JP2714405B2 - Manufacturing method of processed brown rice - Google Patents

Description

The present invention relates to a method for producing processed brown rice. In detail, the present invention is capable of cooking rice in the same simple manner as that used for polished rice, and furthermore, it is possible to obtain a brown rice with good nutritional quality, which does not impair the nutritional value of the cooked rice. The present invention relates to a method for producing processed brown rice.

[Prior Art] Brown rice is rich in nutrients such as lipids, proteins, minerals, vitamins and the like as compared with polished rice, and its effectiveness has recently been reviewed from the viewpoint of health food. However, since the endosperm of brown rice is covered with a tough outer skin called bran layer such as peel, seed coat and aleurone layer, water is less likely to penetrate into the endosperm than polished rice. If it is cooked as it is using the usual cooking method and cooking utensils adopted for it, it will be possible to obtain only hard, crisp brown rice. Therefore, when cooking brown rice,
It is necessary to use special cooking utensils such as using a pressure cooker or cooking twice, or to use a complicated rice cooking method, which is one factor that hinders the expansion of brown rice consumption.

Therefore, various attempts have been made to provide brown rice that can be easily cooked in a short period of time and has a good texture as well as polished rice. Known methods currently include: (1) a method in which a large number of cuts are formed by a cutting blade over substantially the entire periphery of brown rice peel (JP-A-63-173548); and (2) superheated steam from brown rice. (3) Absorbing brown rice, steaming and leaving it to stand to produce processed brown rice, by heating and expanding to cause cracks in the brown rice skin to make it easier to cook rice. (JP-A-61-152251), (4) a method of bringing brown rice or the like into contact with carbon dioxide in a supercritical state (JP-A-59-78656), and the like.

However, the rice cooked with the brown rice obtained by the method (1) is still inferior in texture due to the dryness. In the methods (2) and (3), the brown rice is heated to 100 ° C. or more by steam heating. In the case of (3), since pressure bias treatment is involved, deterioration of various nutrients contained in brown rice, deterioration and damage of endosperm part, destruction and collapse of brown rice grains, etc. , Texture, nutritional value and the like were inferior.

In addition, since the method of (4) does not partially remove the surface layer, the improvement of the water absorption of brown rice is not yet sufficient.
Moreover, since the degreasing from brown rice was not sufficient, it was difficult to cook rice, had a strong off-flavor, and had poor texture and storage stability.

[Description of the Invention] The present inventors can cook rice in the same simple manner as polished rice using the cooking utensil used for polished rice as it is,
Moreover, the research has been continued for the purpose of producing brown rice which is high in nutritional value when cooked and has a good texture without losing its shape. As a result, the inventors have found that the above object can be achieved by treating the surface of brown rice with carbon dioxide in a liquid or supercritical state after performing a specific damage treatment, thereby completing the present invention.

That is, the present invention is a method for producing processed brown rice, which comprises removing part of the surface layer of brown rice over the entire surface of the brown rice, and then contacting the brown rice with liquid or supercritical carbon dioxide.

Brown rice is made by removing rice husk from rice husk,
Structurally, it consists of the upper part called bran such as peel, seed coat, aleurone layer, etc., a small amount of germ at the lower base of rice grain, and a central endosperm part that occupies most of the rest . The weight ratio of each part to the whole brown rice grain is generally about 5 to 7% of bran part, about 2 to 3% of germ part, and the rest is endosperm part (about 92%). White rice (polished rice, polished rice) is obtained by removing the bran and germ from brown rice by milling or other processing to produce only the endosperm. Normal rice is usually about 90-92% of the raw brown rice. Milling yield (milling yield).

In the present invention, "peeling and removing a part of the surface layer of brown rice over the entire surface of brown rice" means that a part of the bran (peel, seed coat, aleurone layer, etc.) in the upper layer of brown rice is removed. And, optionally, along with the germ portion at its lower base, to delaminate over the entire surface of the brown rice particles. At this time, it is preferable to remove and remove a part of the surface layer as uniformly as possible.

