JPH06170107A - Freezing and concentrating method of high water-content material and apparatus thereof - Google Patents

Abstract

PURPOSE:To obtain ice crystal with high purity which is easy to be separated with pressure as low as possible by providing not only pressure but also energy to high water-content material in supercooled state. CONSTITUTION:A high water-content material is sealed in a container 6 and put in a crystallization apparatus 1, which is like a pressure container. Since the crystallization apparatus 1 is cooled in a cooling jacket 17, the high water- content material becomes in supercooled state. The crystallization apparatus 1 is filled with an isostatiac medium and further the isostatic medium at the temperature higher than that of the high water-content material is introduced into the apparatus by a high pressure pump 15. When the temperature of the isostatic medium exceeds the temperature of the high water-content material, the material is released from the pressure applied to it. Consequently, the high water-content material is released from the supercooled state and freezed to become granular ice crystal and then the ice crystal is grown.

Description

Detailed Description of the Invention

[0001]

The present invention relates to liquid foods, cosmetics,
Alternatively, the present invention relates to a method and an apparatus for concentrating a high-moisture material such as a pharmaceutical product, and in particular, a freeze-concentration method and a method for concentrating it by partially freezing the high-moisture material and separating only water therein as ice. It relates to the device.

[0002]

2. Description of the Related Art There are various methods for concentrating a material containing a large amount of water, and a freeze concentration method is known as one of them. When water becomes ice, it has the property of removing impurities and freezing. The freeze concentration method utilizes such a property of water to concentrate the high-moisture content material. In that method, the high moisture material is partially frozen and the solvent water is made into pure ice crystals. Therefore, when the ice is separated, the high moisture material is concentrated. Such a freeze concentration method is characterized in that microbial contamination, deterioration of solute, and dissipation of volatile aromatic components can be suppressed to an extremely low level. Therefore, it is considered to be the most ideal method for concentrating high-grade foods, cosmetics, or pharmaceuticals that emphasizes nutritional components, colors, aromas, flavor components, and the like.

The present inventors have made extensive studies on such a freeze concentration method, and previously proposed a new freeze concentration method and apparatus for a high water content material (Japanese Patent Application No. 4-108380).
issue). The freeze concentration method is as follows: 1) First, preliminarily precooled high-moisture material is enclosed in a flexible container, and the container is placed in a crystallizer filled with a static pressure medium. Then, the crystallizer is cooled by a refrigerant, and the high moisture material is brought into a supercooled state via the static pressure medium. 2) Next, a static pressure medium is further injected into the crystallizer by a high-pressure pump to apply static pressure to the supercooled high-moisture material, and then the static pressure is removed. As a result, the supercooled state of the high-moisture material is destroyed, and the high-moisture material is partially frozen. The state is maintained for an arbitrary time, and ice is grown under normal pressure. 3) Then, apply static pressure to the high-moisture material again to partially thaw the ice. Then, the ice crystals become particles. 4) Then, remove static pressure and grow ice again at normal pressure. This gives a large granular ice that is easy to separate. 5) Finally, separate the ice. That is.

[0004]

However, in the case of this freeze concentration method, the supercooled state of the high-moisture material is destroyed only by static pressure to partially freeze the high-moisture material. There is a problem in that a high static pressure is required in the step of forming the. For example, the temperature of the refrigerant, that is, the temperature of the high-moisture material in the supercooled state is set to -2 to -15
When it is set to ℃, 100 to 1 to destroy the supercooling.
A pressure as high as 500 kg / cm ² is required. According to experiments, when freeze-concentrating a 3% concentration coffee liquid, the refrigerant temperature is-
At 4 to -5 ℃, 700 to freeze
A pressure of kg / cm ² was required. Further, when the supercooling is destroyed by freezing only by such static pressure and frozen, the obtained ice nucleus crystals are needle-shaped. Therefore, in the freeze concentration method described above, it is necessary to apply static pressure again to the frozen high moisture content material and partially thaw the ice. Further, a high static pressure is required even in the thawing process. For example, when freeze-concentrating a 3% strength coffee liquid,
When the refrigerant temperature was set to -4 to -5 ° C, the pressure of 700 kg / cm ² was still required for the pressure thawing.

The present invention has been made in view of the above problems, and an object thereof is a method for freeze-concentrating a high-moisture material capable of obtaining pure ice crystals which can be easily separated by using a pressure as low as possible. And to provide a device.

