JPH08252070A - Production of cooked rice - Google Patents

Abstract

PURPOSE: To shorten the rice cooking time, miniaturize rice cooking equipment, prevent the quality of cooked rice after cooking thereof from deteriorating and improve the yield of the amount of the cooked rice. CONSTITUTION: This method for producing cooked rice is to add deaerated water in an amount of 1.6-1.75 times based on the weight of initially charged raw material milled rice as cooking water thereto and start the heating within at least 10min after adding the water in the method for producing the cooked rice comprising adding the deaerated water freed of a dissolved gas as the cooking water to the washed rice grains and heating the rice grains or washing the rice grains with the deaerated water freed of the dissolved gas, adding the deaerated water as the cooking water to the rice grains after washing and heating the rice grains.

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 cooked rice, that is, an improvement in a method for cooking rice.

[0002]

2. Description of the Related Art Conventionally, when cooking cooked rice, first, polished rice as raw material rice (hereinafter referred to as "raw material polished rice", usually has a water content of about 14%) is washed and dipped in rice. , I added cooking water and heated it (cooked rice) and steamed it as a finish.

The following operations are performed in each of the above steps. << Rinsing process >> Removes dirt, bran, etc. from the surface of the raw white rice. << Dip Step >> In the next heating step, about 30% by weight of water is infiltrated into the rice grains in a step for performing uniform heating via water. << Watering / Heating Step >> In the rice cooking step, the rice grains after soaking are heated by adding cooking water, and the water permeated is used to heat the rice grains evenly To gelatinize (alpha). << Steaming process >> It is the aging process of cooked cooked rice,
Sufficient alpha and remove excess water from cooked rice to remove stickiness on cooked rice surface.

The general time required for each of the above steps is
5 minutes for washing rice, 1-2 hours for soaking, 20 minutes for watering and heating,
It takes 1 hour 45 minutes to 2 hours 45 minutes for 20 minutes to steam. In addition, the amount of water used was about 7 times the weight of the initially added raw white rice in the rice washing process, and about 1 to 3 times the amount of water was required in the dipping process. Generally, the amount of water required for cooking water is about 1 to 1.5 times the weight of the initially added raw white rice, and about 2.3 times the weight of the initially added raw rice is used. It has been obtained (the amount of water is slightly different depending on the taste when the cooked rice is used for processed cooked rice such as sushi and fried rice, etc.). Therefore, the total time required for the conventional rice cooking method is usually 2 to 3 hours, and the required amount of water has reached 9 to 12 times the weight of the initially added raw white rice.

This conventional cooking method is the same for cooking rice at home and for cooking a large amount at a lunch center, etc. In order to cook delicious rice, it is necessary to go through the above-mentioned steps. It is also a stereotype.

However, in recent years, among the above steps, a method of shortening the rice washing time has been proposed, and the amount of water used at that time is also reduced to the same amount as the weight of the raw white rice initially charged. The so-called non-washed rice, which has been treated so that washing rice can be omitted after pearling, is being adopted, and the overall cooking time is being shortened, but the dipping, watering, heating, and steaming steps are almost the same as before. It is done without change.

[Problems to be Solved by the Invention]

Meanwhile, as the demand for cooked rice increases with the recent progress of the restaurant industry and the like, the problems that will be required more and more in the future are improvement in productivity and reduction in production cost. Also,
When producing cooked rice and a product obtained by processing this cooked rice, as mentioned above, the dipping process requires a predetermined time, and this time cannot be shortened.Therefore, it is necessary to anticipate this time and start the operation immediately. I couldn't get cooked rice. In the rice washing process, with the advent of the same amount of rice washing method and non-washed rice, the amount of water used and the time can be shortened or omitted, but in the subsequent dipping process, the shape of the dipping tank and the dipping procedure can be improved. Only ingenuity regarding the method such as this can be seen.

In particular, this dipping process requires the longest time in all the processes, and the equipment cost required for the dipping device is
It accounts for 1/4 to 1/3 of the whole. Therefore, in order to reduce the production cost and improve the production efficiency, the omission or reduction of the dipping process is a problem.

However, if the dipping process is simply omitted, the surface of the rice grains is watery and the inside is hard rice grains, so-called "Nakagome" rice, and when the amount of water is increased, it becomes sticky. And the quality of cooked rice is inferior. That is, at present, there has not been proposed yet a satisfactory method for substantially shortening the time of the dipping process while omitting the dipping process itself while maintaining the quality of cooked rice.

Therefore, the inventor has carried out research on a method of omitting the dipping step which has been conventionally indispensable while maintaining at least the quality of cooked rice, and completed the present invention.

