JPH05316969A - Quickly cooked rice packed in container and its preparation - Google Patents

Abstract

PURPOSE:To prepare a delicious product preservable for >=6 months at normal temperature by heating water-soaked rice with steam using a specific method to gelatinize the rice starch, sealing in a container and thermally sterilizing at a specific temperature. CONSTITUTION:Water-soaked rice is temporarily heated with steam at 100-120 deg.C for 5-10min to gelatinize the rice starch. The rice is sealed in a container and sterilized by heating at 95-105 deg.C for preferably 20-40min to obtain the objective product having a water-content of 30-50wt.% and a gelatinization degree of >=80% immediately after the preparation as well as after the storage for 6 months. The time for the temporarily heating at 100-120 deg.C is preferably 0.5-2min.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION The present invention is applicable at room temperature (about 10 to 30).
The present invention relates to a container-prepared cooked rice that can be stored for 6 months or longer at (° C) and can be tasted deliciously, and a manufacturing method thereof.

[0002]

2. Description of the Related Art Cooking rice takes time (about 30 minutes), but this means that the starch in the raw rice is hardly gelatinized and the water content of the raw rice is low. About 1
The cause is that it is as small as 5% by weight (hereinafter simply referred to as%). Therefore, conventionally, at least a few percent of starch in rice is used.
There are many known so-called pre-cooked rice that can be made α to increase the water content and shorten the rice cooking time. However, among them, those having a water content of about 30 to 50% by weight, which are particularly good in flavor and texture, are prone to bacterial growth during storage, and therefore need to be sterilized in the case of long-term storage. is there. However, in order to completely sterilize pre-cooked rice with a water content of 30% or more, it is generally about 120 ° C.
Although it is necessary to sterilize under severe conditions such as heating at the above temperature for a long time, there is a problem that the original flavor and texture of rice are lost.

Therefore, it is the current situation that fast-cooked rice having the original flavor and texture of rice, although it is a sterilized product that can be stored at room temperature for 6 months or more, has not yet been obtained. That is, as a conventional technique for producing early cooked rice, Japanese Patent Laid-Open No.
No. 0-87742 discloses a technique of heat sterilizing rice soaked in water at a temperature of 65 to 90 ° C. by combining high frequency heating and fluid heating. Even if the heating and the fluid heating were combined, complete sterilization was not possible, and it was only possible to obtain pre-cooked rice that could be stored at room temperature for about 3 months. Also,
In JP-A-3-53856, rice whose pH is lowered to 3.5 to 6 and whose water content is set to 35 to 47% is hermetically packaged, and 80 to
A technique of heating at 110 ° C. is disclosed, but since the pH of rice is lowered by organic acids and the like, deterioration of flavor is unavoidable.

Furthermore, although it is not pre-cooked rice, it is disclosed in Japanese Patent Laid-Open No. 3-9
No. 8542 discloses a technique of cooking rice at a temperature of 105 to 120 ° C. for the purpose of obtaining sterile cooked rice without impairing the original flavor of rice. However, complete sterilization cannot be achieved by simply applying the heating condition of 105 to 120 ° C. to sterilization of precooked rice. That is, the cooked rice in Japanese Patent Laid-Open No. 3-98542 is so-called cooked rice, which is easy to sterilize because its water content is usually 60% or more, but early cooked rice having a water content of about 30 to 50% is , As compared with this, it is much more difficult to sterilize. Also, 105-1
There is also a problem that burning odor occurs when sterilizing precooked rice at a temperature of 20 ° C. That is, food is generally charred when heated at a temperature higher than 105 ° C., especially in the case of pre-cooked rice having a lower water content than cooked rice, the surface is apt to char.

The present invention overcomes the above problems, and
It is an object of the present invention to provide pre-cooked rice in a container that can be stored for more than a month and can be tasted deliciously, and a method for producing the same.

[0006]

[Means for Solving the Problems] As a result of various investigations conducted by the present inventors to overcome the above-mentioned drawbacks of conventional fast-cooking rice, as a result of temporary heating when steaming the rice after the immersion treatment in water, It was found that the preservability of the pregelatinized starch was remarkably enhanced by heating and sterilizing at a predetermined temperature, then sterilizing by heating at a predetermined temperature, and the above-mentioned object was achieved. The present invention has been completed.

