JP2022101736A - Method for producing cooking rice - Google Patents

Abstract

To provide a technology that can efficiently produce high-quality cooking rice having appropriate hardness and viscousness without the need for soaking in water before rice cooking.SOLUTION: A method for producing cooking rice of the present invention has a steam heating step in which raw rice is used as a raw material rice and steam at 80 to 100°C is applied to the raw material rice to heat, and a liquid treatment step in which the raw material rice is brought into contact with a treatment liquid. The treatment liquid has a viscosity of more than 0.9 mPa*s and 80 mPa*s or less at a product temperature of 25°C. The treatment liquid preferably contains a thickening polysaccharide. It is preferable to carry out the liquid treatment step while carrying out the steam heating step.SELECTED DRAWING: None

Description

The present invention relates to a method of cooking rice, and more particularly to a method of cooking raw rice that has not been immersed in water.

In recent years, the demand for rice balls and bento boxes displayed at convenience stores and supermarkets has increased, and the demand for cooked rice (rice) that is cooked in large quantities by manufacturers and kept at room temperature, refrigerated, or frozen for a relatively long time. Is increasing. When rice is cooked, it is common to provide a water soaking step of immersing the rice in water as a treatment before starting rice cooking. From the viewpoint of improving the production efficiency of rice cooked rice, it is preferable that the soaking time is short, but if the soaking time is too short, the rice becomes hard rice cooked with a core remaining due to the low water content. Patent Document 1 describes a method for producing rice with a significantly shortened soaking time, which comprises a step of placing raw rice that has not been soaked in water in a superheated steam atmosphere while sprinkling water.

Patent Document 2 describes rice grains of steamed rice obtained in the cooking process after the cooking process and before the vacuum cooling in the method for producing okowa onigiri having each process of water immersion, drainage, cooking, and vacuum cooling. It is described that the surface of the product is coated with a seasoning liquid containing a polysaccharide derived from seaweed. According to the production method described in Patent Document 2, the action of the seasoning liquid suppresses the evaporation of excess water from the steamed rice due to vacuum cooling, so that the produced rice balls are not dry.

Japanese Unexamined Patent Publication No. 2014-226062 Japanese Unexamined Patent Publication No. 2010-284139

An object of the present invention is to provide a technique capable of efficiently producing high-quality rice cooked rice having appropriate hardness and stickiness without requiring water immersion before cooking rice.

The present invention has a steam heating step of using raw rice as raw rice and heating the raw rice with steam at 80 to 100 ° C., and a liquid treatment step of bringing the treatment liquid into contact with the raw rice. Is a method for producing rice cooked rice, wherein the viscosity at a product temperature of 25 ° C. is larger than 0.9 mPa · s and 80 mPa · s or less.

INDUSTRIAL APPLICABILITY According to the present invention, there is provided a method for producing rice cooked rice, which does not require water immersion before cooking rice and can efficiently produce high quality rice cooked rice having appropriate hardness and stickiness.

The method for producing rice cooked rice of the present invention includes a steam heating step of applying steam to the raw rice to heat it, and a liquid treatment step of bringing the treatment liquid into contact with the raw rice. The steam heating step is a step of cooking raw rice, and the liquid treatment step is a step carried out for the purpose of improving the texture of the cooked rice.

In the present invention, raw rice is used as the raw material rice. In the present invention, "raw rice" refers to untreated raw rice that has not been immersed in water. Further, "not immersed in water" here means raw rice that does not substantially absorb water, for example, raw rice that has been washed with water immediately before being used for producing rice cooked rice. Not included.
The type of raw rice is not particularly limited and may be appropriately selected depending on the type of cooked rice to be produced and the like. Examples of raw rice that can be used in the present invention include glutinous rice, glutinous rice, or a combination thereof. Examples of glutinous rice include low-amylose rice, high-amylose rice, and ordinary glutinous rice. These may be used alone or in combination of two or more. Uruchi rice is typically used.
Further, the rice polishing rate of raw rice is not particularly limited, and can be appropriately selected depending on the type of cooked rice to be produced and the like. Examples of the raw rice that can be used in the present invention include white rice, non-washed rice, brown rice, seven-minute rice, germ rice, and raw rice from which bran and the like have been removed by wind. These may be used alone or in combination of two or more.

