JP3037403B2 - Vacuum continuous concentration equipment for liquid edible food - Google Patents

Description

Description: BACKGROUND OF THE INVENTION The present invention relates to an apparatus for continuously reducing the pressure of liquid edibles under reduced pressure, and in particular, continuously irradiating liquid edibles such as fruit juice and milk by microwave irradiation under reduced pressure. It relates to an apparatus for concentrating.

(Prior Art) Japanese Utility Model Publication No. 63-12720 discloses an electromagnetic heating boiler, which comprises an upper inlet for introducing a sugar solution, a steam outlet, and a take-out of the boiled sugar solution. Mouth and
A cylinder provided with a rotor to which a scraper sliding on an inner wall is hinged, the cylinder being made of a magnetic material, an insulator mounted on an outer wall of the cylinder, and an insulator mounted on an outer periphery of the insulator And an excitation coil for generating an alternating magnetic flux, and a housing enclosing the outside of the excitation coil and made of a magnetic material. As a method of heating food using microwaves, there is a method disclosed in Japanese Patent Publication No. 54-36659. According to this method, the temperature of the atmosphere in the heating chamber is raised in advance by hot air from a hot air generator. After the heating, the food to be heated is introduced into the heating chamber, and microwave heating is performed in the heating chamber. Furthermore, in Japanese Patent Publication No. 60-33469,
A paste or powdered food drying apparatus is disclosed. According to the apparatus, a paste or powdered food is accommodated in a closed container, and the inside of the container is depressurized and irradiated with microwaves. In this case, the dielectric heating is performed at a low temperature (40 ° C. or less) and for a short time.

(Problems to be Solved by the Invention) In the case of concentrating a sugar solution containing a reducing sugar such as fructose or glucose as a main component, such as fruit juice as a liquid edible substance, it is disclosed in Japanese Utility Model Publication No. 63-12720. When the apparatus is used, the sugar solution is liable to be browned due to excessive heating due to the contact with the cylinder, and thus, although it can be concentrated, the quality is significantly deteriorated. In order to prevent this deterioration, it is conceivable to set the temperature of the heating cylinder low, but in this case, the processing amount per unit time significantly decreases, while in order to increase the processing amount, the cylinder is made thicker. It is necessary to increase the length of the apparatus, and as a result, the size of the apparatus is increased, and the equipment cost is increased.

According to the apparatus disclosed in the above-mentioned Japanese Patent Publication No. 54-36659, the microwave treatment is performed under the atmospheric pressure. Therefore, the present invention is applicable to the application of the present invention to the concentration of liquid edible food to be treated. Is impossible. Incidentally, the above-mentioned Japanese Patent Publication No. 60-33
The apparatus disclosed in the 469 gazette is mainly for drying paste-like or powdery food by microwave treatment under reduced pressure, and since a belt conveyor is provided in a closed container, However, there is a problem in that the apparatus becomes complicated as a whole.

(Means and Actions for Solving the Problems) According to the present invention, the above-mentioned problems are solved by a closed container, an introduction pipe for feeding liquid edible material into the closed container, and a heating mechanism for concentrating the liquid edible material. And, a continuous concentrating device for liquid edibles, comprising a suction mechanism for discharging steam generated by heating and making the inside of the closed vessel in a reduced pressure state, and a discharge mechanism for sending out concentrated liquid edibles, A gutter-shaped chute in which the liquid edible material sent into the closed container naturally flows down, the gutter-shaped chute is made of a microwave-permeable material, and the heating mechanism is a microwave generator, The problem is solved by a continuous apparatus for reducing the concentration of liquid edibles under reduced pressure, which has at least one irradiation port for irradiating microwaves to the liquid edibles flowing down the chute chute.

