JPH04126034A - Drying of marine product or the like - Google Patents

Abstract

PURPOSE:To dry marine products, etc., in high quality, efficiently and economically by making heat generating materials arranged in a vacuum chamber into a steam permeable box, coating the outer surface of the box with a thin- layer ceramics and controlling steam temperature at a proper value. CONSTITUTION:In drying a marine product, etc., in vacuum, heat generating materials 2... in a vacuum chamber 1 are made into a steam circulating box (steam feed pipe 3 and drain pipe 4), the outer surface of the box is coated with a thin-layer ceramics 2a and, during drying process, temperature of the steam is automatically controlled at a proper value in an about 160-50 deg.C range in relation to properties of target material or dryness.

Description

[Detailed Description of the Invention] (Field of Industrial Application) The present invention is applicable to the production of edible marine products such as blowfish and conger eel, as well as dried mirin, or to general processed foods such as ham, sausage, dried vegetables, dried fruits, etc. Concerning the drying method applied.

(Prior Art) A vacuum drying method has conventionally existed in which an object to be dried is dried in a vacuum atmosphere by the force generated by a heat generating body provided in a vacuum chamber.

In this case, the heat generating device is generally an electric heater or a heat radiation type device that uses hot water as a heat source and heats the object to be dried by emitting infrared rays, or a heat generating device that uses steam or hot water as a heat source. One of the heat conduction types used as a heat source is used, which mainly uses conduction heat transfer to heat the object to be dried.

When drying marine products such as blowfish and conger eel using such a method, the temperature distribution will be uneven due to the characteristics of each heat source if an electric heater or a heat radiation type heat generator using hot water as the heat source is used. This is unavoidable, and in the case of using a heat-conduction type heat generator using steam as the heat source, heat transfer is by conduction, so uneven drying inevitably occurs and high-quality dried products cannot be obtained. . Furthermore, electric heaters or those that use heat radiation type heat generators that use hot water as a heat source have high running costs due to the high cost of electrical energy; The processing efficiency is poor because the heat transfer rate is slow.

For these reasons, when it is desired to produce high-quality dried marine products, the reality is that freeze-drying or cold-air drying, which have been highly reliable in the past, is usually used.

(Problems to be Solved by the Invention) However, the above-mentioned freeze-drying method generally requires high equipment and manufacturing costs, and the cold-air drying method uses cold air at around room temperature, so the drying speed is high. This slows down the process and reduces processing efficiency.

In view of this problem, uninvented products are made with high quality and high quality marine products.
The purpose is to realize a drying method that allows for highly efficient and economical drying.

(Means for Solving the Problems) In order to achieve the above object, the present invention uses a heat generating body in a vacuum chamber as a box body through which steam flows, and the outer surface of the box body is It is coated with a thin layer of ceramic, and during the drying process, the temperature of the air is adjusted to about 1 depending on the properties of the object to be dried or the degree of drying.
It is characterized by automatic control to an appropriate value within the range of 60°C to 50°C.

(Function) The heat generating body is heated by the highly uniformly dispersible steam inside the box, so the entire body has a -like temperature distribution, and as a result, far infrared rays with almost the same characteristics are emitted from the entire ceramic surface. The object to be dried, such as seafood, is heated evenly to the center.

In addition, during the drying process, for example, during the drying period when the moisture content of the object to be dried is high, the temperature of the steam is set to about 15%.
Approximately 0°C (absolute pressure of steam at this time is approximately 5 kg/d)
), and on the other hand, at the end of drying when the moisture content is low, the temperature is set to about 60°C (absolute pressure of steam at this time is about 0.2 kg/cd), which is similar to hot water. If the automatic side door is installed, the object to be dried can be dried with high efficiency while maintaining its own temperature at an appropriate temperature.

Furthermore, since the heat source of the heat generating body is steam, operating costs are lower than those using electric heaters, and drying using steam at a relatively low temperature in a vacuum chamber is advantageous compared to freeze drying. Compared to drying methods that dry at extremely low temperatures, equipment costs and manufacturing costs are lower because there is no need for expensive refrigerators or large amounts of energy to operate them.

(Example) Hereinafter, specific examples of the present invention will be described with reference to the drawings.

1 to 3 show a vacuum drying apparatus used in the present invention, in which FIG. 1 is a system diagram, FIG. 2 is a side view, and FIG. 3 is a partial view.

When carrying out the present invention, a vacuum chamber (the inner tank is, for example, 15
It is set to about 01. ) 1 has a plurality of heat generating bodies 2 and 2 inside it.
...are arranged in a stacked manner.

Each heat generating body 2 has a flat, airtight box shape, and its upper and lower surfaces are coated with a single layer of ceramic 2a as a radiant material.In this case, the object to be dried is seafood such as mirin-boshi. In some cases, the box body is made of stainless steel and coated with zirconia-magnesia as a radiation material. The zirconia-magnesia emits far infrared rays (wavelength 3.5μ to 5.3μ) that exhibits strong permeability to seafood.
It is suitable for emitting radiation.

