JPH0564749A - Method and apparatus for cooling polished rice to keep its quality good - Google Patents

Abstract

PURPOSE:To obtain polished rice having good eating quality by lowering the temp. thereof by adding water to polished rice immediately after polishing processing in a specified ratio to mix the same with said rice and applying air to the moistened polished rice immediately thereafter. CONSTITUTION:The polished rice processed by a rice-polishing machine to be brought to high temp. is guided to a conditioning tank 21 and fed to a receiving cylinder 4 while the flow rate and temp. thereof are measured by a flow rate sensor S and a temp. sensor Tl. Water is ejected from a plunger pump 27 to continuously add it to the polished rice in 0.4-1.5wt.% on the way of feeding from a water supply port 27 to be mixed with the polished rice in a screw feeder 23 to spread over the entire surfaces of grains of polished rice to form water coating layers thereto. When air is applied to the polished rice moving on a net from a suction blower 43, the water of the coating layers is evaporated to take evaporation heat from polished rice to cool the same. Therefore, the polished rice does not generate the deterioration of fat or protein and a crack and is enhanced in its eating quality.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for cooling and refining polished rice and its apparatus for lowering the temperature and adjusting the water content of the polished rice immediately after it is processed.

[0002]

[Prior Art] When processing brown rice with a rice polishing machine,
The temperature of the polished rice immediately after being discharged from the rice polishing machine is generally 10 to 20 ° C. higher than the temperature of the brown rice because it generates heat due to frictional action, etc. When the temperature is 25 ° C, the temperature of milled rice is 35 to 45 ° C. When the high-temperature polished rice is put into the tank as it is, the thermal conductivity between the rice grains is low, so the polished rice will be kept at high temperature for a long time, and the taste of fat such as fat oxidation and protein modification will be improved. The unfavorable phenomenon is promoted, and the high-temperature polished rice causes dew condensation on the wall surface of the tank, etc., and the bran powder adheres to it to form bran beads, which causes mold and grows to a certain size. There are many harmful effects such as peeling of bran balls and mixing with polished rice. Furthermore, if high temperature polished rice is packed in a plastic bag or the like, dew condensation will occur inside the bag. There was also a problem that it could not be shipped. Therefore, Japanese Patent Application Laid-Open No. 61-235662 proposes a device in which polished rice is brought into contact with the outer surface of a container containing a refrigerant such as water and cooled by heat exchange. Furthermore, if the water content of the raw brown rice varies, the water content of the polished rice will also vary, making it difficult to adjust the water content during rice cooking, and if the water content is too low, it is not desirable for rice cooking characteristics.
A technique for tempering polished rice to keep the water content of polished rice at around 15%, which is said to be preferable for cooking rice, has been developed. For example, Japanese Patent Publication No. 60-17499 discloses a gas containing water in polished rice. Contact (with fog, mist, aerosol)
A method of cooling polished rice while allowing the polished rice to absorb water is disclosed. In addition, since it has been conventionally considered that the water content is reduced by about 0.6 to 1.0% along with the processing of milled rice, the refined rice tempering also has the purpose of supplementing the moisture content of this reduction.

[0003]

However, in the cooling device disclosed in Japanese Patent Laid-Open No. 61-235662, the dew condensation of the refrigerant on the outer surface of the container hinders the operation, and
Since the cooling efficiency is low, there is an unavoidable drawback that the device becomes extremely large in terms of processing capacity. In addition, Japanese public Sho6
In the refined rice tempering such as 0-17499,
If the rapid cooling is attempted, the milled rice is rather dried and cracks are formed, so that there is a drawback that it takes an extremely long time for cooling and tempering. Therefore, the present inventor conducted the following experiment in order to elucidate the relationship between cooling of polished rice and changes in water content. (Experiment 1) Under conditions of temperature of 30 ° C. and relative humidity of 60%, brown rice with a temperature of 30 ° C. and a moisture content of 14.8% was slightly over-polished with a single-pass type rice milling machine (whiteness of polished rice). 41%). The polished rice discharged from the rice polishing machine was immediately stored in a closed container so that the water content would not evaporate, and the weight was measured to be 53.88 kg, and the temperature of the polished rice was 50 ° C. The sample was taken out of the container, spread thinly on the tray, left standing for 1 hour, and then weighed to be 53.3.
8 kg, temperature was 31 ° C., and water content was 13.9%.
The water content immediately after rice processing was calculated from these data to be 14.7%. In addition, when observing the polished rice after leaving for 1 hour with a magnifying glass, many fine cracks were formed on the surface. (Experiment 2) The same brown rice as in Experiment 1 was processed under the same conditions under the same conditions, and the polished rice immediately after being discharged from the rice polishing machine is shown in FIG.
It was spread on the net of the device of No. 1 and sucked with a blower for 5 minutes so that the speed of the wind passing through the net was 0.9 m / sec. After that, when the polished rice was measured, the temperature was 29.5 ° C., which was lower than the atmospheric temperature, and the water content was 13.8%. In addition, the surface of the polished rice had thick cracks that could be visually identified.
From the above experimental results, the decrease in water content of 0.6 to 1.0%, which was conventionally thought to occur at the same time as the processing of rice, is actually caused mainly by the cooling of the polished rice after the processing. Recognize. In addition, cooling by wind (air) is mainly performed by removing the heat of vaporization when the water contained in the polished rice evaporates, although there is some heat exchange between the polished rice and the air. Therefore, it is considered that the surface of the polished rice is dried and contracted simultaneously with cooling, causing a strain between the surface of the polished rice and the internal tissue and cracking. In this way, cooling of polished rice with air is generally
Since it is performed at the same time as drying, it is necessary to temper (humidify) while cooling like conventional milled rice tempering, by simultaneously controlling the contradictory effects when the temperature and humidity of the air used are adjusted. It has to be said that it is impossible, and even if hot milled rice can be humidified, when it is cooled, the added water will evaporate and be lost. Therefore, in the conventional milling of milled rice, effective humidification is actually performed after the temperature of milled rice has dropped to around the temperature, and until that time, the operation was mainly for cooling. , It takes a very long time to cool without contact with air (gas) without generating cracks, and addition of water to such an extent that the surface of polished rice becomes wet during cooling and humidification Since the rice grains rapidly penetrate into the rice grains and the rice grains locally expand to cause cracks, it is difficult to control the water content in the air.