In the reduced-pressure continuous concentrator according to the present invention, the suction mechanism is preferably a vacuum pump capable of reducing the pressure inside the closed vessel to 1,000 to 20,000 Pa. Because, if the inside of the closed container is maintained at such a reduced pressure, the boiling point of the water becomes the browning temperature of the edible food when the liquid edible food is heated by microwave energy to evaporate water. Can be effectively suppressed
Under an excessively reduced pressure of less than 00 Pa, glow discharge or corona discharge may occur in a closed container due to microwave energy, whereas under a reduced pressure of 20,000 Pa or more, the effect of reduced pressure contributing to concentration becomes low. It is. The above-mentioned gutter-shaped chute is advantageously formed in a three-dimensional shape from the viewpoint of effectively utilizing the volume in the closed vessel, and is preferably, for example, a cascade chute or a spiral chute.

(Examples, etc.) Next, specific embodiments of the device according to the present invention will be described with reference to the drawings, and test examples in which liquid edible substances are concentrated using the device according to the embodiment will be described. The effect provided by the device of the present invention will be clarified.

FIG. 1 shows an outline of an embodiment of a continuous vacuum concentration apparatus according to the present invention for liquid edible food. The apparatus 10 includes a closed container 12 in the form of a tank. The container is connected to a vacuum pump 16 through a pipe 14, and the inside thereof is evacuated to a pressure of 1000 to 20000 Pa. Closed container 12
The constituent material of the present invention is not particularly limited as long as it is a metallic material that reflects microwaves, but stainless steel is preferable from the viewpoint of rust prevention and corrosion resistance. In addition, the above vacuum pump
Since 12 is used for exhausting a gas containing a large amount of water vapor as described later, it is preferably a water ring type or an ejector type.

The liquid edible food LF is sent from the storage tank 18 through the feed pump 20 and the needle valve 22 to the inside of the closed container 12 through the introduction pipe 24 attached to the closed container 12. The flow rate of the liquid edible LF can be changed by adjusting the opening of the needle valve 22 or controlling the rotation speed of the feed pump 20. The liquid edible LF sent into the closed container 12 through the introduction pipe 24 falls into the gutter-shaped chute 26. The gutter-like chute 26 in the embodiment shown in FIG. 1 includes a plurality of U-shaped unit bodies 261 shown in FIG.
This is a so-called “cascade chute” attached to 63b in an inclined state and alternately in the opposite direction. Note that the gutter-shaped chute may be configured as a spiral chute 26A as shown in FIG. In this spiral chute 26A, a gutter-like body 261A is wound around and fixed to a cylindrical column 263A.

A microwave generator 28 as a heating mechanism is installed on the body of the closed container 12. The microwave generator 28 includes an oscillator 281 and a waveguide 283. The irradiation port 285 is provided with a glass plate 285a having a small microwave loss.
It separates 28 waveguides 283. The microwave is irradiated into the closed container 12 through the above-mentioned irradiation port 285, and is absorbed by the liquid edible material flowing naturally in the gutter-shaped chute 26 (26A), thereby causing the liquid edible material to be concentrated. Since the types of liquid edible foods to be prepared vary widely, including various juices and milk products such as milk, the oscillator 281 has the ability to oscillate 896 MHz, 915 MHz and 2450 MHz microwaves alone or in combination. It is preferable that it is. Since the spread angle of the microwave irradiated from one microwave generator 28 is about 60 degrees, a plurality of microwave generators can be installed when the entire length of the sealed container 12 is long. [Two (28, 28A) are provided in the embodiment shown in FIG. 1].

The above-mentioned gutter-like chute 26 (or 26A) including the columns (263a, 263b, and 263A) is made of a material that transmits microwaves, has a small microwave attenuation rate, and has heat resistance. It is important that the gutter-shaped chute main body 261 (261A) into which the liquid edible material flows is made of a material further having a property that the liquid edible material to be treated hardly adheres and remains. Examples of such a material include a tetrafluoroethylene resin, a polyethylene resin, a polypropylene resin, and the like, and particularly, a tetrafluoroethylene resin is preferable.

