JPH072097B2 - Manufacturing method of packed rice - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for producing packaged cooked rice.

[0002]

2. Description of the Related Art Retort packed rice is known as one of packed rice. For example, in JP-A-3-19661, raw rice is washed, soaked in water for a desired time, steamed, then filled in a packaging bag, and sterilized by heating under pressure. A method for producing retort-packaged cooked rice is disclosed in which the pH of the rice itself after being sterilized under pressure and heat is sterilized by immersing it in an aqueous solution whose pH has been adjusted by the method of 5.8 to 6.2. ing.

[0003]

However, in the method for producing the retort packed cooked rice, acid treatment and heating at a high temperature (for example, heating the central portion of the packaging bag at 120 ° C. for 4 minutes) are carried out.
Since it is sterilized by doing so, the cooked rice is a little sticky, and at the same time, the flavor is slightly inferior. The present invention is intended to provide a method for producing packaged cooked rice which has no stickiness on the surface, has a good flavor, and has a high storage stability.

[0004]

The method for producing packaged cooked rice according to the present invention comprises a first step of immersing raw rice in an aqueous acid solution to adjust the pH of the raw rice to 4.7 to 5.3. 3. The second step of steaming the raw rice to make steamed rice having a moisture content of 53 to 58%, and dipping the steamed rice in an acid aqueous solution to adjust the pH to 4.
2 to 4.6, the third step of adjusting the water content to 59 to 64%, and filling the packaging material with the steamed rice after the pH adjustment, and
And a fourth step of heating at a temperature of 00 ° C. or less. The raw rice is usually washed.

As the acid aqueous solution used in the first step,
Examples thereof include those containing organic acids such as lactic acid, citric acid, acetic acid, phytic acid, tartaric acid, gluconic acid and malic acid, and inorganic acids such as phosphoric acid and salts thereof. The pH of the acid aqueous solution is preferably 2.5 to 3.5. The amount of the acid aqueous solution is equal to 3 to the raw rice.
It is desirable to double the amount. The temperature of the acid aqueous solution is preferably in the range of 5 to 25 ° C.

The reason why the pH of the raw material rice after being dipped in the acid aqueous solution in the first step is limited to the above range is as follows. If the pH of the raw rice is less than 4.7, the acidity becomes too strong and the surface of the steamed rice becomes sticky in the subsequent steaming step. On the other hand, p of the raw rice
When H exceeds 5.3, it is necessary to use an acid aqueous solution having a high acidity in the third step in order to bring the pH after heat sterilization to a desired value, and the treatment of the acid aqueous solution in the first step is significant. It becomes a waste. In the first step, Table 1 below shows specific conditions of the acid aqueous solution for adjusting the pH of the raw rice to 4.7 to 5.3, immersion time, etc. Table 1 Acid aqueous solution Phosphoric acid aqueous solution Aqueous solution Aqueous phosphoric acid solution Aqueous citric acid solution Double amount to rice Double amount Equivalent amount to double amount Concentration 0.09% 0.09% 0.12% 0.15% pH 2.7 2.7 2.45 3.17 Temperature 25 ° C 20 ° C 10 ° C 10 ° C Immersion time 1 hour 16 hours 24 hours 24 hours Post-immersion 5.06 5.01 4.95 4.86 Rice pH

In the second step, the water content of the steamed rice is limited to the above range for the following reason. When the water content of the steamed rice is less than 53%, it becomes difficult to allow the steamed rice to sufficiently absorb the aqueous solution by the subsequent immersion of the acid aqueous solution in the third step. on the other hand,
When the water content of the steamed rice exceeds 58%, the water content of the steamed rice becomes high due to absorption of water during the subsequent immersion of the acid aqueous solution in the fourth step, causing stickiness. In the second step, it is allowed to inject hot water during steaming.

The acid aqueous solution used in the third step may be the same as the acid aqueous solution used in the first step. The pH of the aqueous acid solution is preferably 2.2 to 3.5. For example, a concentration of 0.15%, a pH of 2.
An aqueous solution of 43 of phosphoric acid, an aqueous solution of citric acid having a concentration of 0.2% and a pH of 3.01 can be used.

The reason why the pH of the steamed rice after being immersed in the acid aqueous solution is limited to the above range in the third step is as follows. The pH of the steamed rice is 4.
If it is less than 2, the acidity becomes too high and the cooked rice becomes sour. On the other hand, if the pH of the steamed rice exceeds 4.6, sufficient sterilization cannot be achieved even if the subsequent heat treatment is performed.

The reason why the water content of the steamed rice after being immersed in the aqueous acid solution is limited to the above range in the third step is as follows. When the water content of the steamed rice is less than 59%, the obtained cooked rice becomes hard. on the other hand,
When the water content of the steamed rice exceeds 64%, the resulting cooked rice becomes sticky. The reason for limiting the heating temperature in the fourth step is that the cooked rice becomes sticky when the temperature exceeds 100 ° C. A more preferable heating temperature is in the range of 80 to 100 ° C.

[0011]

According to the present invention, the raw rice is soaked before and after steaming in an aqueous acid solution, and the pH after soaking is regulated so as to have a predetermined value. Highly packed rice can be produced.