Peel, seed coat, aleurone layer, germ part, etc., when partially peeling and removing, described in the method of peeling and removing the bran part etc. which are usually adopted in rice milling operation such as milling and the above-mentioned JP-A-63-173548. It can be performed by employing a method using a cutting blade that has been used. In the case of performing milling or the like, the degree of the processing is made weaker than in the normal rice processing for obtaining white rice. When peeling and removal of a part of the surface layer portion is performed by, for example, grinding, any grinding method such as a friction method and a grinding method can be adopted.

When the degree of peeling and removal of part of the brown rice surface layer in the present invention is represented by the yield relative to the raw brown rice, it is usually about 99.8 to 9
The seed coat, pericarp, aleurone layer, germ and the like may be peeled off until the yield reaches 5.0%, preferably about 99.6 to 98.0%.
When the brown rice surface is peeled off so that the yield is within the above range, the water absorption of brown rice after carbon dioxide treatment in the liquid or supercritical state in the next process is improved, and it is easy to operate with the same operation as white rice In addition to being able to cook rice, the cooked rice has a good appearance and texture when cooked, and has high nutritional value. On the other hand, if the degree of peeling and removal of the brown rice surface layer is too low (the yield is higher than about 99.8%), even if the carbon dioxide treatment in the next step is performed, the water absorption of brown rice does not increase and rice cooking is not easy. Moreover, the texture of the cooked brown rice is inferior. In addition, if the degree of peeling and removal of the brown rice surface layer is too high (the yield is lower than about 95.0%), it becomes closer to white rice and the content of nutrients such as lipids, proteins, minerals, vitamins, etc. becomes extremely small and health foods Brown rice loses its significance.

If the peeling and removal of a part of the brown rice surface layer is performed at a temperature of about 5 to 30 ° C., preferably about 10 to 25 ° C., deterioration or deterioration of the brown rice does not occur.

When peeling and removing a part of the brown rice surface layer, the treatment is preferably performed so that the moisture content in the brown rice is about 12 to 25% by weight. Brown rice may be treated as it is or water may be added as long as the water content is within the above range.
It is preferred that the water content of brown rice is particularly about 15 to 20% by weight, since the surface layer is uniformly removed from brown rice and the brown rice grains are not broken.

In the present invention, brown rice from which part of the surface layer has been peeled off over the entire surface as described above is then treated by contacting it with liquid or supercritical carbon dioxide.

In order to clarify the content of "carbon dioxide in a liquid or supercritical state" used in the present invention, the relationship between the temperature and pressure and the phase state of carbon dioxide will be described below with reference to FIG.

Depending on temperature and pressure, carbon dioxide exhibits each of the solid, liquid, supercritical and gaseous phase states as shown in FIG. 1 [Chemistry and Industry, Vol. 19, Vol. 385-390 (July 1982)]. In FIG. 1, TP is a triple point, and three phases of solid, liquid and gas coexist. Also, in FIG.
CP is a critical point (pressure 72.8 kg / cm ² , temperature 31.3 ° C.), and gas, liquid and supercritical carbon dioxide coexist. In the vicinity of this state, liquid carbon dioxide usually exists in a fine granular state in gaseous carbon dioxide.

As the liquid or supercritical carbon dioxide used in the present invention, of the liquid or supercritical carbon dioxide consisting of the hatched portion in FIG. 1, the temperature is -20 + 100 ° C. and the pressure is 20 kg. / cm ² or more is preferable, and especially one having a temperature of 20 to 40 ° C and a pressure of 100 to 400 kg / cm ² is preferable. The above temperature of -20 + 100 ° C and 20kg / cm ²
When liquid or supercritical carbon dioxide in the above pressure range is used, a part of lipids is extracted from brown rice, unpleasant odors such as sugar odors are removed, and alteration of various components contained in brown rice is altered. , Deterioration and the like are prevented. On the other hand, if the temperature of carbon dioxide is higher than 100 ° C., starch, proteins, lipids, minerals, vitamins, and the like in brown rice are deteriorated or deteriorated, resulting in a decrease in texture and nutritional value, which is not desirable. Also
Using carbon dioxide at a pressure higher than 400 kg / cm ² has almost the same effect as using carbon dioxide at a lower pressure, but at a higher cost.