That is, according to the present invention, (1) pre-cooking in a container, characterized in that the water content is 30 to 50% by weight and the degree of gelatinization of starch is 80% or more immediately after production and after 6 months of storage. Temporarily 1 for rice and (2) rice soaked in water
Pre-cooking in a container, characterized in that starch is gelatinized by heating with steam for about 5 to 10 minutes to raise the temperature to 00 to 120 ° C., then the container is filled and sealed, and then heat sterilized at 95 to 105 ° C. The method of making rice is provided. In the present invention, the term "early cooked rice" refers to processed rice which has a high water content by converting at least a few percent or more of the starch in the rice to a high content of water, and which can be cooked in a short time.

In the pre-cooked rice cooked in a container of the present invention, the degree of gelatinization of starch immediately after production is 80% or more, preferably 90% or more.
The precooked rice cooked in a container of the present invention maintains the α-degree of starch of 80% or more after storage for 6 months after production, and has a good flavor for 6 months or more after production. Here, the water content of 30 to 50% by weight after 6 months of storage and the degree of gelatinization of starch being 80% or more means the quality of rice indicated by the preservability.
Therefore, it goes without saying that the storage period does not matter, and that the rice immediately after production is included in the precooked rice of the present invention. Generally, with respect to foods containing a large amount of starch, the higher the degree of gelatinization of starch, the better the flavor, so the fact that the pre-cooked rice in the container of the present invention retains the degree of gelatinization of 80% or more after long-term storage means
It means that the flavor is good even after long-term storage. The degree of gelatinization of starch being 80% or more means that 80% or more of the total starch contained in rice is gelatinized. The rice used in the present invention may be any type such as non-glutinous rice and glutinous rice.

The packaged precooked rice of the present invention is produced by the production method of the above item (2). When making pre-cooked rice in containers, rice is first soaked in water. As the rice, pearled raw rice is used in accordance with a conventional method, and it is suitable that the time for soaking is about 1 to 3 hours. Next, the rice is pulled out of the water and the drained rice is heated with steam. The steam heating is suitably performed at an average temperature of about 90 to 100 ° C. for about 5 to 10 minutes, but the temperature is temporarily raised to 100 to 120 ° C., preferably 105 to 120 ° C. The heating time for heating is preferably about 0.5 to 2 minutes.

According to the present invention, 1
Without a temporary heating step at 00 to 120 ° C, rice starch cannot be sufficiently gelatinized. Also, 100 to 1
If heated at 20 ° C. for a long time, the starch granules in the rice (cells storing starch) will collapse and a burning odor will occur. In the present invention, steam heating may be performed using a continuous or batch steamer. When pre-cooked rice is made under the above conditions, the water content of rice, which was about 15%, was 30%.
The degree of gelatinization of starch, which was almost 0%, can be increased to 80% or more. In addition, since the starch grains of the obtained precooked rice are hardly disintegrated, the degree of gelatinization of the starch can be maintained at 80% or more for 6 months or more after the production.

Next, this precooked rice is filled and sealed in a container.
The container used can prevent the invasion of bacteria and the like, and its form is not limited. Desirably, those having air impermeability are preferable, containers (bags) made of synthetic resin such as polyethylene and polypropylene, containers in which metal foil is combined,
Alternatively, metal cans are preferred.
The filling amount of the precooked rice in one container is appropriately determined in terms of the sterilization efficiency in the subsequent heat sterilization step. In this case, it is preferable to enclose a deoxidizer in the container together with the pre-cooked rice, because the oxidation of fat contained in the pre-cooked rice can be prevented and the deterioration of flavor can be prevented. Next, in order to sterilize the pre-cooked rice packed in this container, use a water bath or a pressure heating sterilizer to obtain 95 to 1
It is performed by heating to 05 ° C. The sterilization time varies depending on the filling amount of the early-cooked rice and the like, but about 20 to 40 minutes is suitable. In addition, sterilizing at a relatively low temperature of 95 to 105 ° C.
This is to prevent the starch granules from being broken and to prevent charring and browning. By this sterilization process, the fast-cooked rice is completely sterilized, and the germ count in 1 g of the fast-cooked rice becomes 10 or less, which is a substantially sterile state.

