JP2022146552A - Sugar-containing raw material liquid concentrated liquid foodstuff, raw material liquid concentration system, and raw material liquid concentration method - Google Patents

Abstract

To provide a sugar-containing raw material liquid concentrated liquid foodstuff that maintains high-quality appearance and flavor, and to provide a raw material liquid concentration system and raw material liquid concentration method that is suitable for producing the concentrated liquid.SOLUTION: Provided is a foodstuff, which is a foodstuff that is a concentrated liquid of a raw material liquid derived from a natural product containing a sugar-containing solute and a liquid medium, and in which the concentrated liquid has a Brix value of 50 or more, the visible light transmittance of the concentrated liquid at a wavelength of 560 nm as measured by an ultraviolet-visible spectrophotometer is 80% or more and 99% or less, and the aroma component collected from the concentrated liquid in 50°C atmosphere contains vanillin.SELECTED DRAWING: Figure 4

Description

The present invention provides a food product that is a concentrate obtained by concentrating a raw material liquid containing sugar, and a deterioration in appearance and a decrease in flavor due to deterioration, reduction, etc. of components in the raw material liquid when concentrating the raw material liquid containing sugar. The present invention relates to a raw material liquid concentrating system and a raw material liquid concentrating method capable of suppressing and efficiently concentrating the raw material liquid.

BACKGROUND OF THE INVENTION Consumer health trends in recent years have led to increased consumer interest in naturally harvested, extracted or concentrated foodstuffs. For example, in the case of raw food liquids containing sugar, the raw liquids are placed in an evaporator to heat and evaporate the water content, and the concentrated liquid obtained is added as a natural sweetener to various dishes and confectionery. is being done. However, when a raw material solution containing sugar is heated at a high temperature, many components contained in the raw material solution are degraded or lost. There was a problem that a significant decrease in flavor occurred.

Therefore, a reverse osmosis membrane method is generally used as a method for concentrating the raw material liquid without the need for heating. For example, Patent Document 1 describes a method of concentrating maple syrup using a reverse osmosis membrane method. Further, Patent Document 2 describes a method of concentrating maple syrup to a relatively high concentration by reverse osmosis.

Japanese Patent Application Laid-Open No. 2003-70448 U.S. Pat. No. 9,622,505

However, in the methods described in Patent Documents 1 and 2, since it is necessary to apply a pressure higher than the osmotic pressure of the concentrate, there is a limit to the concentration concentration, and heating is required for concentration to a high concentration. Heating, however, degrades or eliminates the useful ingredients contained in the raw material liquid for food, thus degrading the appearance of the food. Furthermore, since the reverse osmosis membrane method applies high pressure, useful components are adsorbed on the membrane, resulting in a decrease in flavor components and a problem that long-term operation is not possible.

The present invention solves the above problems, and is a food product that is a concentrate containing a high concentration of sugar and retains the original appearance and flavor of the food raw material liquid, and for the production of such a high-quality concentrate. An object of the present invention is to provide a suitable raw material liquid concentration system and raw material liquid concentration method.

The present invention includes the following aspects.
[1] A foodstuff that is a concentrate of a raw material liquid derived from a natural product containing a sugar-containing solute and a liquid medium,
The concentrated liquid has a Brix value of 50 or more,
The visible light transmittance of the concentrated liquid at a wavelength of 560 nm as measured by an ultraviolet-visible spectrophotometer is 80% or more and 99% or less,
A foodstuff, wherein the aromatic component collected from the concentrate in a 50° C. atmosphere contains vanillin.
[2] The food product according to item 1, wherein the visible light transmittance of the concentrate at a wavelength of 560 nm is 85% or more and 99% or less as measured by an ultraviolet-visible spectrophotometer.
[3] The aroma components collected from the concentrate in an atmosphere of 50° C. contain vanillin and acetophenone,
3. The foodstuff according to item 1 or 2, wherein the peak area of vanillin when the aroma component is analyzed by gas chromatography is 1.5 times or more and 10 times or less that of acetophenone.
[4] Any one of items 1 to 3, wherein the rate of change in the sugar content/magnesium ion concentration value of the concentrated liquid compared to the sugar content/magnesium ion concentration value of the raw material liquid is 5% or less. foodstuffs as described in section.
[5] The foodstuff according to any one of items 1 to 4, wherein the raw material liquid is at least one selected from the group consisting of maple sap, white birch sap, and coconut liquid endosperm.
[6] A raw material liquid concentration system for producing the foodstuff according to any one of items 1 to 5,
a heating unit that heats the raw material liquid to 30° C. or higher and 80° C. or lower;
a vacuum distillation section for distilling and concentrating the raw material liquid by reducing the pressure of the gas phase in contact with the raw material liquid to −80 kPa or less;
A raw material liquid concentration system.
[7] The raw material liquid concentration system according to item 6, wherein the vacuum distillation section is a membrane distillation section having a porous membrane.
[8] The raw material liquid concentrating system includes a raw material tank that stores the raw material liquid, the heating section, the membrane distillation section that has a porous membrane, the raw material liquid from the raw liquid tank to the heating section, a circulation pump that sequentially circulates the membrane distillation section and circulates it to the raw material liquid tank;
The membrane distillation section is divided by the porous membrane into a liquid phase section in which the raw material liquid flows and a gas phase section in which the vapor generated from the raw material liquid passes through the porous membrane and diffuses. cage,
At the raw material liquid inflow portion of the membrane distillation section,
The raw material liquid temperature is 30° C. or higher and 80° C. or lower,
The pressure of the gas phase in the membrane distillation unit is reduced to -80 kPa or less,
A raw material liquid concentration system according to item 7.
[9] A raw material liquid concentration system according to item 7 or 8, wherein the porous membrane is a hollow fiber membrane.
[10] The porous membrane is selected from the group consisting of polysulfone, polyethersulfone, polyethylene, polypropylene, polyvinylidene fluoride, polytetrafluoroethylene, ethylene/tetrafluoroethylene copolymer, polychlorotrifluoroethylene, and the like. 10. The raw material liquid concentration system according to any one of items 7 to 9, which is composed of at least one kind of resin.
[11] A method for producing the food according to any one of items 1 to 5 using the raw material liquid concentration system according to any one of items 6 to 10,
a heating step of heating the raw material liquid in the heating unit;
a concentration step of circulating the heated raw material liquid through the vacuum distillation section and concentrating it by vacuum distillation;
A method, including
[12] The method according to item 11, wherein the contact portion of the heating portion with the raw material liquid is at 90°C or less.
[13] The method according to item 11 or 12, wherein the heating unit is a heat exchanger that circulates a heat medium that is steam at 50°C or higher or hot water at 50°C or higher.
[14] The method according to any one of items 11 to 13, wherein the heating section utilizes waste heat.
[15] An item further comprising an additional concentration step of circulating the concentrated raw material liquid through an evaporator after the concentration step, wherein the temperature of the raw material liquid in the additional concentration step is equal to or higher than the temperature of the raw material liquid in the concentration step. The method according to any one of 11-14.
[16] The method according to any one of items 11 to 15, further comprising a preconcentration step of preconcentrating the raw material liquid with a reverse osmosis membrane.
[17] The method according to any one of items 11 to 16, further comprising a filtration step of filtering the raw material liquid with a filtration membrane to remove impurities, and subjecting the filtered raw material liquid to the concentration step.
[18] The method according to item 17, wherein the filtration membrane has a pore size of 20 µm or less.
[19] The method according to item 18, wherein the filtration membrane has a pore size of 1.0 μm or less.
[20] The method according to any one of items 17-19, wherein the filtration membrane is arranged in a cross-flow arrangement.
[21] The method according to any one of items 17 to 20, further comprising a backwashing step of backwashing the filtration membrane.
[22] The method according to any one of items 17 to 21, wherein the concentration step and the filtration step are performed in independent raw material liquid flow paths.
[23] The vacuum distillation section is a membrane distillation section having a porous membrane, and the step of removing the raw material liquid adhering to the porous membrane by passing water through the porous membrane is carried out per day. 23. The method of any one of items 11-22, performed one or more times.
[24] Items 11 to 23, wherein the step of removing membrane contaminants adhering to the porous membrane by passing a chemical solution of pH 5 or lower or pH 9 or higher through the porous membrane is performed at least once a week. The method according to any one of .

According to one aspect of the present invention, foodstuffs that are concentrates containing a high concentration of sugar that retain the original appearance and flavor of the food raw material liquid, and suitable for the production of such high-grade concentrates A feedstock concentration system and a feedstock concentration method may be provided.

FIG. 1 is a schematic diagram for explaining the shape and function of a hollow fiber porous membrane. FIG. 2 is a schematic diagram for explaining the shape and function of the pleated porous membrane. FIG. 3 is a schematic diagram for explaining the shape and function of the spiral porous membrane. FIG. 4 is a schematic diagram showing an example of the membrane module of this embodiment. FIG. 5 is a schematic diagram showing an example of the membrane module of this embodiment. FIG. 6 is a conceptual diagram for explaining the raw material liquid concentration system and the raw material liquid concentration method of the present embodiment. FIG. 7 is a conceptual diagram for explaining the raw material liquid concentration system and the raw material liquid concentration method of the present embodiment.

Hereinafter, an embodiment of the present invention (hereinafter also referred to as the present embodiment) will be specifically described in detail as a non-limiting example. Elements with the same reference numerals in the drawings of the present disclosure are intended to have similar configurations or functions.

<<Concentrated solution of raw material containing sugar>>
One aspect of the present invention provides a foodstuff that is a concentrate of a raw material liquid derived from a natural product that includes a sugar-containing solute and a liquid medium. In one aspect, the concentrate has a Brix value of 50 or greater. In one embodiment, the concentrated liquid has a visible light transmittance of 80% or more and 99% or less at a wavelength of 560 nm as measured by an ultraviolet-visible spectrophotometer. In one aspect, the aroma component collected from the concentrate in a 50° C. atmosphere contains vanillin.

In one aspect, the raw material liquid comprises a sugar-containing solute and a liquid medium. Sugars include, for example, monosaccharides (eg, glucose, fructose, galactose, mannose, ribose, deoxyribose, etc.), disaccharides (eg, maltose, sucrose, lactose, etc.), sugar chains (eg, glucose, galactose, mannose, fucose, xylose, glucuronic acid, iduronic acid, etc.; saccharide derivatives such as N-acetylglucosamine, N-acetylgalactosamine, N-acetylneuraminic acid, etc.).

The raw material liquid of the present disclosure may be, for example, a general raw material liquid containing a sugar-containing solute and an aqueous medium. Examples of raw material liquids include water-containing products that are highly nutritious and collected from nature, such as maple sap, birch sap, honey, coconut liquid endosperm, sugarcane sugar solution, and monk fruit juice. In a preferred embodiment, the raw material liquid is at least one selected from the group consisting of maple sap, birch sap and coconut liquid endosperm.

