaminonaphthalene and the like can be mentioned, and these alone or a mixture thereof can be used. In the present invention, in particular, one or more selected from m-phenylenediamine and p-phenylenediamine are preferably used.

The hollow filament-like forward osmosis membrane can have, for example, a hollow filament-like support membrane and a separation active layer on the outer surface or inner surface of the support membrane, or both surfaces.
The support film and the separation active layer in the hollow thread-like forward osmosis membrane may be made of the same material as the support membrane and the polyamide in the separation active layer of the flat membrane-like forward osmosis membrane.

It is convenient to apply the forward osmosis process in the present invention after modularizing the forward osmosis membrane.
The form of the module may be, for example, a pleated module, a spiral module, etc. when the forward osmosis membrane is flat membrane-like, and a hollow fiber when the forward osmosis membrane is hollow fiber-like. It can be a hollow fiber membrane module or the like in which a bundle is filled in a cylinder.
Hereinafter, the configuration of the hollow fiber membrane module will be described in detail by taking it as an example.

An example of the configuration of the hollow fiber membrane module in the present invention is shown in FIG.
The hollow fiber membrane module 1 has a structure in which a tubular body is filled with a thread bundle composed of a plurality of hollow fiber 4 and both ends of the hollow fiber thread bundle are fixed to the cylinder by adhesive fixing portions 5 and 6. .. The tubular body has shell-side conduits 2 and 3 on its sides and is sealed by headers 7 and 8. Here, the adhesive fixing portions 5 and 6 are solidified so as not to block the holes of the hollow fibers, respectively.
The headers 7 and 8 have core-side conduits 9 and 10 that communicate with the inside (hollow portion) of the hollow fiber 4 and do not communicate with the outside, respectively. With these conduits, the liquid can be introduced into or taken out from the inside of the hollow fiber 4.
The shell-side ducts 2 and 3 communicate with each other on the outside of the hollow fiber 4 and not on the inside, respectively. With these conduits, the liquid can be introduced or taken out from the outside of the hollow fiber 4.

The hollow fiber membrane module 1 has a hollow fiber yarn bundle composed of a plurality of hollow fiber membranes 4. Total membrane area of the hollow fiber yarn bundle is preferably at 0.001 m ² or more, 0.001 m ² or more 1,000 m ² is or less, more preferably from a practical point of view.

In the hollow fiber membrane module 1, the hollow fiber support membrane is first provided in order to prevent the separation active layer formed on the surface of the hollow fiber support membrane from being damaged during contact with the guide roll, handling during module formation, and the like. After modularization, it is preferably produced by forming a separation active layer on the surface of the hollow fiber support membrane. By going through such a step, it is possible to prevent the formed separation active layer from being damaged.

The method of concentrating the treatment liquid by the forward osmosis process in the present invention will be described with reference to FIG.
The treatment liquid tank 11 is filled with a treatment liquid (liquid food to be concentrated). The treatment liquid enters the forward osmosis membrane module 15 through the pipe 12 by the pump 14, passes through the module 15, and then returns to the treatment liquid tank 11 through the pipe 13.
The inductive solution tank 16 is filled with the inductive solution. The inductive solution enters the forward osmosis membrane module 15 through the pipe 8 by the pump 19, passes through the module 15, and then returns to the inductive solution tank 16 through the pipe 18.
Here, the treatment liquid passes through the core side conduits (reference numerals 9 and 10 in FIG. 1) to the inside of the hollow fiber constituting the hollow fiber side, and the induction solution passes through the shell side conduits (reference numerals 2 and 3 in FIG. 1). It passes through the outside of the hollow fiber. At this time, the treatment liquid and the induction solution are in contact with each other through the wall of the hollow fiber which is a forward osmosis membrane, but they do not directly intersect with each other. Then, when the treatment liquid and the induction solution come into contact with each other through the wall of the hollow fiber, the water in the treatment liquid moves to the induction solution side through the forward osmosis membrane, and the treatment liquid is concentrated.
At least one of the treatment solution and the inductive solution may be concentrated by an operation of circulating in the system, or may be concentrated by a one-pass operation.

