JPS59156273A - Method for expanding and drying food under reduced pressure - Google Patents

Abstract

PURPOSE:To prepare a dry food which can be reconstituted or reconstituted and cooked to give a food having nearly the same palatability as that of the original food or the cooked original food, by rapidly evacuating a food under specific condition to effect freezing of the water in the food, and drying the product with heat. CONSTITUTION:A food is transferred from a pressurized state to an evacuated state rapidly enough to cause the expansion of the food and the freezing of water in the food. The change from the pressurized state to the evacuated state increases the degree of expansion. The food is maintained to the evacuated state until the water in the food is frozen, preferably until the lowering of the food temperature is stopped after the complete freezing, and is dried with heat by conventional heating means such as infrared heating, microwave heating, etc.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a vacuum swelling and drying method (Vr) for foods, and more specifically, it restores foods in a short time by adding hot water, etc., and the texture after restoration is the same as the texture before drying. This invention relates to a vacuum swelling drying method for foods that can obtain dried foods that are almost unchanged in texture or have almost the same texture when cooked after being reconstituted as when cooked before drying.

BACKGROUND ART Many instant foods that can be easily reconstituted by adding hot water or the like have been produced in the past, and a wide variety of research and development efforts have been conducted on drying techniques. Typical examples include hot air drying method, microwave drying method, freeze drying method, deep-frying method, vacuum drying method, etc. There is a drying method in which a dried product is exposed to heat for a short period of time, then heated and then rapidly released into the atmosphere (C) to obtain a swollen product.

However, the dried foods obtained by such conventional drying methods (C) are not satisfactory in terms of reconstitution properties, particularly in terms of texture after reconstitution or texture of cooked foods after reconstitution. First, if you compare the texture after folding or the texture of the A processed after restoring and drying: Comparing the texture of the anai (or the texture of the food cooked before drying), the former has no elasticity, and the texture of the food cooked before drying. It lacked stickiness. It had noticeable defects such as stickiness, and it could be said that it had a texture that was almost the same as the latter, and there was no C.

The purpose of this invention is to provide a new drying method developed for drying dry foods that eliminates the disadvantages of dry foods. The special method is to apply VC at a speed of enough to freeze the water in the food under rapid depressurization conditions in summer, heat dry it after the water in the food freezes, and then return it to normal pressure. This is a vacuum swelling treatment method for prizes.

The method of the present invention will be described below. Foods that can be dried by the method of the present invention include vegetables, grains, beans,
Carvings such as dough moldings made mainly from grains, solid objects processed and cooked from these solid objects, livestock meat, processed livestock products such as ham and bacon, marine products such as fish, shellfish, shrimp, and seaweed, @There are sawfish and their processed products, and processed egg products such as tamagoyaki and dashimaki.

In order to effectively achieve the objectives of the present invention, it is desirable that the moisture content of these solid foods be about 50 or more. In the method of the present invention, the food is first placed under reduced pressure from the entire pressurized state. When placing food from pressurized to reduced pressure, it is common to place the food under pressure after cooking it under pressure, but this is not necessarily the case; for example, increasing the pressure difference can be used. It can also be applied to cases where you want to check the degree of swelling. At least the following two conditions must be satisfied when food is placed under reduced pressure from full pressure.

The first condition is that the food be placed under a certain reduced pressure at a sufficient age to cause puffing. When food is placed under a total vacuum, the boiling point of water naturally decreases, and the water content in the food is reduced by
In particular, the phenomenon of transpiration of free water occurs, and the transpiration phenomenon occurs quickly and rapidly, in other words, by placing the food under reduced pressure for a short period of time, the food puffs up. Therefore, the light-minute speed at which food puffing occurs as used in the present invention refers to a speed sufficient to rapidly evaporate the moisture in the food in a short period of time. The phenomenon of swelling due to water evaporation of food differs depending on the type of food, and therefore the speed sufficient for swelling to occur also varies depending on the type of food, but it is preferably within about 1 second.

