KR960004999B1 - PREPARATION PROCESS OF Ñß-DRY RICE BY VACUUM DRYING - Google Patents

Abstract

M-dry rice is the dry rice that is cahnged from Ù-starch into M-starch and fixed. The M-dry rice is prepared by : (a) washing polished rice; (b) immersing in water for 2-4 hrs.; (c) drying for 30 min.-2 hrs ; (d) cooking at 98-100 deg.C for 10-15 min.; (e) cooling by sprinkling cold water; (f) drying to 1-8 % water content under 80-90 deg.C and pressure of below 1Torr. The M-dry rice shrinks less and shows better absortivity when hot water is added than general dry rice. It can be preserved for 3yrs.

Description

Method for preparing alpha dried rice by vacuum drying

The present invention, after immersing and dehydrating the rice for a certain time to fix the cooked rice in boiling water by alpha (α) to dry by re-hydrating with hot water to facilitate the absorption of water in the preparation of alphami can easily eat It is about.

The term "alpha dried rice" used in the present invention refers to dried rice which is fixed by changing the fixed rice to alpha (α) by fixing the cooked rice with alpha and then drying the rice, that is, the raw starch (β-starch) contained in the rice. Means.

Alpha dried rice has been spotlighted as an emergency portable food and has been used as an essential food in overseas expeditions.

In recent years, the dietary needs of the national diet is made simple, and the consumption tendency of processed foods is increasing.

Accordingly, the inventors of the present invention, such as rice, which is a country's own staple food, is prepared with a glutinous rice and various vegetables in general rice to prepare an instant diet of balanced mutual impact.

The requirements for dry rice include readily brittleness, α-saturated holding state, portability, and long-term preservation. Many studies and technical developments are underway to satisfy these matters.

Typical drying methods for producing alpha dried rice include, for example, freeze drying, vacuum drying, hot air drying, and sunlight drying, and the freeze drying method of the drying method is in the form of aesthetics. Because it maintains internal pores, water absorption is quick and restoration is shortened.However, the texture of rice is not soft, the α-saturation maintenance state is reduced than heat drying, and manufacturing cost is significantly higher than other drying methods, making it difficult to commercialize. There is a point.

In addition, the vacuum drying method delays the restoration due to less generation of the internal space, and the hot air drying method is more severe than the vacuum drying method, so that the restoration is further delayed, and the daylight drying method is not satisfactory in terms of long-term preservation. there is a problem.

In addition, the drying methods other than lyophilization, the adhesion of fine particles and fine particles by the viscous and moisture evaporation of most of them, and the crushed grains when separating the grains and the dry rice form is severely contracted, so that the water is hard when rehydrated There is a disadvantage that the adsorption rate is slowly progressed.

The present invention is made to solve these drawbacks,

(a) a process for cleanly cleaning the foreign matter on the film of the milled rice,

(b) a step of immersing the washed rice in water for 2 to 4 hours, containing water evenly inside the rice, and dehydrating for 30 minutes to 2 hours.

(c) boiling water 100 ℃ in water, the soaked rice instantaneously put the temperature of the water is maintained at 100 ℃ to heat for 10 to 15 minutes to cook rice.

(d) A step of quenching the heated rice by cold water.

(e) Pressure-Reducing Vacuum Dryer Achieved by providing a process in which rice is kept at an internal temperature of 80 to 90 ° C. and dried to obtain a water content of 1 to 8% by weight under a vacuum of 1 Torr or less by instantaneous pressure reduction for a short time. .

The manufacturing method by this invention is demonstrated concretely.

Process 1: washing raw materials

Clean the foreign substances on the film of rice.

2nd process: underwater immersion

The washed rice is immersed for 2 to 4 hours to contain water evenly inside the rice and dehydrated naturally for 30 minutes to 2 hours. The immersion time depends on the temperature of the water, but after 2-4 hours at room temperature, rice is sufficiently called.

In the present invention, the immersion time is not particularly limited, and the rice only needs to be called.

Third process: cooking

In boiling water of 98 to 100 ° C, the rice soaked in the water is instantaneously added and cooked by heating for 10 to 15 minutes while maintaining the water temperature to be 98 to 100 ° C.

Accordingly, the rice starch is quickly converted to α- form, and the space formation and irregular state of the tissue is made to facilitate the absorption of moisture after drying.

The heating time is not limited even if it is 10 minutes or less, as long as it can be practically cooked. However, if more than 15 minutes, the rice is loosened and the restorability is shortened, while the texture after drying, cooking must be done within 15 minutes.

In addition, the reason for cooking operation in boiling water of 98 to 100 ° C is to form a space inside the grain of the dried rice and to remove a part of the sticky starch.

When the boiling water is less than the 98 ℃ the internal space formation rate is lowered and it is not easy to remove the sticky starch.

In addition, since heat is not rapidly transferred to the rice kernels, it takes time for the β-starch to convert to the α-starch, and the rice starch stays in water for a long time, thereby reducing the texture.

4th process: rapid cooling

The cooked rice is sprinkled with cold water, quenched and dehydrated naturally. As the hot rice is instantaneously cooled, the α-starch is fixed, and the rice grains are separated into grains due to the watering, which facilitates drying.

In addition, the moisture content is maintained 70% gives an aging inhibitory effect.

Here, aging refers to a phenomenon in which amorphous α-ized starch having an irregular molecular arrangement is changed into β-starch having regular molecular arrangement by a factor, for example, temperature, water content, and pH.

5th process: vacuum drying

The rice is put in a state where the internal temperature of the vacuum dryer is maintained at 80 to 90 ° C. and the pressure is reduced in a short time. At this moment, vacuum drying is carried out so that the water content is 1 to 8% by weight at 1 Torr or lower.