The contact between liquid or supercritical carbon dioxide and brown rice is
Usually, it is good to carry out for about 30 minutes to 5 hours. If the treatment time is shorter than about 30 minutes, extraction of lipids from brown rice and removal of off-flavors such as sugar odor may be insufficient, and conversely, if the treatment time is longer than the above range, each component such as lipids may be removed. The nutritive value and texture are reduced due to excessive extraction and removal. Moreover, too long contact times lead to increased processing costs.

In treating brown rice with carbon dioxide in a liquid or supercritical state in the present invention, any method and apparatus can be adopted as long as the contact between brown rice and carbon dioxide can be performed uniformly and smoothly. Such contact treatment may be a batch method or a continuous method.

Hereinafter, the treatment of brown rice with carbon dioxide in a liquid or supercritical state in the present invention will be schematically and exemplarily described with reference to FIG. 2 taking the case of using carbon dioxide in a supercritical state as an example.

First, pump the liquid carbon dioxide filled in the cylinder 1
Through the heating device 3 by P ₁ is pumped to extraction vessel 4 having a Jiyaketsuto 4a capable of flowing hot water. At this time, if the valve CV-1 is closed until the temperature becomes equal to or higher than the critical point of carbon dioxide, the carbon dioxide in the extraction tank 4 enters a supercritical state.

The extraction tank 4 is previously filled with brown rice from which a part of the surface layer has been peeled and removed, and the brown rice is brought into contact with carbon dioxide in a supercritical state. Temperature of the heating device 3 in this case, it is possible to form a supercritical state of carbon dioxide at the desired temperature and pressure by adjusting the operating pressure needed by the pump P ₁ and the valve CV-1. In the extraction tank 4, brown rice is brought into continuous aeration contact with carbon dioxide in a supercritical state for a predetermined time, and the valve CV-1 is opened to continuously discharge carbon dioxide containing extract from brown rice into the separation tank 5 in a gaseous state. Let it.
Rapidly by adjusting the gradual opening degree of the hydraulic pressure and the valve V ₁ of the even or the pump P ₁ to reduce the pressure within the extraction tank 4 by appropriately adjusting the degree of opening of the valve CV-1 in this It can be reduced, and any of them can be adopted in the present invention. However, it is preferable to gradually reduce the pressure without impairing the appearance of processed brown rice.
The extract is separated in the separation tank 5 from carbon dioxide containing extracts (lipids, odor substances, coloring components, etc.) from brown rice.
After carbon dioxide after separation of the extract was further purified through filter 6, and liquefied led to liquefier 7, then contacted with brown rice by circulating the extracted vessel 4 again led back to the heating device 3 by a pump P ₁ Let it. Performing entrainer process is introduced into the extraction tank 4 the ethanol in the container 8 by the pump P _2, if necessary.

[Effect of the Invention] In the present invention, processed brown rice is produced by peeling and removing a part of the surface layer portion of brown rice over the entire surface of brown rice and then contacting it with carbon dioxide in a liquid or supercritical state. Degreasing and removal of off-flavor substances and the like from brown rice are performed more efficiently and uniformly as compared with a case where the raw rice is directly contacted with liquid or supercritical carbon dioxide without performing any peeling and removing treatment.

As a result, the processed brown rice manufactured according to the present invention has a high water absorption, and can be easily cooked in the same manner as white rice using the cooking utensils used for white rice, and the cooked brown rice has a sugar odor or the like. It has a good texture without any off-flavors or dryness.

In addition, the brown rice produced according to the present invention has a low calorie due to a high degreasing rate, and can be stored without deterioration for a long time due to a high degreasing rate and a deodorization rate.