In the steam heating step, the raw rice (raw rice) is heated by applying steam at 80 to 100 ° C. If the temperature of steam is less than 80 ° C, rice cannot be cooked sufficiently and the rice may become too hard. If the temperature of steam exceeds 100 ° C (that is, superheated steam is applied to the raw rice), the heating temperature is too high. Therefore, the surface of the rice may be dried and the rice may be overheated. The temperature of steam is preferably 85 to 100 ° C, more preferably 90 to 100 ° C.

In the steam heating step, the time for applying steam to the raw material rice (steam treatment time) is not particularly limited, and may be appropriately selected depending on the type of the raw material rice and the like. When the steam treatment time is short, the rice is hard cooked rice with a core remaining in the rice due to the low water content, and the texture of the cooked rice tends to be dry and unfavorable. If the steam treatment time is too long, the texture of the cooked rice tends to be sticky and unfavorable due to the high water content. The steam treatment time is preferably 10 to 60 minutes, more preferably 15 to 50 minutes, and even more preferably 20 to 45 minutes from the viewpoint of further improving the texture of the cooked rice. The "steam treatment time" here means the total time of applying steam to the raw rice to be treated. For example, when the treatment of applying steam to the raw rice is carried out in a plurality of times, the treatment is performed. It means the total time of multiple processes.

In the steam heating step, the method of applying steam to the raw rice is not particularly limited. The steam applied to the raw rice may be saturated steam or not necessarily saturated steam. For example, it may be a method of applying steam to the raw rice in a non-sealed space and open to the atmosphere, or a method of applying steam to the raw rice in a state of being placed in a closed space. As an example of the method of applying steam to the raw rice, there is a so-called batch method in which the raw rice is placed in a closed or non-closed space and steam is supplied to the space. As another example of the method of applying steam to the raw rice, a so-called continuous method of supplying steam to the space while continuously sending the raw rice through a transport path such as a belt conveyor arranged in a non-sealed space. Can be mentioned.

During the steam heating step, the raw rice to be treated may be agitated using a stirring device such as a rice scoop. By such a stirring operation, it is possible to suppress unevenness in the cooking of rice cooked rice.
Further, in the steam heating step, a process of heating the raw material rice may be performed in parallel with the process of applying steam to the raw material rice.

According to the steam treatment of raw rice such as the steam heating step, the rice can be cooked without the soaking step of immersing the rice in water, so that the production time of the cooked rice is shortened and the production efficiency is improved. However, it was found that the rice cooked rice obtained by the conventional steam treatment has problems in texture such as dryness and weak stickiness.
The liquid treatment step was adopted to solve such a problem of steam treatment of raw rice, and is a treatment having a viscosity of more than 0.9 mPa · s and 80 mPa · s or less at a product temperature of 25 ° C. It is characterized by bringing the liquid into contact with the raw rice. By adopting the liquid treatment step in addition to the steam heating step, it becomes possible to efficiently produce high-quality rice cooked rice having appropriate hardness and stickiness. If the viscosity of the treatment liquid is less than 0.9 mPa · s or more than 80 mPa · s, the effect of improving the texture of the cooked rice is poor, which is not preferable. The "viscosity" referred to here is a value measured using a B-type viscometer in accordance with JIS Z 8803 "Viscosity of Liquid-Measuring Method". The viscosity of the treatment liquid is preferably 70 mPa · s or less, more preferably 60 mPa · s or less. The lower limit of the viscosity of the treatment liquid, 0.9 mPa · s, is slightly higher than the viscosity of water at a water temperature of 25 ° C. That is, on the premise that the viscosity of the treatment liquid is larger than the viscosity of water having a water temperature of 25 ° C., it is preferably 1 mPa · s or more, more preferably 1.5 mPa · s or more.

