JPH0779668B2 - Vacuum expansion and drying method for food - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION <Industrial field of application> The present invention relates to a method for vacuum-expanding and drying a food. More specifically, the texture after restoration is almost the same as that before drying by pouring hot water or the like. The present invention relates to a vacuum expansion drying method for foods, by which dried foods that can be restored in a short time can be obtained.

<Prior art> Many improvised foods that can be easily reconstituted by pouring hot water have been developed, and along with that, various researches and developments have been made on drying technology.
Typical examples thereof include a hot air drying method, a microwave drying method, a freeze drying method, a frying method, and a reduced pressure drying method. Further, there is a puffing drying method in which a material to be dried is exposed to a flow of superheated steam under pressure for a short time, and heated and dehydrated is rapidly released into the atmosphere to obtain a puffed product.

<Problems to be Solved by the Invention> The dry food obtained by such a conventional drying method is
There is a drawback in that the restorability, especially the texture after restoration, cannot be obtained.

The present applicant has developed a vacuum-expansion drying method for foods, which was previously filed, as a method for obtaining a dry food that solves such drawbacks (Japanese Patent Application No. 56-135469).

And the gist thereof is to put the food in a rapid depressurized state such that the water in the food freezes at a rate sufficient for the food to swell, and after the water in the food freezes, it is heated and dried, and then the This is a method for expanding and drying food under reduced pressure, which is characterized by returning to pressure.

However, in the case of foods such as beef, chicken, mushrooms, cabbage, etc., the above method has not always been satisfactory in terms of restoration time and texture after restoration.

<Means for Solving the Problem> The inventors of the present invention have conducted various studies in order to solve these problems, and as a result, before subjecting the food to a vacuum swelling drying treatment, by preliminarily subjecting the food to water penetration, The present invention has been completed based on the finding that the above can be solved.

The gist of the present invention completed in this manner is that, after water-penetrating the food, the food is rapidly depressurized at a rate sufficient to cause the food to swell and the water in the food to freeze. Once the water in the food is frozen, it is heated and dried, and then returned to normal pressure.

The details of the present invention will be described below.

Foods that can be dried according to the present invention include vegetables, fruits,
Dough molding mainly composed of cereals, beans, cereals, or solid food obtained by processing and cooking these solids, meat, processed meat products such as ham and bacon, marine products such as fish, shellfish, shrimp and seaweed, and these It is a solid product such as a processed product, an egg-baked product, and an egg processed product such as a dashi roll, and in order to effectively achieve the object of the present invention, a solid product having a water content of about 50% by weight or more is preferable. And, among the above foods, livestock such as beef, poultry such as chicken, leafy vegetables such as cabbage and cabbage, stem and bulb vegetables such as leeks and onions, wild vegetables such as bracken and spring, enoki mushrooms, etc. The effects of the present invention can be best exhibited in foods such as mushrooms.

In the present invention, the food is first subjected to water infiltration treatment, but before that, the food may be cut into an appropriate size, sliced, processed by treatment such as molding, in which case the thickness of the food is 20 mm or less. Is more preferable from the viewpoint of achieving the object of the present invention. Further, boil treatment may be performed.
The action of this boil treatment varies depending on the type of food to be treated, but the general action is to make it edible, to moderately harden the tissue and to easily maintain the tissue gap formed during vacuum expansion, and to dry it. For example, it suppresses changes in the color of time.

Examples of the method for water permeation treatment of food include a method such as pressure reduction substitution and pressure treatment. This treatment will generally increase the water content in foods, but in particular
An increase of about 10% by weight is preferable. However, in the case of mushrooms, the water content tends to decrease by the water infiltration treatment, but the object of the present invention can be effectively achieved. By this water infiltration treatment, it is possible to increase the size of ice crystals when the food is frozen and to make it porous when the product is swelled under reduced pressure in the subsequent step, and thus it is possible to improve the reconstitution of the obtained dried product. Further, it becomes possible to improve the drying efficiency.

The water-penetrated food is then subjected to vacuum expansion treatment. In the vacuum expansion treatment, the following two conditions must be satisfied.

