JPH01300865A - Modification of grain - Google Patents

Abstract

PURPOSE:To remarkably shorten the preparation time of the subject grain and to eliminate the water-washing step, by adding water to starch-containing grain, heating the grain in the presence of high-pressure gas, releasing the pressure and drying the product. CONSTITUTION:Starch-containing grain having a water-content of 20-30% (e.g., rice or barley) is heat-treated in a high-pressure gas (preferably CO2, N2, Ar, He or air) (preferably at 40-150 deg.C under a pressure of 100-500 bar), discharged into an atmosphere of normal temperature and pressure and dried to effect the modification of the grain.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a method for modifying grains of rice, wheat, etc., which have excellent water absorption properties.

[Conventional technology]

For example, cooked rice is usually obtained by subjecting white rice to heat treatment such as cooking, but the rice splits for about 1 hour during cooking. That is, according to the conventional method, white rice is washed with water, water absorption treatment is performed for 20 to 30 minutes, and rice cooking treatment is performed for 20 to 30 minutes.
0 to 30 minutes, and some additional steaming time is required.

For this reason, instant rice processed by retorting, hot air drying, freeze drying, etc., which requires only a short cooking time, has been developed and is now commercially available.

In addition, a product is known that is made by steaming and drying white rice, gelatinized rice, or puffed rice, which is made by treating rice with high-temperature, high-pressure steam and releasing it at room temperature and pressure.

[Problem to be solved by the invention]

As mentioned above, the conventional method involves processing cooked rice and shortening the cooking time when eating and drinking. It's not what it brings. Moreover, in the case of pregelatinized rice, the rice grain structure is vitrified, resulting in poor water absorption.
``It is known that it takes a long time to cook, and in the case of buffed rice, the rice grain structure is extremely destroyed, so it easily disintegrates in water and does not have the texture of normal cooked rice.

In addition, a method has been proposed in which polished rice is repeatedly subjected to high heat and rapid cooling to cause cracks in the rice grains, improving water absorption and shortening cooking time, but this method also disintegrates in water. It is easy and unsatisfactory.

In view of the above, the present invention provides a method for modifying grains that can significantly shorten cooking time by treating the grains to improve water absorption and appropriately gelatinize the starch without destroying the tissue. It is intended for the purpose of providing.

[Means to solve the problem]

The present invention is based on a technical idea different from the conventional processing means described above, and the interior of starch-containing grains of rice, wheat, etc. is modified into grains that are formed porous and suitably gelatinized. Starch-containing grains of rice, wheat, etc. containing or having been made to contain at least 20% moisture are heat-treated at a temperature of at least 40°C or higher for a desired period of time in the presence of high-pressure gas, and then This is a grain modification method characterized by reducing pressure. Further, the gases used in this reforming method are preferably carbon dioxide, nitrogen, argon, helium, and air, and the heat treatment pressure is 100 to 500.
Preferably, it is a bar.

〔Example〕

As described above, the present invention is capable of shortening the cooking time when making starch-containing grains, such as rice, into boiled rice using a conventional method, while still retaining the texture and aroma characteristic of boiled rice. For this purpose, it is required that the structure of the cooked rice is not destroyed but porous, and that the starch is suitably pregelatinized.

As a result of various studies on technical means that satisfy these conditions, the present inventors found that after adding water to starch-containing grains such as rice and wheat,
It has been found that by heating this grain to a temperature at which it is suitably gelatinized in the presence of high-pressure gas, the interior of the grain becomes porous and a product with extremely high water absorption can be obtained.

The present invention is based on this knowledge, and will be explained below using examples using polished rice.

White rice usually has a moisture content of 10 to 15%, but this moisture content is adjusted to about 20 to 35%.

The moisture content may be adjusted by any method such as washing or soaking the white rice in water, or uniformly spraying the white rice with water. A surfactant, ethanol, etc. may be mixed with the water to speed up the permeability.

The polished rice adjusted to the desired moisture content in this way is
After filling the pressure-resistant container 1 shown in the figure, gas,
For example, carbon dioxide is introduced.

Carbon dioxide is led from the cylinder 2 to the heat exchanger 3, and
After heating in the range of 150° C., the pressure is increased via the pump 4 and the material is press-fitted into the pressure container 1 . In addition, 5 in the figure is a pressure regulating valve,
6 is a pressure gauge, 7 is a gas release valve, and a heater 8 is attached to the outer periphery of the pressure vessel 1.

By the above operation, the filled white rice in the pressure container 1 can be heated up to several tens of minutes.
The heat treatment is performed for the desired time of several hours, but according to the findings of the present inventors, when carbon dioxide is used, the treatment temperature is 50℃.
Preferably, the temperature is ~100°C and the processing pressure is 100-500 bar.

