JPH0965840A - Production of low-protein rice - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain low-protein rice which is useful for the patients with kidney diseases by simply and effectively removing the proteins from the rice grains through their treatment with a protease and alkali soaking. SOLUTION: The hydrolytic treatment of the protein in rice grains with a protein-hydrolyzing enzyme such as an acidic protease is combined with the alkaline soaking treatment with 0.1-1.0% of sodium hydroxide and/or potassium hydroxide solution at 35-45 deg.C for 1-24 hours to give rice of low protein.

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to a method for producing rice with a low protein content by removing protein by both decomposing rice with a proteolytic enzyme and treating it with an alkali. The present invention relates to a method for producing low-protein rice useful for patients who must have kidney disease.

[0002]

2. Description of the Related Art In renal disease, especially in patients with nephritis or renal failure, hypernitrogenemia in which nitrogen components such as urea nitrogen, creatinine and uric acid in blood are accumulated, the protein which is the source of nitrogen component It is known from the past that it is necessary to control the intake of. And, it has been confirmed that the intake and the low protein diet prevent and suppress these kidney diseases. Rice is a food that has long been used as a typical grain in Japan, as well as wheat, in many countries around the world in addition to Japan, and is often used as a staple food, making it one of the major sources of protein. There is. Therefore, for kidney disease patients who have to refrain from protein intake, consuming the same amount of normal rice as a healthy person has been one of the obstacles in suppressing the progression of the disease.

As a means for solving such problems, various studies and developments of low protein rice have been conducted. For example, after starch is gelatinized, it is shaped into rice granules,
As described in JP-A-6-217719, a method of lactic acid fermenting rice with sugars and lactic acid bacteria, and as described in JP-A-6-303925, sugars, lactic acid bacteria, and proteases are used. A method of performing lactic acid fermentation and enzymatic decomposition, and a method of treating rice with an acid and a proteolytic enzyme as described in JP-B-60-2023 are known, and rice with a low protein content is obtained. Further, Japanese Patent Application Laid-Open No. 7-115920 describes a technique of removing allergen proteins by immersing rice in an alkaline solution.

However, although the method of gelatinizing starch and processing it into rice granules can provide rice with a low protein content, it has a starchy odor compared to conventional rice, and it becomes hard when it is chilled. However, it is inferior in sensory and physical properties compared to ordinary rice. In addition, the method of treating rice with sugar and lactic acid bacteria decomposes the protein by the fermentative power of lactic acid bacteria, so it takes a long time to remove about half of the protein, and the problem is that the fermentation odor remains in the rice. The removal rate is also insufficient. The method of using saccharides, lactic acid bacteria, and proteolytic enzymes in combination can obtain a sufficient protein removal rate in a shorter time than that using saccharides and lactic acid bacteria, but since lactic acid bacteria are used, it takes time to culture the lactic acid bacteria, The operation is complicated. The method of using an acid and an enzyme together is not sufficient in terms of appearance because the rice grains are significantly disintegrated. Dip rice in alkali
The technique described in Japanese Patent Publication No. 920 mainly removes proteins that become allergens, and the removal rates of other proteins are not sufficient. Therefore, it has been desired to develop a method for producing low-protein rice which is capable of easily removing 50% or more of proteins and has excellent sensory and physical properties.

[0005]

SUMMARY OF THE INVENTION An object of the present invention is to provide a method for easily and effectively removing proteins from rice grains to produce sensorially excellent low protein rice.

[0006]

The present inventors have completed the present invention as a result of earnest research for solving the above problems. That is, the present invention relates to a method for producing low-protein rice, which is characterized by combining both a proteolytic treatment with a proteolytic enzyme and a treatment by immersion in an alkali. According to the present invention, low-protein rice is obtained by combining immersion of rice in a solution containing a proteolytic enzyme and immersion in an alkaline solution. By dipping in an alkaline solution, the protein removal rate is higher than that obtained by enzymatic decomposition alone, and it is possible to produce sensory low protein rice.

The manufacturing method of the present invention will be described in detail below. First, the milled rice is washed with water to remove dirt adhering to the rice and then immersed in a solution containing a proteolytic enzyme. In this step, it is suitable that the pH is decomposed for 6 to 24 hours at the optimum pH and the optimum temperature of the protease used. As the enzyme to be used, an acidic, neutral or alkaline proteolytic enzyme of animal, plant or microbial origin can be used. In the enzymatic decomposition, when an acidic protease is allowed to act under acidic conditions, the growth of various bacteria is small, and favorable results in hygiene can be obtained. The enzyme concentration is 0.01 to the weight of rice.
1.0% is suitable, and within this range, the protein is effectively removed, and the rice collapses little. It is preferably 0.02 to 0.05%. The enzymes can be used alone or in combination of two or more.
When the enzyme is used, it is possible to effectively permeate the enzyme into the rice by removing the air bubbles in the rice grain by depressurizing the enzyme solution in which the rice is soaked after adding the enzyme.
After enzymatic decomposition, wash the rice with water to remove the enzyme.