The treatment liquid may have a viscosity at a product temperature of 25 ° C. within the above-mentioned specific range, and its composition is not particularly limited. Specifically, a thickener is contained so that the viscosity at a product temperature of 25 ° C. exceeds 0.9 mPa · s.
As the thickener, a polymer substance that dissolves or disperses in water and produces viscosity and is edible can be used without particular limitation, and examples thereof include gelling agents and thickening polysaccharides. Can be used alone or in combination of two or more.
Examples of the gelling agent include gelatin, agar, carrageenan, and pectin.
Examples of the thickening polysaccharide include modified starch; disaccharides such as sucrose; and polysaccharides of trisaccharide or higher. The modified starch is a general term for starch as a raw material that has been physically, enzymatically or chemically processed. Examples of starch used as a raw material for processed starch include tapioca starch, wheat starch, corn starch, potato starch, and rice starch. The method for processing starch for obtaining modified starch is not particularly limited, and examples thereof include a crosslinking treatment, an esterification treatment, an etherification treatment, and an oxidation treatment, and two or more kinds of processing methods may be combined.

Among the thickeners, thickening polysaccharides are preferable, and polysaccharides having trisaccharide or more are particularly preferable, because they are excellent in the effect of improving the texture of cooked rice. That is, the treatment liquid used in the liquid treatment step preferably contains a thickening polysaccharide, particularly a polysaccharide of trisaccharide or more. Examples of polysaccharides having a trisaccharide or higher include guar gum, white fungus polysaccharide, xanthan gum, locust bean gum, and tamarind gum.
The white fungus polysaccharide is a white fungus extract containing a polysaccharide derived from the white fungus, or a composition containing the white fungus extract as a main component. The white jellyfish polysaccharide can be a polysaccharide polymer containing α-1,3-mannose in the main chain and D-fucose, D-xylose and D-glucuronic acid in the side chains. As the white fungus polysaccharide, for example, those described in JP-A-2019-41735 can be used. As the white fungus polysaccharide, a commercially available product can be used, and an example thereof is "Tremel gum" manufactured by Unitech Foods Co., Ltd.

The content of the thickener in the treatment liquid may be adjusted so that the viscosity of the treatment liquid at a product temperature of 25 ° C. is within the above-mentioned specific range, but the action effect of the thickener (effect of improving the texture of cooked rice). The content of the thickening polysaccharide in the treatment liquid is preferably 0.01 to 0.2% by mass, more preferably 0, based on the total mass of the treatment liquid. It is 0.02 to 0.15% by mass.

When the thickener is contained in the treatment liquid, from the viewpoint of ensuring that the action and effect of the thickener are more reliably exerted, the liquid treatment step is applied to the total mass of the raw rice (raw rice). The thickener is used as a solid content, preferably 0.05% by mass or more, more preferably 0.1% by mass or more, still more preferably 0.11 to 0.7% by mass, and particularly preferably 0.15 to 0.6. It is preferable to add by mass%. If the amount of the thickener added is too small, it is meaningless to use the thickener, and if the amount of the thickener added is too large, the taste and texture of the cooked rice may be deteriorated. The increase in viscosity makes it difficult to spray the treatment liquid, which may make it difficult to bring the treatment liquid into contact with the raw rice. In the liquid treatment step, the content of the thickener in the treatment liquid, the method of contacting the treatment liquid with the raw rice, and the method of contacting the treatment liquid with the raw rice so that the amount of the thickener added to the raw rice as a solid content is within such a preferable range. It is preferable to adjust the contact time, the spraying time, the spraying amount, etc. when spraying the treatment liquid on the raw rice.