Maple sap is generally collected from maple trees during the period of the year when the sugar content is the highest and the temperature difference between day and night is large (eg March to April in the northern hemisphere). Since tree sap is necessary for the growth of trees, various strict standards are set for its collection from the stage of drilling holes in trees. Normally, sap contains only 2-4% sugar by weight, and approximately 40 L of sap is required to make 1 L of syrup. The liquid medium dissolves or disperses the solute in the raw material liquid. In typical embodiments, the liquid medium is water. The raw material liquid may be any fluid, and may be, for example, an emulsion.

In one embodiment, maple sap is used as the starting liquid and maple syrup is obtained as the concentrated liquid. The quality of maple syrup is graded. In general, the closer the sap is collected to the beginning of the season, the lighter the color of the sap, the more delicate the taste of the resulting maple syrup, and the higher the light transmittance. Maple syrup with high light transmittance is called extra light, while maple syrup with low light transmittance is called dark, and the higher the light transmittance, the better the quality.

The Brix value of maple syrup is generally 66.5%, which is comparable to granulated sugar and white sugar. On the other hand, maple syrup tends to have a lower calorie content than, for example, white sugar and honey, and a higher content of minerals such as calcium and potassium than other sweeteners.

Birch sap is the sap obtained from birch trunks and is generally harvested in the spring. Birch syrup is made from birch sap and can be produced in the same manner as maple syrup. Birch sap is also used as a raw material for the artificial sweetener xylitol. In addition to sugar, sap contains organic acids such as amino acids and malic acid, and organic substances such as polysaccharides and glycosides. It also contains many minerals, including potassium, calcium, and magnesium. Since some of these contain components that exhibit a moisturizing effect on the human epidermis, they are often used in cosmetics. Also in this birch syrup, the higher the light transmittance, the more delicate the taste and the better the quality.

Coconut liquid endosperm refers to the translucent liquid endosperm contained in immature coconut fruit. Coconut liquid endosperm is rich in nutrients because it contains a lot of minerals, and it can be a natural hydration material because it has almost the same osmotic pressure as the human body and a mineral composition close to that of body fluids. Of the minerals abundantly contained in coconut liquid endosperm, magnesium and potassium in particular are known to be effective in relieving swelling and activating metabolic enzymes. In coconut liquid endosperm as well, the higher the transmittance of light, the finer the taste and the better the quality.

In one aspect, the concentrate has a Brix value (that is, a sugar content value measured with a Brix meter) of 50 or higher. The Brix value before concentration (that is, the raw material liquid) is approximately 1 to 5. When such a raw material liquid is concentrated to a concentrated liquid having a Brix value of 50, the concentration rate is about 10 times to about 50 times. That is, the fact that the Brix value of the concentrate is 50 or more is an index of the concentrate having a high concentration ratio. In one aspect, the concentrate of the present disclosure has a high light transmittance even at a high concentration ratio of Brix value of 50 or higher. This high light transmittance is an index that the transmittance of the raw material liquid before concentration is well maintained. The Brix value of the concentrate is preferably 50 or more, or 60 or more from the viewpoint of obtaining a concentrate with a high concentration rate. Although the upper limit of the Brix value of the concentrate is not particularly limited, it may be, for example, 75 or less, or 70 or less from the viewpoint of ease of manufacturing the concentrate.

Concentrates may include ingredients that are beneficial to health, such as, for example, reducing swelling and activating metabolic enzymes. The visible light transmittance of the concentrate at a wavelength of 560 nm as measured by an ultraviolet-visible spectrophotometer is 80% or more, from the viewpoint of providing a concentrate containing a high proportion of these components and with few degraded products or impurities. , preferably 85% or more. In addition, the transmittance is 99% or less, and preferably 95% or less from the viewpoint of providing a high-quality concentrate (particularly having a delicate flavor). More preferably, the visible light transmittance of the concentrate at a wavelength of 560 nm measured by an ultraviolet-visible spectrophotometer is 80% or more and 99% or less, and more preferably 85% or more and 99% or less.

In one embodiment, the concentrate contains vanillin as an aroma component. In the present disclosure, that the concentrate contains vanillin means that vanillin is detected by gas chromatography analysis of the concentrate (that is, the amount is equal to or greater than the detection limit). Vanillin is a sweet-smelling compound often used in food flavors and perfumes. According to the reference (J. Japan Association on Odor Environment Vol. 36 No. 4 2005), vanillin is classified as a sweet, soft and warm scent. By concentrating the raw material liquid by an appropriate method, the concentrated liquid comes to emit a sweet scent due to the natural vanillin.

The vanillin-derived sweet scent emitted from the concentrate can be detected by analyzing the aroma components collected from the concentrate under an atmosphere of 50°C by gas chromatography. The boiling point of vanillin is 285°C, but since the quality of foodstuffs is generally judged at room temperature, it is appropriate to set the concentration liquid heating atmosphere at 50°C or lower when collecting aromatic components. Since the concentration at which the human sense of smell begins to smell vanillin is sufficiently lower than the detection sensitivity of gas chromatography, if vanillin is detected by gas chromatography, it can prove that humans can smell vanillin.

In one embodiment, the concentrate contains acetophenone as an aroma component. In the present disclosure, that the concentrate contains acetophenone means that acetophenone is detected (that is, the amount is equal to or greater than the detection limit) in the gas chromatography analysis of the concentrate. Acetophenone, like vanillin, is used as a food flavoring agent. According to said reference, acetophenone has an odor reminiscent of herbs. Acetophenone can be detected in a similar manner as vanillin.

Preferably, the aroma components collected from the concentrate in a 50° C. atmosphere contain vanillin and acetophenone. More preferably, the fragrance emitted from the concentrate contains vanillin and acetophenone in a predetermined ratio. Specifically, the peak area of vanillin when the aroma component collected from the concentrated liquid is analyzed by gas chromatography in an atmosphere of 50 ° C. is preferably 1.5 to 10 times that of acetophenone, It is more preferably 1.5 times or more and 8.0 times or less, and still more preferably 1.5 times or more and 5.0 times or less. This gives the concentrate a complex and delicate flavor and improves the quality of the concentrate.

Preferably, the concentrate has magnesium ions as the inorganic ion component in solution. Magnesium ions give a bitter taste, so when contained in an appropriate balance, the flavor of the concentrate is enhanced. Specifically, more preferably, from the viewpoint of maintaining the flavor derived from natural products and providing a concentrated liquid with well-balanced sweetness and bitterness, the concentrated liquid is compared with the value of sugar concentration/magnesium ion concentration of the raw material liquid. is 5% or less, more preferably 4% or less, still more preferably 3% or less. Here, the above rate of change is expressed by the following formula (1):

で表される。

is represented by

According to one aspect of the present invention, it is possible to obtain a high-quality food product with excellent flavor while maintaining the original appearance of the raw food product liquid as described above. Such foodstuffs can be produced, for example, by a distillation method, a forward osmosis method, etc., and it is advantageous to adjust the heating temperature, the heating atmosphere, etc. in the production process. For example, a method using heating and vacuum distillation can be advantageous in improving the quality of food products, such as moderately removing the odor of the raw material liquid and developing a unique and complex aroma and flavor due to the Maillard reaction in the production of maple syrup. . Accordingly, the present disclosure also refers to vacuum distillation, particularly membrane distillation procedures suitable for the manufacture of food products according to one aspect of the invention as described above.

《Porous membrane》
A porous membrane suitable for producing the food product of the present embodiment by concentrating the raw material liquid by membrane distillation will be described in detail below. A porous membrane has pores (communicating pores) communicating from one side of the membrane to the other side. The communicating pores may be included in a network of membrane material such as a polymer, and may be branched pores or straight pores. The pores have the characteristic of allowing steam to pass through but not the water (liquid) to be treated.

It is desirable for the porous membrane to be hydrophobic to prevent wetting. A water contact angle is an indicator of hydrophobicity. In the present embodiment, any portion of the porous membrane preferably has a water contact angle of 90° or more, more preferably 110° or more, and still more preferably 120° or more. Although there is no particular upper limit to the water contact angle, in reality it is preferably about 150° or less. A water contact angle is a value measured at 25° C. by the sessile drop method. The droplet method is a method in which, for example, 2 μL of pure water is dropped on the surface of an object to be measured, and the angle formed by the object to be measured and the droplet is digitized by analysis from the projected image.

The pore size and pore size distribution of the porous membrane also have a strong causal relationship with wetting suppression. The average pore diameter of the porous membrane of the present embodiment is preferably in the range of 0.01 μm or more and 1.0 μm or less, and more preferably in the range of 0.03 μm or more and 0.6 μm or less. When the average pore diameter is 0.01 μm or more, the vapor permeation resistance does not become too large, and the production rate of the raw material concentrate does not slow down. It is preferable because the effect of suppressing wetting is large. From the viewpoint of achieving both the production speed of the raw material liquid concentrate and the suppression of wetting, it is preferable that the pore size distribution of the porous membrane is narrow. Specifically, it preferably has a pore size distribution in which the ratio of the maximum pore size to the average pore size is in the range of 1.2 to 2.5. The pore size of the porous membrane is a value measured by the method for measuring the average pore size (also known as the half-dry method) described in ASTM: F316-86.

From the viewpoint of production speed of the raw material liquid concentrate, the porosity of the porous membrane is preferably 50% by volume or more and 85% by volume or less. When this value is 50% by volume or more, the production rate of the raw material concentrate is good, and when it is 85% by volume or less, the strength of the membrane itself is good, and problems such as breakage occur during long-term use. unlikely to occur.

In the porous membrane according to the present embodiment, a heated raw material solution is circulated on one side of the membrane, and the other side is kept in a reduced pressure state. can be taken out from the raw material liquid. At that time, the vapor moves by using the vapor pressure difference, which is the difference between the vapor pressure of the raw material liquid and the absolute pressure on the decompression side, as a driving force. For membrane distillation at low temperature, it is preferable to have a membrane that allows vapor to pass efficiently even with a slight difference in vapor pressure. Moreover, the raw material liquid for foodstuffs often becomes highly viscous as it is concentrated. Therefore, in the low-temperature concentration of a high-viscosity raw material liquid, the transmembrane pressure difference tends to increase, and the membrane tends to get wet.

In the process of concentrating a natural product-derived raw material liquid containing a sugar-containing solute and a liquid medium, the viscosity of the solution gradually increases as the degree of concentration (concentration ratio) increases. In the case of the conventional membrane distillation method, when the viscosity of the solution is 3 cP or more, the pressure loss associated with the passage of the raw material liquid through the flow path increases, so that the liquid cannot be efficiently concentrated. In addition, long-term operation in such a state causes the membrane to become wet, that is, wetting, and the concentration performance deteriorates over time. Furthermore, when the viscosity of the solution exceeds 600 cP, it becomes difficult to send the solution using a solution sending pump.

