JPH0269149A - Production of processed unpolished rice - Google Patents

Abstract

PURPOSE:To obtain the title rice cookable into unpolished rice with high nutritive value and good eating feel through a simple method similar to the case with polished rice by removing part of the surface layer over the entire surface of unpolished rice followed by bringing the resultant unpolished rice into contact with a liquid CO2 or CO2 in the supercritical state. CONSTITUTION:Part of the surface layer, corresponding to rice bran (matrix skin, seed skin and/or paste powder layer), of unpolished rice is removed over the entire surface of unpolished rice grains. When said removal operation is to be made by e.g., beating in a mortar, it should be made under conditions milder than those in the case with normal rice cleaning treatment for obtaining polished rice. Thence, the resultant unpolished rice is brought into contact with a liquid CO2 or CO2 in the supercritical state. This state is pref. such that, as shown in the figure, the temperature is -20-100 deg.C and the pressure >=20kg/cm<2>. As a result, part of lipids as well as such offensive odors as of rice bran will be extracted or eliminated with the various constituents in the unpolished rice prevented from deterioration, thus obtaining the objective processed unpolished rice.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Field of Application 1] The present invention relates to a method for producing processed brown rice. In detail, the present invention makes it possible to cook rice using a simple method similar to that used for polished rice, and to obtain brown rice that does not lose its nutritional value and has a good texture. Regarding the manufacturing method of processed brown rice.

[Prior art] Since brown rice is richer in nutrients such as lipids, proteins, minerals, and vitamins than polished rice, its properties have recently been reconsidered from the standpoint of health food. However, because the endosperm of brown rice is covered with a tough outer skin called the bran layer, which includes pericarp, seed coat, and aleurone layer, it is difficult for water to penetrate into the endosperm compared to polished rice, and brown rice is converted into polished rice. If you cook rice as is using the usual cooking methods and cooking utensils used for rice, you will only get hard and dry brown rice. Therefore, cooking brown rice usually requires the use of special cooking utensils or time-consuming cooking methods, such as using a pressure cooker or double-cooking, and this is one of the obstacles to expanding the consumption of brown rice. This is due to two factors.

Therefore, various attempts have been made to provide brown rice that can be easily cooked in a short time and has a good texture just like polished rice. Currently known methods include: (1) creating many cutting scratches with a cutting blade almost all around the skin of brown rice (Japanese Patent Application Laid-open No. 63173548); (2) heating brown rice with superheated steam; A method for making rice easier to cook by causing cracks in the outer skin of brown rice by swelling it (Japanese Patent Application Laid-Open No. 61-61775); (3) A method for producing processed brown rice by absorbing water, leaving it to stand, then steaming and compressing it; Tokukai Showa 6
1-152251), (4) a method of bringing brown rice etc. into contact with carbon dioxide in a supercritical state (Japanese Unexamined Patent Publication No. 59-78656).

However, cooked brown rice obtained by method (1) is still dry and has poor texture;
In method (3), brown rice is heated to over 100°C by steam heating, and in the case of (3), pressure treatment is also involved, resulting in deterioration of various nutrients contained in brown rice, deterioration and damage to the endosperm, and The brown rice grains were destroyed, crumbled, etc., and the cooked brown rice was inferior in appearance, texture, nutritional value, etc.

In addition, since method (4) does not remove part of the surface layer, the water absorption of brown rice is not yet sufficiently improved, and the fat from the brown rice is not sufficiently removed.
<, and had a strong off-odor and poor texture and shelf life.

[Contents of the invention] The present inventors have discovered that rice can be cooked in the same simple way as polished rice using the same cooking utensils used for polished rice, and that it has high nutritional value and loses its shape when cooked. We have continued our research with the aim of producing brown rice that has a good texture and is free from grains. As a result, the present invention was completed by discovering that the above object can be achieved by subjecting the surface of brown rice to a specific damage treatment and then treating it with liquid or supercritical carbon dioxide.

