JP3310081B2 - Production method of highly hydrous 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 cooked rice having a high water content . More specifically, the present invention relates to a method for suppressing the decrease in the taste of cooked rice stored at a relatively low temperature after production by cooking rice with a large amount of water .

[0002]

2. Description of the Related Art In recent years, convenience stores (CVs) have been developed.
S) and lunches and prepared foods sold at supermarkets are increasing year by year. In addition, various types of rice, such as white rice, brown rice, and cooked rice, are centrally cooked at one place and delivered to each user. And some of these kinds of rice are
Processed into lunch boxes, rice balls, sushi, etc., and consumed by consumers.

For example, in the case of lunches sold at CVS or the like, rice prepared in advance at a rice cooking center is transported to a lunch box factory, processed into a lunch box or onigiri, and then delivered to each store. I have. As a result, the rice cooked at the rice cooking center will be eaten by consumers only after a lapse of about 12 to 36 hours.

Generally, the delivery of cooked rice (including bento and white rice) is carried out at about 20 ° C. in order to prevent the deterioration of rice and to minimize the growth of microorganisms. However, although this temperature is not in a temperature range that causes extreme starch degradation, starch degradation has progressed steadily, and it has been required to suppress rice degradation.

[0005] Also, with regard to take-out lunches (including onigiri and sushi), cooked rice is often eaten after a lapse of time without eating immediately, thereby suppressing the deterioration of the taste of cold rice. Was required.

[0006] Conventionally, as an additive for improving the taste of rice, an enzyme preparation containing enzymes such as amylase, protease, papain, diastase, and lipase as main components,
Formulations such as glycerin fatty acid esters and other food emulsifiers, edible oils, salt, sugars, chlorella extracts, and various seasonings are commercially available.

[0007] However, the effects of these preparations are observed immediately after cooking or shortly after storage under heat, but when stored at a low temperature, for example, 20 ° C or lower, the effect is not sufficiently sustained and satisfactory. No effect was obtained.

[0008]

SUMMARY OF THE INVENTION The present invention is intended for cooking rice.
Until eating, long time at relatively low temperature, for example, 20 ℃ or less
Rice starch even if kept at a temperature of about 24-36 hours
A method for producing cooked rice in which the decline in taste due to its origin has been suppressed
It was made to provide.

[0009]

The present inventor has solved the above-mentioned problems.
As a result of intensive studies to solve the problem, the amount of water added when cooking rice
Is larger than the general amount of water, that is, 1. of the raw rice weight.
By cooking rice with 6 to 1.7 times the amount of water,
That taste deterioration over time is suppressed, and
The softening of the rice grain surface caused by
Or adding transglutaminase to cooking water
And found that the present invention was completed based on this finding. That is, the method of the present invention comprises
Has become. 1 When cooking rice, transglutaminer
Add an additive consisting of ze to immersion water or cooking water and wash
Rice cooked with 1.6-1.7 times the amount of water of raw rice
A method for producing cooked rice, characterized by being cooked.

[0010]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention is advantageously applied to rice cooking, so-called ulch rice, but the application of the present invention is not limited to this ulch rice cooking.
Hereinafter, the present invention will be described in detail.

[0011] Usually, rice used for various business uses a continuous rice cooker with a strong thermal power. These rice cookers
Although the heat source is gas or steam, gas-type continuous rice cooking equipment is generally widely used.

When rice is cooked in a continuous rice cooker regardless of the type of heat source, the washed rice is immersed, and then an appropriate amount of cooked water is added.
After being added, it is cooked, and then subjected to a cooling process, if necessary, through a mullet and loosening process, and is used for various types of lunches, rice balls, and sushi.

At this time, the immersion of the washed rice, the amount of cooked water, and the steaming conditions are important factors that greatly affect the taste of cooked rice . In particular, many researchers have reported that the amount of cooked water is closely related to the degree of gelatinization that affects the texture of cooked rice , and that the amount of cooked water during cooking has a significant effect on the quality of cooked rice. Is a known fact. By the way, say here
Cooking rice water refers to the water used to cook washed rice.
The amount is determined based on the weight of raw rice before washing.