The first condition is to put the food under a specific vacuum at a rate sufficient to cause puffing. The term "sufficient speed for food swelling" means a speed sufficient for rapidly evaporating water in the food in a short time. In general, the swelling phenomenon of various foods due to water evaporation varies depending on the type of the food, and the speed at which the food swells also varies depending on the type of the food, but it is preferably within 1 second.

Next, the second condition is that the specific degree of pressure reduction described in the first condition is set to a degree of pressure reduction sufficient to freeze the water in the food. Specifically, it is 600 pascals or less, preferably about 106 pascals or less.

After satisfying the above two conditions and placing the food under reduced pressure,
It is held until the water in the food freezes, preferably until it freezes and the product temperature does not decrease. By this treatment, the shape of the puffed food is kept as it is, and the dried food finally obtained is brought into the puffed state, whereby the restoration by hot water or the like can be accelerated. There are the following two pressure reducing methods for satisfying the above two conditions.

The first method is a method in which puffing of the food and freezing of water in the food are performed in one step, that is, the puffing of the food is sufficient under a reduced pressure such that the water in the food is frozen. It's a fast method. According to this method, food swelling and food icing occur almost instantly.

The second method is a method of puffing the food and freezing the water in the food in two stages, that is, decompressing the food at a speed sufficient to cause the puffing of the food (a pressure reduction sufficient to freeze the water in the food). This is a method in which the food is inflated under a reduced pressure that does not reach a certain degree) and then the reduced pressure is reduced to a sufficient reduced pressure so that the water in the food freezes. According to this method, the expansion of the food and the freezing of the water in the food occur separately over time.

The water in the food is frozen by the method as described above, but the change over time of the product temperature of the food at this time is abbreviated as Japanese Patent Application No. 56-135469, which is the prior application, that is, the one not subjected to water infiltration treatment. Although the same tendency is exhibited, the freezing time is faster than that of the previous application, and the temporal characteristics of the present invention can be found in this respect. Figure 1 shows the outline of the change over time. In the figure, the vertical axis represents temperature (° C.), the horizontal axis represents decompression processing time (minutes), and the curve represents changes in the temperature of the food. The term "food product temperature" as used herein refers to the temperature detected by the temperature sensor when a temperature sensor is inserted in the food, and the same applies hereafter. When the food is subjected to water infiltration treatment and then subjected to vacuum expansion treatment by the above-mentioned two methods, the food temperature of the food is rapidly lowered and the food is supercooled.
This phenomenon is because the water in the food rapidly evaporates to remove the heat of vaporization, and the food is inflated due to the rapid evaporation of water at this time. After that, the product temperature of the food is slightly increased. This is a phenomenon that occurs because the heat energy released when the water in the food in the supercooled state freezes causes the temperature of the food to rise. Further, in the case of the present invention, this phenomenon occurs at an early stage as compared with the case where the water permeation treatment is not performed. After that, the product temperature of the food gradually decreases, which is considered to be because the frozen water in the food gradually sublimes. After that, since the temperature of the food becomes constant, it is preferable to heat and dry the food at this point, but the present invention can be heat dried at any time before that, that is, after the food is frozen. From the standpoint of achieving the purpose of, no stabbing is supported. The heating and drying is carried out by a conventional heating means such as infrared heating or microwave heating, but radiant heating by infrared rays or the like is most preferable, and the heating temperature is a temperature at which the product temperature becomes 60 ° C. or less. preferable.

By the method as described above, the dried food object of the present invention is obtained.

<Example> Example 1 (beef) After cutting beef into a die of about 10 mm x 10 mm x 10 mm, 3
Boiled for a minute. After that, the beef that had been boiled in hot water was immersed in water, allowed to stand at 2660 pascals for 5 minutes, subjected to water infiltration treatment under reduced pressure, and then returned to normal pressure in about 4 minutes. This process boiled 200g of beef to about 215g. Then, the water was simply drained and immediately put into a vacuum dryer, and the degree of vacuum in the vacuum dryer was reduced to about 4000 Pascal within 1 second. Then, the pressure in the reduced pressure drying apparatus was reduced to 70 Pascal or less within 4 minutes, and after 5 minutes from the start of depressurization, it was dried by a heater. Drying was carried out under the conditions of a heater temperature of 100 ° C. for 1 hour and then a heater temperature of 50 ° C. for 6 hours. Then, the inside of the reduced pressure drying apparatus was returned to normal pressure to obtain dried beef. The dried beef obtained was slightly whitish and had good restorability.