The inducing solution refers to a solution that exhibits a higher osmotic pressure than the treatment liquid and has a function of moving water from the treatment liquid via a forward osmosis membrane. This inductive solution exhibits high osmotic pressure by containing the inductive solute in a high concentration. The solvent is preferably the same as the solvent of the treatment liquid, and in the case of liquid foods, it is typically water.
Examples of the induced solute include water-soluble salts such as sodium chloride, potassium chloride, magnesium chloride, calcium chloride, sodium sulfate, magnesium sulfate, sodium thiosulfate, sodium sulfite, ammonium chloride, ammonium sulfate, and ammonium carbonate;
Common sugars such as sucrose, fructose, glucose;
Special sugars such as oligosaccharides and rare sugars;
Monoalcohols such as methanol, ethanol, 1-propanol, 2-propanol;
Glycos such as ethylene glycol and propylene glycol;
Polymers such as polyethylene oxide and propylene oxide;
Examples thereof include a copolymer of the above-mentioned polymer.

As a method of recovering the water transferred to the induction solution through the forward osmosis membrane from the induction solution, for example,
A method of recovering water by using a polymer in which the aqueous solution exhibits temperature-induced phase separation as the solute in the inductive solution and changing the temperature of the inductive solution after water transfer;
A method of recovering water by concentrating the induction solution after water transfer using an NF membrane, a reverse osmosis membrane, or the like;
A method of recovering water by using magnetic fine particles as an inductive solute in an inductive solution and applying a magnetic force to the inductive solution after water transfer;
And so on.
The water recovered as described above, the induction solution after removing the water, or both of them may be reused as appropriate.

The larger the amount of water permeation of the forward osmosis membrane module 15, the more preferable it is. However, when the raw water to be treated (treated water) is flowed under conditions where there is as little pressure loss as possible, the permeation amount is 200 kg / (m ² x hr) in order to avoid the possibility that the treated water will be depleted and precipitation will occur. It is preferable to adjust as follows.
The water permeation amount of the forward osmosis membrane module 15 in the present specification is the amount of water that moves from the treatment liquid to the induction solution due to the difference in osmotic pressure between the treatment liquid and the induction solution when the treatment liquid and the induction solution are arranged across the forward osmosis membrane. , Means the amount allocated per unit area of the forward osmosis membrane and per unit time, and is defined by the following formula (1).
F = L / (M × H) ・ ・ ・ (1)
Here, F is the amount of water permeation (kg / (m ² × hr)), L is the amount of permeated water (kg), M is the surface area of the forward osmosis membrane (m ² ), and H is the time (hr).

In the concentration method of the present invention, the amount of water permeation can be controlled by adjusting the concentration of the induction solution. The higher the water permeability, the higher the concentration efficiency, but there is a risk that food components will adhere to the surface of the membrane during the concentration process and the water permeability will decrease.
For example, when concentrating the coffee extract, the amount of water permeation is preferably in the range of ^{0.1 kg / (m 2} × hr) or more and 20 kg / (m ^{2 × hr) or less.} Considering the concentration efficiency and the life of the film, it is more preferable to concentrate in the range of ^{0.5 kg / (m 2} × hr) or more and 10 kg / (m ^{2 × hr) or less.} If the amount of water permeation is smaller than this, the efficiency of concentration may be lowered, and if the amount of water permeation is larger than this, the life of the membrane may be shortened.

The material of the concentrator used in the method of the present invention is unlikely to cause adsorption or permeation of aroma components of liquid foods (particularly coffee) during the concentration process, and the aroma components are lost due to evaporation into the atmosphere. It is preferable that the material is less likely to occur. The concentrator is preferably composed of, for example, a fluoromaterial such as perfluoroalkoxy alkane resin (PFA) or polytetrafluoroethylene (PTFE); a metal coated therein or the like.