That is, the present invention is a method for producing processed brown rice, which is characterized in that a part of the surface layer of the brown rice is peeled off over the entire surface of the brown rice, and then brought into contact with liquid or supercritical carbon dioxide.

Brown rice is made by removing the chaff from the rice grains, and its structure consists of the upper layers called bran, such as the pericarp, seed coat, and aleurone layer, a small amount of germ at the lower base of the rice grain, and the rest. It consists of a central endosperm part that occupies the majority.

The weight ratio of each part to the whole grain of brown rice is generally about 5 to 7% for the bran part, about 2 to 3% for the germ part, and the rest for the endosperm part (about 92%). White rice (polished rice, milled white rice) is made by removing the bran and germ from brown rice through milling or other polishing processes, leaving only the endosperm. This is the rice milling yield (milling yield).

In the present invention, "peeling and removing part of the surface layer of brown rice over the entire surface of brown rice" means that part of the upper layer of brown rice corresponding to the bran (pericarp, seed coat, aleurone layer, etc.) is removed. , meaning exfoliation over the entire surface of the brown rice grain, possibly along with the germ part at its lower base. At that time, it is preferable to peel off and remove a portion of the surface layer as uniformly as possible.

When removing part of the pericarp, seed coat, aleurone layer, germ, etc., methods for peeling and removing the bran, etc., which are normally adopted in rice milling operations such as milling, or the above-mentioned JP-A-63-173548 can be used.
This can be carried out by employing the method using a cutting blade, etc., as described in the above publication.

When milling or the like is used, the degree of polishing is made weaker than in the normal rice milling process used to obtain polished rice. When removing a part of the surface layer by, for example, polishing, any polishing method such as a friction method or a grinding method can be employed.

The degree of peeling and removal of a part of the surface layer of brown rice in the present invention is usually expressed as a yield of about 99.8 to 99.8 to
The seed coat, pericarp, aleurone layer, germ, etc. are preferably peeled off until a yield of 95.0%, preferably about 99.6 to 98.0% is achieved. If the surface of brown rice is peeled to achieve a yield within the above range, the water absorption rate of the brown rice will improve after being treated with liquid or supercritical carbon dioxide in the next process, and it can be easily processed in the same way as white rice. To be able to cook rice, and to have brown rice with good appearance and texture and high nutritional value when cooked. On the other hand, if the degree of exfoliation removal of the first part of brown rice is too low (if the yield is higher than about 99.8%), the water absorption rate of brown rice will not increase even if it is treated with diacid and carbon dioxide in the next process. It is not easy to cook rice, and the texture of the cooked brown rice is inferior. Furthermore, if the degree of exfoliation of the surface layer of brown rice is too high (if the yield is lower than about 95.0%), it will become more similar to white rice and the content of nutrients such as lipids, proteins, minerals, and vitamins will be extremely low. The significance of brown rice as a health food will be lost.

Remove part of the surface layer of brown rice at a temperature of about S to 30°C1
Preferably, if the temperature is about 10 to 25°C, brown rice will not change in quality or deteriorate.

Further, when removing a part of the surface layer of brown rice, it is preferable to carry out the treatment so that the water content in the brown rice is about 12 to 25% by weight. As long as the moisture content is within the above range,
Brown rice may be ground as is or water may be added. It is preferable to keep the moisture content of the brown rice at about 15 to 20 M% in particular so that the surface layer of the brown rice can be peeled off uniformly and the brown rice flour will not be crushed.

In the present invention, brown rice from which part of Table 1 has been peeled off over its entire surface as described above is then treated by contacting it with liquid or supercritical carbon dioxide.

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

Depending on the temperature and pressure, carbon dioxide exhibits various phase states such as a solid state, a liquid state, a supercritical state, and a gas state as shown in Fig. 1 [Chemistry and Industry (Chemistry and Industry) Vol. 19, No. 385 -Page 390 (July 1982) 1゜In Figure 1, TP is a triple point, and the three phases of solid, liquid, and gas coexist. Also, in Figure 1, CP is the critical point (
(pressure cuff 2.8 #9/am”, temperature 31.1'C), gas, liquid, and supercritical carbon dioxide coexist. Near this state, liquid carbon dioxide usually exists in gaseous carbon monoxide. Carbon exists in a fine granular state.