This is due to the fact that the temperature is higher than the gelatinization temperature of the starch in the treated polished rice, the relationship between expansion due to high pressure → reduced pressure, and practical factors due to thermal conductivity. Therefore, in order to perform the heat treatment efficiently, carbon dioxide may be passed through the pressure vessel 1 while maintaining a predetermined pressure and temperature, or a stirring means may be provided within the pressure vessel 1.

After performing the above heat treatment for a predetermined time, the gas in the pressure container 1 is released from the gas release valve 7, the pressure inside the container 1 is reduced to atmospheric pressure, the filled white rice is taken out, and the moisture content is 15%.
Perform the drying process to achieve the following.

The drying process may be optional, such as hot air drying, and as a result, porous white rice with a milky white appearance similar to glutinous rice can be obtained without the rice grains becoming lumpy.

The reason why porosity is formed by the method of the present invention is that starch is heated in a relatively low moisture environment, which suppresses viscous chains and bonds between starch granules, and that when the pressure is reduced from high pressure. This is thought to be due to a synergistic effect with swelling.

The polished rice produced by the method of the present invention absorbs water extremely quickly, and it takes less than 1 minute to reach a water absorption rate of 30%. On the other hand, the water absorption rate of untreated white rice is 20%
It takes 20 minutes to achieve this, and several tens of hours are required to increase the water absorption to 30%.

As described above, this treated rice does not substantially require washing or soaking in water, and can be subjected to heat treatment such as cooking or boiling immediately after adding water. Furthermore, it is possible to obtain white rice with excellent texture without leaving any hard core and with no rice bran odor.

This processed rice can be used as regular rice, porridge, and rice at home, and as instant food in industry.

It can also be supplied for various purposes as a raw material for processed products such as baby food. Furthermore, since this treated white rice has been pregelatinized, it can be hydrolyzed with amylase and can be used as a raw material for fermentation without heat treatment.

Due to a design change, the high-pressure gas that can be used for processing is carbon dioxide, but argon is suitable.

It is also possible to use helium, nitrogen, air, etc., and the objects to be treated are not limited to white rice, but can also include oats such as brown rice, barley, and wheat, grains or powders such as buckwheat, and corn. It can also be applied to make starch granules, raw noodles, etc. porous.

Experimental example 300g of 91% Koshihikari rice from Niigata Prefecture in 1986
After spraying 60g of water uniformly onto the water and heating it at a pressure of 200bar and a temperature of 70℃ for 1 hour, the water content was 15%.
Dry with a hair dryer until As a result, 299g
Pure white treated rice was obtained.

The results of examining the bulk specific gravity, degree of gelatinization, fat, and water absorption of this treated rice are shown in the following table and Figure 2.

Diastase method 0. Soxhlet extraction method Next, put 60 g of the above treated rice in a bowl and add 90 g of water to it.
When the rice was heated in a microwave oven for 3 minutes, fluffy rice without a core was obtained.

Further, when 30 g of the above-mentioned treated rice was heated in 100 g of boiling water for 5 minutes, it became a coreless porridge.

〔Effect of the invention〕

As described in detail above, the present invention has been developed by heat-treating starch-containing grains such as rice and wheat containing 20 to 30% moisture in the presence of high-pressure gas, reducing the pressure, and drying the grains. Since the grains are modified to be porous, the water absorption rate is significantly increased and the cooking time can be significantly shortened. Moreover, since the bran odor is removed, washing with water can be omitted.

Furthermore, since it does not cause tissue destruction such as cracking as in conventional methods, there is no inconvenience such as disintegration in water, and it is possible to obtain rice that does not impair the texture peculiar to cooked rice by cooking in a conventional manner.

Next, since it can be hydrolyzed by amylase, it can be used as a raw material for wJ fermentation without heat treatment. In addition, fat removal can be controlled by operating conditions, resulting in a desired fat content adjustment, which provides storage and low-calorie product benefits.

[Brief explanation of the drawing]

FIG. 1 is a system diagram of an apparatus for carrying out the reforming method of the present invention, and FIG. 2 is a graph showing the water absorption rates of treated rice and untreated rice treated by the reforming method of the present invention. 1...Pressure container 2...Cylinder 3...Heat exchanger 4...Pump 5...Pressure regulating valve 6...
・Pressure gauge 7... Gas release valve 8... Heater 1st factor 2nd factor j receiving j negative time (min)

Claims (1)

[Claims] 1. Starch-containing grains of rice, wheat, etc. containing 20 to 30% moisture are heat-treated in the presence of high-pressure gas, then released to room temperature and pressure, and then dried. A method for modifying grains. 2. The method for reforming grains according to claim 1, wherein the high pressure gas is carbon dioxide, nitrogen, argon, helium or air. 3. The method for modifying grains according to claim 1 or 2, wherein the heat treatment temperature is 40 to 150°C. 4. The method for modifying grains according to claim 1, 2 or 3, wherein the heat treatment pressure is 100 to 500 bar.