Usually, the required amount of cooking water is used as it is,
As described above, a portion of the rice immersion water washed in advance
Or use rice that has been washed beforehand
After that, drain the water and add rice cooking water.
The rice was weighed and the rice absorbed water by immersion
Calculate the amount of water and subtract it from the required amount of cooking water.
Add the amount of water to the cooking water. At the time of the rice washing, to water absorption about 10% or so with respect to raw rice weight, but this amount
Is ignored.

[0015] Normally, the cooking conditions of wurch rice, which is the staple food of the Japanese, are individually determined by each individual and cannot be determined unconditionally. For example, New Food Industry Vol. 31, No.
6, 65-79 (1989), the amount of water added to rice after washing is
It is generally said that the weight of rice is 1.5 times the weight of rice, and the Journal of the Japan Food Industry Association Vol. 32, No. 6, 386-390
According to (1985), in Koshihikari from Niigata Prefecture, the amount of water 1.2 times the weight of fresh rice after washing is the optimal amount of water for taste.

However, Japanese Journal of Home Economics Vol.38 No.7 567
575 (1987), Journal of Home Economics, Vol.31 No.8 568-573
(1980), etc., the cooking method is gas cooking rice directly,
Electric rice cooker Regardless of the difference in rice cooking, when cooking rice with rice cooking water of about 1.3 to 1.4 times the amount of raw rice,
It is reported that there is a tendency to cook rice that is relatively easy to eat.

From these literatures, it can be concluded that although the taste of rice varies greatly between individuals, more water, that is, more than about 1.4 times the weight of raw rice, tends to deteriorate the texture. Is also possible.

[0018] Further, in the patent of a quality improving agent for cooked rice, the cooking condition of cooked rice described in the working examples is often found to be 1.3- to 1.4-fold water-hydrated.

For example, in Japanese Patent Application Laid-Open No. 5-153242,
All the examples described in the examples are all 1.4-fold water, and in JP-A-4-66065, most of the described examples are examples in which rice is cooked with 1.3-fold water. .

From this fact, it can be determined that the amount of water added during rice cooking is 1.3 to 1.4 times the weight of rice, which is the staple food of the Japanese, and is suitable for the rice cooking conditions of glutinous rice.

Normally, the water content of cooked rice prepared by adding 1.3 to 1.4 times the amount of water with respect to raw rice is determined in advance by the water contained in the rice,
Considering the water that evaporates during cooking and cooling,
It is around 56-61%.

For example, the amount of water in the white rice in a lunch box sold in a convenience store or the like and the white rice sold in a single item is about 58-61% even after a vacuum cooling process or the like after production. It can be said that the rice was cooked under the condition of water addition.

Further, cooked rice containing more water than this has a remarkable decrease in taste, and it is natural that commercial cooked rice is not produced due to softening of rice grains and poor separation from the pot. At present, various types of cooked rice are cooked in these situations, but in the present invention, it is apparent that the conventional rice cooking method has more water.
It is characterized by cooking rice in large quantities .

That is, currently, commercial rice and / or
Alternatively , in other rice cooking facilities, the above-described watering condition, that is, the previously washed rice is 1.3 to 1.5 times the raw rice weight.
While rice is cooked with the amount of water added , in the present invention, 1.6 to 1.7 is used.
It is characterized by cooking rice with twice the amount of water .

As a patent for transglutaminase acting on rice, there is JP-A-5-15324. However, the invention merely uses transglutaminase in rice for the purpose of improving the flavor of cereals, mainly rice, that is, to reduce off-flavors such as old rice odor, bran odor, and wheat odor. Has a fundamentally different purpose.

As an additional example, see JP-A-5-15324
In the gazette, most of the examples are in accordance with the method of producing retorted cooked cooked rice, aseptic-filled cooked rice, and also in the method of cooking cooked rice used in such retort cooked rice and aseptic cooked rice, the amount of water added is rice weight This is about 1.4 times that of the present invention, which is also greatly different from the present invention.