In other words, the inventors of the present invention have a pH of 4. I thought that it could be achieved by setting it to 2 to 4.6. However, when the washed raw rice is dipped in an acid aqueous solution to adjust the pH to 4.2 to 4.6, steamed, packed into a packaging material, and heat-treated at 100 ° C. or less to give sticky cooked rice, It turned out that the flavor was also inferior. This is because the acidity of the surface of the cooked rice before the heat treatment at the temperature is relatively higher than that of the inside because the raw rice is brought to a target pH of 4.2 to 4.6 by one-time immersion of the acid aqueous solution. It is presumed that this is due to the fact that it becomes higher.

From the above, according to the present invention, after the raw rice is immersed in an aqueous acid solution to adjust the pH to 4.7 to 5.3,
By steaming, the steamed rice is made slightly neutral from the final pH value, and the acid concentration becomes uniform over the entire surface and inside due to the diffusion of acid during steaming. Subsequently, the steamed rice is immersed again in the acid aqueous solution. In this process,
Since the target pH is adjusted to 4.2 to 4.6 and the pH of the steamed rice is adjusted to the acidic side in advance, the acidity of the surface approximates that of the inside. Then
By filling the packaging material with the above-mentioned pH-adjusted steamed rice and heat-treating at 100 ° C. or lower, sterilization can be performed without causing stickiness on the surface. Therefore, it is possible to produce a packaged cooked rice that has no stickiness on the surface, has a good flavor, and has a high storage stability. The packed cooked rice produced by the above steps can be easily eaten by treating it in a microwave oven or immersing it in hot water and heating it.

[0014]

Embodiments will be described in detail below with reference to embodiments of the present invention. Example 1

First, 15 kg of non-glutinous rice was washed while overflowing water until the bran on the surface was completely removed. Subsequently, after thoroughly removing the water of the washed raw rice, it was immersed in 20 kg of a phosphoric acid aqueous solution having a temperature of 25 ° C. and a concentration of 0.09% (pH; 2.7) for 2 hours. The pH of the rice after it was taken out from the phosphoric acid aqueous solution and sufficiently removed from the phosphoric acid aqueous solution was 5.06.

Next, 4 kg of the pH-adjusted rice was weighed, stored in a steamer lined with bleached rice, smoothed, and then steamed for 15 minutes. The pH of the steamed rice obtained is
The water content was 5.40 and the water content was 55.5%.

Next, the steamed rice is immediately concentrated to a concentration of about 0.1.
5% (pH; 2.39) phosphoric acid aqueous solution 40.06 kg
Was soaked for 1 minute. The pH of the steamed rice after removal from the phosphoric acid aqueous solution and sufficient removal of the phosphoric acid aqueous solution is 4.3.
2. The water content was 62.0%.

Next, 200 g of the pH-adjusted steamed rice
In a packaging bag consisting of a three-layer laminated film of polyester / stretched nylon / unstretched polypropylene,
After air-packed at -60 cc, packaged cooked rice was produced by heating at 95 ° C for 35 minutes.

The packaged cooked rice thus obtained had good storability without any spoilage observed even when left at room temperature for 12 months. The packaged cooked rice was directly placed in a microwave oven to heat the cooked rice, which was then opened and eaten. as a result,
It was confirmed that the product had no stickiness and had a good texture and flavor. Example 2

First, 15 kg of non-glutinous rice was washed while overflowing water until the bran on the surface was completely removed. Subsequently, after thoroughly removing the water of the washed raw rice, it was immersed in 30 kg of a citric acid aqueous solution having a temperature of 9 ° C. and a concentration of 0.15% (pH; 3.17) for 18 hours. The pH of the rice after removal from the citric acid aqueous solution and sufficient removal of the citric acid aqueous solution was 4.86.

Next, the pH-adjusted rice was weighed in an amount of 4 kg each, stored in a steamer lined with bleaching, leveled, and steamed for 15 minutes. The pH of the steamed rice obtained is
The water content was 5.10, and the water content was 55.5%.

Next, the steamed rice is immediately concentrated to a concentration of about 0.2.
0% (pH; 3.01) citric acid aqueous solution 40.08k
g for 1 minute. PH of steamed rice after removing from the citric acid aqueous solution and sufficiently removing the citric acid aqueous solution
Was 4.22 and the water content was 63.8%.

Next, 200 g of the pH-adjusted steamed rice
In a packaging bag consisting of a three-layer laminated film of polyester / stretched nylon / unstretched polypropylene,
After air-packed at -60 cc, packaged cooked rice was produced by heating at 95 ° C for 35 minutes.

The packaged cooked rice thus obtained had good storability without any spoilage observed even when left at room temperature for 12 months. The packaged cooked rice was directly placed in a microwave oven to heat the cooked rice, which was then opened and eaten. as a result,
It was confirmed that the product had no stickiness and had a good texture and flavor.

[0025]

As described above in detail, according to the present invention, it is possible to produce packaged cooked rice which has no stickiness on the surface and has a high shelf life.
As a result, heat treatment in a microwave oven or the like has the remarkable effect of easily eating cooked rice having a good flavor and texture.

Claims (1)

[Claims] 1. A first step of immersing raw rice in an aqueous acid solution to adjust the pH of the raw rice to 4.7 to 5.3, and steaming the raw rice to a water content of 53 to 58%. The second step of making steamed rice, and dipping the steamed rice in an acid aqueous solution to adjust the pH to 4.2 to 4.
6. The third step of adjusting the water content to 59 to 64%, and the packaging material is filled with the steamed rice after the pH adjustment.
And a fourth step of heating at a temperature of ℃ or less.