In the concentration method using the forward osmosis process of the present invention, the only pressure required to be applied from outside the system is the pressure for feeding the treatment liquid and the induction solution. Therefore, the method of the present invention does not require filtration at a high operating pressure unlike the concentration method using a reverse osmosis process, so that clogging (fouling) due to adsorption of food components in the treatment liquid to the membrane surface occurs. It is characterized by its small size and long membrane life.

Hereinafter, the present invention will be specifically described based on Examples. However, the present invention is not limited to the examples.

[experimental method]
(Making a forward osmosis module)
A 20% by mass hollow yarn spinning stock solution was prepared by dissolving polyether sulfone (manufactured by BASF, trade name "Ultrason") in N-methyl-2-pyrrolidone (manufactured by Wako Pure Chemical Industries, Ltd.). A wet hollow fiber spinning machine equipped with a double spinner was filled with the above stock solution and extruded into a coagulation tank filled with water to form hollow fibers by phase separation. The obtained hollow fiber was wound on a winder. The outer diameter of the obtained hollow fiber was 1.0 mm, the inner diameter was 0.7 mm, the diameter of the fine pores on the inner surface was 0.05 μm, and the water permeability was 1,020 kg / m ² / hr / 100 kPa. This hollow fiber was used as a support film.
The 130 hollow fiber support membranes are filled in a cylindrical plastic housing having a diameter of 2 cm and a length of 10 cm, and both ends are fixed with an adhesive to have an effective inner surface area of 0.023 m having the structure shown in FIG. ² hollow fiber support membrane modules were produced.
10 g of m-phenylenediamine and 0.8 g of sodium lauryl sulfate were placed in a 0.5 L container, and 489.2 g of pure water was further added and dissolved to prepare 0.5 kg of a first solution used for interfacial polymerization.
0.8 g of trimesic acid chloride was placed in another 0.5 L container, and 399.2 g of n-hexane was added and dissolved to prepare 0.4 kg of a second solution used for interfacial polymerization.
The core side (inside of the hollow fiber) of the hollow fiber support membrane module manufactured above is filled with the first solution, allowed to stand for 30 minutes, then drained, and a thin liquid film of the first solution is placed inside the hollow fiber. Formed. In this state, the second solution was fed to the core side at a flow rate of 0.15 L / min for 3 minutes to perform interfacial polymerization. The polymerization temperature was 25 ° C.
Next, nitrogen at 50 ° C. was flowed through the core side of the hollow fiber support membrane module for 30 minutes to evaporate and remove n-hexane. Further, a forward osmosis module was produced by cleaning both the shell side and the core side with pure water.
^{The water permeation amount of this forward osmosis module was 10.12 kg / (m 2} × hr) when pure water was used as the treatment liquid and 3.5 mass% saline solution was used as the induction solution.

(Coffee extraction)
Sufficiently preheat a 1.2-liter SUS304 closed container with a drip coffee filter, add 70 g of crushed coffee beans (made by Doutor Coffee), add 100 mL of hot water at 85 ° C, steam for 1 minute, and then steam at 85 ° C. 900 mL of hot water was added and the coffee components were extracted for 10 minutes. A coffee extract was obtained by transferring 0.5 L of the obtained extract to a tank made of 1LPTFE with a capacity of 1 LPTFE while filtering with a filter in a closed system and cooling to 25 ° C.

(Analysis of coffee aroma components)
As the measurement samples, the above coffee extract and the concentrated coffee extract diluted with water to a predetermined ratio were used. 1 mL of each sample is placed in a 20 mL headspace bottle, purged with nitrogen, heated at 80 ° C. for 1 hour, and then solid-phase microextraction (SPME) for 15 minutes is performed on the gas phase portion for GC / MS analysis. Served. In the present disclosure, all the organic components present in the gas phase portion are used as aroma components, and their quantification is performed to examine the retention rate (% by weight) of the aroma components before and after concentration.