In the present invention, by increasing the amount of water added during cooking, the gelatinization of the starch proceeds sufficiently and smoothly even under all kinds of cooking conditions. As a result, during the low-temperature storage period, for example, at a temperature of 20 ° C. or lower. The purpose of the present invention is to provide a method for suppressing the deterioration of starch for about 24 to 48 hours, and does not expect the effect of reducing the off-flavor of rice.

That is, the role of transglutaminase in the present invention is to suppress the outflow of starch paste generated when rice is cooked in a situation where the amount of water is large, and to maintain the texture of cooked rice.

For example, under general rice cooking conditions, water pickling is carried out at a temperature of about 15 to 30 ° C. for about 30 to 90 minutes, and under these conditions, the method of the present invention has a sufficient effect.

Further, when the liquid temperature at the time of immersion in water was raised to about 40 ° C., the effect of the method of the present invention was further enhanced.

When transglutaminase was allowed to act during immersion in water, the effect of the method of the present invention was observed at a water temperature in the range of 5 to 50 ° C.

A sufficient effect was observed even when transglutaminase was added to the cooking water used for cooking rice after the rice was immersed . At this time, it was found that the rice cooker was previously heated to about 30 to 45 ° C., preferably about 40 ° C., and the use of transglutaminase was more effective.

The type of the rice cooker used in the present invention is an electric rice cooker (a general household round type, a commercial three-dimensional rice cooker, etc.).
And rice cookers (general household round type, commercial three-dimensional rice cooker, etc.), continuous rice cookers (gas type square pot, round type, steam type continuous rice cooker line), pressure cooker rice cooker, etc. Although there is some difference in the amount of water evaporated during rice cooking depending on the type of the apparatus, the method of the present invention is not significantly affected.

The heating power of these rice cookers varies depending on the type of each device, but generally, if the heating power is sufficient to cook rice, the effect of the present invention can be sufficiently exerted.

It is known that a continuous rice cooker for commercial rice cooks rice with high heat and good taste compared to an electric rice cooker in a general household. However, the method of the present invention is intended for use in such a rice cooking facility. Sufficient effects can be exhibited even when not used.

When transglutaminase is used, the type and pH of immersion water or rice cooking water are as follows:
There is no particular limitation.

For example, in commercial rice, water used for immersing rice and cooking rice is generally tap water. However, recently, to improve the taste of rice, alkaline electrolyzed water,
There are also cases where so-called food water such as magnetized water (magnetic water), ionized water, deaerated water, highly purified water, high-frequency low-voltage treated water, and low-mineral water is used.

Since the effect of transglutaminase in the method of the present invention is an enzymatic action on rice protein, it is not basically affected by these types of water. However, in view of the characteristics of the present enzyme, the pH of water used for immersion or cooking water is preferably about 5 to 8.

The transglutaminase used in the method of the present invention does not have any problem whether it is extracted from animal liver or the like or produced by culturing using microorganisms.

For example, animal-derived transglutaminase is known from JP-A-58-149645, and a microorganism-derived transglutaminase is known from Japanese Patent Application No. 62-125067. However, since animal-derived extract enzymes are very expensive, it is desirable to use microbial transglutaminase for application to foods. When these transglutaminases are used, it may be necessary to use calcium or the like in combination depending on their properties. In addition, transglutaminase has its activity alienated by metal ions such as Cu2 + and Zn2 + (Japanese Patent Application Laid-Open No. 2-18661), and therefore, care must be taken when using the product of the present invention.

The role of transglutaminase in the method of the present invention is to catalyze the formation of a peptide cross-link by transferring the α-amino group in a peptide to another amino acid in a protein contained in about 10% of rice. Thus, the dissolution of starch paste is suppressed. Therefore, in the protein in rice, it is possible to suppress degradation of rice by starch origin by the same principle as in the case where the enzyme catalyzing these phenomena is present other than transglutaminase.

In the method of the present invention, the method of adding transglutaminase during rice immersion or immediately before cooking rice has relatively good workability.
The effect was recognized when added in (unit) / g or more.