[0006]

To achieve this object, the present invention destroys the supercooled state by applying not only pressure but also temperature energy to the high-moisture content material in the supercooled state. I am trying to do it. That is, the method for freeze-concentrating a high-moisture material according to the present invention is described in Japanese Patent Application No.
In the freeze concentration method of No. 108380, the static pressure medium that applies static pressure to the high-moisture material in the supercooled state by press-fitting it into the crystallizer is more than the temperature of the refrigerant that keeps the high-moisture material in the supercooled state. Is controlled to a high temperature, and when the temperature of the static pressure medium in the crystallizer becomes higher than the temperature of the high moisture material, the static pressure is removed to destroy the supercooled state of the high moisture material. The high moisture material is characterized by being partially frozen. After the freezing, ice crystals are grown by atmospheric pressure freezing with the ice generated by the freezing as a nucleus. In that case, the magnitude of static pressure applied to the supercooled high-moisture material is 10 to 100 kg / cm ²
The range is. Further, the freeze-concentrator for a high-moisture material according to the present invention is the freeze-concentrator of Japanese Patent Application No. 4-108380 mentioned above, in which a pipe for introducing a static pressure medium into the crystallizer,
A medium temperature control jacket for controlling the temperature of the static pressure medium is provided, and a medium temperature detector and material for detecting the temperature of the static pressure medium and the high-moisture material in the crystallizer are provided in the crystallizer. And a temperature detector are provided.

[0007]

In this way, the static pressure medium controlled to a temperature higher than the temperature of the refrigerant is fed into the crystallizer, and the static pressure is removed after the static pressure is applied to the supercooled high-moisture material. By doing so, it becomes possible to destroy the supercooled state even with a low static pressure. And, since the ice generated by releasing the supercooled state in this way becomes a particulate crystal, the ice grown at room temperature with it as a grain is granular and has a very low solute content. Become. The reason why the supercooled state is destroyed by such a low static pressure cannot be properly explained at present, but the following may be considered. That is, since the temperature of the static pressure medium and the high-moisture material is changed by applying the static pressure, the application of the static pressure raises the temperature of each of the static pressure medium and the high-moisture material in the supercooled state. Is estimated to act as energy for That is, since the static pressure medium and the high-moisture material change in volume (dv) due to compression (pressure P), the added work W is W = ∫P · dv, which is an increase in internal energy. Therefore, W = C
_The temperature rises by ΔT represented by _P · M · ΔT (C _P is the specific heat of the liquid, M is the weight of the liquid). On the contrary, when the static pressure is released, the temperature decreases by ΔT. Then, since the temperature of the static pressure medium around the high-moisture material increases due to the application of the static pressure, and the temperature of the static pressure medium decreases due to the release of the static pressure, the high-moisture material and the static pressure medium Due to the transfer and transfer of heat to and from, it is possible to send a static pressure medium controlled to a temperature higher than the temperature of the refrigerant that cools the high-moisture material into the crystallizer, in order to apply a small static pressure. It is assumed that they will be linked. At the moment when the supercooling of the high-moisture material in the supercooled state breaks, the temperature of the high-moisture material in the negative temperature rises to around 0 ° C., and it can be judged by monitoring the temperature. It has been confirmed by the method that the supercooled state is destroyed even if the static pressure is low as described above.

[0008]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a vertical side view showing an embodiment of a crystallizer used in a freeze concentration apparatus according to the present invention. As is clear from this figure, this crystallizer 1 comprises a thick-walled cylindrical main body 2 whose upper end is open and whose lower end is closed by a bottom wall. At the upper end opening of the crystallizer main body 2, a material extraction cap 4 fixed to the main body 2 by tightening a ground nut 3 is provided. An O-ring 5 is attached to the outer peripheral surface of the material extraction cap 4, and the O-ring 5 liquid-tightly seals between the crystallizer main body 2 and the material extraction cap 4. . The crystallizer 1 is thus formed as a pressure vessel which is sealed by the material extraction cap 4. On the lower surface of the material take-out cap 4, the cap 4
A material container 6 which is inserted into the internal space of the crystallizer main body 2 when the upper end opening of the crystallizer main body 2 is closed is attached. The material container 6 is a thin pipe made of tetrafluoroethylene resin or the like, and rubber stoppers 7, 8 are provided at both upper and lower ends.
Each is sealed by. The upper rubber stopper 7 is fixed to the lower surface of the material extraction cap 4 by adhesion or the like. Therefore, by fitting the rubber stopper 7 to the upper end of the material container 6, the material container 6 can be attached to the material take-out cap 4. The material container 6 divides the inside of the crystallizer main body 2 into two chambers inside and outside the material container 6. The inside of the material container 6 becomes a material storage chamber 9 in which a high moisture material is stored, and the outside becomes a static pressure medium chamber 10 into which a static pressure medium is introduced. Since the side wall of the material container 6 is easily deformed,
The volumes of these two chambers 9 and 10 are variable.