[0011]

The present invention has been made to solve the above-mentioned problems. The invention according to claim 1 cooks rice grains washed with deaerated water from which dissolved gas is removed. In the method for producing cooked rice that is added as water and heated,
1.6 with respect to the weight of the raw white rice initially charged with the deaerated water
It is characterized in that the water is added as cooked water up to 1.75 times, and heating is started within at least 10 minutes after the addition of water, and the invention according to claim 2 uses degassed water from which dissolved gas has been removed. In the method for producing cooked rice in which rice grains are washed, and the deaerated water is added as cooking water to the washed rice grains and heated, 1.6-1. It is characterized in that it is watered as 75 times the cooked water, and heating is started within at least 10 minutes after the watering, and the invention according to claim 3 is characterized in that it is boiled within at least 10 minutes after the start of heating. Further, the invention according to claim 4 is characterized in that the dissolved oxygen concentration of the degassed water from which the dissolved gas has been removed is 1 ppm or less immediately before heating.

[0012]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Specific embodiments of the present invention will be described in detail below with reference to the drawings. First, an embodiment of the method for producing cooked rice according to the present invention will be described with reference to the process chart shown in FIG.

Deaerated water is prepared in advance as water for use in washing rice and cooking water. What is this deaerated water?
Dissolved gas is removed from drinking water such as tap water and well water by vacuum degassing or membrane degassing. The degree of degassing is generally 1 ppm or less (more preferably 0.5 ppm or less) in terms of dissolved oxygen concentration (DO value). "1ppm or less (more preferably 0.5ppm or less)"
The degree of degassing means that the dissolved oxygen concentration immediately before heating is 1 ppm or less. As a simple confirmation method,
It refers to a state where the heating temperature is 95 ° C. and no bubbles are generated. It should be noted that nitrogen, oxygen (ratio 2: 1) and carbon dioxide are dissolved in ordinary water that has not been degassed (hereinafter referred to as "normal water"), but the same in each of the above degassing methods. Since it is degassed in proportion, it is generally indicated by the amount of oxygen that is easy to measure.

Then, the rice grains (polished rice) to be cooked are washed with deaerated water (rice washing step). In this operation, the rice bran and dust adhering to the rice grains are mainly stirred and washed away in a large amount of water, and at the same time, continuous washing with overflow or washing once for a short time is done so as not to produce broken rice. In multiple times. Washing in a short time here means washing within 5 minutes, and thereafter, it is important that 10 minutes or more do not elapse immediately before heating in a state of being immersed in water. In addition, it is generally known that about 10% of the weight of the raw white rice is absorbed during the washing operation.

Next, deaerated water as cooking water is added to the rice grains after washing to heat the rice, and the rice is cooked (watering / heating step). The amount of water added as cooking water at this time is 5% to 25% larger than that in normal rice cooking (rice cooking with a dipping step). Here, if the amount of water added is 5% or less, the hardness becomes higher than the hardness that is normally preferred, and if the amount of water added exceeds 25%, the product becomes sticky and the taste is significantly deteriorated. That is, the amount of water used in the present invention is 1.6 to 1.75 times as much degassed water as the cooking water with respect to the initial weight of the raw white rice. In addition, it is important for heating after water addition to avoid water absorption at normal temperature as much as possible, and promote water absorption during heating, and start heating within at least 10 minutes after water addition. This is because if the rice grains after washing are soaked in water at a normal temperature (15 ° C to 40 ° C) for 10 minutes or more, the water absorption amount increases, and the dipping step is not actually omitted. . Also, the heating time naturally varies depending on the rice cooker based on the amount of rice cooked (total amount of rice + water added), but when cooked by a general rice cooker (boiling type rice cooker), it boils within at least 10 minutes. To adjust the firepower. In the rice cooking method that omits the soaking step, that is, the so-called non-immersing method, it is not desirable that the heating time be long, and it is desirable that the heating power be adjusted so that it boils within 7 minutes. Thus, according to the watering / heating step in the present invention, as will be described later, normal rice cooking (rice cooking by the conventional method described later)
It was confirmed that the yield (weight after cooking) was improved by 5% to 10% as compared with the quality (quality after cooking) in (1).

When deaerated water is used as cooking water in this water addition / heating step, the deaerated water permeates while taking in the air in the rice grains, so that it is faster and more uniform than the one using ordinary water. Water penetration is performed. As a result, according to the present invention, it is possible to heat the starch in the rice grain while swelling the starch even if water is not permeated into the rice grain in the dipping step, that is, even if the dipping step is omitted. Therefore, it is possible to obtain cooked rice in which starch has been gelatinized (gelatinized) sufficiently. In addition, the deaerated water that has penetrated into the rice grains has a smaller amount of dissolved oxygen than normal water, so there are few bubbles from the inside of the rice grains during heating, and as a result, cell collapse on the surface of the rice grains is suppressed, and The amount of stickiness due to starch spillage is also reduced. Furthermore, since the dissolved oxygen is removed from the deaerated water as cooking water in this case, it is possible to prevent the oxidation of various umami components in the rice grains during rice cooking, for example, reducing sugars such as glucose. As a sweet rice.