[Example 1]
The forward osmosis treatment was performed using the forward osmosis concentrator shown in FIG. The forward osmosis module 15 in FIG. 2 is a hollow fiber membrane module having the structure shown in FIG.
0.5 kg of coffee extract was placed in the treatment liquid tank 11, and 1 kg of saline solution having a concentration of 2% by weight was placed in the induction solution tank 16. The saline solution, which is the inductive solution, was sent to the shell side of the forward osmosis module 15 at a flow rate of 370 mL / min through the pipe 17 by the liquid feed pump 19. The saline solution that came out of the module 15 was returned to the tank 16 through the pipe 18 and used for circulation. The coffee extract, which is the treatment liquid, was sent to the core side of the forward osmosis module 15 at a flow rate of 170 mL / min through the pipe 12 by the liquid feed pump 14. The coffee extract from the module 15 was returned to the tank 11 through the pipe 13 and circulated. By this operation, the coffee extract in the processing liquid tank 11 is gradually concentrated.

The water permeability at the initial stage of concentration was 4.1 kg / (m ² × hr).
Forward osmosis treatment is performed while changing the concentration of the saline solution according to the concentration of the coffee extract in the treatment liquid tank 11 so that the water permeation amount is maintained within the range of 4.0 ± 1 kg / (m ^{2 × hr).} Then, the coffee was finally concentrated to 50 g (concentration ratio 10 times). In order to maintain the above water permeability, the concentration of the saline solution was changed from 2% by weight to 5% by weight.

The coffee extract before concentration and the diluted solution obtained by adding pure water to the coffee extract after concentration and diluting it 10 times were used as samples, and the coffee components were analyzed by the above method. The maintenance rate of coffee was examined. The results are shown in Table 1.
In addition, after the coffee extract was concentrated, the presence or absence of clogging (fouling) of the forward osmosis membrane in the forward osmosis concentrator used for the concentration treatment was confirmed by the following method.
When the forward osmosis concentrator after the concentration treatment was used as it was, the treatment liquid was the original coffee extract before concentration, and the induction solution was the same 2 wt% saline solution as in the initial concentration, the amount of water permeation was examined. It was 9 kg / (m ² x hr). Since the value of this water permeability was almost the same as the value at the initial stage of the concentration treatment, it was confirmed that there was almost no clogging of the forward osmosis membrane due to the concentration treatment.

[Example 2]
4 kg of coffee extract was placed in the treatment liquid tank 1, the induction solution was 5 kg of 20 wt% saline solution, and the coffee extract solution was the same as in Example 1 except that the concentration of the saline solution was not adjusted during the concentration. Was concentrated.
The water permeability at the initial stage of extraction was 15.1 kg / (m ² × hr).
When the amount of the treatment liquid was concentrated to 0.2 kg, the concentration operation was stopped (concentration ratio 20 times). The maintenance rate of the amount of coffee aroma before and after concentration was examined by the same method as in Example 1 except that the dilution ratio of the coffee extract after concentration was set to 20 times. The results are shown in Table 1.
Using the forward osmosis membrane module used for the concentration treatment, the water permeability when the treatment solution was the original unconcentrated coffee extract and the induction solution was 20% by weight saline was 5.1 kg / (m ² x hr). )Met.

[Comparative Example 1]
A reverse osmosis membrane (manufactured by Nitto Denko Corporation, product number "NTR-759HR") in which the separation active layer is a polyamide polymer and the support layer is polysulfone is used for 3 kg of coffee extract, and the operating pressure is 3.0 MPa. Was concentrated 10 times.
The coffee extract after concentration was diluted 10-fold, and the maintenance rate of the amount of coffee aroma before and after concentration was examined by the same method as in Example 1. The results are shown in Table 1.
The water permeability at the initial stage of concentration is 26.2 kg / (m ² x hr), and the water permeability when the treatment liquid is returned to the original coffee extract after concentration is 4.2 kg / (m ² x hr). It was confirmed that the reverse osmosis membrane was largely clogged by the concentration operation.