Liquid edible food to be treated is gutter chute 26 (26A)
In the process of flowing down naturally from the upper part to the lower part, it receives microwave irradiation, absorbs its energy and evaporates water to concentrate to the desired concentration, but as the concentration increases, the viscosity increases. The increased flow can reduce fluidity, which can result in the absorption of excessive microwave energy and an overheating condition. In order to prevent such a situation from occurring, the unit shown in FIG.
The inclination angle of 261 is set to be larger from the upper part to the lower part, and in the embodiment shown in FIG. 3, the winding pitch of the gutter-shaped spiral chute 261A is set to be gradually larger at the lower part than at the upper part. As a result, even if the viscosity increases with the increase in the concentration due to the microwave treatment, the liquid edible material naturally flows down at a substantially constant flow rate.

The liquid edible material, which has been irradiated with microwaves while flowing down the gutter-shaped chute as described above and concentrated to a predetermined concentration by evaporating water, flows into the discharge pipe 30 and passes through the pipe to form a closed container. And then cooled.

Since the closed container 12 is connected to the vacuum pump 16 via the pipe 14 as described above, the vapor generated from the liquid edible material in the gutter-shaped chute inside the closed container is supplied to the pipe 14 and the vacuum. Although the steam is forcibly discharged to the outside via the pump 16, a part of the steam touches the inner wall of the closed container, cools and condenses, drops as water droplets, and naturally flows down the gutter-shaped chute 26 (26A). The concentration of the liquid edible being concentrated may be reduced. To prevent this, although not shown, the closed container is formed into a double-walled structure, and hot water flows between the inner wall and the outer wall, or an electric heater is provided to lower the surface temperature of the inner wall by 70%. Measures such as heating to about ° C can be taken.

Preliminary test example The first test was performed on apple juice with a moisture content of 29.5% by weight.
A concentration test was performed using the apparatus as shown in the figure.

This preliminary test was carried out in the same manner as in Test Example 1 described below, but for examining the effect of the pressure in the closed vessel, and therefore, the pressure was set to various values. The wavelength of the irradiated microwave was 2450 MHz, and the microwave irradiation output was set to 6.5 kW.

The results of examining the degree of browning of each of the obtained samples in the same manner as in Test Example 1 described below are as shown in Table 1 below. When the pressure in the closed container was set at 1000 to 10,000 Pa, the browning was almost eliminated. It has been found that apple juice can be concentrated without producing it.

Test Example 1 For apple juice having a water content of 29.5% by weight,
A concentration test was performed using the apparatus as shown in the figure.
The pressure in the sealed container was 3500 Pa, the wavelength of the irradiated microwave was 2450 MHz, and the microwave irradiation output was 2.5 and 4.
By setting to 6 and 6.5KW, the moisture content is 18.9,
10.0 and 20% by weight concentrates were obtained, respectively. At this time, the flow rate of the juice was 190 ml / min, and the time required to pass through the gutter-shaped chute was 15 sec. The temperatures of these concentrates were 55, 70 and 110 ° C., respectively. these,
Each was poured into a transparent container having a radius of 3 cm and a height of 1 cm, and allowed to cool to room temperature. Then, the containers were placed on white paper to obtain test samples (samples A, B, and C).

For each of these samples, an expert panel consisting of 30 persons visually checked the degree of browning in the samples using the following evaluation criteria as guidelines.

 0: no browning is observed; 1: slight browning is observed; 2: considerable browning is observed.

The average value of the evaluation points given by the panelists was calculated and expressed as the degree of browning in the sample, as shown in Table 2 below. Using the apparatus of the present invention, the juice was almost completely prevented from browning. It has been found that it can be concentrated to a high concentration.