In the water adding / heating step, if heating is started without sufficiently absorbing water to the inside of the rice grain using normal water, a paste layer is formed on the surface layer of the rice grain, and this paste layer allows heat transfer to the inside. Disturbed. Further, when water is usually used, the permeation into the rice grain is hindered by the air inside the rice grain, so the starch in the rice grain is heated before it swells, and the starch inside the rice grain is sufficiently gelatinized. Not done Therefore, the surface of the rice grains is watery and the inside is hard rice grains, so-called "nakagome" rice. From this, the superiority of the rice cooking method according to the present invention can be confirmed.

After the watering / heating step, the steaming step is carried out in the same manner as in the conventional one, in which the heat of the cooked rice is retained and the rice grains are sufficiently gelatinized. After this, various processing is carried out according to the purpose of various final products. It is sent to each process such as arranging and forming.

Next, the results when the present invention is applied will be described based on the experimental results. First, Table 1 shows
Method 1 for testing rice cooking test using deaerated water and tap water
~ 4 is a combination when deaerated water or tap water is used for washing rice and cooking water, and Method 5 is the above Method 1
For comparison with up to 4, conventional rice washing, soaking, watering,
Rice is cooked using tap water in each heating process.
Then, with respect to each cooked rice, changes with time in water content, hardness, etc. were measured, and the results are shown in Table 2.

[0020]

[Table 1] ◎: Deaerated water (DO value: 0.5 ppm) ○: Deaerated water (DO value: 1.0 ppm) △: Deaerated water (DO value: 2.0 ppm) ●: Tap water (DO value: 10.0 ppm) )-: Omitted *: Time required from start of heating to boiling is 10 minutes *: Start of heating 5 minutes after completion of washing rice

The following Table 2 shows the water content, hardness, reducing sugar content of cooked rice in the production method according to the present invention and the conventional method,
The amount of water and the alpha conversion rate are shown, and the amount of water is dry,
It is known that hardness affects the texture, reducing sugar amount affects umami (sweetness) and nutrition, tongue amount affects gloss and texture, and alpha conversion rate affects umami.

[0022]

[Table 2] Reducing sugar: Somogene Nelson method (glucose conversion: mg / rice g) Aunt: Phenol-sulfuric acid method (glucose conversion: mg / rice g) Alpha conversion rate: β-amylase / pullulanase method

From Table 2, comparing Method 1 and Method 2 (method of the present invention) with Method 5 (conventional method) after 6 hours of rice cooking, there is almost no difference in water content and hardness. In Method 1 and Method 2, the amount of reducing sugar is large and the amount is small. That is, the cooked rice obtained by the present invention has a large amount of reducing sugar as compared with cooked rice obtained through a dipping step with normal water as in the conventional method, and therefore has excellent umami (sweetness) and nutrition, Since the amount is small, it is said that it is excellent in gloss and texture, and the quality equal to or higher than that of the cooked rice by the conventional method can be obtained. Further, after 24 hours of cooking rice, the difference between the two becomes large, and the cooked rice according to the present invention shows little change in quality with time.

In comparison between Method 1 and Method 2 (method of the present invention) and Method 3 (comparative example of deaerated water),
After 6 hours of cooking rice, there is almost no difference, but cooking rice 2
There is a noticeable difference after 4 hours. That is, the cooked rice according to the present invention has little change in quality over time, whereas the cooked rice according to Method 3 has a higher hardness and a lower α-converting rate over time,
The quality changes with time are large.

Further, in comparison between Method 1 and Method 2 (method of the present invention) and Method 4 (comparative example of tap water), there is not much difference in water content after 6 hours of cooking rice, but hardness, There is a significant difference in the amount of reducing sugar and the amount of bean paste. That is, in comparison between the two, the cooked rice according to Method 4 has higher hardness and a larger amount of sticky rice than the cooked rice according to the present invention. It can be seen that you can only obtain cooked rice that does not look good, such as gloss. Comparing this point 24 hours after cooking rice, it becomes even more remarkable.

From the above, when the cooked rice is produced by using degassed water as in the method according to the present invention, water permeates well into the rice grains and the starch, protein, lipid, etc. due to oxygen in the water Because it can suppress the oxidation of rice and the tissue destruction of rice grains,
Even if the conventional dipping process is omitted, the following quality improvements can be seen. (1) You can make cooked rice with excellent luster and viscoelasticity. (2) There is little deterioration in flavor and it is cooked white. (3) Rice with little change in color can be made.

This means that cooked rice (rice) is unlikely to be eaten immediately after cooking like commercial cooked rice, and cooked rice which is particularly suitable for use after several hours or 30 hours can be provided. Shows. In addition, cooked rice cooked with degassed water is excellent in terms of shelf life, convenient for distribution, and shortens the time of 1 to 2 hours by omitting the dipping process, and it is also possible to change the manufacturing time zone. Is shown.