Example 2 (Mushrooms) Mushrooms were vertically cut to a thickness of 1/2 to 1/3, boiled for 7 minutes, and then water-penetrated under reduced pressure under the same conditions as in Example 1. The mushrooms thus obtained weighed 198 g. After this, heater temperature 80 ℃
Was dried for 1 hour and then for 6 hours at a heater temperature of 50 ° C., and dried under reduced pressure to obtain a dried mushroom under the same conditions as in Example 1.

Example 3 (cabbage) 200 g of cabbage was shredded into a width of 3 to 4 mm, and then subjected to boil treatment and water infiltration treatment under reduced pressure under the same conditions as in Example 1. The weight of the cabbage thus obtained was 212 g. After that, vacuum cabbage was dried under the same conditions as in Example 1 except that the temperature of the heater was set to 50 ° C. from the beginning to obtain dried cabbage.

Comparative Example Beef, mushrooms, and cabbage were not subjected to a water infiltration treatment, but beef was treated in Example 1, mushrooms were treated in Example 2, and cabbage was dried under reduced pressure under the same conditions as in Example 3 to dry beef and dried mushrooms. , Dried cabbage was obtained.

The shapes of the fibers inside the dried beef, dried mushrooms, and dried cabbage obtained by the present invention and the comparative example were compared by an electron microscope, and their resilience was confirmed by immersing in hot water and observing changes in water absorption over time. The results are shown in FIGS. The water absorption amount is the weight after immersion converted to the weight when the sample before immersion is 1 g. Also, in the figure, the vertical axis represents the weight of the sample, and the horizontal axis represents the immersion time.

Comparing the electron micrographs in FIGS. 2 to 4, in the case of the beef in FIG. 2, the internal state (a) of the sample obtained by the present invention has clearer small holes and cracks, On the other hand, in the internal state (b) of the sample obtained by the comparative example, strong attachment of muscle fibers is seen. Then the third
In the case of mushrooms and cabbage shown in FIGS. 4 and 5, the internal state (a) of each sample obtained by the present invention is the internal state (b) of each sample obtained by the comparative example.
Is more porous. As for the restorability, as is clear from FIGS. 5 to 7, the water absorbency when immersed in hot water is excellent, and this tendency is particularly remarkable in the case of cabbage. This indicates that the product obtained by the method of the present invention has a better resilience with hot water or the like.

<Effect> According to the present invention, it is possible to obtain a dry food having excellent restorability and excellent texture after restoration, even for foods that are not always satisfactory in terms of restoration time and texture in the conventional drying method. .

[Brief description of drawings]

FIG. 1 is a drawing showing an outline of changes over time in the temperature of food products when the food products are vacuum-expanded. FIG. 2 is an electron micrograph showing the shape of fibers inside the dried beef obtained by Example 1 and Comparative Example, and FIG. 3 shows the shape of fibers inside the dried mushroom obtained by Example 2 and Comparative Example. Electron micrographs, FIG. 4 are electron micrographs showing the shapes of the fibers inside the dried cabbage obtained in Example 3 and Comparative Example. In each figure, (a) is the present invention and (b) is a comparative example. Is. 5 to 7 show changes in water absorption with time in hot water of dried beef, dried mushrooms and dried cabbage obtained in Examples 1 to 3 and Comparative Example.

 ─────────────────────────────────────────────────── ─── Continuation of front page (72) Inventor Rie Kato 1-5-7 Mikitei Sakae-cho, Higashi-Osaka City, Osaka Prefecture House Food Industry Co., Ltd. Akiteru Tamura (56) References , A) JP 62-201540 (JP, A)

Claims (1)

[Claims] 1. A food is subjected to forced water permeation treatment by vacuum displacement or pressure treatment, and thereafter, the food is rapidly heated at a rate sufficient for the food to swell and to an extent that water in the food self-freezes. A reduced pressure swelling and drying method for a food, which is characterized in that the food is placed under a reduced pressure, the water in the food is frozen, then dried by heating, and then returned to normal pressure.