The liquid or supercritical carbon dioxide used in the present invention includes liquid or supercritical carbon dioxide consisting of the shaded area in FIG. Pressure is 20&ζ/cm”
The above is preferred, and particularly preferred is the temperature of 20-40°O and the pressure of 100-400 kg/cm''. When using liquid or supercritical carbon dioxide within the pressure range of Deterioration etc. are prevented. On the other hand, when the temperature of carbon dioxide is higher than 100℃, the starch, protein, lipid, minerals in brown rice
It is undesirable that vitamins etc. deteriorate or change quality, resulting in a decrease in texture, nutritional value, etc. Also 400kg/cm”
Using carbon dioxide at a higher pressure has approximately the same effect as using carbon dioxide at a lower pressure, but at a higher cost.

Contact between liquid or supercritical carbon dioxide and brown rice
Usually, it is best to do this for about 30 minutes to 5 hours. If the processing time is shorter than about 30 minutes, the extraction of lipids from brown rice and the removal of odor such as bran odor may be insufficient.On the other hand, if the processing time is longer than the above range, the extraction of lipids from brown rice and the removal of odor such as bran odor may be insufficient. Excessive extraction and removal will reduce nutritional value and texture. Moreover, too long a contact time results in increased processing costs.

In the present invention, when brown rice is treated with carbon dioxide in a liquid or supercritical state, any method and apparatus can be employed as long as the brown rice and carbon dioxide can be brought into uniform and smooth contact.

Such contact treatment may be a batch method or a continuous method.

Below, the treatment of brown rice with liquid or supercritical carbon dioxide in the present invention will be schematically and exemplified with reference to FIG. 2, taking as an example the case where supercritical carbon dioxide is used.

First, pump P
The mixture is fed under pressure via a heating device 3 to an extraction tank 4 equipped with a jacket 4a through which hot water can flow. At this time, if the valve cv-t is closed until the temperature exceeds the critical point of carbon dioxide, the carbon dioxide in the extraction tank 4 becomes supercritical.

The extraction tank 4 is filled in advance with brown rice from which a portion of the surface layer has been peeled off, and here the brown rice is brought into contact with carbon dioxide in a supercritical state.

At this time, the temperature of heating device 3, pump P1 and valve C
Supercritical carbon dioxide at a desired temperature and pressure can be formed by appropriately adjusting the operating pressure using V-1. The brown rice is brought into continuous aeration contact with carbon dioxide in a supercritical state for a predetermined time in the extraction p14, and the valve CV-1 is opened to continuously lead out the carbon dioxide containing the extract from the brown rice to the separation tank 5 in gaseous form. . At this time, valve CV-
The pressure inside the extraction tank 4 can be gradually lowered by appropriately adjusting the opening of the pump P, or it can be lowered rapidly by adjusting the operating pressure of the pump P and the opening of the valve V. In the present invention, any of them can be adopted.

However, it is preferable to gradually lower the pressure so that the appearance of processed brown rice is not impaired. A separation tank 5 separates the extract from brown rice from the carbon dioxide containing the extract (lipids, odorants, coloring components, etc.). The carbon dioxide after separating the extract is further purified through a filter 6, and then led to a liquefaction device 7 to be liquefied, and then transferred to a heating device 3 by a pump P1.
It is again guided to the extraction tank 4 and brought into contact with the brown rice. Pump P2 to pump ethanol, etc. in the container 8 as needed.
is introduced into the extraction tank 4 and subjected to entrainer treatment.