The results of the above-mentioned scientific and physical tests are in good agreement with the results of the sensory test shown in FIG.
FIG. 2 is a graph showing the results of a sensory test of cooked rice according to the method of the present invention and the conventional method. In FIG.
"-" Is due to cooked rice based on the method of the present invention, and "-●-" is due to cooked rice based on the conventional method.

From the results shown in FIG. 2 as well, the cooked rice obtained by the method of the present invention has good quality when cooked, and the dipping step can be omitted. Therefore, the cooking time can be shortened and the size of the hardware in the cooking step can be reduced. It also has an advantage.

Furthermore, FIG. 3 shows the relationship between the amount of water added and the weight of cooked rice when the same weight of raw white rice is used. It is set as a case where rice is cooked in a state where 1.5 times the amount of cooking water is added to the weight of the raw white rice initially added to obtain 2.3 times the amount of the raw white rice. As can be seen from FIG. 3, according to the method of the present invention, when trying to obtain cooked rice of quality equal to or higher than that of Method 5 (conventional method) (sensory test good region), deaerated water was added. The amount of water is increased by 5% to 15% in the conventional method. This means that degassed water penetrates while taking in air bubbles present in rice grains, and it is possible to suppress the tissue destruction of rice grains due to the air bubbles, so that compared to the conventional method, the rice grain surface is tensioned. This is because it can contain a large amount of water evenly.

In addition to the quality of cooked rice, the above is an effect of improving productivity and reducing production cost. That is, the rice cooking line can be simplified by omitting the dipping process, the manufacturing time can be shortened, and the amount of water used can be greatly reduced. It shows that the yield of cooked rice can be improved.

In the above description, the method of using deaerated water in the rice washing step and the hydration / heating step has been explained. In the method of the present invention, normal water is used in the rice washing step. Alternatively, it is possible to omit the rice washing step by using non-washed rice.
In short, in the method of the present invention, at least by using degassed water in the water adding / heating step, the dipping step,
Furthermore, it is possible to omit even the rice washing step.

[0033]

As described above, according to the method of the present invention, even if the dipping step is omitted, the rice grain is uniformly permeated with water, which facilitates heat conduction during heating, and as a result, the paste of the rice grain can be obtained. Since it can be sufficiently converted into starch (uniform gelatinization of starch), it has a high alpha ratio (hard to age), good moisture retention, excellent viscoelasticity, and is white, glossy and does not lose its shape. You can get high quality cooked rice.

Further, according to the method of the present invention, it is not necessary to immerse the rice grains in water prior to cooking rice, and therefore the time required for this immersion is not required, so that the time for the overall cooking process can be shortened. Since this can be achieved and such time can be shortened, it is possible to immediately cook rice (emergency rice) and increase production.

Further, as described above, since the dipping step can be omitted, a large-capacity dipping tank, which has been indispensable in the past, and
A conveyor line for maintaining the dipping time on the line is no longer required, and the rice cooking equipment can be made smaller and less expensive.

Further, according to the method of the present invention, when the cooked rice having the same quality as the cooked rice obtained by the conventional rice cooking method is obtained, the weight of cooked rice is increased by about 5% to 15%.
Materials can be saved, which also leads to lower manufacturing costs.

[Brief description of drawings]

FIG. 1 is a schematic diagram for explaining a process diagram to which a method for producing cooked rice according to the present invention is applied.

FIG. 2 is a graph showing the results of a sensory test of cooked rice in the manufacturing method according to the present invention and the conventional method.

FIG. 3 shows a manufacturing method according to the present invention and a conventional method,
It is a graph which shows the relationship between the amount of water and the weight of cooked rice when the raw material white rice of the same weight is used.

Claims (4)

[Claims] 1. A method for producing cooked rice, wherein deaerated water from which dissolved gas has been removed is added as cooking water to heated rice grains, and the rice is heated. A method for producing cooked rice, characterized in that the water is cooked as 1.75 times as water, and heating is started within at least 10 minutes after the water is cooked. 2. A method for producing cooked rice in which rice grains are washed with deaerated water from which dissolved gas has been removed, and the deaerated water is added to the rice grains after washing as cooking water to heat the deaerated water. 1.6 to 1.7 based on the weight of the raw white rice initially charged
A method for producing cooked rice, which comprises boiling water 5 times and then starting heating within at least 10 minutes after the addition of water. 3. The method for producing cooked rice according to claim 1, wherein boiling is performed within at least 10 minutes after the start of heating. 4. The method for producing cooked rice according to claim 1 or 2, wherein the dissolved oxygen concentration of degassed water from which dissolved gas has been removed is 1 ppm or less immediately before heating.