A continuous steamer will be described with reference to the drawings as an example of an apparatus used for carrying out the present invention. Figure 1
Is a schematic view of this continuous steamer, and in the figure, 1 is a heat treatment device having a spiral conveyor 2. Reference numeral 3 is a supply unit for supplying rice 4 to the heat treatment device 1, and rice is sent forward by the spiral conveyor 2 in the heat treatment device. No. 5 is early cooked rice obtained by heating with steam. Heat treatment device 1
Steam is introduced into and heated. In the figure, 6 is an inlet for this steam. For example, when steam at 120 ° C. is introduced, in the zones (A), (B) and (C), (A) shows a temperature of about 90 ° C. or more and less than 120 ° C. Band, (B) is about 12
0 ° C band, (C) same as (A) About 90 ° C or more 120
It can be a band below ℃

[0013]

The reason why the packaged pre-cooked rice of the present invention can maintain the starch gelatinization degree of 80% or more even after storage for 6 months after the production is that the starch granules during the pre-cooked rice hardly disintegrate and are clean. It is considered that the starch is retained in the starch granules. That is,
When the cut surfaces of the rice grains of the fast-cooked rice of the present invention and the conventional fast-cooked rice are observed with an electron microscope, the conventional fast-cooked rice shows that the starch grains in the vicinity of the outer periphery of the circular cross section collapse into a paste form. Was recognized. On the other hand, in the circular cross section of the rice grain of the early-cooked rice of the present invention, the presence of clean starch grains was confirmed over the entire surface, and the collapse of starch grains in the vicinity of the outer periphery was close to zero. The observation result of this electron microscope enables the following excellent actions of the fast-cooked rice of the present invention. The starch contained in rice is present in the starch granules, but when the rice is steamed or cooked, the starch is gelatinized, and the starch granules usually disintegrate and the starch flows out from the inside. It is said that the pregelatinized starch that has flowed out of the starch granules gradually becomes β-form over time, but the pregelatinized starch that has not flowed out of the starch granules is difficult to be beta-formated over time. On the other hand, it is said that the gelatinized starch is most likely to be gelatinized under the condition that the water content is 30 to 70%. Therefore, the conventional water content is 30-50%
Even for the pre-cooked rice, the degree of α conversion is 80 immediately after it is made.
Even if it is more than 100%, the starch granules are disintegrated, so that the degree of gelatinization is reduced to about 70% after storage for several weeks.

On the other hand, in the case of the pre-cooked rice packaged in a container of the present invention, most of the starch grains are not disintegrated, and therefore the degree of gelatinization of the starch should be kept at 80% or more even if it is stored for 6 months or more after the production. You can Moreover, since most of the starch grains of the early cooked rice are not disintegrated, it is considered that complete sterilization can be performed at a relatively low temperature of 95 to 105 ° C. That is, when the starch granules disintegrate and the starch flows out from the inside, the polysaccharide molecules such as amylose and amylopectin, which are the components of the starch, are dispersed. The dispersed amylose and amylopectin are, so to speak, naked and easily serve as a nutrient source for bacteria, and promote the growth of bacteria. Moreover, it is because amylose or amylopectin protects the bacteria present in the precooked rice from heat, and it cannot be completely sterilized unless it is heated to 120 ° C. or higher. However, in the precooked rice of the present invention, many of the starch grains have not collapsed,
Bacteria are difficult to reproduce and heat is easily transmitted to the bacteria.
It seems that complete sterilization at a relatively low temperature of 05 ° C or less has become possible.

As described above, the container-prepared early cooked rice of the present invention is
Since it is completely sterilized and the number of bacteria is 10 or less in 1 g, it is in a substantially sterile state, so that it can be stored at room temperature for 6 months or longer without any fear of spoilage.