[Comparative Example 2]
By the same reverse osmosis membrane treatment as in Comparative Example 1, 3 kg of the coffee extract was concentrated 10 times to obtain a concentrated solution, and the concentrated removal solution at this time was collected.
The collected concentrated removal liquid was evaporated at 82 ° C. under a pressure of 51.3 kPa, and the evaporated components were cooled at 5 ° C. with a condenser to collect the concentrated aroma liquid.
The collected concentrated aroma solution was mixed with the 10-fold concentrated solution to obtain a 9.5-fold concentrated coffee extract (316 g).
The maintenance rate of the coffee aroma before and after concentration was examined by the same method as in Example 1 except that the dilution ratio of the obtained concentrated coffee extract was 9.5 times. The results are shown in Table 1.

When coffee was concentrated using a reverse osmosis membrane, the retention rate of aroma components was 36%. The maintenance rate of the aroma component was only 55% by weight by the method of heating and evaporating the aroma component in the concentrated removal liquid, collecting it with a condenser, and combining it with the concentrated liquid.
On the other hand, in the method for concentrating coffee using the forward osmosis membrane of the present invention, 98% by weight of the aroma component was retained at a concentration ratio of 10 times. Even when the concentration ratio was 20 times, 90% by weight of the aroma component was retained.

The concentration method using the forward osmosis membrane of the present invention can be applied to the concentration of liquid foods containing aroma components. In particular, it is preferably used in the process of producing concentrated coffee from a coffee extract, in which the loss of aroma components is minimized and concentrated coffee having a large amount of aroma is produced.

1 Hollow fiber membrane module 2, 3 Shell side conduit 4 Hollow fiber 5, 6 Adhesive fixing part 7, 8 Header 9, 10 Core side conduit 11 Treatment liquid tank 12, 13 Liquid feed piping 14 Liquid feed pump 15 Forward osmosis module 16 Induction solution tank 17, 18 Liquid feed piping 19 Liquid feed pump

Claims (7)

Cormorant rows concentrated by forward osmosis process, a method for concentrating liquid food,
The liquid food is a coffee extract,
The amount of water permeation in the forward osmosis process is ^{controlled in the range of 0.1 kg / (m 2} × hr) or more and 20 kg / (m ² × hr) or less.
A method for concentrating liquid foods. The concentration method according to claim 1 , wherein the water permeation amount is controlled in the range of ^{0.5 kg / (m 2} x hr) or more and 10 kg / (m ^{2 x hr) or less.} The forward osmosis process is performed using a hollow fiber forward osmosis membrane having a hollow fiber membrane-like support membrane and a separation active layer on the outer or inner surface of the support membrane, or both surfaces. To be
The support membrane contains at least one selected from polysulfone, polyethersulfone, polyacrylonitrile, polyethylene, polypropylene, polyamide, polyvinylidene fluoride, and cellulose acetate as a main component.
The separation active layer is made of polyamide.
The concentration method according to claim 1 or 2. The concentration method according to claim 3, wherein the forward osmosis process is performed using a hollow fiber membrane module in which the hollow fiber-shaped forward osmosis membrane is modularized. The forward osmosis process is carried out using a flat membrane-like forward osmosis membrane having a support layer and a separation active layer on the support layer.
The support layer is made of a non-woven fabric.
The separation active layer is composed of a support membrane and a polyamide.
The support membrane contains at least one selected from polysulfone, polyethersulfone, polyacrylonitrile, polyethylene, polypropylene, polyamide, polyvinylidene fluoride, and cellulose acetate as a main component.
The concentration method according to claim 1 or 2. The concentration method according to claim 5, wherein the forward osmosis process is performed using a pleated module or a spiral module in which the flat membrane-like forward osmosis membrane is modularized. The concentration method according to any one of claims 1 to 6, wherein the inducing solution used in the forward osmosis process is an aqueous solution of an inducing solute selected from salts, sugars, monoalcohols, glycols, or polymers.

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