JPH0341150B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method of drying food using microwaves.

Recently, many dried and processed vegetables, meat, fried eggs, etc. have been developed as instant food ingredients.
Hot air drying, vacuum freeze drying, microwave drying, etc. are used as the drying means. However, the dried product obtained by hot air drying has the disadvantage that the tissue becomes hard due to severe drying and shrinkage, and its restorability is extremely poor. Furthermore, although the dried product obtained by vacuum freeze-drying is somewhat satisfactory in terms of restorability, it has problems such as long drying time and high drying cost.

On the other hand, in the case of microwave drying, although there are no problems like the above-mentioned drying methods, the phenomenon of uneven heating of the material to be dried inevitably occurs. Therefore, it is difficult to uniformly dry the material to be dried, and as a result, the obtained dried material cannot be reconstituted uniformly, which is a drawback.

Furthermore, when drying a product containing a large amount of seasoning liquid, such as seasoned fried tofu, using each of the above drying methods, the seasoning liquid may be dried with the seasoning liquid spread over a part of the drying product, or There was a drawback that the seasoning liquid sometimes flowed out from the dried material as drips.

The present invention aims to solve all of these drawbacks and provide a method for obtaining a dried food with uniform drying conditions in each part of the dried material and excellent restorability, as well as a method for obtaining a snack food with a good texture. That is. The gist of the present invention for achieving the above object is to store food to be dried in a microwave-permeable and gas-permeable container, and then store the container in a substantially vertical circular shape in a microwave dryer. This is a food drying method characterized by microwave drying the food to be dried in a container while rotating the container.

Hereinafter, the contents of the present invention will be explained in detail.

The present invention is for drying foods to be dried using microwaves, but foods that can be dried by the present invention include foods such as vegetables, eggs, meat, fried tofu, and fruits, as well as foods such as flour dough. This includes all foods that need to be dried to make them instant or snackable, such as foods soaked in seasoning liquids or coated with seasoning liquids.

When drying such food to be dried, the food to be dried is stored in a container and dried using microwaves. The container for storing the food to be dried needs to be microwave permeable and gas permeable. If a container that does not simultaneously satisfy these two conditions is used, the object of the present invention cannot be achieved. Specific examples of containers that satisfy the above two conditions include materials that transmit microwaves, such as synthetic wood such as Teflon, polypropylene, and polyethylene, ceramics, glass fiber,
Some containers are made of carbon fiber, plywood, quartz, etc., and have small holes large enough to allow gas to pass through.

Next, the food to be dried housed in a container that satisfies the above two conditions is subjected to microwave drying in a microwave dryer. In this case, it is important to rotate the container in a substantially vertical circle in the microwave dryer.

To rotate the container in a substantially vertical circle means to rotate the container itself, which is supported by a horizontal axis, by rotating the container itself around the horizontal axis.
By rotating the container 180 degrees, the surface of the container becomes the back surface, and the same rotational movement as rotating the container so that the back surface becomes the front surface is performed. Therefore,
In addition to supporting and rotating the container on a horizontal axis, supporting and rotating the container in other ways,
It may be rotated, but in any case the container must be rotated in a substantially vertical circle. If microwave drying is performed in a stationary state, uneven drying cannot be prevented. Furthermore, in the method of drying while supporting and rotating on a vertical axis, that is, rotating in a substantially horizontal circle, the moisture or seasoning liquid in the food to be dried moves and concentrates in the lower part of the food to be dried, resulting in a uniform drying process. You can't get it in a dry state. This also applies to the case of drying in the stationary state described above. On the other hand, if the food is dried while rotating in a substantially vertical circle, the contact between the food to be dried and the microwave energy can be carried out efficiently and uniformly, and the moisture or seasoning liquid in the food to be dried can be unidirectionally distributed. It can prevent you from concentrating. As a result, it becomes possible to dry the food while keeping the concentration of water or seasoning liquid uniform in each part of the food to be dried. In order to achieve this effect more effectively, it is preferable to apply microwaves from above the food to be dried. In addition, when drying foods that contain a large amount of components that are easily denatured by heat, or foods that require restoration with hot water, etc., microwave drying under reduced pressure is recommended. It is preferable to adopt it. By performing microwave drying treatment under reduced pressure, the food to be dried can be dried at a relatively low temperature, and the resulting dried food has a porous structure that easily absorbs water.
In addition, when obtaining snacks using fruits, etc., the fruits, etc. are dipped in a seasoning liquid and then dried under reduced pressure in a microwave using the method of the present invention, whereby the taste of the seasoning liquid is evenly dispersed. It is possible to obtain a snack food which has a soft and very light texture while sufficiently retaining the flavor of fruits and the like.