[0016]

EXAMPLES The present invention will be described in more detail based on test examples and examples. The test method in the following example is as follows. The water content of rice was measured using an infrared moisture meter (Ket Co., Ltd., heat source 400 ° C.) under the condition of a measurement time of 30 minutes. The degree of gelatinization of starch was measured by an enzymatic method using a pharmacopoeia amylase. The number of bacteria was measured by the pour plate method. At that time, a standard agar medium (manufactured by Eiken Chemical Co., Ltd.) was used as a medium, and the medium was cultured at 35 ° C. for 2 days.

Test Example 1 Non-glutinous rice (having a water content of about 15%) that has been polished is immersed in water for about 2 hours and then drained. It was then heated for about 9 minutes using the continuous steamer shown in FIG. At that time, the temperature of the steam blown into the steamer from the inlet 6 was changed in 5 ways to obtain 5 types of unsterilized precooked rice. After cooling each unsterilized pre-cooked rice to 30 ° C or less with a vacuum cooler, filling and sealing 150 g each in a polyethylene bag, and sterilizing with a pressure heat sterilizer at 105 ° C for 30 minutes, 5 types A pre-cooked rice (sample) packed in a container was obtained. The degree of gelatinization of starch and the number of bacteria in 1 g of each sample were measured. Then, each sample was stored at about 20 ° C. for 6 months, and then the degree of gelatinization of starch and the number of bacteria in 1 g of the sample were measured. The results are shown in Table 1.

[0018]

[Table 1]

From Table 1, it can be seen that Samples 2 to 4 maintain the degree of gelatinization of starch of 80% or more even after storage for 6 months immediately after the production, and the temperature of the steam blown into the steamer is preferably 100 to 120 ° C. That is, 100 to 120 ° C temporarily
It can be seen that by performing steam heating to raise the temperature to above, it is possible to obtain early-cooked rice with a good flavor that can maintain the degree of gelatinization of starch of 80% or more after storage for 6 months.

Test Example 2 Polished non-glutinous rice (water content: about 15%) is immersed in water for about 2 hours and then drained. Then, this was heated using the same continuous steamer as in Test Example 1 for about 9 minutes. At this time, the inlet 6
The temperature of the steam blown into the steamer was 110 ° C. The unsterilized precooked rice thus obtained was cooled to 30 ° C. or less by a vacuum cooler, filled in a polyethylene bag at 150 g each, and sealed, and then sterilized using a pressure heat sterilizer. At that time, the sterilization temperature was changed in four ways to obtain samples of four types of pre-cooked rice packed in containers. The sterilization time is 30 minutes in all. The degree of gelatinization of the above-obtained four types of samples and unsterilized starch, and the number of bacteria in 1 g of the sample were measured. Further, the above 5 kinds of samples were stored at about 20 ° C. for 6 months, and then the degree of gelatinization of starch and the number of bacteria were measured. The results are shown in Table 2.

[0021]

[Table 2]

Since the samples 8, 9 and 10 are in a substantially sterile state immediately after production and after being stored for 6 months, the sterilization temperature is 95 ° C.
It turns out that it is necessary to do the above. However, 105
Sterilization at a temperature above ℃ is not preferable because it causes a burning odor.

Example 1 Non-glutinous rice (having a water content of about 15%) that has been milled is soaked in water for about 2 hours and then drained. This was supplied to the continuous steamer supply part 3 in FIG. 1, steam at 120 ° C. was introduced from the inlet 6 and heating was performed for about 9 minutes. At this time, (A), (B),
The heating conditions in the zone (C) were set as follows. Band (B): Temperature is about 120 ° C. Rice passes in about 1.5 minutes. (A) + (C) band ・ Temperature of about 90 ℃ or more and less than about 120 ℃.
Rice passes in about 7.5 minutes. The pre-cooked rice 5 discharged from the continuous steamer was rapidly cooled with a vacuum cooler to reduce the product temperature to about 30 degrees or lower. The moisture content of the thus-prepared cooked rice is about 36%, and the degree of gelatinization is about 9
It was 2%. 1k of this early cooked rice in a polyethylene bag
Each was filled with g, and an oxygen scavenger (manufactured by Mitsubishi Gas Chemical Co., Inc.) was added and sealed. Next, this rice in a container was sterilized at 105 ° C. for 25 minutes using a pressure heat sterilizer. Pre-cooked rice in a container immediately after production has a water content of about 36% and a degree of gelatinization of about 96%.
And no bacteria were detected. Further, when cooked with the same amount of water in an electric rice cooker for about 16 minutes and tasted, the taste and texture were extremely good. The pre-cooked rice in a container stored for 6 months at a temperature of about 20 ° C. after production had a water content of about 32% and a degree of gelatinization of about 87%, and no bacteria were detected. Also, when the rice was cooked with the same amount of water in an electric rice cooker for about 16 minutes and tasted, the flavor and texture were not different from those immediately after the preparation.