Next, the second condition is to make the specific degree of vacuum mentioned in the first red stamp sufficient to freeze the moisture in the food. The relationship between freezing of water and the degree of reduced pressure is that reduced pressure lowers the boiling point of water, which causes transpiration of water, but this evaporation of water removes the heat of vaporization, which increases VcI.
The relationship is such that as the water becomes f-, the temperature of the water decreases, and finally it freezes. The degree of reduced pressure at which water freezes under reduced pressure due to this phenomenon is 609.14 pascals (4.58 torr). Therefore, the degree of vacuum sufficient to freeze water in food according to the present invention is 609.14 pascals (4,58 to
rr) or less, preferably 106.4 Pascal (0
, 8 torr) or less.

After satisfying the above two conditions and placing the food under total vacuum,
The food is maintained until the moisture in the food freezes, preferably until the food temperature no longer decreases. By maintaining the delicacy of the puffed food through this treatment and making the final dried food in a puffed state, it becomes possible to speed up restoration using hot water or the like. After all of the water in the food has been frozen, the food is dried by heating using a conventional heating method such as infrared heating or microwave heating.

If the frozen water in the food is completely melted in this heating drying process and then all of the water evaporates, it will immediately cause the food in a puffed state to shrivel.On the other hand, if the frozen water is evaporated by sublimation, it will eventually The texture of the resulting dried food after being restored with hot water or the like tends to be different from the texture before drying.

Therefore, in heating drying, it is preferable to completely evaporate the frozen water in the food by sublimation without completely melting the frozen water in the food in order to prevent the above-mentioned drawbacks. The most preferable heating drying means is radiant heating using infrared rays or the like. Next, the dried food obtained by heating and drying is returned to normal pressure, and then transferred to the next process such as a packaging process.

Next, the method of the present invention will be explained using cooked rice as an example. First, polished rice is washed with water, soaked in water, and then cooked in a conventional manner. Next, the temperature of the resulting cooked rice is completely raised under pressure, and then a vacuum swelling treatment is performed.

The conditions for vacuum swelling treatment of cooked rice are (1) degree of vacuum is 59;
It should be 8.5 pascals (4,49 torr) or less, preferably 106.4 pascals (0,80 tarr) or less. (2) The rate of pressure reduction is to be carried out from normal pressure to the desired degree of pressure reduction within 1 second. By subjecting the cooked rice to vacuum expansion treatment according to these conditions, the moisture in the cooked rice is rapidly vaporized, and after the cooked rice is expanded, all of the remaining moisture in the cooked rice is removed in that state. It is frozen to maintain the puffed state of cooked rice.

Summary of temperature changes over time of cooked rice during vacuum expansion treatment Vessel 1
As shown in the figure. The vertical axis is the temperature (°C), the horizontal axis is the vacuum processing time (min)'(i-), and the curve shows the change in product temperature.When cooked rice is processed under the above two vacuum swelling conditions, (I) ), the content of cooked rice rapidly decreases and becomes supercooled.This phenomenon is due to the rapid evaporation of the water in the cooked rice and the heat of vaporization. The cooked rice expands.Then, as shown in (b), the temperature of the cooked rice rises slightly.This is due to supercooling wv
This phenomenon occurs because the temperature of the cooked rice increases due to the thermal energy released when the water in the cooked rice freezes. After that, the temperature of the cooked rice gradually decreases as shown in (c), but this is thought to be because the frozen water in the cooked rice is gradually sublimating. After the phenomenon of (c) occurs, the temperature of the cooked rice becomes constant as shown in ), so it is preferable to completely heat and dry the cooked rice at this point. However, there is no problem in achieving the purpose of the present invention. The heating and drying methods include four-ray heating, heating in a barrel, or heating using microwaves, and the rice is dried in a trench at room temperature, which is the same temperature as that of cooked rice. After drying, the vacuum expanded cooked rice is returned to normal pressure and then taken out.

Note that the curve showing changes in product temperature shown in Figure 1 shows approximately the same tendency not only in the case of cooked rice but also in other foods, but as the moisture content of the food decreases, the change in product temperature decreases. ′
Around the time (it becomes harder to appear in ri rabbits).