In carrying out the present invention, the microwave output, the rotation speed of the container, and the degree of pressure reduction when carried out under reduced pressure may be determined by the practitioner as appropriate, taking into consideration the type, amount, size, etc. of the food to be dried. All you have to do is implement it. Furthermore, the timing of rotating the container in a substantially vertical circular shape may be at the same time as the application of microwaves, or may be before or after the application of microwaves, taking into account the type of food to be dried, etc. may be determined as appropriate.

By the method described above, it is possible to obtain a dried food that satisfies the objectives of the present invention.

Next, a case in which the method of the present invention described above is carried out using a reduced pressure microwave drying apparatus will be described with reference to the drawings.

After the food to be dried A is stored in a container 2 made of Teflon having a large number of small holes 1, a lid 4 made of Teflon having a large number of small holes 3 is placed. Next, the container 2 is fixed to the container holding frame 6 in the vacuum microwave drying device 5. Horizontal shafts 7 and 8 are fixed to the container holding frame 6, and a pulley 9 is fixed to the tip of the horizontal shaft 7. The pulley 9 is connected to a motor 12 by a V-belt 10 and a pulley 11. One horizontal shaft 8 is held by a gripping frame 14 of a support rod 13 of the vacuum microwave drying device 5 . After fixing the container 2 to the container holding frame 6, the lid 15 of the vacuum microwave dryer 5 is closed, and then the vacuum pump 17 connected via the exhaust pipe 16 is operated to dry the vacuum microwave dryer 5. Adjust the inside to the desired degree of decompression. Thereafter, the microwave oscillator 18 is activated to apply microwaves to the reduced pressure microwave drying device 5 via the waveguide 19.

Simultaneously with, before or after activating the microwave oscillator 18, the motor 12 is activated to rotate the horizontal shafts 7, 8 in a substantially vertical circular shape. Due to the rotation of the horizontal shafts 7 and 8, the container 2 as well as the container holding frame 6 are rotated in a substantially vertical circle. In this way, the food to be dried is dried.

Example 1 One piece of fried tofu weighs about 9g (size: about 70mm x 70mm)
Season 1,000 pieces by boiling them in a seasoning liquid for about 30 minutes. After seasoning, cool to about 40℃, stack 20 pieces of seasoned fried tofu and press until the weight becomes 330g to remove excess seasoning liquid. Then 20
After placing a layer of seasoned fried tofu in a Teflon container with many small holes and placing a Teflon lid with many small holes, the pressure reduction degree is 1300 Pascal, the microwave output is 50KW, and the vertical circular rotation speed of the container is placed.
Dry in a vacuum microwave at 6 rpm. Each piece of dried fried tofu weighs about 9.5 g and measures about 80 mm x 80 mm, and the degree of dryness, swelling,
The degree of dispersion of the seasoning liquid was uniform in both cases, and was clearly superior to that obtained by standing and drying under the same conditions.

In addition, with the method of the present invention, the seasoning liquid in the seasoned tofu did not flow out as drips at all during drying, whereas when dried under the same conditions, a considerable amount of the seasoning liquid in the seasoned tofu ran out as drips. Ta.

Regarding the resiliency in hot water, dry fried tofu obtained by the method of the present invention was soaked in hot water (approximately 100°C) for 30 seconds.
The material was completely restored by simply immersing it in water, whereas the material left to dry under the same conditions was not completely restored unless it was immersed in hot water (approximately 100 degrees Celsius) for 90 seconds. Not only that, the taste of the seasoned fried tofu after restoration was inferior to the former because the seasoning liquid dripped out during drying. In the latter case, the parts of the deep-fried tofu that had a lot of seasonings were overheated and produced a burnt odor, and in extreme cases, the fried tofu stuck to each other.