In this embodiment, a porous membrane particularly suitable for concentrating the raw material liquid may be used. Specifically, in one aspect, the air permeability of the porous membrane is 500 L/h·m ² ·kPa or more, preferably 1000 L/h·m ² ·kPa or more, or 2000 L/h·m ² · kPa or more, or 2500 L/h·m ² ·kPa or more. The air permeability is preferably 5000 L/h·m ² ·kPa or less. When the air permeability is 500 L/h·m ² ·kPa or more, the membrane resistance to vapor transfer does not become too large, and the concentration operation is easy under low temperature conditions with a slight difference in vapor pressure. Further, when the air permeability is 5000 L/h·m ² ·kPa or less, the air permeability does not become too large and the pressure resistance of the membrane is good.

In the present embodiment, the thickness of the porous membrane is preferably 10 μm to 1,000 μm, more preferably 15 μm to 1,000 μm, from the viewpoint of water permeability in membrane distillation and mechanical strength of the membrane. preferable. If the film thickness is 1,000 μm or less, it is possible to suppress a decrease in distilled water production efficiency. On the other hand, if the film thickness is 10 μm or more, it is possible to prevent deformation of the film during use under reduced pressure.

The shape of the porous membrane may be hollow fiber-like or sheet-like. The sheet-like porous membrane may be, for example, pleated or spiral. FIG. 1 is a schematic diagram showing an example of a hollow fiber porous membrane. Referring to FIG. 1, the porous membrane 11 has a hollow filamentous (cylindrical) shape, and the outer wall portion is composed of the porous membrane. The water to be treated A is introduced into the hollow portion of the porous membrane 11, for example. Then, the steam B separated from the water to be treated passes through the outer wall of the hollow fibers and diffuses to the outside of the hollow fibers, and the water to be treated A' after distillation passes through the hollow portion of the porous membrane 11 to the outside. discharged to The structure may be such that the water A to be treated is introduced from the outer wall of the porous membrane 11, and the steam B separated from the water to be treated passes through the outer wall of the hollow fiber and diffuses into the hollow portion of the hollow fiber. When the porous membrane is hollow fiber, the axial direction of the membrane cartridge for membrane distillation preferably coincides with the axial direction of the hollow fiber porous membrane.

FIG. 2 is a schematic diagram showing an example of a pleated porous membrane. Referring to FIG. 2, the porous membrane 11 is obtained by, for example, folding a rectangular sheet-like porous membrane alternately into mountain folds and valley folds along a fold line parallel to one side of the rectangle, and then folding the porous membrane 11 with the direction parallel to the fold line as an axis. It is rounded and has a cylindrical shape with many folds (pleats). The water A to be treated is introduced, for example, into the central hollow portion of the porous membrane 11 . Then, the steam B separated from the water to be treated passes through the porous membrane 11 and diffuses to the outside, and the water to be treated A' after distillation passes through the central hollow portion of the porous membrane 11 to the outside. discharged to The water A to be treated may be introduced from the outside of the porous membrane 11, and the steam B separated from the water to be treated may pass through the porous membrane 11 and diffuse into the central hollow portion. When the porous membrane is pleated, the axial direction of the membrane cartridge for membrane distillation preferably coincides with the axial direction of the cylinder of the porous membrane rolled into a cylindrical shape having pleats.

FIG. 3 is a schematic diagram showing an example of a spiral porous membrane. Referring to FIG. 3 , for example, two porous membranes 11 are composed of a liquid phase spacer 18 and a gas phase spacer 19 together with a porous membrane 11, a liquid phase spacer 18, a porous membrane 11, and a gas phase spacer. 19 is laminated in order of 4 layers, and is wound around a rod-shaped body 17 as a winding axis. The water A to be treated is introduced into the liquid phase formed by the liquid phase spacer 18, for example. The steam B separated from the water A to be treated passes through the porous membrane 11, diffuses into the gas phase portion formed by the gas phase portion spacer 19, and passes through the rod-like body 17 and is discharged to the outside. Symbol B ^* in FIG. 3 indicates how the steam separated from the water A to be treated passes through the porous membrane 11 and diffuses into the gas phase.

When the membrane cartridge for membrane distillation is housed in the housing for membrane distillation, the rod-shaped body 17 communicates with the gas phase portion of the membrane distillation module to take out the steam in the gas phase portion to the outside of the membrane distillation module. Acts as a tube. Therefore, the rod-shaped body 17 may have a structure in which gas can pass from the side surface of the rod to the inside of the rod. There may be. Moreover, this rod-shaped body 17 may protrude from the membrane module to the outside.

When the porous membrane has a spiral shape, the axial direction of the membrane cartridge for membrane distillation is aligned with the direction of the winding axis of the wound body composed of the two porous membranes, the liquid phase spacer, and the gas phase spacer. It is preferable that

As described above, the porous membrane may have a hollow fiber shape, a pleated shape, or a sheet shape, but the hollow fiber shape is preferable in that the membrane module can be made compact by increasing the membrane area per unit volume.

When the porous membrane is a hollow fiber membrane, in one aspect, the inner diameter is 0.3 mm or more and 2.0 mm or less, preferably 0.5 mm or more and 1.5 mm or less. When the inner diameter is 0.3 mm or more, even if the pressure loss due to the increase in the concentration of the raw material solution increases, the liquid transfer does not become difficult. does not become too large and the dead volume of the concentration system does not become too large.

When the porous membrane is a hollow fiber membrane, at 25 ° C., the inside of the hollow fiber (that is, the hollow portion) is filled with an ethanol (EtOH) aqueous solution having a concentration of 20% by mass, and when it is pressurized to 200 kPa, it permeates to the outside of the hollow fiber. In one aspect, the water permeation rate of the EtOH aqueous solution is 100 mL/h·m ² or less, preferably 50 mL/h·m ² or less. When the water permeation rate is within the above range, it is difficult to wet the membrane, so that the inconvenience of the membrane getting wet due to the increase in the transmembrane pressure difference accompanying the increase in the concentration of the raw material solution and the concentration performance being lowered can be avoided satisfactorily. The water permeation rate is preferably low from the viewpoint of suppressing wetting of the membrane, but from the viewpoint of obtaining good membrane distillation performance, in one embodiment, it is 0.1 mL/h·m ² or more, or 1.0 mL/h·m ² or more.

The porous membrane according to this embodiment preferably contains a hydrophobic polymer as a main component. A hydrophobic polymer is a polymer that has a low affinity for water. From this point of view, the porous membrane is selected from the group consisting of polysulfone, polyethersulfone, polyethylene, polypropylene, polyvinylidene fluoride, polytetrafluoroethylene, ethylene-tetrafluoroethylene copolymer, and polychlorotrifluoroethylene. It is preferably composed of at least one resin. Polyvinylidene fluoride, ethylene/tetrafluoroethylene copolymer, and polychlorotrifluoroethylene are more preferred from the viewpoint of hydrophobicity, film formability, mechanical durability, and thermal durability. It is more preferable that impurities such as plasticizers are removed by scouring after polymerizing these polymers or after forming films from them.

As a method for producing the porous membrane, there is a thermally induced phase separation method in which phase separation is caused by cooling a resin membrane in a molten state to form a porous layer, or a method in which a resin membrane in a solution state is brought into contact with a non-solvent. A dry-wet method (non-solvent phase separation method) in which phase separation is caused to form a porous layer can be suitably used.

From the viewpoint of pressure resistance and efficient vapor transfer for circulating high-viscosity raw material liquids, a hydrophobic polymer coating is applied to the porous membrane obtained by the thermally induced phase separation method or the non-solvent phase separation method. is preferred. Hydrophobic polymer is applied to all or part of the raw material liquid side (liquid phase side) surface, the vapor permeation side (gas phase side) surface of the porous membrane, and the inside of the membrane (wall surface inside the pore) Water repellency may be imparted to the membrane or the water repellency of the membrane may be enhanced by forming a protective coating.

Hydrophobic polymers coated onto the porous membrane include, for example:
(A) Silicone-based polymer and polymer gel that form a crosslinked structure by reacting with a silane coupling agent;
(a) Resins having siloxane bonds, such as dimethylsilicone gel, methylphenylsilicone gel, reactive modified silicone gel into which an organic functional group such as an amino group is introduced, and fluoroalkyl-modified silicone gel;
(c) A polymer having a (per)fluoroalkyl group, (per)fluoropolyether group, alkylsilyl group, fluorosilyl group, etc. in the side chain dissolved in a solvent;
(d) Hydrophobic polymer thin films having fluoroalkyl groups, alkylsilyl groups, fluorosilyl groups, etc. in side chains;
(e) Water repellents having fluoroalkyl groups, alkylsilyl groups, fluorosilyl groups, etc. in side chains, and the like.
As the hydrophobic polymer, in particular, one or more selected from (meth)acrylate monomers having a (per)fluoroalkyl group or (per)fluoropolyether group having 1 to 12 carbon atoms, and vinyl monomers Polymers are preferred.

《Membrane module》
In this embodiment, a membrane module particularly suitable for concentrating a raw material liquid containing sugar may be used. 4 and 5 are schematic diagrams showing an example of a membrane module. 4 and 5, in one aspect, the membrane module 10 has a porous hollow fiber membrane 1 and a substantially cylindrical or polygonal columnar module case 2 that houses the hollow fiber membrane 1 . In one aspect, the hollow fiber membrane 1 may be the hollow fiber membrane according to the present embodiment described above. Here, the “substantially cylindrical shape” includes, for example, a cylindrical shape, an elliptical cylindrical shape, and similar shapes. The term “substantially polygonal columnar shape” includes, for example, a polygonal columnar shape having a polygonal base with 3 to 100 vertices, and shapes similar thereto. "Shape similar to these" includes shapes with cut corners such as cylinders and polygonal prisms, shapes with rounded corners, shapes with bent or curved axes, and combinations thereof. It is a concept. The shape of the membrane module is preferably a columnar shape, an elliptical columnar shape, a polygonal columnar shape whose bottom surface is a polygon having 4 to 12 vertices, and a shape similar thereto, such as a columnar shape, an elliptical columnar shape, a square columnar shape, and a shape similar to these. Shapes similar to these are more preferred.

The module case 2 has, at both ends in the axial direction, membrane fixing portions 21 in which the hollow fiber membranes 1 are fixed with a fixing resin so as to have open ends, and the hollow fiber membranes 1 through which the raw material liquid is supplied through the open ends. and an opening 22 for circulating the raw material liquid for circulating inside. The module case 2 may have a steam extraction port 23 on a side surface portion that communicates with the gas phase portion of the membrane module 10 to take out the steam in the gas phase portion to the outside of the membrane module 10 .

A membrane module may consist of a cartridge and a housing. In that case, it can be used as a membrane module by setting a cartridge with hollow fiber membranes fixed by a fixing resin to a housing having a vapor outlet. The hollow fiber membrane bundle fixed in the membrane module may optionally have one or more members selected from nets, non-woven fabrics, cartridge cases, and the like.

<Membrane fixing part>
It is desirable that the fixing resin for adhesively fixing the hollow fiber membrane in the membrane fixing portion 21 has good mechanical strength and heat resistance up to, for example, about 100.degree. Examples of resins that can be used as the fixing resin include thermosetting epoxy resins and thermosetting urethane resins. Epoxy resin is preferable from the viewpoint of heat resistance, but urethane resin is preferable from the viewpoint of handling.