Then, the rice is dipped in an alkaline solution. As the alkali, sodium hydroxide, potassium hydroxide and the like can be used, and these may be used alone or in combination. The conditions for immersion are 0.1 to 0.1
It is suitable to carry out the immersion treatment at 1.0% at 35 to 45 ° C. for 1 to 24 hours. Within this range, the rice grains are less damaged,
The rice has a good appearance. Preferably, it is suitable to immerse the alkaline solution at a concentration of 0.2 to 0.5% at 35 to 45 ° C. for 10 to 24 hours. The pH during immersion in alkali is 1
1 to 14 are desirable from the viewpoint of protein removal efficiency.

After treatment with an alkaline solution, the rice is washed with water, or immersed in an acid solution such as hydrochloric acid, citric acid or succinic acid, and then washed with water to remove alkali, thereby producing a sensory excellent low protein rice. You can get it. In using the low-protein rice obtained by the above method, it is possible to cook the rice immediately after removing the alkali, or to dry it and store it like normal rice, and cook it when necessary. Regarding the order of the enzymatic decomposition and the alkali immersion, it does not matter whether the enzymatic decomposition is performed first or after the alkali treatment, but when the enzymatic reaction is performed after the alkali immersion, the influence of the remaining alkali is Optimum pH for enzyme reaction due to
It is necessary to carefully adjust the pH.

[0010]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, the present invention will be described specifically with reference to examples.

[0011]

[Example 1] 150 g per 50 g of cosilica from Uonuma, Niigata
Water was added, the mixture was stirred lightly, the water was removed, and the rice was washed. This washing operation was repeated 4 times to remove the dirt adhering to the rice. Next, add 150 g of 2.5 mM succinic acid solution and 15 mg of Protease M Amano (Amano Pharmaceutical Co., Ltd.),
A vacuum treatment was performed at 10 to 20 mmHg for 30 minutes at room temperature to expel air in the rice grains and allow the enzyme to penetrate into the rice grains. After the pressure reduction treatment, 0.1 M succinic acid was added to adjust the pH to 4.5, and the mixture was enzymatically decomposed at 50 ° C. for 24 hours.
The protein removal rate was measured by sampling 18 hours later. After 24 hours, remove the succinic acid solution and
The rice was washed 3 times with 50 g of water, 150 g of 0.3% sodium hydroxide solution was added, and it was immersed at 40 ° C. for 24 hours. After that, the alkaline solution was removed, and the rice was rinsed 3 times with 150 g of water to obtain low protein rice. In addition, the following experiment was conducted for comparison.

To 50 g of Koshihikari produced in Uonuma, 150 g of water was added, and the mixture was lightly stirred and then the water was removed to wash the rice. This washing operation was repeated 4 times to remove the dirt adhering to the rice. Next, add 150 g of 2.5 mM succinic acid solution and 15 mg of Protease M Amano (Amano Pharmaceutical Co., Ltd.)
A vacuum treatment was performed at 0 mmHg for 30 minutes at room temperature to expel the air inside the rice grain and allow the enzyme to penetrate into the inside of the rice grain. After the reduced pressure treatment, 0.1 M succinic acid was added to adjust the pH to 4.5, and the mixture was enzymatically decomposed at 50 ° C. for 48 hours. After 48 hours, the succinic acid solution containing the enzyme was removed, and the rice was rinsed 3 times with 150 g of water to obtain low protein rice. The protein removal rate was evaluated as follows. That is, the amount of crude protein per solid content before and after protein removal was determined by the Kjeldahl method, and the value obtained by subtracting the value of the amount of crude protein after removal from the amount of crude protein before removal was the percentage of the amount of crude protein before removal. Expressed as The solid content was measured by the heat drying method.

The protein removal rates of the low protein rice obtained in this example are summarized in Table 1. As shown in Table 1, the removal rate of protein was 33.6% after 24 hours of enzymatic degradation, but it was 6 hours after 18 hours when immersed in an alkaline solution.
6.1%, increased to 68.8% in 24 hours, and the protein removal rate was 4 even after only enzymatic degradation for 48 hours.
The value was 8.2%, which was lower than the value obtained by removing protein in 48 hours by combining enzymatic decomposition and alkali treatment.

[0014]

Example 2 To 50 g of Koshihikari from Uonuma, 150 g of water was added, and the mixture was lightly stirred, and then the water was removed to wash the rice. This washing operation was repeated 4 times to remove the dirt adhering to the rice. Next, 150 g of 2.5 mM succinic acid solution and 15 mg of flavorzyme (Novo) were added,
The air in the rice grain was expelled by subjecting it to a reduced pressure treatment with mHg at room temperature for 30 minutes to permeate the enzyme into the inside of the rice grain. After decompression treatment,
It was prepared by adding 0.1 M succinic acid to adjust the pH to 4.5, and enzymatically decomposed at 50 ° C. for 24 hours. The protein removal rate was measured by sampling 18 hours later. After 24 hours, remove the succinic acid solution, wash the rice 3 times with 150 g of water, and add 0.3% sodium hydroxide solution 150
g was added and the mixture was immersed at 40 ° C. for 24 hours. After that, the alkaline solution was removed, and the rice was rinsed 3 times with 150 g of water to obtain low protein rice. In addition, the following experiment was conducted for comparison.