Further, these effects in the present invention are also observed for rice rice and other foreign rice such as indica rice, and are not particularly affected by the type and shape of rice and the content ratio of amylose and amylopectin.

In the present invention, for the purpose of further enhancing the effects of the present invention, components which have been conventionally used with the expectation of improving effects of rice, such as enzymes such as cellulase and diastase, are used as main components. Enzyme preparations, glycerin fatty acid esters, food emulsifiers including sucrose fatty acid esters, edible oils, salt, saccharides, inorganic salts, chlorella extract, etc., even in combination within the range of enhancing the effects of the present invention, especially No problem.

The rice cooked with transglutaminase as described above is heated at 90 ° C. for 15 minutes or more by cooking rice, and the activity of the cooked rice cooked is inactivated. .

The cooked rice produced according to the present invention is
The amount of water in cooked rice is higher than that of cooked rice produced by ordinary water addition, so-called 1.2- to 1.5-fold water addition, and it can be confirmed by measuring the water content of cooked rice.

[0047]

EXAMPLES The present invention will be described below in detail with reference to examples, but the present invention is not limited to these examples.

Example 1 400 g of commercially available Koshihikari was washed with water and drained, and then a transglutaminase solution of 50 u / g with respect to the weight of raw rice (liquid temperature: 40 ° C.)
Immerse in a predetermined amount. After immersion treatment in a 40 ° C thermostat for 60 minutes, rice cooker E manufactured by Sanyo Electric Co., Ltd. with immersion rice and immersion water
Cooked in CJ-U3R. Then, after 30 minutes spotty 20
The mixture was quenched to 10 ° C., stored at 10 ° C. for 24 hours, and subjected to a sensory test. In addition, the example of the cooked rice cooked by the conventional method was also described as a comparative object. Further, in order to more specifically express the effects of the present invention, the cutting force of cooked rice was measured using a rheometer J type manufactured by Fudo Industry Co., Ltd.
The results are shown in Table 1.

[0049]Sensory test evaluation  “Degree of starch deterioration” ○: Not deteriorated Starch deterioration is not felt △: Slightly deteriorated Starch deterioration is recognized compared to immediately after cooking rice
×: Deteriorated Deterioration of starch clearly felt “Rice texture” A: Preferable texture Rice grain is firm and preferred
Good texture B: Slightly good texture The grain of rice is slightly weak, but acceptable
It is in the range C: bad texture
Shaky

[0050]

[Table 1]

As shown in Table 1, by increasing the amount of water added during cooking, deterioration of starch during storage at 10 ° C. for 24 hours is suppressed. That is, cooked rice cooked with a water content of 1.3 times increases the cutting power of cooked rice grains after storage at 10 ° C. for 24 hours, and a deterioration phenomenon of starch is observed. Also, increase the amount of water during cooking,
That is, by cooking rice at 1.5 times or more the weight of the washed rice, no significant change was observed in the cutting force after 24 hours at 10 ° C., and the deterioration of starch was suppressed. However, organoleptically, the texture of the rice was weak, and the stickiness due to the outflow of starch paste was recognized, and the commercial value was low.
On the other hand, rice is cooked with 1.65 times the amount of water by the method of the present invention.
The rice grains of the cooked rice were solid, the starch glue flow was small, and the rice was excellent organoleptically. Further, the starch was hardly deteriorated due to the large amount of water.

(Example 2) After washing and draining 400 g of commercially available Sasanishiki, it was immersed in a predetermined amount of immersed water with respect to the weight of raw rice (adjusted to be 1.35 to 1.6 times water with respect to the weight of raw rice; water temperature 25 ° C) Soak for 90 minutes. Then, along with the immersion water, rice cooker GK-
Rice was cooked in 15 L-A (P), and after unevenness for 30 minutes, it was rapidly cooled to 20 ° C. and stored at 10 ° C. for 24 hours, and then a sensory test was performed. In addition, examples of cooked rice cooked by a conventional method are also described for comparison. The sensory test was performed by the method according to Example 1. Further, for concrete expression, the stress relaxation of the cooked rice was measured using a rheometer J type manufactured by Fudo Kogyo Co., Ltd. Table 2 shows the results.