The filling rate of the hollow fiber membranes based on the cross-sectional area obtained by cutting the membrane fixing portion along a plane perpendicular to the axial direction of the membrane module is preferably 15% or more, more preferably 20%, from the viewpoint of miniaturization of the membrane module. That's it. In order to uniformly fix the hollow fibers by the fixing resin, the filling rate is preferably 74% or less, more preferably 70% or less. The filling rate (%) of the hollow fiber membranes is calculated by (total cross-sectional area of the hollow fiber membranes)/(cross-sectional area of the membrane fixing portion)×100. The cross-sectional area of the hollow fiber membrane refers to the area of the portion surrounded by the outer periphery of the hollow fiber, and is a concept including the area of the hollow portion.

<Effective film length>
The effective length of the hollow fiber membranes 1 in the membrane module 10 is defined as the shortest distance between two membrane fixing portions arranged at both ends in the axial direction of the membrane module.

When the high-viscosity raw material liquid is passed through the inside of the hollow fiber membrane, the pressure loss in the laminar flow region is proportional to the effective length and inversely proportional to the inner diameter. The effective length of the hollow fiber membrane is preferably 100 times or more, or 250 times or more the inner diameter of the hollow fiber membrane, from the viewpoint of increasing the effective length ratio per total length of the hollow fiber membrane (that is, using the membrane more effectively). Or 500 times or more, and preferably 1000 times or less, or 800 times or less than the inner diameter of the hollow fiber membrane in order to reduce pressure loss.

<Steam outlet>
The vapor outlet 23 in the membrane module 10 communicates with the vapor phase portion of the membrane module, and vapor in the vapor phase portion can be withdrawn to the outside of the membrane module. The vapor extracted to the outside of the membrane module may be condensed and recovered, for example, by a vapor condensing section, which will be described later.

In order to prevent pressure loss accompanying an increase in steam flow rate under reduced pressure, the steam outlet preferably has an area sufficient to keep the steam flow rate below a desired value. From this point of view, the opening area of the steam outlet 23 of the module is preferably 1/1500 or more of the membrane area of the hollow fiber membrane 1, more preferably 1/1000 or more. When the main body of the module case 2 has a plurality of steam outlets 23, the opening area of the steam outlets is evaluated as the total area of all the openings. Although the size of the vapor outlet is not limited, as described above, the vapor outlet does not impair the mechanical strength of the membrane module because the membrane module has a substantially cylindrical or polygonal columnar shape. A range is more preferred. From this point of view, the opening area of the vapor outlet 23 of the membrane module 10 is more preferably 1/250 or less of the membrane area of the hollow fiber membrane 1 .

<Opening for distribution of raw material liquid>
The raw material liquid flow openings 22 in the membrane module 10 are provided outside the membrane fixing portions 21 arranged at both ends of the membrane module 10 in the axial direction. The membrane module 10 is connected to the raw material flow path of the raw material liquid concentrating system through the raw material liquid flow opening 22, so that the raw material liquid can be circulated inside the hollow fiber membranes.

In order to prevent an increase in pressure loss when the high-viscosity raw material liquid to be concentrated is circulated, the opening area of the raw material liquid circulation openings 22 is preferably 0.2 times or more the total opening cross-sectional area of the hollow fibers. Also, in order to reduce the dead space in the source liquid flow path piping, it is preferably 8.0 times or less, more preferably 5.0 times or less, of the total opening cross-sectional area of the hollow fibers.

<Module case>
As described above, since the membrane distillation in this embodiment is operated with the gas phase portion of the hollow fiber membrane in a decompressed state, compressive stress is applied to the module case 2 in its axial direction. In order to suppress the dimensional change of the membrane module due to this compressive stress, the membrane module may be covered with a module case except for both ends in the axial direction. The module case may be composed of a single member or a plurality of members. It may have any member configuration. The module case has a steam outlet 23 with a sufficient area so as not to block the flow of steam generated from the raw material liquid. The module case may be made of resin and/or metal, for example. From the viewpoint of workability when installing the steam outlet 23 and durability against compressive stress, the module case is made of, for example, polypropylene, polysulfone, polyethersulfone, polyvinylidene fluoride, polyphenylene ether, ABS resin, fiber-reinforced plastic, and It is preferably composed of at least one resin selected from the group consisting of vinyl chloride resins and/or at least one metal selected from the group consisting of stainless steel, brass, brass, and titanium.

<<Raw material liquid concentration system and raw material liquid concentration method>>
One aspect of the present invention provides a raw material liquid concentrating system for producing foodstuffs that are the above concentrated liquid, the system comprising a vacuum distillation section. The reduced-pressure distillation section has a function of extracting water vapor from the raw material liquid under an atmosphere of less than 100° C. and concentrating the raw material liquid by reducing the pressure of the gas phase section in contact with the heated raw material liquid. Since the raw material liquid can be concentrated while being maintained at an appropriate temperature, a concentrated liquid can be produced in which the flavor components in the raw material liquid are well maintained. In addition, raw material liquids derived from natural products often contain insoluble components, and excessive heating causes aggregation and scorching of the insoluble components. Therefore, if concentration can be performed at a lower temperature, scorching can be suppressed, which is advantageous in that long-term operation becomes possible. Specifically, the raw material liquid is heated to 30° C. or higher and 80° C. or lower, and the high-quality concentrated liquid is obtained by heating and concentrating the raw material liquid under the condition that the gas phase in contact with the raw material liquid is reduced to −80 kPa or lower. can be obtained efficiently.

One aspect of the present invention is a raw material liquid concentrating system for producing a food product according to the present embodiment, in which a heating unit that heats the raw material liquid to 30° C. or more and 80° C. or less and a gas phase in contact with the raw material liquid are Provided is a raw material liquid concentrating system having a vacuum distillation section for distilling and concentrating the raw material liquid by reducing the pressure to -80 kPa or less. One aspect of the present invention also provides a method for producing the food product of the present embodiment using the raw material liquid concentration system, that is, a raw material liquid concentration method. In one aspect, the vacuum distillation section may be a membrane distillation section having a porous membrane.

6 and 7 are conceptual diagrams for explaining the raw material liquid concentration system and the raw material liquid concentration method of the present embodiment. 6 and 7, the raw material liquid concentration system 100 according to the present embodiment includes a raw material liquid tank 101 that stores the raw material liquid, a heating unit 103 that heats the raw material liquid, and the heating unit 103 A membrane distillation section 104 composed of a membrane module having a porous membrane for concentrating the heated raw material liquid, and the raw liquid is circulated from the raw liquid tank 101 to the heating section 103 and the membrane distillation section 104 in this order. and a circulation pump 102 (for example, a gear pump) that circulates the raw material liquid pump 101 through the raw material liquid pump 101 . The porous membrane is arranged to receive feedstock liquid on one side of the membrane and discharge vapor on the opposite side. The membrane distillation section 104 is divided by the porous membrane into a liquid phase section in which the raw material liquid flows and a gas phase section in which the vapor generated from the raw material liquid passes through the porous membrane and diffuses. It has a structure that can put the part into a decompressed state. In one aspect, the membrane module that constitutes the membrane distillation section 104 may be the aforementioned hollow fiber membrane module or flat membrane module.

In one aspect, the raw material liquid concentration system 100 is configured such that the raw material liquid temperature is 30° C. or higher and 80° C. or lower at the raw material liquid inflow portion of the membrane distillation section. It is configured such that the pressure is reduced to -80 kPa or less.

6 and 7, the method for producing a raw material liquid concentrate, which is one form of foodstuffs, according to the present embodiment includes, for example, a step of heating the raw material liquid in a heating unit 103; and a concentration step of concentrating the raw material liquid by membrane distillation in the vacuum distillation section by circulating the raw material liquid through the gas phase section in the vacuum distillation section. In one aspect, the vacuum distillation section may be a membrane distillation section having a porous membrane. In this method, the raw material liquid concentrated in the concentration step is circulated to join the raw material liquid before concentration, for example, the raw material liquid in the raw material liquid tank 101 .

In the method for producing a raw material liquid concentrate of the present embodiment, in one aspect, the raw material liquid temperature is 30° C. or higher and 80° C. or lower at the raw material liquid inflow portion of the membrane distillation section. The pressure on the part side is reduced to -80 kPa or less.

The raw material liquid concentrating system 100 may have a vapor condensing section 105 that condenses the vapor generated in the membrane distillation section 104 . In one aspect, the vapor condenser 105 is connected to the vapor outlet 23 of the membrane module 10 via a vapor line. A demister may be installed in the steam pipe to prevent the raw material liquid from mixing with the condensed water.

In addition to the above, the raw material liquid concentration system 100 may further include, for example, a condensate tank 106, a withdrawal pump 107, a pressure reducing device 108, a flow rate regulator (not shown), a pressure regulator (not shown), and the like. . In addition to the heating unit 103, the raw material liquid concentrating system 100 may further include a structure capable of retaining heat in the raw material liquid flow path including the raw material liquid tank 101 and the vapor condensing unit.

The vapor condensing portion 105 diffuses from the vapor phase portion communicating with the membrane distillation portion 104 (eg, the vapor outlet 23 of the membrane module 10) and the membrane distillation portion 104 (eg, the vapor outlet 23 of the membrane module 10). and a cooling body for condensing the vapor. The cooling body is maintained at a low temperature by circulating a cooling medium (for example, cooling water) inside. The structure of the cooling body may be, for example, a structure in which tubes are assembled or a structure in which plates are stacked. When the cooling body portion comes into contact with the steam that has diffused into the gas phase portion of the steam condensation portion 105, the steam is cooled and condensed to become distilled water (permeated water). Distilled water can be obtained by storing this in the condensate tank 106 and recovering it.

In the membrane distillation section 104, one side (gas phase section) of the membrane distillation section separated by the porous membrane is brought into a reduced pressure state to reduce the vapor pressure difference, which is the difference between the vapor pressure of the raw material liquid and the absolute pressure of the reduced pressure section. As a driving force, vapor can be extracted from the raw material liquid. When the raw material liquid is at a high temperature, the vapor pressure difference increases and the concentration efficiency improves. On the other hand, from the viewpoint of suppressing deterioration of the concentrate and decomposition or discoloration of valuables, it is advantageous to keep the raw material liquid at a predetermined temperature or lower. That is, in order to improve the concentration efficiency while maintaining the quality of the concentrate, the raw material liquid temperature at the raw material liquid inflow portion of the membrane module of the membrane distillation unit 104 is preferably 30° C. or higher and 80° C. or lower, and 40° C. More preferably, the temperature is 70° C. or higher. If the temperature is equal to or lower than the above upper limit temperature, the quality can be easily maintained, and if the temperature is equal to or higher than the above lower limit temperature, the vapor pressure of the raw material liquid will not become too low, and the concentration will proceed satisfactorily.