Next, in order to clarify the effects of the method of the present invention, a comparative experimental example will be described using cooked rice as an example.Before that, the specific equipment used in the comparative experimental example will be explained based on FIG. do. However, the apparatus shown in FIG. 2 is an example of a specific apparatus that can be used in carrying out the method of the present invention, and the present invention is not limited thereto.

1 indicates the entire drying chamber, and the upper and lower parts of the drying chamber 1 are equipped with lids 2,
3 is provided, and a shelf 4 for placing food items is provided inside. The shelf 4 can be turned over using a handle 5.

Drying chamber IL7) An infrared lamp 6 is installed inside the lid 2. A vacuum chamber 7 is connected to the side wall of the drying chamber 1 by a pipe 8, and a cock 9 for opening and closing the vacuum chamber 7 is installed on the pipe 8. A vacuum pump 11 is connected to the vacuum chamber 7 by a pipe 121C and a VC cord/l/metal wrap 10 for reducing the internal pressure, and the vacuum chamber 7 is also provided with a pressure gauge 13. . One side wall of the drying chamber 1 is provided with a pressure gauge 14 for measuring the degree of reduced pressure inside the drying chamber 1, and an air supply pipe 15 is connected to it separately.
The air supply vibrator 15 is provided with a cock 16 for opening and closing the air supply pipe 15. The air supply vibrator 15t/i: is equipped with a compressor 17, and the pipe 8 is further equipped with a cock 18 and a pipe 19.

The following comparative experiment was conducted using all of the above devices.

Comparative Experiment Example 0 Method of the Present Invention The lid 2 of the drying chamber 1 was opened, and cooked rice 1002, which had been cooked in a conventional manner at the drowsy rice cooking rate, was supplied onto the shelf 4 in the drying chamber 1, and then the lid 2 was closed. Next - Cook 16ki#L Cooks 9 and 18 are closed and the temperature of rice cooked by external heating is 't105.
℃. Separately, with the cock 9 closed, the vacuum pump 11 is operated to reduce the pressure in the vacuum chamber 7 to 66-5 Pascals (0.5 torr). After completing the above operations, with cock 9.16i closed, open cock 18 to exhaust the air in the drying chamber l through pipe 19, then immediately close cock 18 and fully open chic 9 to release the air in the drying chamber l. It passes through the entire pipe 8 and moves to the vacuum chamber 7, and the inside of the drying chamber 1 and the inside of the vacuum chamber 7 are connected for an extremely short time (1
(within seconds) to achieve the same degree of decompression. The degree of decompression at this time is approximately 40
It is 0 pascal (3 torr). Immediately thereafter, the vacuum pump 11 is used to
torr) to 40 Pascals (0,
3 torr) i. During this time, the temperature of the cooked rice in the drying chamber l changes as shown in FIG. After placing the cooked rice under reduced pressure, it was maintained for 3 minutes (time point X in Figure 1), and then an infrared lamp (IOOV, RS5W, irradiation distance 10 cm
) until the temperature of cooked rice reaches about 30°C. After that, close cock 9, stop vacuum pump 11, and cock 1.
After gradually opening 8 to return the inside of the drying chamber to normal pressure, open the lid 3, rotate the handle 5 to invert the shelf 4, and take out the dried cooked rice. 0 Conventional freeze-drying 100 pieces of cooked rice cooked by the same method as method (1) of the present invention
After freezing at -40℃ under normal pressure, supply a heat transfer shelf,
Depressurization degree 66.5 Pascal (0.5tOrr), heat transfer shelf 3
After freeze-drying at 0°C until the temperature of the cooked rice reaches about 30°C, the pressure is returned to normal and the dried cooked rice is taken out.

8f' each of dry cooked rice obtained by the above method! ! - After pouring 150 f' of boiling water into the beer, cover and soak for 5 minutes. Thereafter, the boiling water was drained, and the lid was closed and held for 10 minutes to completely restore each dry cooked rice.