The treatment liquid may contain additives other than the thickener as long as the effects of the present invention are not impaired. Additives other than thickeners include, for example, salt, sugar, sweetener, vinegar, soy sauce, miso, dashi, consomme, sodium glutamate, ketchup, curry powder, saffron and other seasonings; amylase, transglutaminase and the like. Enzymes; Fats and oils such as salad oil, soybean oil, rapeseed oil, corn oil, sesame oil, butter; Antioxidants such as vitamin E; Coloring agents, fragrances, preservatives, shelf life improvers, etc. It can be used alone or in combination of two or more.

In the liquid treatment step, the method of bringing the treatment liquid into contact with the raw material rice is not particularly limited, and examples thereof include a method of spraying the treatment liquid on the raw material rice and a method of immersing the raw material rice in the treatment liquid, and there are a plurality of types of methods. May be combined. From the viewpoint of improving production efficiency, a method of spraying the treatment liquid on the raw rice is preferable. The method of spraying the treatment liquid is not particularly limited, but spraying using a spraying means such as a spray is preferable from the viewpoint of uniformly adhering the treatment liquid to the entire raw rice.

In the liquid treatment step, the product temperature of the treatment liquid when the raw material rice is brought into contact with the raw rice by spraying the treatment liquid or the like is not particularly limited, but particularly when the liquid treatment step is carried out during the steam heating step. From the viewpoint of not inhibiting the heating of the raw rice by steam, such a heating temperature or a temperature relatively close to such a heating temperature is preferable, specifically, 30 to 90 ° C., more preferably 50 to 80 ° C.

The spraying time when the treatment liquid is sprayed on the raw material rice may be appropriately adjusted according to the viscosity of the treatment liquid, the content of the thickener if the treatment liquid is contained, and the like, and is not particularly limited. It is preferably a minute. The spraying time of such a treatment liquid is 1 to 60 minutes, more preferably 2 to 50 minutes, still more preferably 3 to 40 minutes. The preferable range of the spraying time of such a treatment liquid is particularly effective when the treatment liquid contains the thickener in the above-mentioned preferable range. If the spraying time is too short, it is meaningless to provide the liquid treatment step, and if the spraying time is too long, the contact time between the raw material rice and the treatment liquid becomes too long, and the texture of the cooked rice is preferably sticky. There is a risk that it will not be there. The "spraying time" here means the total time for spraying the treatment liquid on the raw rice. For example, when the liquid treatment step is divided into a plurality of times, the liquid treatment step of the plurality of times is performed. Means the total time.

The spray amount when spraying the treatment liquid on the raw material rice may be appropriately adjusted according to the viscosity of the treatment liquid, the content of the thickener if the treatment liquid contains, and the like, and is not particularly limited. It is preferably 50 to 500 parts by mass, and more preferably 100 to 300 parts by mass with respect to 100 parts by mass of the raw rice. The preferable range of the spray amount of the treatment liquid is particularly effective when the treatment liquid contains the thickener in the above-mentioned preferable range. The "spray amount" here means the total amount of the treatment liquid sprayed on the raw rice, and for example, when the liquid treatment step is carried out in a plurality of times, the spray amount of the treatment liquid in each liquid treatment step. Means the sum of.

During the liquid treatment step, specifically, for example, while spraying the treatment liquid on the raw rice, or after spraying the treatment liquid on the raw rice, the raw rice is prepared using a stirrer such as a rice scoop. You may stir. By such a stirring operation, the treatment liquid (thickener in the treatment liquid) added to the raw rice becomes uniformly distributed throughout the raw rice, so that the action effect of the treatment liquid (improvement of the texture of the cooked rice) Effect) can be played more reliably.

In the present invention, the order of carrying out the steam heating step and the liquid treatment step is not particularly limited, and both steps may be carried out simultaneously or sequentially. In the latter case, the steam heating step and the liquid treatment step may be carried out in this order, or vice versa.
As a preferred embodiment of the method for producing rice cooked rice of the present invention, there is an embodiment in which both steps are carried out at the same time, that is, the liquid treatment step is carried out during the steam heating step. More specifically, there is a form in which the raw material rice is heated by applying steam at 80 to 100 ° C. and the treatment liquid is sprayed on the raw material rice at an appropriate timing.