When the pressure in the gas phase of the membrane distillation section 104 is lowered, the vapor pressure difference between the raw material liquid and the gas phase increases, thereby improving the concentration efficiency. When performing membrane distillation at a low temperature, it is advantageous to keep the pressure of the gas phase below a predetermined value. Specifically, when the atmospheric pressure is 0 kPa, the pressure in the gas phase is preferably −80 kPa or less, more preferably −90 kPa or less. The pressure is preferably as low as possible, but from the viewpoint of facilitating process control, in one aspect, it may be −99 kPa or more, or −97 kPa or more.

When the raw material liquid is passed through the membrane distillation unit 104, a raw material liquid pressure of a predetermined value or higher is advantageous in order to uniformly distribute the raw material liquid over the entire porous membrane. Specifically, the raw material liquid pressure is preferably 10 kPa or higher, more preferably 30 kPa or higher. Considering the pressure resistance of the porous membrane and the module case, it is advantageous to keep the raw material liquid pressure at a predetermined value or less. Specifically, it is preferably 300 kPa or less, or 210 kPa or less.

In membrane distillation, when the transmembrane pressure difference, which is the pressure difference between the liquid phase and the gas phase, exceeds the liquid entry pressure (LEP), the raw material liquid moves from the liquid phase to the gas phase. This leads to loss of raw material liquid. Therefore, in the membrane distillation section 104, it is advantageous to keep the transmembrane pressure difference below the liquid entry pressure. Specifically, the pressure difference between the liquid phase portion and the gas phase portion (that is, the pressure difference between the raw material liquid pressure and the gas phase portion pressure) is preferably 395 kPa or less, or 380 kPa or less, or 300 kPa or less. . From the viewpoint of obtaining good concentration efficiency, the differential pressure is preferably 50 kPa or more, 80 kPa or more, or 90 kPa or more.

In membrane distillation, it is difficult to directly heat the surface of the membrane on which water in the raw material evaporates. Therefore, it is advantageous to keep the linear velocity of the raw material liquid at a predetermined value or higher in order to supply the latent heat necessary for evaporation. Specifically, the raw material liquid linear velocity on the membrane surface of the liquid phase portion in the membrane distillation section is preferably 0.05 m/s or more. On the other hand, since the pressure in the liquid phase increases as the linear velocity of the raw material liquid increases, it is advantageous to suppress the linear velocity to a predetermined value or less. Specifically, the raw material liquid linear velocity on the surface of the porous membrane in the membrane distillation section is preferably 1.0 m/s or less, more preferably 0.5 m/s or less.

<Heating of raw material solution>
In the heating step, from the viewpoint of suppressing the decomposition or denaturation of the raw material liquid due to heating, it is preferable to heat the raw material liquid by bringing it into contact with a heating section at 90° C. or less. The heating unit 103 for heating the raw material liquid, which is useful for the heating step, may have a structure that heats the raw material liquid by heating a part of the raw material liquid flow path. As a method for heating the raw material liquid, a method of heating the raw material liquid by supplying a heat amount from a heat medium to the raw material liquid by a heat exchanger, and a method of heating a piping portion with an electric heating wire, a flame, or the like can be used. . Since the pipe surface of the heating unit is the hottest in the source liquid flow path, the surface temperature of the heating unit 103 (that is, the surface temperature of the heating unit 103 (i.e., It is preferable that the temperature of the part to be heated) is 90° C. or less.

In order to keep the surface temperature of the heating part 103 as low as possible, it is more preferable to heat the raw material liquid by supplying heat from a heat medium to the raw material liquid using a heat exchanger. It is more preferable to use steam decompressed to atmospheric pressure or less. From the viewpoint of heat utilization efficiency, the temperature of hot water or steam is preferably 50° C. or higher. The temperature of hot water or steam is preferably 100° C. or less from the viewpoint of avoiding deterioration, decomposition, discoloration, etc. of the target component in the raw material liquid. Moreover, from the viewpoint of reducing the concentration energy cost, waste heat generated in processes other than the concentration process may be used to heat the raw material liquid.

<Preprocessing>
In the raw material liquid concentration method of the present embodiment, in order to improve the energy efficiency of the entire concentration method, pretreatment is performed before the concentration process for the purpose of preconcentration, removal of impurities (for example, fiber content in sap, etc.). you can go Referring to FIG. 7, in one embodiment, the raw material liquid is first supplied to a preliminary tank 109 upstream of the raw material liquid tank 101, and the raw material liquid is introduced into the pretreatment section 111 via the liquid feed pump 110 for pretreatment. After that, it may be supplied to the raw material liquid pump 101 . The pretreatment unit 111 may be a filtration membrane for impurity removal, a reverse osmosis membrane for preconcentration, a combination thereof, or the like. In one aspect, the concentration step and the filtration step and/or pre-concentration step as a pretreatment step are performed in independent raw material liquid flow paths.

More specifically, in one aspect, as shown in FIG. 7, the raw material liquid concentrated in the membrane distillation section 104 may be circulated to the raw material liquid tank 101 without passing through the pretreatment section 111 . That is, in one aspect, the raw material liquid concentrated in the concentration step may be circulated to join the raw material liquid before concentration after the pretreatment step (that is, the pretreatment section is connected in series with the membrane distillation section. may be placed).

On the other hand, in another aspect, in addition to the raw material liquid circulation path returning from the raw material tank 101 to the raw material tank 101 via the membrane distillation section 104, the raw material liquid is supplied from the raw material liquid tank 101 to the raw material liquid tank 101 via the pretreatment section 111. (ie, the pretreatment section may be arranged in parallel with the membrane distillation section). Such a pretreatment mode is advantageous in that it is possible to remove impurities newly generated due to an increase in concentration due to concentration of the raw material solution over time while maintaining the circulation flow rate of the raw material solution in the raw material solution circulation channel.

<Filtration membrane>
In one aspect, the pretreatment section may have a filtration membrane. There is a high possibility that insoluble components such as dietary fiber are present in the raw material liquid, and if membrane distillation is performed as it is, excessive pressure rise in the liquid phase, membrane breakage due to abrasion, and insoluble component deposition on the membrane surface. It may cause film clogging due to Therefore, it is preferable to remove the insoluble components in order to carry out membrane distillation more efficiently. A membrane filtration method is suitable for removing insoluble components. In one aspect, a filtration membrane having a pore size of 20 μm or less is preferable from the viewpoint of efficiently removing insoluble components in the raw material liquid. More preferably, the pore size of the filtration membrane is 1.0 μm or less. From the viewpoint of filtration efficiency, the pore size of the filtration membrane may be, for example, 0.1 μm or more, or 0.3 μm or more.

<Cross-flow filtration>
From the viewpoint of preventing clogging of the filtration membrane, it is preferable to perform the removal of insoluble components by the above-described membrane filtration by a cross-flow filtration method. Cross-flow filtration can use a cross-flow filtration membrane module with flat or hollow fiber membranes. In one aspect, the filtration membrane module has a total of two or more inlets and outlets on the side of the flow path for the liquid to be filtered, and has one or more outlets on the side of the flow path for the permeated liquid. By applying pressure while circulating the liquid to be filtered through such a filtration membrane module, it is possible to obtain a permeated liquid while preventing deposition of insoluble components on the membrane surface. Although there are no particular restrictions on the circulation flow rate of the liquid to be filtered and the flow rate of the permeated liquid, from the viewpoint of performing efficient filtration, the circulation flow rate of the liquid to be filtered is preferably at least three times the flow rate of the permeated liquid. It is more preferably 10 times or more.

<Backwashing of filtration membrane>
In the removal of insoluble components by the filtration membrane, backwashing may be performed periodically for the purpose of removing the insoluble components deposited on the surface of the filtration membrane and maintaining the membrane performance. Examples of the fluid used for backwashing include water, permeated liquid in the membrane filtration process, condensed water obtained in membrane distillation, and the like. Alternatively, an air backwash method, which is a backwash method using air, may be used. The timing of performing backwashing can be determined from the increase in the transmembrane pressure difference of the filtration membrane, the decrease in the permeate flow rate, and the like. Also, backwashing may be performed at a preset cycle (for example, once an hour).

<Reverse osmosis membrane>
Preferred examples of reverse osmosis membranes are, but not limited to, cellulose acetate hollow fiber membranes and composite membranes having a separation layer containing polyamide. A reverse osmosis membrane is used for pre-concentration of a raw material liquid, and by placing the raw material liquid on the separation layer side of the reverse osmosis membrane and pressurizing it, only moisture in the raw material liquid can be permeated and removed. In this case, as the raw material liquid is concentrated, the solute concentration in the raw material liquid may exceed the saturation concentration and precipitate as an insoluble component. Moreover, as a pretreatment part, you may use a reverse osmosis membrane and the above-mentioned filtration membrane together. In this case, for example, it is more preferable to circulate the raw material liquid through the reverse osmosis membrane and the filtration membrane in this order (that is, arrange the reverse osmosis membrane upstream of the filtration membrane) from the viewpoint of improving the removal efficiency of insoluble components. .

<Cleaning of porous membrane>
In the method for concentrating the raw material liquid in the present embodiment, the membrane is used for the purpose of removing insoluble components that have precipitated along with the concentration of the raw material liquid, preventing contamination of the raw material liquid when switching the raw material liquid, and especially removing the raw material liquid adhering to the porous membrane. The liquid phase portion of the module can be washed periodically. Specifically, it is preferable to pass water through the liquid phase portion of the membrane module at least once a day for washing. It is also preferable to wash with a chemical solution at least once a week for the purpose of removing components that are difficult to dissolve in water, sterilizing the inside of the system, and particularly removing membrane contaminants attached to the porous membrane. Drinking water, water permeated through a reverse osmosis membrane, condensed water obtained in the raw material concentration system of the present embodiment, and the like may be used as the water used for washing. The chemical solution used for cleaning is a chemical solution with a pH of 5 or less (e.g., an acidic aqueous solution such as hydrochloric acid or a citric acid aqueous solution) or a chemical solution with a pH of 9 or higher (e.g., an alkaline aqueous solution such as a sodium hydroxide aqueous solution or a sodium hypochlorite aqueous solution). can be used. Also, by using the acidic aqueous solution and the alkaline aqueous solution in order, both the inorganic component and the organic component can be efficiently removed.

<Additional concentration by evaporation>
In the raw material liquid concentration method of the present embodiment, for the purpose of sterilizing the concentrated raw material liquid, flavoring by heating, etc., in order to improve the energy efficiency of the entire concentration method, an evaporator (not shown) is used after the concentration process. Additional concentration steps can be included. In order to obtain the desired sterilization or flavoring effect, in the additional concentration step, the concentrated raw material liquid is preferably heated to the temperature of the raw material liquid in the concentration step by membrane distillation or higher. In one aspect, the evaporator may be positioned downstream from the aforementioned filtration membrane.

EXAMPLES Hereinafter, exemplary embodiments of the present invention will be described in more detail with reference to examples, but the present invention is not limited to the following examples.