A material temperature measuring thermocouple 11 as a temperature detector for the high moisture material is attached to the material take-out cap 4. The thermocouple 11 penetrates the material take-out cap 4 and the upper rubber stopper 7 and projects into the material storage chamber 9 inside the material container 6. In this way, the temperature of the high-moisture material in the material container 6 is measured from outside the crystallizer 1. On the other hand, at the bottom of the crystallizer main body 2, a medium temperature measuring thermocouple 12 as a temperature detector for the static pressure medium is attached so as to penetrate the bottom wall thereof. The thermocouple 12 extends to the vicinity of the material container 6 arranged in the crystallizer main body 2, and the thermocouple 12 causes the temperature of the static pressure medium near the material container 6 to be outside the crystallizer 1. It is supposed to be measured from. Further, on the upper part of the crystallizer main body 2, a pressure gauge 13 for detecting the pressure inside the main body 2 is attached.
A pressure pump pipe 14 that communicates with the static pressure medium chamber 10 inside the crystallizer main body 2 is further connected to the lower portion of the crystallizer main body 2. At the tip of the pressure pump pipe 14, the high pressure pump 1
5 are connected, and the pressure pump 15 introduces a static pressure medium such as ethanol into the static pressure medium chamber 10 under pressure to apply a static pressure to the crystallizer main body 2. A medium temperature adjusting jacket 16 for controlling the temperature of the static pressure medium introduced into the static pressure medium chamber 10 in the crystallizer main body 2 is provided in the middle of the pressure pump pipe 14 connecting the pressure pump 15 and the crystallizer main body 2. Is provided.

A cooling jacket 1 is provided on the outer periphery of the crystallizer main body 2.
7 is provided. The cooling jacket 17 has a refrigerant inlet 18 and a refrigerant outlet 19, and the temperature inside the crystallizer main body 2 is controlled by circulating the refrigerant through the inlet 18 and the outlet 19. The freeze concentrator is constituted by such a crystallizer 1 and high-pressure pump 15 as well as a precooler for precooling the material and a separator for separating the concentrated liquid and ice. Since the container and the separator may be ordinary ones, the description thereof will be omitted here.

Next, the procedure for concentrating the high-moisture content material using the freeze concentrating device thus constructed will be described together with its operation. For example, when concentrating the solution, the solution is previously cooled to 2 to 0 ° C. using a precooler. Then, the solution is put into a material container 6 whose lower end is sealed with a rubber stopper 8. At this time, prevent bubbles from entering the solution. Then, the upper end of the material container 6 is fitted into the rubber stopper 7 fixed to the material take-out cap 4 and sealed. Thereby, the material container 6 is attached to the material take-out cap 4. On the other hand, the inside of the crystallizer main body 2 is filled with a static pressure medium such as ethanol having a low freezing temperature. In addition, the cooling jacket 17 of the crystallizer 1
Circulate a refrigerant of -2 to -15 degrees Celsius, and
Keep at 2 to -15 ° C. And the crystallizer body 2
The material take-out cap 4 to which the material container 6 is attached is attached to the upper end opening of the, and the gland nut 3 is tightened to seal.

When the material container 6 is set in the crystallizer 1 kept at a low temperature below the freezing point in this way, the solution enclosed in the material container 6 is gradually cooled. Therefore, the solution is in a supercooled state. Therefore, when the temperature of the solution detected by the material temperature measuring thermocouple 11 becomes −0.5 to −10 ° C., a static pressure medium is injected into the crystallizer main body 2 by using the high pressure pump 15, and Increase the internal pressure to 10-100 kg / cm ² . At this time, room temperature water is circulated through the medium temperature control jacket 16 to keep the static pressure medium introduced into the crystallizer main body 2 at room temperature. That is, the temperature of the static pressure medium is set higher than the temperature of the refrigerant supplied to the cooling jacket 17. When the pressure in the crystallizer main body 2 is increased, the material container 6 arranged inside is compressed, and a static pressure is applied to the solution in the material container 6. Then, when the temperature of the static pressure medium detected by the medium temperature measuring thermocouple 12 becomes higher than the temperature of the solution detected by the material temperature measuring thermocouple 11, the high pressure pump 15 is set free and the crystallizer The pressure inside the body 2 is released. Then, the solution in the material container 6 in the supercooled state is released from the supercooled state by the energy of the applied pressure and temperature. Therefore, the solution freezes rapidly and ice crystals are produced. When ice is generated, the temperature of the material temperature measuring thermocouple 11 is 0 ° C. due to the heat generated by the ice. Therefore, the ice is aged for 10 to 60 minutes. In this way, the ice crystals produced when the supercooled solution is forcibly destroyed by applying energy of low pressure and temperature of 100 kg / cm ² or less to the supercooled solution are not needle-like particles. It has a shape close to. Therefore, the ice crystal grown with the ice crystal as a nucleus becomes granular.