(Effects of the invention) In yq-1!, a part of the surface layer of brown rice is removed by kneeling the whole surface of the brown rice, and then it becomes liquid or super-containing!
7. Processed brown rice is produced by contacting it with carbon dioxide, so compared to the case where the surface layer is brought into contact with liquid or supercritical carbon dioxide without any peeling and removal treatment. As a result, degreasing and removal of odor substances, etc. from brown rice are performed more efficiently and uniformly.

As a result, the processed brown rice produced according to the present invention has a high water absorption rate, can be easily cooked in the same way as white rice using cooking utensils used for white rice, and the cooked brown rice plate does not have a bran odor. It has a good texture without any strange odor or dryness.

Furthermore, the brown rice produced according to the present invention has a high defatting rate, so it has low calories, and its high defatting rate and deodorizing rate allow it to be stored for a long period of time without deterioration.

Furthermore, since the present invention does not involve high-temperature treatment unlike conventional techniques that use superheated steam, there is no deterioration of nutrients such as proteins, lipids, vitamins, and minerals contained in brown rice.
It is possible to produce brown rice with high nutritional value and good texture without deterioration or damage to the endosperm.

In addition, the present invention does not involve pressurizing or shaping brown rice as in the prior art, so brown rice plates with a good appearance when cooked are produced without internal damage, collapse, or void formation in the brown rice. be done.

The present invention will be specifically explained below by examples and the like with reference to the drawings, but the present invention is not limited by these examples.

Examples 1 to 4 and Comparative Examples 1 to 6 Friction jet type rice miller C3-25B (Toyo Rice Mill Seisakusho layer)
Brown rice (moisture level: 813% by weight) was fed into the rice bowl at a rate of 5 to 9 minutes, and the milling machine roll was rotated at a circumferential speed of 100 to 300 m/minute to achieve the yield shown in Table 1 below. The surface layer of brown rice was peeled off uniformly over the entire surface by milling without adjustment.

Next, 2,000 liters of brown rice from which part of the surface layer has been peeled off is 1
It was filled into the 0Q extraction tank 4, and extracted using the two methods described below.

In the first method, liquid carbon dioxide at a pressure of 58/cm2 and a temperature of 20°C is pumped to the heating device 3 at LO kg/hr using a pump P1 and heated to 45°C. The hot water is led to the extraction tank 4, and the pressure inside the extraction tank 4 is set to 200 hg/c using the valve CV-1.
It was continuously aerated and contacted with brown rice for 5 hours while being maintained at a supercritical state. During the aerated contact, the pressure including the lipid valve was 2.
00Ja9/cm", supercritical carbon dioxide at a temperature of 45°C was added to Jakera h5a by adjusting the valve cv-i.
The mixture was introduced into a separation tank 5 in which hot water at a temperature of °C was flowed, and the pressure was reduced to 50 kg/cm'' by adjusting the valve CV-2.

The carbon dioxide from which the extract from brown rice has been separated in the separation tank 5 is purified through a filter 6 and then liquefied in the liquefaction device 7, and the liquid carbon dioxide at a temperature of 5° C. and a pressure of 40 kg and 7 cm is passed through the liquid reservoir 2 and sent to the pump P. It was recirculated to the heating device 3. When the liquid carbon dioxide in the liquid reservoir 2 is insufficient, it is sequentially supplied from the pump 1 (Examples 1 to 3).

12 method is 58 kg/cm”, temperature 20°
The liquid carbon dioxide of C is sent from the pump l to the heating device 3 at a rate of 10 to 9/hr and heated to 25°C (liquid state a), and then water at 25°C is poured into the jacket 4a of the extraction tank. 4 and was subjected to continuous liquid flow contact treatment with brown rice for 5 hours. During the liquid contact treatment, the liquid carbon dioxide contained in the lipid valve is transferred to the jacket 5a by adjusting the valve CV-1.
The liquid carbon dioxide was injected into a separation tank 5 filled with warm water at 10°C to cause a phase change from liquid carbon dioxide to gaseous carbon dioxide, and the mixture was separated into a lipid valve and gaseous carbon dioxide. 501g with valve CV-2
The gaseous carbon dioxide whose pressure is regulated to 1/cm" is purified through a filter 6 and then liquefied in a liquefier 7 to a temperature of 5°C1.
Liquid carbon dioxide at a pressure of 40°/cm 2 was recycled via the reservoir 2 to the heating device 3 by means of a pump P.