(Sugar content of concentrate)
The sugar contents of the raw material liquid and the concentrated liquid were measured using a sugar meter (Atago PAL-1). The saccharimeter was corrected to 0% with distilled water before measurement.

(Visible light transmittance of raw material liquid)
The permeability of the concentrate was measured by filtering the concentrate using an ultrafiltration filter (Amicon Ultra-0.5, PLGC Ultracell-10 membrane, 10 kDa, UFC501008), and then measuring the filtrate with a screw cap for a spectrophotometer. A sufficient amount of the sample was placed in a two-sided transparent quartz cell (GL Sciences Co., Ltd. S15-UV-10, optical path length 10 mm, optical path width 10 mm), and the UV/vis spectrum was measured. Glycerin was used as a blank. UV/vis analysis conditions are as follows.
-UV/vis conditions-
UV/vis device: JASCO JASCO V-770
Measurement mode: Abs
Measurement wavelength: 800-200nm
Data acquisition interval: 0.5 nm
Light source: D2, WI
Light source switching: 340 nm
Correction: Baseline

(Aroma component analysis)
Flavor components were collected from the concentrate under an atmosphere of 50°C. Specifically, 1 g of the concentrated liquid was added to a 20 mL screw bottle with a septum stopper, heated at 50° C. for 20 minutes, and then SPME was inserted to adsorb gas components for another 10 minutes. This adsorbed component was thermally desorbed at the GC/MS injection port and subjected to GC/MS measurement. Vanillin and acetophenone in the aroma components were analyzed using SPME-GC/MS. SPME-GC/MS analysis conditions are as follows.
-SPME-GC/MS conditions-
SPME-GC/MS device: Agilent GC-7890 MSD-5977B
Ionization method: EI (70 eV)
Mass range: 29-800
Column: DB-WAX (30 m × 0.25 mm × 0.25 μm)
Carrier gas: Helium Flow rate: 1.2 mL/min
Transfer temperature: 250°C
Temperature conditions: 40°C (7 minutes Hold) ⇒ 10°C up/min ⇒ 250°C (7 minutes Hold)
Inlet temperature: 250°C
SPME Fiber: 65 μm PDMS/DVB
Injection method: Splitless
Heating temperature: 50°C x 30 min (20 min volatile component extraction ⇒ 10 min adsorption)
Area Range: Vanillin 23:31-23:38
Acetophenone 14:32-14:41

(Measurement of magnesium ion concentration)
Magnesium ion concentration was measured using Thermo Fisher Scientific ICP-MS, model "iCAP Q". In addition, in this measurement, the sample obtained by diluting "ICP mixed standard solution D" manufactured by Kanto Chemical Co., Ltd. 10 times, 100 times, 1000 times, and 10000 times was measured on each day of sample measurement, and the calibration curve updated.

(Sensory evaluation of flavor)
The obtained raw material liquid concentrate was tasted by five panelists, and the flavor was evaluated according to the following two criteria.
1. Original Flavor of Raw Materials A: All five panelists judged that the original flavor of raw materials was strong.
B: 1 or more and 4 or less panelists judged that the original flavor of the raw material was strong.
C: None of the panelists judged that the original flavor of the raw material was strong.
2. Balance of flavor A: All five panelists judged that the balance of flavor (sweetness, flavor, bitterness) was good.
B: 1 or more and 4 or less panelists judged that the balance of flavors (sweetness, flavor, bitterness) was good.
C: None of the panelists judged that the flavor (sweetness, flavor, bitterness) was well-balanced.

[Coloring]
Evaluation was made according to the following criteria.
A: Visible light transmittance at 560 nm is 85% or more B: Visible light transmittance at 560 nm is 80% or more and less than 85% C: Visible light transmittance at 560 nm is 75% or more and less than 80% D: Visible light transmittance at 560 nm is less than 75%

(Measurement of physical properties of hollow fiber membrane)
[Outer diameter, inner diameter, and film thickness]
Regarding the outer diameter and inner diameter of the hollow fiber membrane, the hollow fiber membrane was sliced with a razor in a direction perpendicular to its longitudinal direction, and the outer diameter and inner diameter of the cross section were measured using a microscope. The film thickness was calculated by the following formula (2).
Film thickness (mm) = [outer diameter (mm) - inner diameter (mm)]/2 (2)

[Average pore diameter]
The average pore size of the hollow fiber membrane was measured by the average pore size measurement method (also known as half-dry method) described in ASTM: F316-86. The measurement was performed on a hollow fiber membrane having a length of about 10 cm using ethanol as a liquid under standard measurement conditions of 25° C. and a pressure increase rate of 0.01 atm/sec. The average pore diameter was determined by the following formula (3).
Average pore diameter [μm] = 2,860 × (surface tension of liquid used [dyne/cm]) / (half dry air pressure [Pa]) (3)
Here, a value of 21.97 dyne/cm was used as the surface tension of ethanol at 25°C.

[Maximum pore diameter]
The maximum pore size of the hollow fiber membrane was measured using the bubble point method. One end of an 8 cm-long hollow fiber membrane was closed, and a nitrogen gas supply line was connected to the other end via a pressure gauge. In this state, nitrogen gas was supplied to replace the inside of the line with nitrogen, and then the hollow fiber membrane was immersed in ethanol. At this time, the hollow fiber membrane was immersed in ethanol while the line was under a very slight pressure of nitrogen so that ethanol would not flow back into the line. While the hollow fiber membrane was immersed, the nitrogen gas pressure was slowly increased, and the pressure P at which nitrogen gas bubbles began to stably emerge from the outer wall of the hollow fiber membrane was recorded. From this value, the maximum pore diameter d [μm] of the hollow fiber membrane is expressed by the following formula (4):
d=C1γ/P (4)
{In the formula, C1 is a constant, γ is surface tension [dyne/cm], and P is pressure [Pa]. } was calculated by The value of the product of the constant C1 and the surface tension γ when ethanol was used as the immersion liquid was C1γ=0.0879 [N/m].

[Porosity]
The porosity of the hollow fiber membrane was determined by the method described below.
The hollow fiber membrane is cut into a certain length, its weight is measured, and the porosity is calculated by the following formula (5):
Porosity (%) = 100 - [mass of hollow fiber membrane (g) x 100]/[polymer density (g/cm ³ ) x {(outer diameter (cm)/2) ² - (inner diameter (cm)/2 ) ² } x 3.14 x length (cm)] (5)
obtained by

[Air Permeability]
Measured according to ISO 9237. Dry air was flowed into the membrane module, and the pressure (kPa) between the inlet and outlet of the membrane module and the dry air flow rate (L/h) at the outlet of the membrane module were measured. The air permeability (L/m ² ·h·kPa) was calculated by dividing the dry air flow rate (L/h) by the differential pressure (kPa) between the inlet and the outlet and the membrane area.

[Viscosity of raw material liquid]
The viscosity of the raw material liquid was measured as solution viscosity using a Thermo Scientific viscometer (model name “HAAKE ViscoTester iQ”).

《Implementation of membrane distillation》
The membrane distillation in Examples 1 to 10 and Comparative Examples 3 and 4 was performed by a raw material liquid concentration system having a configuration according to FIG. 6 or 7, which was provided with a membrane module having a configuration according to FIGS. rice field.

The membrane module as the membrane distillation section was configured as described in each example and comparative example, and the outlet of the vapor condensation section was connected to the condensate tank by piping. Then, the pressure in the system was adjusted by connecting the gas phase portion of the condensate tank to a decompression device via a pressure regulator.

A heating section using a heat exchanger was provided in the raw material liquid flow path, and warm water was used as the heating medium. A gear pump was used as a circulation pump to circulate the raw material liquid in the raw material liquid flow path, and the pressure of the raw material liquid was adjusted using a back pressure valve provided at the outlet of the membrane module. Cooling water (CW) at 10° C. was circulated through the steam condenser at a flow rate of 10 L/min.

[Flux measurement]
Perform membrane distillation and measure the weight of the distilled water that has flowed into the condensate tank using a gravimeter or an integrating flowmeter, and use the following formula (6):
Flux = weight of distilled water obtained by membrane distillation with an operating time of 1 hour/membrane area/operating time (1 hour) (6)
Flux was calculated according to

<<Example 1>>
[Hydrophobicization of Hollow Fiber Membrane]
About 1000 PVDF (polyvinylidene fluoride) hollow fiber membranes with an inner diameter of 0.68 mm, an outer diameter of 1.25 mm, an average pore diameter of 0.21 μm determined from ASTM-F316-86, a maximum pore diameter of 0.29 μm, and a porosity of 72% , After being completely immersed once in fluororesin water repellent FS-392B (0.5% by weight) manufactured by Fluoro Technology Co., Ltd., it is pulled out and dried to make the inner and outer surfaces of the hollow fiber membrane hydrophobic. polymer was applied.

[Production of hollow fiber membrane module]
In fabricating the membrane module, a thermosetting epoxy resin was used as the fixing resin, and the hollow fiber membranes were adhered and fixed in the module case by centrifugal bonding to form membrane fixing portions at both ends in the axial direction. The membrane fixing parts were configured so that the shortest distance between the two membrane fixing parts (that is, the effective length of the hollow fiber membrane) was about 300 mm.

A cylindrical polysulfone case having an inner diameter of 55 mm and an outer diameter of 60 mm was used as the module case. This case is provided with three steam outlets with an area of 0.0010 m ² by 2.5S piping on the outer peripheral side surface. Caps for connecting the module to the raw material flow path of the membrane distillation system were attached to both ends of the case. The cap was provided with an opening of 2.0S and 0.0018 m ² as an opening for the raw material liquid flow. The obtained membrane module had an air permeability of 4800 L/h·m ² ·kPa, and a water permeation rate of 20% by weight EtOH aqueous solution at a pressure of 200 kPa was 40 mL/h·m ² .

Using the membrane module obtained in [Preparation of Membrane Module] above, a raw material liquid concentration system having a configuration according to FIG. It took 9.9 hours to concentrate unfiltered maple water (Brix 2.0, viscosity 3.2 cP) to Brix 70 (viscosity 370 cP), and the total flux of the entire concentration test was 13.3 kg/m ² · was h. The visible light transmittance of the obtained raw material concentrate was 83%, the peak area of vanillin was 8.0 times that of acetophenone, and the weight ratio of sugar to Mg ion was 99% of the initial value. As a result of the sensory evaluation of the flavor, the original flavor of the raw material was B, and the flavor balance was A.

From the above results, it was verified that the concentrated liquid obtained by the method of Example 1 is a high-quality syrup with a well-balanced flavor while retaining the flavor of the raw material liquid to some extent without excessive coloring.

<<Example 2>>
Hot water of 50°C is used as a heat medium in the heating section, the maximum temperature of the surface of the heating section is 45°C, the raw material liquid temperature at the raw material liquid inlet of the membrane module for membrane distillation is 35°C, and the decompression section is -95 kPa. A concentration test was conducted under the same conditions as in Example 1, except for one thing. It took 30.5 hours to concentrate maple water to a Brix of 70, and the total flux of the entire concentration test was 4.3 kg/m ² ·h. The visible light transmittance of the resulting raw material concentrate was 90%, the peak area of vanillin was 1.4 times that of acetophenone, and the weight ratio of sugar to Mg ion was 98% of the initial value. As a result of the sensory evaluation of the flavor, the original flavor of the raw material was A, and the flavor balance was B.