To 50 g of Koshihikari produced in Uonuma, 150 g of water was added, and the mixture was lightly stirred and then the water was removed to wash the rice. This washing operation was repeated 4 times to remove the dirt adhering to the rice. Next, add 150 g of 2.5 mM succinic acid solution and 15 mg of flavorzyme (Novo Co.), and add 10 to 20 mm.
After depressurizing treatment with Hg at room temperature for 30 minutes, the air in the rice grain was expelled to allow the enzyme to penetrate into the rice grain. After depressurization, p
It was prepared by adding 0.1 M succinic acid so that H was 4.5, and enzymatically decomposed at 50 ° C. for 48 hours.

After 48 hours, the succinic acid solution was removed to obtain 150
The rice was rinsed 3 times with g water to obtain low protein rice. The protein removal rate was calculated by the same method as in Example 1. Table 2 shows the protein removal rates of the low-protein rice obtained in this example.
Summarized in As shown in Table 2, the removal rate of protein was 31.3% after 24 hours of enzymatic decomposition, but it was 64.7% in 18 hours when immersed in an alkaline solution.
It increased to 67.3% in 4 hours, and the protein removal rate was 52.3% even if only enzymatic degradation was performed for 48 hours, and protein removal was performed in 48 hours by combining enzymatic degradation and alkali treatment. It was lower than the one.

[0017]

Example 3 To 50 g of Koshihikari produced in Uonuma, 150 g of water was added, and the mixture was lightly stirred, and then the water was removed to wash the rice. This washing operation was repeated 4 times to remove the dirt adhering to the rice. Next, 150 g of 50 mM succinic acid solution and 15 mg of Protease M Amano (Amano Pharmaceutical Co., Ltd.) were added, and enzymatic decomposition was carried out at 50 ° C. for 24 hours. After 24 hours, the succinic acid solution was removed, the rice was washed 3 times with 150 g of water, 150 g of 0.3% sodium hydroxide solution was added, and the mixture was immersed at 40 ° C. for 16 hours. After that, the alkaline solution was removed, and the rice was rinsed 3 times with 150 g of water to obtain low protein rice. The protein removal rate was calculated by the same method as in Example 1. The protein removal rate was 53.8% at the end of 24 hours of enzymatic decomposition, whereas it was 65.4% by the subsequent alkali treatment.

[0018]

Example 4 To 250 g of Koshihikari produced in Uonuma, 750 g of water was added, lightly stirred, and then water was removed to wash rice. This washing operation was repeated 4 times to remove the dirt adhering to the rice. Next, 500 g of 50 mM succinic acid solution and 75 mg of Protease M Amano (Amano Pharmaceutical Co., Ltd.) were added, and enzymatic decomposition was carried out at 50 ° C. for 24 hours. After 24 hours, the succinic acid solution was removed, the rice was washed 3 times with 750 g of water, 500 g of 0.3% sodium hydroxide solution was added, and it was immersed at 40 ° C. for 16 hours. After that, remove the alkaline solution, rinse the rice 3 times with 750 g of water, soak it in 3% citric acid solution at room temperature for 30 minutes, remove the citric acid solution, rinse with water and drain.
Got low protein rice. The protein removal rate was 70%.

50 parts by weight of water was added to 100 parts by weight of this rice, and the rice was heated and cooked at 95 ° C. for 25 minutes. In addition, Example 1
The rice was cooked with low-protein rice that had been decomposed for 48 hours with only the enzyme, and the cooked Koshihikari rice from Uonuma, which had not been deproteinized, was compared and evaluated for taste and smell. As a result of the sensory test, the rice from which protein was removed by enzyme and alkali had no difference in taste and smell from the rice not subjected to deproteinization. Although the appearance of the rice produced by treating with only the enzyme for 48 hours was the same as that of the rice not subjected to the deproteinization treatment, the rice had a different odor and was uncomfortable compared to the ordinary rice.

[0020]

[Table 1]

[0021]

[Table 2]

[0022]

EFFECTS OF THE INVENTION According to the production method of the present invention, the combined use of an enzyme and an alkali can more effectively remove the protein of rice grains than the enzymatic decomposition alone, and the sensory aspect is the same as ordinary rice, and the appearance is also the same. Low protein rice with few cracks can be easily produced.

Claims (3)

[Claims] 1. A method for producing low-protein rice, which comprises combining both a proteolytic treatment with a proteolytic enzyme and a treatment by immersion in an alkali. 2. The method for producing low protein rice according to claim 1, wherein the enzyme is an acid protease. 3. The condition for alkali immersion is that it is immersed in 0.1 to 1.0% sodium hydroxide and / or potassium hydroxide at 35 to 45 ° C. for 1 to 24 hours. 1. The method for producing low protein rice according to 1.