Furthermore, the present invention does not involve high temperature treatment as in the prior art using superheated steam, so that proteins, lipids, vitamins, minerals and other nutrients contained in brown rice are not degraded, and there is no alteration or damage of the endosperm. It is possible to produce brown rice with high nutritional value and good texture.

In addition, in the present invention, since there is no pressure unevenness treatment or expansion treatment of brown rice as in the prior art, damage to the inside of brown rice,
Brown rice with good appearance is produced when cooked without collapsing or voiding.

Hereinafter, the present invention will be specifically described with reference to the drawings by way of examples and the like, but the present invention is not limited to those examples.

Examples 1-4 and Comparative Examples 1-6 Brown rice (water content 13% by weight) was supplied to a friction blasting type milling machine CS-25B (manufactured by Toyo Rice Milling Machine Co., Ltd.) at a rate of 5 kg / min to form a milling machine roll. Milling was performed while rotating at a peripheral speed of 100 to 300 m / min so as to obtain the yield shown in Table 1 below, thereby uniformly peeling and removing the surface layer portion of the brown rice over the entire surface.

Next, 2000 g of brown rice from which the surface layer was partly removed was filled into a 10-liter extraction tank 4 and subjected to an extraction process in the following two systems.

The first method is to pump liquid carbon dioxide at a pressure of 58 kg / cm ² and a temperature of 20 ° C. to a heating device 3 by a pump P ₁ at a pressure of 10 kg / hr.
After heating to 5 ° C., it was led to the extraction tank 4 in which hot water of 45 ° C. was flown through the jacket 4a, and the pressure in the extraction tank 4 was maintained at 200 kg / cm ² (supercritical state) using the valve CV-1. Brown rice and 5
A continuous aeration contact treatment was performed for a period of time. The supercritical carbon dioxide at a pressure of 200 kg / cm ² and a temperature of 45 ° C. containing lipids in contact with aeration is guided to a separation tank 5 in which warm water at 40 ° C. is flowed through a jacket 5a by adjusting a valve CV-1. Adjust CV-2 to 50kg / c
the pressure was reduced to m ^2. The carbon dioxide from which the extract from the brown rice is separated in the separation tank 5 is purified through a filter 6 and then liquefied by a liquefaction unit 7. Liquid carbon dioxide at a temperature of 5 ° C. and a pressure of 40 kg / cm ² is pumped through a reservoir 2 through a liquid reservoir 2. It was recirculated to the heating device 3 by ₁ . When the liquid carbon dioxide in the liquid reservoir 2 runs short, the liquid carbon dioxide is sequentially supplied from the cylinder 1 (Examples 1 to 3).

After the second method which has been heated to 58kg / cm ^2, 25 ° C. turned out to the heating device 3 at 10 kg / hr temperature 20 ° C. of the liquid carbon dioxide by the pump P ₁ from the cylinder 1 (liquid state), 25 the Jiyaketsuto 4a The mixture was introduced into the extraction tank 4 in which water at a temperature of 5 ° C. was flown, and was subjected to continuous liquid contact with brown rice for 5 hours. During the liquid contact treatment, the liquid carbon dioxide containing lipid is injected into the separation tank 5 in which the warm water at 50 ° C. is flowed through the jacket 5a by adjusting the valve CV-1, and the liquid carbon dioxide is converted into the gaseous carbon dioxide. To separate lipid and gaseous carbon dioxide. 50kg with valve CV-2
The gaseous carbon dioxide adjusted to / cm ² is purified through a filter 6 and then liquefied by a liquefaction unit 7 at a temperature of 5 ° C. and a pressure of 40 ° C.
It was recycled to the heating device 3 by a pump P ₁ through the reservoir unit 2 the liquid carbon dioxide kg / cm ^2. When the liquid carbon dioxide in the liquid reservoir 2 runs short, the liquid carbon dioxide is sequentially supplied from the cylinder 1 (Example 4).

[Measurement of water absorption] 1000 g of brown rice is immersed in 2000 ml of water at 18 ° C.
00g was taken out and its water absorption was measured.