Example 2 Seasoned fried tofu obtained in the same manner as Example 1
Stack 10 sheets and press until the weight reaches 148g to remove excess seasoning liquid. After that, 10 layers of seasoned fried tofu were placed in a Teflon container with many small holes, and after placing a Teflon lid with many small holes, the pressure reduction degree was 19950 Pa, the microwave output was 20 KW, and the vertical circle of the container was placed. Dry in a vacuum microwave at a rotation speed of 3 rpm. The resulting dry fried tofu weighs approximately 9.5g each and measures approximately 77mm x 77mm.
mm, and had the same excellent characteristics as in Example 1.

Example 3 Fresh apples are peeled and cored and then shredded into fan-shaped pieces with a thickness of 4 mm, a short arc of 10 mm, a long arc of 25 mm, and a width of 20 mm to obtain 10 kg of apple pieces. Next, 10 kg of the apple pieces were mixed with 8 kg of sucrose, 0.12 kg of L-asconbic acid, and 31.88 kg of water.
About 14 kg of apple pieces were obtained by immersing them in 40 kg of a syrup solution consisting of the following: and immersing them under reduced pressure at a degree of vacuum of 2660 Pascals for 10 minutes. After placing it in a Teflon container with many small holes and placing a Teflon lid with many small holes, it was left standing under the conditions of vacuum degree of 2660 Pascal and microwave output of 20 KW and microwaved for 1 minute. The surface of the apple pieces is slightly dried by applying
Vacuum microwave drying was performed under the conditions of 60 KW and a vertical circular rotation speed of 4 rpm. The dried apple pieces obtained were a snack food with uniform dryness, porous state, and seasoning liquid dispersion, a very light texture, and sufficient apple flavor.

Example 4 Fresh green asparagus is washed with water and then cut into approximately 5 cm lengths to obtain 8 kg of asparagus pieces. Boil it in 0.5% saline solution (70℃) for about 2 minutes. Thereafter, the asparagus pieces are immersed in a solution consisting of 10% by weight of common salt and 10% by weight of sorbitol at a vacuum degree of 7980 Pascals for about 5 minutes to obtain about 10 kg of asparagus pieces. Next, approximately 10 kg of the asparagus pieces were placed in a Teflon container with many small holes, a Teflon lid with many small holes was placed, and microwaves with an output of 50 KW were applied for 20 minutes under normal pressure. do.

In this case, the container is rotated at a vertical circular rotation speed of 6 rpm from 1 minute after the microwave application. After stopping the application of microwaves, the container is ventilated for 3 minutes while continuing to rotate.

The dried asparagus pieces obtained were uniform in dryness, porous state, and seasoning liquid dispersion, and had good restorability with hot water.

[Brief explanation of drawings]

FIG. 1 shows a reduced pressure microwave drying apparatus which is an example of an apparatus for carrying out the method of the present invention. In the figure, 1, 3...Small hole, 2...Container, 4...Container lid, 5...Reduced pressure microwave dryer, 6...Container holding frame, 7, 8...Horizontal axis, 9, 11... ...Pulley, 10...V belt, 12...Motor, 1
3... Support rod, 14... Gripping frame, 15... Lid of the vacuum microwave dryer, 16... Exhaust pipe, 17...
...Vacuum pump, 18...Microwave oscillator, 19
...Indicates a waveguide.

[Claims]

1. In a method for producing distilled liquor by distilling the fermented moromi under reduced pressure using a distillation can with indirect heat exchange, the heat supply to the moromi in the distillation can is carried out by using a liquid heat medium of 100°C or less in the distillation. A method for producing distilled liquor by vacuum distillation, characterized by carrying out circulating supply into cans. 2. The method for producing distilled liquor by vacuum distillation according to claim 1, wherein the temperature of the liquid heat medium is 60 to 100°C. 3. The method for producing distilled liquor by vacuum distillation according to claim 1 or 2, wherein the liquid heat medium is hot water.