If the drying temperature is lowered below 80 ° C., the drying time is long, the α-degree of deterioration decreases and the digestibility decreases. If the drying temperature is above 90 ° C., it is difficult to obtain a unique color taste of dry rice. Particularly, when the temperature reaches 95 ° C or higher, the surface color changes to yellow and the value of the product is lost. Thus, α-degradability of dried rice is closely related to digestibility when ingested by humans. The higher the value, the better the digestion, but the lower the value, the slower the digestion.

In addition, the resilience of the dried alpha-mi is higher the water absorption rate as the moisture content of the dried rice, the higher the water absorption rate, the water absorption rate is faster than the case of containing 8% by weight or less when the moisture exceeds 8% by weight. However, too much moisture content of dried rice adversely affects the long-term preservation of dried rice, and in view of this point, the minimum moisture that can exert the effect of dried rice, that is, 8% by weight or less, is more preferable. Preferably 5% by weight or less.

The dried rice obtained in this way had less morphological shrinkage, weaker grain adhesion, and was easily separated into grains with less force, thereby reducing the occurrence of crushed grains. When rehydrating with hot water, the water absorption rate was faster than that of conventional dry rice.

In addition, without using any food additives during processing, it is possible to increase α-degradability by high temperature instantaneous treatment, which is a physical condition, and the preservation effect of dried rice is more eluted with unsaturated fatty acids of rice than conventional dried rice. Years) is possible.

EMBODIMENT OF THE INVENTION Hereinafter, this invention is demonstrated in detail based on an Example.

Example 1

After washing the rice twice, soaked in 20 ℃ water for 2 hours, dehydrated for 30 minutes, heated in 100 ℃ boiling water for 10 minutes, and then quenched with cold water at 5 ℃ to maintain the temperature of 80 ℃. The mixture was depressurized to 30 Torr or less within 1 minute, and continuously depressurized and dried for 6 hours and 30 minutes at 1 Torr or lower to prepare an alpha dried rice having a water content of 2.9% by weight.

Example 2

The rice pretreated in Example 1 was heated in 100 ° C. of boiling water for 15 minutes, and then alpha dried rice having a water content of 3.1 wt% was prepared in the same manner as in Example 1 except that the rice was quenched with cold water.

In order to confirm the effect of the alpha dried rice prepared in the above Example was carried out as follows.

Comparative Example 1

Instead of the vacuum drying method by the instantaneous depressurization of Example 1, by using a hot air drying method, alpha dried rice having a water content of 3.2% by weight was dried by heat drying at 80 ° C for 10 hours.

Comparative Example 2

Instead of the vacuum drying method by the instantaneous depressurization of Example 1, the freeze-drying method was used to reduce the pressure to 30 Torr or less within 5 seconds and continue to reduce the pressure to reach -20 ° C within 15 minutes. The dried product was dried at 80 ° C. under a reduced pressure of 0.3 Torr for 12 hours to prepare alpha dried rice having a water content of 3.0 wt%.

Comparative Example 3

Instead of the drying step of Example 1, cold air low humidity drying and hot air drying were performed in parallel. It was dried for 10 hours while raising the end temperature to 30 ° C. using the low humidity condition to the maximum to obtain a dried rice having a moisture content of 13% by weight.

Thereafter, heat dried at a temperature of 80 ° C. for 2 hours using a hot air dryer to prepare alpha dried rice having a water content of 3.3 wt%.

[Comparative Example 4]

The rice was washed twice and cooked using an electric rice cooker, which is a conventional cooking method, followed by washing with cold water, followed by the same vacuum drying method as in Example 1 to prepare alpha dried rice having a water content of 2.9% by weight.

Sensory tests and experimental results of the alpha dried rice obtained in Examples and Comparative Examples are shown in Table 1 and Table 2.

* Note) Large grain: Fine grain less than 1/2 of the total grain after grain separation

Density: Volume to weight ratio in steady state

Water absorption rate: Water absorption rate after heating for 15 minutes

Moisture absorption rate: Moisture content by hot water restoration time (Measurement condition: 105 ℃ drying method)

As can be seen from the above experiments, the smaller the degree of adhesion of the grain after drying, the larger the amount of large grains to make the grain, and the smaller the larger the grain, the lower the density and the higher the absorption rate and absorption rate.

Therefore, Comparative Examples 1 and 3 had a poor restoring effect as compared with Examples 1 and 2, and Comparative Example 2 had a very fast restoring force, but the texture was not good.

In addition, when comparing Examples 1 and 2 and Comparative Example 4, it can be seen that the water absorption speed of the cooking in boiling water during the cooking process proceeded faster than the general cooking method, and thus the resilience was greatly reduced.

And the preservation experiment with respect to the alpha dried rice obtained in Example 1 was performed as follows.

[Storability Experiment of Example 1]

In order to perform the preservation experiment, it was sealed in a three-ply wrapper (Nylon 15 + Al 7 + PE80μ) and carried out in a thermostat at 52 ° C ± 2 ° C.

The results are shown in Table 3.

Claims (1)

The manufacturing method of alpha dried rice which consists of a process of following (a)-(e). (A) process to clean the foreign substances on the film of rice, (B) The process of immersing the washed rice in water for 2 to 4 hours, containing water evenly to the inside of the rice and dehydrating for 30 minutes to 2 hours. (C) A step of cooking rice by boiling the water soaked in 98 to 100 ℃ and boiling water for 10 to 15 minutes while maintaining the water temperature of 98 to 100 ℃. (D) A step of quenching the heated rice by cold water. (e) process of drying rice so that the moisture content is 1 to 8% by weight under a vacuum of 1 Torr or less by the instantaneous depressurization after adding rice while maintaining the internal temperature of the vacuum dryer at 80 to 90 ° C.