[Cooking method of brown rice] After washing the brown rice one piece in water, soak it in water for 2 hours, drain, add 230cc of water, and use an automatic rice cooker RZ-480 made by Hitachi Home Appliances.
Cooked as it was at MT (cooking time 20 minutes).

Of the results obtained above, the change over time in the water absorption of brown rice is shown in FIG. 3, and the content ratio of each component in brown rice and the texture are shown in Table 1 below.

In addition, for brown rice that has not been subjected to any surface removal and removal treatment and carbon dioxide treatment, the time-dependent change in the water absorption rate, the content ratio of each component and the texture of the cooked rice are examined in the same manner as described above, and the results are obtained. 3 and Table 1 (Comparative Example 1).

Furthermore, even for brown rice which has been subjected to the surface layer peeling and removing treatment in the same manner as in Examples 1 to 3 above but not to be subjected to carbon dioxide treatment, the water absorption of the brown rice over time, the content of each component, and the texture of cooked rice And the results are shown in FIG. 3 and Table 1, respectively (Comparative Examples 2 to 4).

In addition, Examples 1 to 3 were not subjected to the peeling removal treatment of the surface layer portion
Similarly, brown rice treated with only carbon dioxide in the supercritical state was also examined for water absorption, content of each component, and texture of cooked rice in the same manner as described above. The results were shown in FIG. 1 (Comparative Example 5).

In addition, the brown rice that was subjected to only the carbon dioxide treatment in the liquid state in the same manner as in Example 4 without performing the peeling removal treatment of the surface layer portion also had the same water absorption rate, content ratio of each component, and texture of the cooked rice as in the above. The results are shown in FIG. 3 and Table 1 (Comparative Example 6).

In FIG. 3, I, II, III, and IV represent the changes over time in the water absorption of the brown rice obtained in Examples 1 to 4, and V to X are obtained in Comparative Examples 1 to 6, respectively. The change over time in the water absorption of brown rice is shown.

From the results in Table 1 and FIG. 3, the processed brown rice produced by the present invention, in which a part of the brown rice surface layer is peeled and removed over the entire surface and then treated with liquid or supercritical carbon dioxide, is one of the processed brown rice. Compared to untreated brown rice or untreated brown rice, the water absorption is greatly improved and rice can be easily cooked like ordinary white rice, and the cooked rice has a greatly improved texture. You can see that it is. In addition, the brown rice produced by the present invention is not inferior to the untreated brown rice in terms of nutritional value.

[Brief description of the drawings]

FIG. 1 is a diagram showing the relationship between the pressure-temperature of carbon dioxide and its phase state. FIG. 2 is a schematic diagram showing one embodiment of the apparatus and steps used in the liquid or supercritical carbon dioxide treatment of the present invention. FIG. 3 is a graph showing the change over time in the water absorption of brown rice. In FIG. 2, 1 is a cylinder filled with liquid carbon dioxide, 2 is a reservoir of liquid carbon dioxide, 3 is a heating device, 4 is an extraction tank, 4a is a jacket of the extraction tank, 5 is a separation tank, and 5a is a separation tank. Tank jacket, 6 is a filter, 7 is a liquefier, 8
Solvent tank, P ₁ and P ₂ pumps, CV-1 and the CV-
Reference numeral 2 denotes a pressure control valve. In FIG. 3, I to IV show the changes over time in the water absorption of the brown rice obtained in the examples of the present invention, and V to X show the changes over time in the water absorption of the brown rice obtained in the comparative example.

 ────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Tokuji Yotsuya 3-3-23 Misaki-cho, Chiyoda-ku, Tokyo Inside Showa Carbonate Co., Ltd. (56) References JP-A-59-78656 (JP, A) 60-133870 (JP, A) JP-A-63-173548 (JP, A)

Claims (1)

(57) [Claims] The present invention is characterized in that the surface portion of brown rice is peeled and removed over the entire surface of brown rice so as to be 99.8 to 95.0% in terms of the yield relative to the raw brown rice, and then is brought into contact with liquid or supercritical carbon dioxide. A method of producing processed brown rice for cooking rice.