From the above results, it was verified that the concentrated liquid obtained by the method of Example 2 was a high-quality syrup with almost no coloration and a somewhat well-balanced flavor while retaining the flavor of the raw material liquid.

<<Example 3>>
Before the concentration operation of the raw material liquid by membrane distillation, the raw material liquid is filtered under reduced pressure using a filter paper with a pore size of 20 μm, hot water of 70 ° C. is used as a heating medium in the heating part, the maximum temperature of the heating part surface is 65 ° C., and membrane distillation is performed. A concentration test was conducted under the same conditions as in Example 2, except that the raw material temperature at the raw material liquid inlet of the membrane module was 55°C. It took 12.9 hours to concentrate the maple water to a Brix of 70, and the total flux of the entire concentration test was 10.2 kg/m ² ·h. The visible light transmittance of the obtained raw material concentrate was 86%, the peak area of vanillin was 1.9 times that of acetophenone, and the weight ratio of sugar to Mg ion was 101% of the initial value. As a result of the sensory evaluation of the flavor, the original flavor of the raw material was A, and the flavor balance was A.

From the above results, it was verified that the concentrated liquid obtained by the method of Example 3 is a very high-quality syrup with a good balance of flavor while retaining the flavor of the raw material liquid with almost no coloring.

<<Example 4>>
A concentration test was performed under the same conditions as in Example 3, except that before the operation of concentrating the raw material liquid by membrane distillation, a PVDF hollow fiber membrane with a pore size of 0.8 μm was used and cross-flow filtration was performed while periodically backwashing. gone. It took 10.9 hours to concentrate the maple water to a Brix of 70, and the total flux of the entire concentration test was 12.0 kg/m ² ·h. The visible light transmittance of the resulting raw material concentrate was 87%, the peak area of vanillin was 3.0 times that of acetophenone, and the weight ratio of sugar to Mg ion was 102% at the initial stage. As a result of the sensory evaluation of the flavor, the original flavor of the raw material was A, and the flavor balance was A.

From the above results, it was verified that the concentrated liquid obtained by the method of Example 4 is a very high-quality syrup with a well-balanced flavor while retaining the flavor of the raw material liquid with almost no coloring.

<<Example 5>>
Simultaneously with the start of the concentration operation of the raw material liquid by membrane distillation, cross-flow filtration was performed using a PVDF hollow fiber membrane with a pore size of 0.8 μm in a raw material liquid circulation flow path different from the membrane distillation module while periodically backwashing. A concentration test was conducted under the same conditions as in Example 3, except for the above. It took 10.7 hours to concentrate maple water to a Brix of 70, and the total flux of the entire concentration test was 12.2 kg/m ² ·h. The visible light transmittance of the resulting raw material concentrate was 87%, the peak area of vanillin was 3.3 times that of acetophenone, and the weight ratio of sugar to Mg ion was 104% at the initial stage. As a result of the sensory evaluation of the flavor, the original flavor of the raw material was A, and the flavor balance was A.

From the above results, it was verified that the concentrated liquid obtained by the method of Example 5 is a very high-quality syrup with a well-balanced flavor while retaining the flavor of the raw material liquid with almost no coloring.

<<Example 6>>
A concentration test was conducted under the same conditions as in Example 4, except that factory waste water at 70° C. was used as the heating medium in the heating section. It took 10.5 hours to concentrate the maple water to a Brix of 70, and the total flux of the entire concentration test was 12.5 kg/m ² ·h. The visible light transmittance of the obtained raw material concentrate was 88%, the peak area of vanillin was 3.6 times that of acetophenone, and the weight ratio of sugar to Mg ion was 100% of the initial value. As a result of the sensory evaluation of the flavor, the original flavor of the raw material was A, and the flavor balance was A.

From the above results, it was verified that the concentrated liquid obtained by the method of Example 6 is a very high-quality syrup with a well-balanced flavor while retaining the flavor of the raw material liquid with almost no coloring.

<<Example 7>>
A concentration test was conducted under the same conditions as in Example 4, except that the raw material liquid was concentrated to Brix 20 using a reverse osmosis membrane before the operation of concentrating the raw material liquid by membrane distillation. It took 2.2 hours to concentrate the maple water to a Brix of 70, and the total flux of the entire concentration test was 6.0 kg/m ² ·h. The visible light transmittance of the resulting raw material concentrate was 92%, the peak area of vanillin was 1.4 times that of acetophenone, and the weight ratio of sugar to Mg ion was 95% of the initial value. As a result of the sensory evaluation of the flavor, the original flavor of the raw material was A, and the flavor balance was B.

From the above results, it was verified that the concentrated liquid obtained by the method of Example 7 was a high-quality syrup with almost no coloration and a somewhat well-balanced flavor while retaining the flavor of the raw material liquid.

<<Example 8>>
A concentration test was conducted under the same conditions as in Example 4, except that the raw material liquid was concentrated to Brix 50 by membrane distillation and then heated and concentrated to Brix 70 at a temperature of 100° C. or higher using an atmospheric distillation apparatus. The time taken to concentrate maple water to Brix 50 was 6.2 hours, and the total flux of the entire concentration test was 15.0 kg/m ² ·h. The visible light transmittance of the Brix70 concentrate was 81%, the peak area of vanillin was 10.3 times that of acetophenone, and the weight ratio of sugar to Mg ion was 99% of the initial value. As a result of the sensory evaluation of the flavor, the original flavor of the raw material was B, and the flavor balance was B.

From the above results, it was verified that the concentrated liquid obtained by the method of Example 8 is a high-quality syrup that is not excessively colored, retains the flavor of the raw material liquid to some extent, and has a somewhat well-balanced flavor. .

<<Example 9>>
Using 140 kg of maple water with an initial Brix of 2.0 as the raw material liquid, it was concentrated to Brix 20 with a reverse osmosis membrane, then concentrated to Brix 50 by membrane distillation under the same conditions as in Example 1, and then Brix 70 by atmospheric distillation equipment at 100 ° C. It was heated and concentrated at the above temperature. It took 5.9 hours to concentrate maple water to a Brix of 50 by membrane distillation, and the total flux of the entire concentration test was 16.0 kg/m ² ·h. The visible light transmittance of the Brix70 concentrate was 83%, the peak area of vanillin was 10.6 times that of acetophenone, and the weight ratio of sugar to Mg ion was 94% of the initial value. As a result of the sensory evaluation of the flavor, the original flavor of the raw material was B, and the flavor balance was B.

From the above results, it was verified that the concentrated liquid obtained by the method of Example 9 is a high-quality syrup that is not excessively colored, retains the flavor of the raw material liquid to some extent, and has a somewhat well-balanced flavor. .

<<Example 10>>
A concentration test was conducted under the same conditions as in Example 4, except that 93 kg of coconut water with an initial Brix of 3.0 was used as the raw material liquid. The time taken to concentrate to Brix 70 was 8.8 hours, and the total flux of the entire concentration test was 9.5 kg/m ² ·h. The visible light transmittance of the obtained raw material liquid concentrate was 80%. Although vanillin was detected in the aroma components, acetophenone was not detected. The weight ratio of sugar to Mg ion was 102% at the initial stage. As a result of the sensory evaluation of the flavor, the original flavor of the raw material was B, and the flavor balance was B.

From the above results, it was verified that the concentrated liquid obtained by the method of Example 10 is a high-quality syrup that is not excessively colored, retains the flavor of the raw material liquid to some extent, and has a somewhat well-balanced flavor. .

<<Example 11>>
A concentration test was conducted under the same conditions as in Example 4, except that 112 kg of birch sap with an initial Brix of 2.5 was used as the raw material solution. The time taken to concentrate to Brix 70 was 11.2 hours, and the total flux of the entire concentration test was 9.0 kg/m ² ·h. The visible light transmittance of the obtained raw material liquid concentrate was 82%. Although vanillin was detected in the aroma components, acetophenone was not detected. The weight ratio of sugar to Mg ions was 99% at the initial stage. As a result of the sensory evaluation of the flavor, the original flavor of the raw material was B, and the flavor balance was B.

From the above results, it was verified that the concentrated liquid obtained by the method of Example 11 was a high-quality syrup with a somewhat well-balanced flavor while retaining the flavor of the raw material liquid to some extent without excessive coloring. .

<<Example 12>>
[Fabrication of forward osmosis hollow fiber membrane module]
A polyethersulfone hollow fiber membrane having an outer diameter of 1.0 mm, an inner diameter of 0.7 mm, and a fine pore diameter of 0.05 μm on the inner surface is used as a support layer, and 1600 of the hollow fiber support layers are used as support layers, with an inner diameter of 55 mm and a length of 460 mm. A hollow fiber support layer module having an effective inner membrane surface area of 1.6 m ² was produced by filling a cylindrical plastic housing and fixing both ends with an adhesive. The hollow fiber support layer module was subjected to interfacial polymerization using an m-phenylenediamine aqueous solution and an n-hexane solution of trimesic acid chloride to prepare a forward osmosis hollow fiber membrane module having a polyamide separation layer inside.

Using the forward osmosis hollow fiber membrane module, concentration was performed using a forward osmosis concentration system. The forward osmosis concentration system has a function of causing a raw material solution to flow inside the hollow fiber membranes and a draw solution having an osmotic pressure to flow outside the hollow fiber membranes. By bringing the raw material liquid and the draw solution into contact with each other through the forward osmosis membrane, the water in the raw material liquid can be transferred to the draw solution and the raw material liquid can be concentrated.

Using 140 kg of maple water of initial Brix 2.0 as a raw material solution and 280 kg of a 20% by mass magnesium chloride aqueous solution as a draw solution, a concentration test was conducted by flowing the raw material solution and the draw solution in parallel. The raw material liquid temperature at the raw material liquid inlet of the forward osmosis hollow fiber membrane module was 25°C. It took 8.5 hours to concentrate the maple water to a Brix of 70, and the total flux of the entire concentration test was 10.0 kg/m ² ·h. The visible light transmittance of the resulting raw material concentrate was 95%, the peak area of vanillin was 0.3 times that of acetophenone, and the weight ratio of sugar to Mg ion was 106% at the initial stage. As a result of the sensory evaluation of the flavor, the original flavor of the raw material was B, and the flavor balance was B.

From the above results, it was verified that the concentrated liquid obtained by the method of Example 11 is a high-quality syrup with almost no coloration and a somewhat well-balanced flavor while retaining the flavor of the raw material liquid.