Example 2 Polished glutinous rice (water content: about 15%) is immersed in water for about 2 hours and then drained. This was heated for about 7 minutes using the same continuous steamer as in Example 1. That is, the spiral conveyor 2 was rotated a little faster than in Example 1 so that rice could pass through the steamer in about 7 minutes. The temperature of the steam blown into the steamer through the inlet 6 was 110 ° C. As a result, rice passes through the zone (B) in the steamer (section of about 110 ° C) in about 1 minute,
The zones (A) and (C) are above about 90 ° C. and below about 110 ° C. and passed in about 6 minutes. The discharge temperature of rice was about 90 ° C. The fast-cooked rice discharged from the continuous steamer is rapidly cooled with a vacuum cooler to bring the product temperature to about 30 ° C or lower. The moisture content of the thus obtained precooked rice is about 41%, and the degree of gelatinization is about 9
It was 0%. Put this precooked rice in a polyethylene bag 15
Each was filled with 0 g, an oxygen absorber (manufactured by Mitsubishi Gas Chemical Co., Inc.) was put therein, and the mixture was sealed, and sterilized at 102 ° C. for 30 minutes using a pressure heating sterilizer. The pre-cooked rice in a container immediately after production had a water content of about 41% and a degree of gelatinization of about 92%, and no bacteria were detected. In addition, about 50% of the amount of red beans boiled soup and a small amount of boiled azuki beans in a microwave oven (600
W) When cooked for 3 minutes to prepare red rice and tasted it, both the flavor and texture were extremely good. The pre-cooked rice packaged in a container, which was stored at a temperature of about 20 ° C. for 6 months after production, had a water content of about 35% and a degree of gelatinization of about 86%, and no bacteria were detected. In addition, when I cooked red rice by cooking for 3 minutes in a microwave oven (600W) with a small amount of red bean juice and a small amount of red bean juice for about 50% of early cooked rice, I tried it and tasted it. Both the flavor and texture were the same as those immediately after the product was made.

[0025]

The pre-cooked rice in a container of the present invention has a water content of 30.
~ 50% by weight, the degree of gelatinization of starch after storage for 6 months after production is 8
Since it is 0% or more, it can be stored for 6 months at room temperature.
Both flavor and texture are good. According to the method for producing packaged pre-cooked rice of the present invention, it is possible to produce packaged pre-cooked rice having a water content of 30 to 50% by weight and having a starch gelatinization degree of 80% or more after storage for 6 months. You can In addition, since it is sterilized at 105 ° C or lower, there is no fear of burning, burning odor, or browning.

[Brief description of drawings]

FIG. 1 is a schematic diagram of a continuous steamer used for carrying out the present invention.

[Explanation of symbols]

1 Heat treatment device 2 Spiral conveyor 3 Supply part 4 Drained rice 5 Precooked rice 6 Steam (A), (C) Temperature zone of 90 ° C or more and less than 120 ° C (B) Zone of 120 ° C

Claims (2)

[Claims] 1. A pre-cooked rice packaged in a container, which has a water content of 30 to 50% by weight immediately after production and after storage for 6 months and has a degree of gelatinization of starch of 80% or more. 2. The rice soaked in water is temporarily treated with 10
Pre-cooking in a container, characterized in that the starch is gelatinized by heating with steam for about 5 to 10 minutes at a temperature of 0 to 120 ° C., then the starch is filled into a container and sealed, and then sterilized by heating at 95 to 105 ° C. How to make rice.