After the ice has grown in this way, the gland nut 3 is loosened, and the material extraction cap 4 is removed from the crystallizer main body 2. Further, the material container 6 attached to the material extraction cap 4 is pulled out from the rubber stopper 7, and the suspension of the concentrated liquid and the ice crystals in the material container 6 is transferred to a separator. Then, it is filtered and washed to separate it into a concentrated liquid and ice crystals. In this case, since the produced ice crystals are granular as described above, the concentrated liquid rarely adheres to the ice crystals. Therefore, the separation is extremely efficient.

Thus, according to this freeze concentration method,
A granular ice crystal containing no concentrate can be obtained by simply removing the supercooled state of the solution, partially freezing the solution, and growing the ice. Moreover, the ice crystals, which become the ice nuclei, are generated by applying energy of a low pressure and temperature of 10 to 100 kg / cm ² to the supercooled solution. Therefore, the high-pressure pump 15 or the like having a small capacity can be used, and its operation becomes easy. Further, since granular and large ice crystals are obtained, the concentrated liquid can be easily separated by simple filtration, washing and the like. Therefore, the separation efficiency between the ice crystals and the concentrated liquid can be significantly increased. Further, according to the freeze-concentrator, only high pressure and temperature energy are applied to the supercooled solution in the crystallizer 1 by the high-pressure pump 15 and the medium temperature control jacket 16, so that ice crystals can be prevented from being destroyed in the supercooled state. Therefore, the apparatus for carrying out the freeze concentration method described above can be made extremely simple.

[0015] Such a freeze concentration device was actually prototyped,
The concentration experiment was conducted using it. A coffee liquid prepared by dissolving commercially available instant coffee in distilled water was used as the material to be concentrated. Then, in order to measure the coffee concentration in the ice crystals, first, the absorbance of coffee liquid of various concentrations was measured by a spectrophotometer, and a calibration curve of the coffee liquid concentration and the absorbance was obtained. The concentration of coffee liquid is proportional to the absorbance value, and the higher the concentration, the higher the absorbance. A coffee liquid having a concentration of 3% was prepared as a concentrated raw material. The crystallizer main body 2 had an inner diameter of 30 mm and a length of 250 mm, and the material container 6 was a tube of tetrafluoroethylene resin having a diameter of 20 mm and a length of 170 mm. A 50% ethanol solution was used as the static pressure medium, and the ethanol solution was filled in the crystallizer main body 2. On the other hand, a 30% ethylene glycol liquid was used as the refrigerant, and the cooling jacket 17 was circulated at a flow rate of 17 liters per minute. The temperature of the refrigerant is -4
The temperature was set to -5 ° C, and the crystallizer 1 was kept at -4 ° C or -5 ° C by circulating in advance. Also,
Water at room temperature was circulated through the medium temperature control jacket 16 provided in the pressure pump pipe 14.

Under such preparations, the concentrated 3% coffee liquid was precooled to 0.5 ° C. in advance, and the coffee liquid was placed in the material container 6 stoppered with the rubber stopper 8. The amount was about 45 g. Then, the material container 6 was set in the crystallizer 1 filled with the ethanol solution.
Then, the temperature change of the coffee liquid was monitored by the thermocouple 11 for measuring the material temperature, and the temperature change of the static pressure medium was monitored by the thermocouple 12 for measuring the medium temperature. When the thermocouple 11 for measuring the material temperature showed -0.5 to -4.5 ° C,
The ethanol solution was pressed into the crystallizer 1 using the high-pressure pump 15 to increase the pressure in the crystallizer 1 to 10 to 100 kg / cm ² . Then, when the medium temperature measuring thermocouple 12 showed a temperature higher than that of the material temperature measuring thermocouple 11, the pressure was rapidly released to bring the inside of the crystallizer 1 to atmospheric pressure. At this time,
The time from pressure increase to pressure release was about 20 seconds. 10
After about 40 minutes, the material container 6 is taken out, the material in the container is transferred to a separator, and suction filtration is performed with the separator.
It was washed with 10 ml of distilled water at 0 ° C. Thus
Separated into ice crystals and concentrated solution. Then, the absorbance of the obtained ice was measured. For comparison, 300 kg / cm ² and 700 kg / c were stored in the crystallizer 1 by the high-pressure pump 15.
A similar experiment was carried out by applying a pressure of m ² to forcibly break the supercooled state of the solution contained in the crystallizer 1 to freeze it.