<<Example 13>>
140 kg of maple water with an initial Brix of 2.0 was used as a raw material liquid, and heated and concentrated at a temperature of 100° C. or higher to a Brix of 70 using a vacuum distillation apparatus. The maximum temperature of the surface of the heating section was 65° C., the average temperature of the raw material liquid in the vacuum distillation apparatus was 55° C., and the pressure reduction section was −95 kPa. The time taken to concentrate to Brix 70 was 42.0 hours. The visible light transmittance of the Brix70 concentrate was 83%, the peak area of vanillin was 2.9 times that of acetophenone, and the weight ratio of sugar to Mg ion was 100% of the initial value. As a result of the sensory evaluation of the flavor, the original flavor of the raw material was B, and the flavor balance was A.

From the above results, it was verified that the concentrated liquid obtained by the method of Example 12 is a high-quality syrup with a somewhat well-balanced flavor while retaining the flavor of the raw material liquid without excessive coloring.

<<Example 14>>
Same as Example 1 except that the porous flat membrane having an air permeability of 4800 L/h·m ² · kPa and a thickness of 20 μm after the water-repellent treatment is folded into a pleated shape and stored in a cylindrical case. A flat membrane module was produced in the same manner. Using the flat membrane module, a concentration test was conducted under the same conditions as in Example 2, except that the raw material liquid temperature at the raw material liquid inlet of the membrane module was 55°C. The time taken to concentrate to Brix 70 was 10.2 hours, and the total flux of the entire concentration test was 8.0 kg/m ² ·h. The visible light transmittance of the Brix70 concentrate was 82%, the peak area of vanillin was 3.0 times that of acetophenone, and the weight ratio of sugar to Mg ion was 99% of the initial value. As a result of the sensory evaluation of the flavor, the original flavor of the raw material was B, and the flavor balance was A.

From the above results, it was verified that the concentrated liquid obtained by the method of Example 13 is a high-quality syrup with a well-balanced flavor while retaining the flavor of the raw material liquid to some extent without excessive coloring.

<<Comparative example 1>>
A commercially available maple syrup (grade A, golden/delicate taste) was subjected to visible light transmittance measurement, aroma component analysis, and sensory evaluation. The visible light transmittance was 75%, and the peak area of vanillin was 5.0 times that of acetophenone. As a result of the sensory evaluation of the flavor, the original maple water flavor was C, and the flavor balance was B.

From the above results, it was verified that the syrup of Comparative Example 1 was not a high-grade syrup because it was excessively colored and the raw material liquid had a poor flavor, although the flavor balance was good to some extent.

<<Comparative Example 2>>
Using maple water with an initial Brix of 2.0 as the raw material liquid, 50 g of the raw material liquid was placed in an eggplant flask, frozen with liquid nitrogen, and then connected to a freeze dryer (manufactured by Tokyo Rikakikai Co., Ltd., FD-1000). Freeze-drying was performed for 72 hours under reduced pressure conditions of -95 kPa. The raw material concentrate obtained by concentration had a Brix of 70 and a visible light transmittance of 97%. Vanillin and acetophenone were not detected in the aroma components, and the initial weight ratio of sugar and Mg ion was 100%. As a result of the sensory evaluation of the flavor, the original flavor of the raw material was C, and the flavor balance was C.

From the above results, it was verified that the concentrated liquid obtained by the method of Comparative Example 2 was not colored, but the flavor of the raw material liquid was poor, the flavor balance was low, and it was not a high-quality syrup.

<<Comparative Example 3>>
A pipe wrapped with a ribbon heater is used as a heating unit, the raw material liquid is heated at a surface temperature of 110°C, and the concentration is performed under the same conditions as in Example 2 except that the raw material liquid temperature at the raw material liquid inlet of the membrane module is 90°C. did the test. It took 7.3 hours to concentrate maple water to a Brix of 70, and the total flux of the entire concentration test was 18.0 kg/m ² ·h. The visible light transmittance of the raw material concentrate was 73%, the peak area of vanillin was 8.3 times that of acetophenone, and the weight ratio of sugar to Mg ion was 106% of the initial value. As a result of the sensory evaluation of the flavor, the original flavor of the raw material was C, and the flavor balance was B.

From the above results, it was verified that the concentrated liquid obtained by the method of Comparative Example 3 was not a high-quality syrup because it was excessively colored and the raw material liquid had a poor flavor, although the flavor balance was somewhat good.

<<Comparative Example 4>>
A concentration test was conducted under the same conditions as in Example 2, except that the raw material liquid temperature at the raw material liquid inlet of the membrane module was 80° C. and the pressure in the decompression section was −20 kPa. It took 262 hours to concentrate maple water to a Brix of 70, and the total flux of the entire concentration test was 0.5 kg/m ² ·h. The visible light transmittance of the raw material concentrate was 65%, the peak area of vanillin was 13.1 times that of acetophenone, and the weight ratio of sugar to Mg ion was 94% of the initial value. As a result of the sensory evaluation of the flavor, the original flavor of the raw material was C, and the flavor balance was C.

From the above results, it was verified that the concentrated liquid obtained by the method of Comparative Example 4 was excessively colored, the raw material liquid had a poor flavor, the flavor balance was low, and it was not a high-quality syrup. Table 1 shows the operating conditions, operating results, and evaluation results of the obtained concentrate in the concentration test.

1 Hollow Fiber Membrane 2 Module Case 10 Membrane Module 11 Porous Membrane 17 Rod-shaped Body 18 Liquid Phase Spacer 19 Gas Phase Spacer 21 Membrane Fixing Part 22 Raw Material Distribution Opening 23 Vapor Outlet 100, 200 Raw Material Concentrating System 101 Raw material liquid tank 102 Circulation pump 103 Heating unit 104 Membrane distillation unit 105 Steam condensation unit 106 Condensate tank 107 Withdrawal pump 108 Decompression device 109 Spare tank 110 Liquid sending pump 111 Pretreatment unit A Water to be treated A' To be treated after distillation Water B Steam separated from the water to be treated B ^* Steam separated from the water to be treated, passing through the porous membrane and diffusing into the gas phase

Claims (24)

A foodstuff that is a concentrate of a raw material liquid derived from a natural product containing a sugar-containing solute and a liquid medium,
The concentrated liquid has a Brix value of 50 or more,
The visible light transmittance of the concentrated liquid at a wavelength of 560 nm as measured by an ultraviolet-visible spectrophotometer is 80% or more and 99% or less,
A foodstuff, wherein the aromatic component collected from the concentrate in a 50° C. atmosphere contains vanillin. 2. The foodstuff according to claim 1, wherein the visible light transmittance of the concentrate at a wavelength of 560 nm is 85% or more and 99% or less as measured by an ultraviolet-visible spectrophotometer. The aroma components collected from the concentrate in an atmosphere of 50 ° C. contain vanillin and acetophenone,
The foodstuff according to claim 1 or 2, wherein the peak area of vanillin when the aroma component is analyzed by gas chromatography is 1.5 times or more and 10 times or less that of acetophenone. 4. The method according to any one of claims 1 to 3, wherein a rate of change in the sugar content/magnesium ion concentration value of the concentrated liquid compared to the sugar content/magnesium ion concentration value of the raw material liquid is 5% or less. Groceries as stated. The food product according to any one of claims 1 to 4, wherein the raw material liquid is at least one selected from the group consisting of maple sap, birch sap, and coconut liquid endosperm. A raw material liquid concentration system for producing the food product according to any one of claims 1 to 5,
a heating unit that heats the raw material liquid to 30° C. or higher and 80° C. or lower;
a vacuum distillation section for distilling and concentrating the raw material liquid by reducing the pressure of the gas phase in contact with the raw material liquid to −80 kPa or less;
A raw material liquid concentration system. 7. The raw material liquid concentration system according to claim 6, wherein the vacuum distillation section is a membrane distillation section having a porous membrane. The raw material liquid concentrating system includes a raw material tank that stores the raw material liquid, the heating unit, the membrane distillation unit that has a porous membrane, and the raw material liquid that is transferred from the raw material tank to the heating unit and the membrane distillation unit. a circulation pump for circulating in the raw material liquid tank by circulating the parts in order,
The membrane distillation section is divided by the porous membrane into a liquid phase section in which the raw material liquid flows and a gas phase section in which the vapor generated from the raw material liquid passes through the porous membrane and diffuses. cage,
At the raw material liquid inflow portion of the membrane distillation section,
The raw material liquid temperature is 30° C. or higher and 80° C. or lower,
The pressure of the gas phase in the membrane distillation unit is reduced to -80 kPa or less,
The raw material liquid concentration system according to claim 7. The raw material liquid concentration system according to claim 7 or 8, wherein the porous membrane is a hollow fiber membrane. At least one porous membrane selected from the group consisting of polysulfone, polyethersulfone, polyethylene, polypropylene, polyvinylidene fluoride, polytetrafluoroethylene, ethylene/tetrafluoroethylene copolymer, polychlorotrifluoroethylene, and the like. 10. The raw material liquid concentration system according to any one of claims 7 to 9, which is composed of a seed resin. A method for producing the food according to any one of claims 1 to 5 using the raw material liquid concentration system according to any one of claims 6 to 10,
a heating step of heating the raw material liquid in the heating unit;
a concentration step of circulating the heated raw material liquid through the vacuum distillation section and concentrating it by vacuum distillation;
A method, including 12. The method according to claim 11, wherein the contact portion of the heating portion with the raw material liquid is 90[deg.] C. or less. The method according to claim 11 or 12, wherein the heating unit is a heat exchanger that circulates a heat medium that is steam at 50°C or higher or hot water at 50°C or higher. A method according to any one of claims 11 to 13, wherein the heating section utilizes waste heat. Claims 11 to 11, further comprising an additional concentration step of circulating the concentrated raw material liquid through an evaporator after the concentration step, wherein the temperature of the raw material liquid in the additional concentration step is equal to or higher than the temperature of the raw material liquid in the concentration step. 15. The method of any one of 14. The method according to any one of claims 11 to 15, further comprising a preconcentration step of preconcentrating the raw material liquid with a reverse osmosis membrane. The method according to any one of claims 11 to 16, further comprising a filtration step of filtering the raw material liquid with a filtration membrane to remove impurities, and subjecting the filtered raw material liquid to the concentration step. 18. The method of claim 17, wherein the filtration membrane has a pore size of 20 [mu]m or less. 19. The method of claim 18, wherein the filtration membrane has a pore size of 1.0 [mu]m or less. A method according to any one of claims 17-19, wherein the filtration membrane is arranged in a cross-flow arrangement. The method according to any one of claims 17 to 20, further comprising a backwashing step of backwashing the filtration membrane. 22. The method according to any one of claims 17 to 21, wherein the concentration step and the filtration step are performed in independent raw material liquid flow paths. The vacuum distillation section is a membrane distillation section having a porous membrane, and the step of removing the raw material liquid adhering to the porous membrane by passing water through the porous membrane is performed at least once a day. A method according to any one of claims 11 to 22, wherein Any one of claims 11 to 23, wherein the step of removing membrane contaminants adhering to said porous membrane by passing a chemical solution of pH 5 or lower or pH 9 or higher through said porous membrane is performed at least once a week. or the method described in paragraph 1.

Images