When liquid carbon dioxide in the liquid reservoir 2 is insufficient, it is sequentially supplied from the pump I (Embodiment 4).

[Water absorption constant 31] Brown rice 10009 was soaked in 2000 mQ of water at 18°C, 100 g of it was taken out every 30 minutes, and its water absorption rate was measured.

[How to cook brown rice] Wash brown rice, soak in water for 2 hours, drain, add 230cc of water, and use Hitachi Home Appliances automatic rice cooker RZ.
- Rice was cooked as is at 480MT (cooking time 20 minutes).

Among the results obtained above, the changes over time in the water absorption rate of brown rice are shown in Figure 3, and the content ratios and texture of each component in brown rice are shown in Table 1 below.

In addition, for brown rice that had not undergone any peeling removal treatment on the surface layer or carbon dioxide treatment, we investigated the changes in water absorption over time, the content ratio of each component, and the texture of the cooked rice in the same manner as above, and examined the results. are shown in FIG. 3 and Table 1 (Comparative Example 1).

Similarly to Examples 1 to 3 above, for brown rice that was only subjected to the exfoliation treatment shown in Table 1 but not treated with carbon dioxide, changes in its water absorption rate over time, the content ratio of each component, and The texture of the cooked rice was examined and the results are shown in Figure 3 and Table 1 (Comparative Examples 2 to 4).

In addition, the water absorption rate, the content ratio of each component, and the texture of cooked rice were also evaluated for brown rice that was subjected to only supercritical carbon dioxide treatment in the same manner as in Examples 1 to 3 without peeling and removing the surface layer. The test was conducted in the same manner as above, and the results are shown in FIG. 3 and Table 1 (Comparative Example 5).

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

In addition, in FIG. 3, I, n, III, and ■ represent the changes over time in the water absorption rate of the brown rice obtained in Examples 1 to 4, respectively, and v-X represents the changes over time in the water absorption rate of brown rice obtained in Examples 1 to 4, respectively. From the results shown in Table 1 and Figure 3 above, which show the changes in the water absorption rate of brown rice over time, it is clear that a part of the surface layer of brown rice is peeled off over the entire surface and then treated with liquid or supercritical carbon dioxide. The processed brown rice produced by the invention has significantly improved water absorption compared to brown rice that has undergone only one of the treatments or brown rice that has not undergone either of the treatments, and can be cooked as easily as regular white rice. It can also be seen that the texture of the cooked rice was greatly improved. Moreover, the brown rice produced according to the present invention is no inferior to untreated brown rice in terms of nutritional value.

[Brief explanation of the drawing]

The M1 diagram is a diagram showing the relationship between pressure and temperature of carbon dioxide and its phase state. FIG. 2 is a schematic diagram showing one embodiment of the apparatus and process used in the liquid or supercritical carbon dioxide treatment of the present invention. FIG. 3 is a graph showing changes over time in the water absorption rate of brown rice. In Figure 2, ■ is a cylinder filled with liquid carbon dioxide, 2 is a liquid carbon dioxide reservoir, 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 filter, 7 is liquefaction device,
8 is a solvent tank, P and P2 are pumps, and CV-1 and Cv-2 are pressure regulating valves. In FIG. 3, I to ■ indicate changes over time in the water absorption rate of brown rice obtained in the examples of the present invention, and V to X indicate changes over time in the water absorption rate of brown rice obtained in comparative examples. Figure 3￥1 Temperature (℃) Water immersion time (minutes)

Claims (1)

[Claims] A method for producing processed brown rice, which comprises peeling and removing a portion of the surface layer of brown rice over the entire surface of the brown rice, and then contacting it with liquid or supercritical carbon dioxide.