[0053]

[Table 2]

The rice cooked at a water content of 1.35 times, which is a general rice cooking condition, had a good texture immediately after cooking and cooling, with no graininess and no stickiness of the rice grains. But,
After storage at 10 ° C. for 24 hours, starch degradation was observed in both texture and stress relaxation value. On the other hand, rice cooked with 1.6-fold water using the method of the present invention, immediately after cooking,
After storage at 10 ° C. for 24 hours, the stress relaxation value did not change, and no starch deterioration was observed. Furthermore, cooked rice produced by the method of the present invention has a large amount of water,
It was good without deterioration of texture due to starch glue outflow.

Example 3 After washing and draining 400 g of commercially available indica rice, a transglutaminase solution (liquid temperature of 40 u / g with respect to the raw rice weight) was used.
℃) Immerse in a predetermined amount. After immersion treatment in a 40 ° C thermostat for 90 minutes, rice cooker ECJ-U manufactured by Sanyo Electric Co., Ltd. with immersion water
Cooked at 3R. Thereafter, after 30 minutes of unevenness, the mixture was rapidly cooled to 20 ° C., stored at 5 ° C. and 10 ° C. for 24 hours, and subjected to a sensory test. Further, as a comparative object, examples of cooked rice cooked by a method not using the method of the present invention are also described. The sensory test was performed by the method according to Example 1. Further, in order to more specifically express the effects of the present invention, the cutting power of cooked rice was measured using a rheometer J type manufactured by Fudo Industry Co., Ltd. Table 3 shows the results.

[0056]

[Table 3]

Indica rice cooked by the method of the present invention
Compared to cooked rice with normal water content (about 1.1 to 1.3 times the raw weight of Indica rice), the texture is not inferior,
Furthermore, the degradation phenomenon of starch during low-temperature storage was also suppressed.

Example 4 After washing and draining 400 g of commercially available Koshihikari, a transglutaminase solution (liquid temperature 40 ° C.) of 30 u / g with respect to the raw rice weight was used.
Immerse in a predetermined amount. After immersion treatment in a 40 ° C thermostat for 90 minutes, rice cooker E manufactured by Sanyo Electric Co., Ltd. with immersion rice and immersion water
Cooked in CJ-U3R. Then, after 30 minutes spotty 20
Rapidly cooled to 5 ° C and stored at 5 ° C for 24 hours. Next, the prototype sample was placed in a microwave RE-S manufactured by Sharp Corporation.
The range was increased at 750, and a sensory test was performed. As a comparative example, an example of cooked rice cooked by a conventional method is also described. Further, in order to more specifically express the effect of the method of the present invention, stress relaxation of cooked rice was measured using a rheometer J type manufactured by Fudo Industry Co., Ltd. Table 4 shows the results.

[0059]

[Table 4]

The cooked rice produced by the method of the present invention was found to have the effect of suppressing the deterioration of cooked rice at 5 ° C. storage as compared with the cooked rice usually produced by adding water (1.35 times). In addition, 5
When the range of cooked rice stored at ℃ is raised, the cooked rice according to the present invention immediately returns to the edible state, and the range of the cooked rice is reduced for a short time compared to the rice cooked with normal water. I was able to recover.

[0061]

According to the present invention, rice cooked by the method of the present invention can prevent starch deterioration during storage at low temperature or distribution at low temperature, and lower the distribution temperature of processed foods using rice.

────────────────────────────────────────────────── ─── Continuation of the front page (56) References JP-A-5-15324 (JP, A) JP-A-6-1553827 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) A23L 1/10

Claims (1)

(57) [Claims] During 1. A rice cooker, adding an additive comprising a transglutaminase soaking water or cooking water, rice washing
A method for producing cooked rice, characterized in that cooked rice is cooked with 1.6 to 1.7 times the amount of water added to the raw rice weight .