[0004]

The present invention solves the above-mentioned drawbacks of the prior art, and cools milled rice that has been heated to a high temperature by milling the rice in a very short time without causing cracks. , The water content is adjusted to a preferable water content, and the method is as follows.
4 to 1.5% by weight of water is added and mixed, and immediately thereafter, air is blown to evaporate the added water to lower the temperature of the polished rice to near the ambient temperature.
The treatment time after the addition of water is started until the evaporation by the wind is completed is about 1 minute or less, and the water content of the polished rice after the treatment is 0 to 0. It will rise by 4%. Further, as the apparatus, a water mixing means for adding 0.4 to 1.5% by weight of water to the milled rice immediately after the milling process and mixing the milled rice on the net and applying a wind to mix the water. And a means for evaporating the water added in the means, further having a sensor of the flow rate of the polished rice, the temperature of the polished rice, and the temperature,
Based on the measured values of these sensors, an automatic control device for adjusting the amount of water to be added and at least one of the evaporation time and the air flow for evaporation is provided.

[0005]

[Function] When water is added to and mixed with milled rice immediately after milled rice, water spreads over the entire surface of the grain of the milled rice and a coating layer is formed by water. If this is immediately blown with air, the heat of vaporization when the water that has become the coating layer evaporates is removed, and there is also a slight heat exchange between the wind (air) and the milled rice, which cools the milled rice. To be done. The amount of water to be added is the same as the amount of water lost by evaporation when the temperature of milled rice is lowered to near the temperature when no tempering is performed. If you want to increase the water content of white rice above the original water content of brown rice, add the amount of water required to increase the water content to the above amount of water, and in each case, add It is within the range of 0.4 to 1.5% by weight. The polished rice with such an amount of water is blown to cool it to a temperature near the ambient temperature, so only the added water is evaporated along with the cooling, which is originally contained in the polished rice. Since water cannot be evaporated,
The polished rice can be cooled and tempered without drying and cracking the surface of the polished rice.

[0006]

1 and 2 show a cooling and refining apparatus for polished rice according to an embodiment of the present invention.
It comprises a water mixing means 20 and an evaporation means 30. Water mixing means 20
Is connected to the upper part of the adjusting tank 21 with a rice grain pipe 22 for introducing the milled rice from the rice milling machine (not shown) in the previous step,
The lower portion of the adjusting tank 21 communicates with a screw feeder 23 that is driven to rotate by a feed motor 24, and a water supply port 26 opened in an outer cylinder 25 of the screw feeder 23 has a water tank (not shown) via a plunger pump 27. No. 1) is connected to a water supply pipe 28. Evaporating means 3
0 is on the step surface 32 provided on the cylindrical side wall of the main body 31,
Disc-shaped net 33 whose bottom surface is appropriately reinforced to prevent deformation
The main motor 34 mounted on the outer peripheral edge of the main body 31
The net 33 can be driven to rotate, and the net 3
The outer peripheral portion of the net 33 is covered with an outer peripheral cover 35 attached to the main body 31 so that the polished rice on the top surface 3 is not spilled, and similarly, the central portion of the net 33 is covered with the support rod 36 through the main body 31.
It is covered with an inner peripheral cover 37 attached to. Also, the main body 3
1 side wall and a part of the outer peripheral cover 35 from the upper end to the net 3
3 The discharge port 38 is formed by notching to the height of the upper surface, and the net 3 between the outer peripheral cover 35 and the inner peripheral cover 37 is formed so as to guide the polished rice to the discharge port 38 by the rotation of the net 33.
A guide plate 39 that obliquely cuts off the upper surface space of 3, the chute 40 is attached to the discharge port 38, the upper end is connected to the discharge side of the screw feeder 23, and the lower end faces the upper surface of the net 33. 41 is fixedly provided to the support rod 36 on the rear surface side of the guide plate 39. In the gap between the lower end of the receiving cylinder 41 and the upper surface of the net 33, the polished rice is contained in the receiving cylinder 4.
The size is set so that it does not stay in 1 and is spread thinly and widely on the net 33. The lower part of the main body 31 has an inverted conical shape, and an intake blower 43 is connected to an intake port 42 at the lower end thereof. Inside the adjustment tank 21, a flow rate sensor S and a temperature sensor T1 for measuring the milled rice to be supplied are provided, and a temperature sensor T2 for measuring the milled rice after the treatment is provided on the chute 40, and further, an appropriate device. An air temperature sensor T3 is provided at various places.