・Comparative experiment items and results are shown in Table 1.

Comparison item a in Table 1 of 100 Noodles is to clarify the differences in the appearance of dry cooked rice due to differences in drying treatment methods, b is to confirm the specific gravity of dry cooked rice, and C is dry cooked rice. d is to clarify the difference in the appearance of dried cooked rice after restoration due to differences in the drying treatment method, e is to confirm the total water absorption rate of
Fi is to clarify the difference in the texture of dried cooked rice after restoration due to the difference in drying treatment means, and f is to confirm the degree of elution of gelatinized starch during restoration.

The comparison results in Table 1 demonstrate the differences in the reconstitution effects of each of the above-mentioned dry cooked rice.

This is true not only for cooked rice but also for the other prizes mentioned above. Furthermore, when dried livestock meat obtained by the method of the present invention is cooked after being reconstituted, the meat has a texture and flavor that are almost the same as those cooked before processing.

As described above, the dried food obtained by the method of the present invention is moderately expanded while retaining its original shape, and when restored using hot water, etc., it can be completely and approximately uniformly restored in a relatively short period of time. The texture of the reconstituted food or the food that is cooked after the reconstitution is almost the same or similar to that of the food before treatment or the food that is fully cooked.

Incidentally, the dried food obtained by the method of the present invention can also be eaten as is as a snack product.

Example 1 Pork thigh (20 plates x 20mm x 10mm) 10
Approximately 10
After holding for a minute, 20.0 Pascal (1,5 Pascal) for about 2 seconds
torr) and further reduce the pressure to 40 pascals (0 torr).
, 3 torr). After maintaining this state for 50 minutes, the product temperature was raised to 80°C at a rate of 10°C/h.
dried until. The obtained dried pork thigh was restored to elastic, flavorful and well-cooked meat by simply immersing it in hot water for 3 minutes.

Example 2 Camembert cheese (20 dishes x 50 dishes x 5 dishes) 100?
After infrared heating under conditions of a total of 2.5 atm and 120° C., the pressure is reduced to 100 Pascal (0.75 torr) in about 5 seconds, and further reduced to 26.7 Pascal (0.2 torr). After maintaining this state for 10 minutes, lO℃
The product was dried under a temperature increase condition of /h until the product temperature reached 501°C. The obtained □ dried Camembert cheese was suitably puffed and suitable as a snack.

[Brief explanation of drawings]

FIG. 1 is a drawing showing the change in temperature of cooked rice over time during the vacuum expansion process. FIG. 2 is a schematic diagram showing an example of a specific apparatus that can be used in carrying out the method of the present invention. 1... Drying room, 2, 3... Lid, 4... Shelf, 5...
・Number, 6...Infrared lamp, 7...Vacuum chamber, 8,12° #Medium...Pipe, 9,16. '
F8...Cook, 10...Pakor trap, 11...
...Vacuum bong 7', 13, 14...Pressure gauge, 15...
・Air supply pipe, 17...Compressor, 18・
...Cook, 19...Air supply vibrator, A...Food procedure amendment April 7, 1980 Kazuo Wakasugi, Commissioner of the Patent Office l Incident indication 1982 patent 1fiJi No. 31691 2, Sounding Title Vacuum puffing and drying method for foods 3 Relationship with the case of the person making the amendment Representative Ikuo Urakami 4 of the patent applicant, attorney 〒104 6 Number of inventions increased by the amendment 0 7, Detailed explanation of the invention subject to the amendment r 4.49 torr stated on page 6, line 17 of the column specification
Correct J to r 4.5 torr J. “Pipe 19” described on page 10, line 18 of the specification is “
"From pipe 19," he corrected. , "19...air supply pipe" written on page 16, line 19 of the specification is corrected to "19...pipe".

Claims (1)

[Claims] The food is placed under pressure and then rapidly depressurized at a rate sufficient to cause the food to swell and to the extent that the water in the food freezes, and after the water in the food freezes, it is heated and dried, and then dried under normal pressure. A vacuum swelling drying method for food, which is characterized by returning the food to .