In the present invention, the liquid treatment step may be carried out continuously, or may be carried out in a plurality of times. As an example of the latter, when the liquid treatment step is carried out during the execution of the steam heating step, there is a mode in which the liquid treatment step is carried out in a plurality of times.

In the present invention, for example, a steam chamber to which steam is supplied inside, a belt conveyor arranged inside the steam chamber to transfer raw rice, and raw rice transferred by the belt conveyor from above to the raw rice. This can be carried out using a rice-cooking rice production device equipped with a nozzle for spraying the treatment liquid toward the rice. In that case, by supplying steam at 80 to 100 ° C. to the inside of the steam chamber, the raw rice being transferred to the inside of the steam chamber by the belt conveyor is heated by the steam (steam heating step). The treatment liquid is sprayed from the nozzle toward the raw rice (liquid treatment step). By devising the arrangement of the nozzles, the liquid treatment step can be carried out continuously or can be carried out in a plurality of times.

The method for producing rice cooked rice of the present invention may further include a cooling step and / or a molding step of the cooked rice obtained through both steps in addition to the steam heating step and the liquid treatment step described above.
In the cooling step, the method for cooling the cooked rice is not particularly limited, and examples thereof include cooling by loosening the cooked rice with a rice scoop, differential pressure cooling, vacuum cooling, or a combination thereof.
The molding step is a step of molding rice cooked rice into a predetermined shape, and can be carried out according to a conventional method using a mold, a container, or the like. In the molding step, a known molding means holder such as a serving device for serving rice cooked rice in a lunch box, a rice ball molding machine, and a sushi robot can also be used.

The method for producing rice cooked rice of the present invention may have a water treatment step of bringing water into contact with the raw rice, in addition to the liquid treatment step. By adopting the water treatment step, it becomes possible to cook rice more reliably in combination with the steam heating step.
The water treatment step is preferably carried out during the steam heating step. The water treatment step may be carried out continuously or may be carried out in a plurality of times. The method of bringing water into contact with the raw material rice in the water treatment step is not particularly limited, but a method of spraying the treatment liquid on the raw material rice is preferable from the viewpoint of improving the production efficiency. The amount of water sprayed on the raw rice is not particularly limited, and may be appropriately adjusted so as to have the desired hardness of the cooked rice.
For example, during the implementation of the steam heating step, the liquid treatment step can be carried out by spraying the treatment liquid, and the water treatment step can be carried out by spraying water. In this case, the spraying of the treatment liquid and the spraying of water may be performed at the same time, or may be performed at different timings.

Hereinafter, the present invention will be described in more detail by way of examples, but the present invention is not limited to the following examples.

[Examples 1 to 8, Comparative Examples 1 to 3, Reference Example 1]
Rice cooked rice was produced using Koshihikari (raw rice, non-washed rice) produced in Niigata Prefecture as the raw material rice. Specifically, 300 g of raw material rice is placed in a steam permeable container having an upper opening, the raw material rice is allowed to stand in a steam chamber together with the container, and the steam chamber is placed at a predetermined temperature ("Steam of steam" in Tables 1 and 2). By continuing to supply saturated steam of (see the column of "Temperature") for a predetermined time (see the column of "Steam treatment time" in Tables 1 and 2), the steam is applied to the raw rice in a state of being open to the atmosphere and heated. The steam heating step was carried out. During this steam heating step, the liquid treatment step of contacting the raw rice with the treatment liquid shown in Tables 1 and 2 (“water containing a thickener, which is a mixture of water and a thickener)) is divided into two parts. Carried out. The time interval between the liquid treatment step and the next liquid treatment step was set to 1 to 12 minutes. In each liquid treatment step, the treatment liquid is sprayed from the upper opening of the container toward the raw rice in the container, and the spray amount of the treatment liquid in each liquid treatment step is 35 to 45 mL / 45 mL per 100 parts by mass of the raw rice. It was a minute. The "spray amount (parts by mass) of the treatment liquid with respect to 100 parts by mass of the raw rice" in Tables 1 and 2 is the total of the spray amounts in all the liquid treatment steps, and the "spray time of the treatment liquid" in Tables 1 and 2 is. , The total spraying time in all liquid treatment steps. The viscosities of the treatment liquids listed in Tables 1 and 2 are based on JIS Z 8803 "Liquid Viscosity-Measuring Method", using a B-type viscometer (TVB-20L, manufactured by Toki Sangyo Co., Ltd.). It is a value measured 1 minute after the start of rotation of the rotor under the condition of the rotor M1 and the rotation speed of 60 rpm.