The internal space of the heat generating body 2 formed in this way has approximately 1
Saturated steam within the range of 60°C to 50°C is allowed to flow. Therefore, in this example, the steam generated in the boiler flows through the steam supply pipe 3 from one side as shown by the arrow f1, and the condensed water in the heat generating body 2 flows from the other side as shown by the arrow f2. The steam supply pipe 3 is provided with a tII1111 valve 5, and the control valve 5 controls the pressure in the drain discharge pipe 4 immediately after the heat generating body 2. One is operated by a pressure contra-PIC-2 which detects and issues an output signal. Therefore, the steam pressure (and the extreme temperature) within the heat generating body 2 can be controlled to an arbitrary constant value. In addition, a drain bot 6 is provided in the middle of the drain discharge pipe 4, and when some of the drain collected in this bot reaches a level higher than that level, the on-off valve 7 is opened in conjunction with the operation of the level controller LIC, and the drain pump 8 is activated. There are two types: one that operates and the level of the drain in the pot 6 is maintained at a constant value, and one that does not.

When drying the objects to be dried, they are placed on the upper surface of the drying steel 9 disposed along the surface of the ceramic 2a in the reciprocal holding 1 of the heat generating body 2. It is done so that it can be placed.

Thereafter, the vacuum pump IO is started, and the air in the vacuum chamber 1 is brought into the atmosphere through the exhaust pipe 11 and the space to be cooled in the cold trap 12.

At this time, the degree of vacuum in the vacuum chamber 1 is approximately 750 mmHg. A control valve 13 operated in conjunction with the pressure controller PIC-1 is provided in the middle of the exhaust pipe 11 to automatically control the pressure of the space to be cooled to a constant pressure.

On the other hand, steam is supplied into the heat generating body 2... to heat the ceramic layer to a desired temperature within the range of 160°C to 50°C. As a result, far infrared rays are emitted from the surface of the ceramic 23. The far infrared rays emitted in this way penetrate to the center of dried objects such as seafood and heat them evenly without quickly destroying them. . At this time, the temperature of the items to be dried, such as seafood, must be kept at a constant temperature (for example, 20°C).
It is necessary to control the pressure of the steam so that it does not exceed the temperature (in the range of ~40°C).

Under these conditions, the moisture in the object to be dried evaporates rapidly at a relatively low temperature corresponding to the degree of vacuum in the vacuum chamber 1.
Moreover, the entire area is dried almost evenly.

The steam continuously emitted from the object to be dried is frozen in the cooled space of the cold trap 12, which is kept at an extremely low temperature by the operation of the refrigerator 14, and at this time, the volume shrinks, causing the vacuum chamber 1 to freeze. This contributes to vacuum maintenance.

In the present invention, the drying process is generally carried out as described above, but in order to carry out the process more effectively, it is carried out as follows.

That is, in the early stage of drying the object to be dried, the temperature of the seedling air is, for example, 1.
The control valve 5 is operated so that the temperature becomes about 50°C, and as the drying progresses, the steam temperature is gradually lowered, and is operated so that the temperature reaches, for example, about 60°C at the end of drying.

Here, the steam temperature during the drying process is determined in advance by determining the ideal relationship between moisture content, drying temperature, and drying time for a specific object to be dried, and creating a drying program, and automatically operating the pressure controller PIC-2 according to this. Alternatively, the pressure controller PIC-2 can be controlled to a specific value by measuring the moisture content of the object to be dried, which changes from moment to moment, and operating the pressure controller PIC-2 so that the steam temperature is adjusted to the moisture content. .

In this way, in the early stages of drying, even though moisture is evaporated at a high rate under high temperatures, much of the heat of vaporization is taken away, so the temperature of the item itself rises excessively. In addition, at the end of drying, the moisture content decreases and evaporation of moisture decreases, so even though less heat of vaporization is taken away, the product is heated at a lower temperature, causing the product temperature to rise excessively. This is not the case. That is,
The object to be dried can be dried to a high quality while maintaining an appropriate temperature, and can be dried efficiently.

In the above embodiment, the upper and lower surfaces of each heat generating body 2 may be formed into a corrugated shape, thereby increasing the strength of the box body against the smoke pressure. It is also optional to provide reinforcing ribs inside each heat generating body 2.

Further, in the present invention, it is realized that the surface of the ceramic 23 of the heat generating body 2 is heated uniformly, but on this premise, it is possible to partially change the heat radiation of the same surface. Therefore, for example, by intentionally making a part of the surface of the ceramic 2a have a different emissivity in relation to the circumstances of the object to be dried, it is possible to dry the object evenly as a result. .

Further, by disposing a reflector for reflecting far infrared rays emitted from the surface of the ceramic 23 near the drying rack 9, uniform drying of the object to be dried can be further promoted.

In the figure, T is a thermometer, PI is a pressure gauge, and M is a motor.

(Effect of the invention) According to the invention, it is possible to evenly dry edible marine products such as blowfish and conger eel, as well as dried mirin (dried mirin), ham, sausage, dried vegetables, dried fruits, and other general processed foods. As a result, high-quality products can be obtained in the same way as with conventional freeze drying or cold air drying, and the drying process can be performed at a higher speed than with cold air drying. Both equipment costs and manufacturing costs can be reduced.

[Brief explanation of the drawing]

1 to 3 relate to a vacuum drying apparatus used in the present invention, in which FIG. 1 is a system diagram, FIG. 2 is a side view, and FIG. 3 is a partial view. ■...Vacuum chamber, 2...Heat generator, 2a...Ceramic. Applicant Handa Iron Works Co., Ltd. - Agent

Claims (1)

[Claims] (1) During the vacuum drying process, the heat generating body in the vacuum chamber is made into a box through which steam flows, and the outer surface of the box is coated with a thin layer of ceramic, and during the drying process A method for drying marine products, etc., characterized in that the temperature of the steam is automatically controlled to an appropriate value within the range of approximately 160°C to 50°C in relation to the properties or degree of drying of the object to be dried.