Test Example 2 A milk milk having a water content of 88.7% by weight, as shown in FIG. 1, except that the gutter-shaped chute is not of a cascade type but of a spiral type as shown in FIG. A concentration test was performed using a certain apparatus. The pressure in the sealed container is 1000 Pa, the wavelength of the irradiated microwave is 915 MHz, and the microwave irradiation output is 2.5 and 4.6 KW
, Yielded concentrates with a water content of 78.1 and 69.2% by weight, respectively. At this time, the flow of city milk is 300m
l / min, and the time required to pass through the gutter chute was 15 sec. The temperature of these concentrates is 46 and 48 ° C
Met. Each of these is poured into a transparent container having a radius of 3 cm and a height of 1 cm, and is allowed to cool to room temperature.
Place the container on a piece of white paper and test samples (Samples D and E)
And

The browning degree of each of these samples was examined in the same manner as in Test Example 1. The results are as shown in Table 3 below, and it was found that using the apparatus of the present invention, milk could be concentrated to a considerable extent with almost no browning.

(Effect of the Invention) In the case of heating and concentrating natural fruit juice or the like having a high content of organic acids, reducing sugars, amino acids, etc., if a conventional apparatus is used, intramolecular condensation of the reducing sugar occurs during heating and browning easily occurs. However, the degree of browning can be significantly reduced by using the apparatus of the present invention.

The device of the present invention can be applied to concentration of various liquid edible foods including milk products such as milk in addition to fruit juice, and at that time, the degree of browning generated in the concentrate can be remarkably suppressed.

According to the apparatus of the present invention, since the liquid edible material is subjected to the microwave irradiation while flowing naturally through the gutter-shaped chute arranged in the decompression container, the concentration treatment is continuously performed. In this case, the product temperature can be set relatively low, and the required processing time is relatively short.

[Brief description of the drawings]

FIG. 1 is an elevation view showing an outline of an embodiment of a continuous decompression apparatus for liquid edible food according to the present invention, in which a main part is shown in cross section, and FIG. 2 is FIG. FIG. 3 is an enlarged perspective view of a unit constituting a cascade-type gutter-shaped chute shown therein, and FIG. 3 is a perspective view of a spiral-type gutter-shaped chute. 10 ………………………………………………………. Inlet pipe for liquid edible food into container, 26… Gutter chute (cascade type), 26A… Gutter chute (spiral type), 28… Microwave generator (heating mechanism), 281… Oscillator, 283 …… Waveguide, 285… Irradiation port, 285a …… Glass plate for partitioning, 30 …… Concentrate discharge pipe (discharge mechanism), LF …… Liquid edible food

──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Takushi Goto Saitama Pref. 5-4-5 Hachiman, Kawashima-cho, Hiki-gun, Saitama Prefecture (72) Inventor Junichi Mikami 2109 Furuyagami, Oji, Kawagoe-shi, Saitama (56) References JP-A-3-216154 (JP, A) JP-A-54-110369 JP, A) JP-A-50-94150 (JP, A) JP-B-40-9125 (JP, B1) JP-B-29-9793 (JP, B1) (58) Fields investigated (Int. Cl. ⁷ , (DB name) A23L 2/10 A23C 1/12 B01D 1/00 B01D 1/30

Claims (3)

(57) [Claims] 1. An airtight container, an introduction pipe for feeding liquid edible material into the airtight container, a heating mechanism for concentrating the liquid edible material, a steam generated by heating is discharged, and the pressure in the airtight container is reduced. A continuous concentration apparatus for liquid edible food, comprising a suction mechanism and a discharge mechanism for sending out concentrated liquid edible food, wherein a gutter-shaped chute in which liquid edible food sent into a closed container flows down naturally. And the gutter-shaped chute is made of a microwave-permeable material, and the heating mechanism is a microwave generator, for irradiating microwaves to the liquid edible material flowing down the gutter-shaped chute. An apparatus for continuously reducing the pressure of a liquid edible substance, comprising at least one irradiation port. 2. The inside of the closed container is suctioned by a suction mechanism of 1000-20000P.
The vacuum concentrating apparatus for liquid edible foods according to claim 1, which is a vacuum pump capable of reducing the pressure in a. 3. The apparatus for continuously concentrating liquid edibles under reduced pressure according to claim 1, wherein the gutter-shaped chute is selected from a cascade chute and a spiral chute.