As a result, it was found that the lower the static pressure applied to the crystallizer 1, the lower the absorbance of the obtained ice crystals, that is, the coffee concentration in the ice crystals. Specifically, when the static pressure is 700 kg / cm ² and the atmospheric pressure freezing time is 30 minutes, the coffee concentration in the obtained ice crystals is 0.2 to 0.3%, and the freezing for 40 minutes is performed. 0.3 to 0.45% when allowed to run, 0.5 for 50 minutes
It was a big value such as ~ 0.65%, but 300kg / cm ²
When the supercooled state is forcibly destroyed by the application of the static pressure of, the freezing time is 0.06 to 0.1 when the freezing time is 30 minutes.
When the static pressure was 100 kg / cm ² and the supercooled state was forcibly destroyed, the coffee concentration in the obtained ice crystals was around 0.05% after freezing for 30 minutes. A low coffee concentration in an ice crystal means that the ice crystal is nearly pure. Therefore, it can be said that the lower the coffee concentration in the obtained ice crystals was, the more efficiently only the water was separated from the coffee liquid. In this way, by destroying the supercooled state by using the low pressure, it is possible to obtain ice of significantly superior quality as compared with the case of destroying the supercooled state by using the high pressure, and the high moisture material It is possible to remarkably increase the separation efficiency.

In the above embodiments, the freeze concentration device was described as a laboratory device, but in industrial implementation, for example, a large number of material containers are installed in one crystallizer, and at the same time, a large amount of material is prepared. Needless to say, the material is processed, and the pre-cooling and the separation are continuously performed. It is also conceivable that a large number of crystallizer main bodies 2 partitioned by pistons into two chambers are used, and a static pressure medium is simultaneously injected under pressure into the one chamber.

[0019]

As is apparent from the above description, according to the present invention, energy of pressure and temperature is applied to a super-moisture material in a supercooled state. The supercooled state can be destroyed to freeze the high moisture material. Moreover, since the ice produced at that time is in the form of particles, the ice grown by using it as nuclei becomes granular crystals. Therefore, the separation efficiency between the ice crystals and the concentrated liquid is increased, and the cost for the separation can be significantly reduced.

[Brief description of drawings]

FIG. 1 is a vertical side view showing an example of a crystallizer used in a freeze concentration apparatus according to the present invention.

[Explanation of symbols]

 1 Crystallizer 2 Crystallizer main body 6 Material container 9 High moisture material Material storage chamber 10 Static pressure medium chamber 11 Thermocouple for material temperature measurement (material temperature detector) 12 Thermocouple for static pressure medium temperature measurement (medium temperature detection) 15) High-pressure pump 16 Medium temperature control jacket 17 Cooling jacket

Claims (3)

[Claims] 1. A crystallizer is divided into two chambers of variable volume, one chamber is filled with a static pressure medium and the other chamber is filled with a high moisture material, and the crystallizer is cooled. After making the high moisture material into a supercooled state by doing, in the static pressure medium chamber of the crystallizer, the static pressure medium controlled to a temperature higher than the temperature of the refrigerant that keeps the high moisture material in the supercooled state And press static pressure to the high-moisture material in the supercooled state, and when the temperature of the static pressure medium in the crystallizer becomes higher than the temperature of the high-moisture material, remove the static pressure. The method of freezing and concentrating a high-moisture material, which comprises partially freezing the high-moisture material by performing the above, growing ice crystals under atmospheric pressure using the resulting ice as a nucleus, and then separating the ice. 2. The freeze concentration method according to claim 1, wherein the magnitude of static pressure applied to the supercooled high-moisture material is in the range of 10 to 100 kg / cm ² . 3. A freeze concentration apparatus comprising a crystallizer for freezing a high-moisture material and growing ice crystals thereof, and a separator for separating the obtained ice crystals from a concentrated liquid; It is formed as a pressure vessel, and its interior is partitioned into two chambers, a static pressure medium chamber into which a static pressure medium is press-fitted and a high moisture material storage chamber pressurized by the static pressure medium. The pipe for introducing the static pressure medium into the medium chamber is provided with a medium temperature control jacket for controlling the temperature of the static pressure medium, and the crystallizer is provided with the temperature of the static pressure medium in the static pressure medium chamber. A freeze-concentrator for high-moisture material, comprising a medium temperature detector for detecting and a material temperature detector for detecting the temperature of the high-moisture material in the high-moisture material storage chamber.