〔Evaluation test〕
For each Example, Comparative Example and Reference Example, the sprayability of the treatment liquid at the time of producing rice cooked rice was evaluated according to the following evaluation criteria. In addition, the rice cooked rice produced in each example, comparative example and reference example is cooled with cold air at 15 ° C. for 20 minutes immediately after production, and then eaten by a specialized panelist to obtain the texture (stickiness, hardness) below. We had them evaluate according to the evaluation criteria. The results are shown in Tables 1 and 2.

<Evaluation criteria for sprayability of treatment liquid>
A: Good because the treatment liquid can be sprayed evenly on the rice.
B: Slightly good because the treatment liquid can be sprayed on the rice.
C: Defective because the viscosity of the treatment liquid is high and it cannot be sprayed.
<Evaluation criteria for stickiness of rice cooker>
A: Good with moderate stickiness.
B: There is no dryness, but there is little stickiness, so it is a little good.
C: It is defective because it feels dry.
<Evaluation criteria for the hardness of rice cooked rice>
A: Moderately soft and good.
B: Somewhat good because some hardness remains.
C: Defective because it is too hard or too soft.

As shown in Table 1, in each example, the viscosity of the treatment liquid used in the liquid treatment step at a product temperature of 25 ° C. is larger than 0.9 mPa · s and 80 mPa · s or less, so that each comparison does not satisfy this. Compared with the example, the sprayability of the treatment liquid and the texture (stickiness, hardness) of the cooked rice were excellent. Since water was used as the treatment liquid in Comparative Example 1, the quality of the cooked rice was inferior to that of each example, and in Comparative Examples 2 and 3, the viscosity of the treatment liquid at a product temperature of 25 ° C. exceeded 80 mPa · s. Therefore, the treatment liquid could not be sprayed, and the result was that the rice cooked rice could not be evaluated.

The thickeners in the treatment liquids are different from each other in each of the examples in Table 2. Among the examples in Table 2, Examples 4 and 5 were particularly highly evaluated, indicating that polysaccharides of trisaccharide or higher are particularly effective as thickeners.

Claims (7)

A steam heating process in which raw rice is used as raw rice and steam is applied to the raw rice at 80 to 100 ° C to heat it.
It has a liquid treatment process that brings the treatment liquid into contact with the raw rice.
A method for producing rice cooked rice, wherein the treatment liquid has a viscosity of more than 0.9 mPa · s and 80 mPa · s or less at a product temperature of 25 ° C. The method for producing rice cooked rice according to claim 1, wherein the time for applying steam to the raw material rice in the steam heating step is 10 to 60 minutes. The method for producing rice cooked rice according to claim 1 or 2, wherein in the liquid treatment step, the treatment liquid is sprayed on the raw material rice, and the spraying time of the treatment liquid is 1 to 60 minutes. The method for producing rice cooked rice according to any one of claims 1 to 3, wherein the treatment liquid contains a thickener. The method for producing rice cooked rice according to claim 4, wherein the thickener is added in an amount of 0.05% by mass or more as a solid content with respect to the total mass of the raw material rice by the liquid treatment step. The method for producing rice cooked rice according to any one of claims 1 to 5, wherein the liquid treatment step is carried out during the steam heating step. The method for producing rice cooked rice according to any one of claims 1 to 6, wherein the liquid treatment step is carried out in a plurality of times.