Next, the operation of this embodiment will be described. The milled rice, which has been heated to a high temperature by the rice milling machine, enters the adjusting tank 21 continuously through the rice grain pipe 22, and the flow rate sensor S and the temperature sensor T1 measure the flow rate and the temperature, while the screw feeder 23 receives the cylinder. The water discharged from the plunger pump 27 is continuously added from the water supply port 27 and mixed by the screw feeder 23, so that water is added to the surface of each polished rice grain. The coating layer is formed.

At this time, the amount of water to be added is the same as the amount of water lost by evaporation when the temperature of milled rice is lowered to near the ambient temperature, unless tempering is performed. For example, when the temperature of milled rice is 35 ° C. and the temperature is 20 ° C., and the specific heat of milled rice is 0.35, in order to lower the temperature of 1 g of milled rice to the temperature, 0.35 × (35−20) = 5.25 The heat of 5.25 cal is taken, and if it is taken by only the heat of vaporization of water (539 cal / g), it is 5.25 / 539 = about 0.0097, that is, 0 of the weight of the polished rice. Although 97% of water will evaporate, it is actually cooled a little by heat exchange between wind (air) and polished rice, so it is sufficient to add the amount of water subtracted from that amount. It seems that about 70 to 90% of the amount of heat taken away as heat of vaporization will be taken, but this changes depending on the relative humidity of the atmosphere and the design of the equipment, so refer to the data from several trial runs. And decide. In addition, when tempering is performed, that is, when it is desired to increase the water content of polished rice after cooling from the original water content of brown rice, it is necessary to increase the water content in the amount of water that is not tempered. Add the amount of fresh water added,
For example, if you want to process milled brown rice with a moisture content of 14.7% to obtain milled rice with a moisture content of 15.0%, add more than 0.3% by weight of milled rice to the added water. In order to prevent the occurrence of cracks, it is desirable that the water content of the milled rice after treatment does not increase by more than 0.4% from the water content of the original brown rice. In any case, the operation of the plunger pump 27 should be adjusted so that the amount of water added is within the range of 0.4 to 1.5% by weight of the milled rice to be treated,
If it is less than 0.4%, it is difficult to form a coating layer on the entire surface of all rice grains of polished rice, and if there is an uncoated portion, that portion may be dried and cracked. When it exceeds 5%, not all the water adheres as a coating layer, and a part of it flows as water droplets.

Since the net 33 rotates in the direction of arrow A, the polished rice put in the receiving cylinder 41 after the coating layer with water is formed is successively developed and moved on the net 33, and the intake blower 43 is moved. Net 33 by suction of
The coating layer is evaporated by the wind blowing from the top to the bottom, and the heat of vaporization of water is taken away, and at the same time, the heat exchange between the polished rice and the wind (air) is also slightly performed and cooled, and reaches the induction plate 39. Then, it is guided to the discharge port 38 along the front wall, slides down the chute 40, and is sequentially discharged. At this time, the temperature of the polished rice after cooling is measured by the temperature sensor T2, and the evaporation time, that is, the rotation speed of the net 33 is adjusted so that this temperature becomes substantially the same as the temperature by the temperature sensor T3.

However, water permeates into the rice grain and the rice grain expands locally, or if the water once deeply permeating into the rice grain is tried to be removed by evaporation, only the surface of the rice grain is dried and cracks occur in the rice grain. It is well known that cracked milled rice turns into rice that has a very bad texture when cooked, and the rate of water penetration into rice grains increases as the water temperature rises. In the invention, since the amount of water added to milled rice is small, regardless of the original water temperature, the added water immediately rises to almost the same temperature as milled rice, and the rate of penetration into rice grains is fast, so the milled rice processing It is desirable to complete the treatment process from addition of water to evaporation within about 30 seconds in the summer when the temperature of the polished rice immediately after becomes high and within about 1 minute in the winter when the temperature is relatively low. Soak the water inside the rice grain Does not, even by local expansion, also by subsequent drying, there is no possibility that cracks occur.

Since the temperature of the milled rice discharged from the chute 40 has dropped to around the ambient temperature, even if the milled rice is thrown into the tank, dew condensation does not occur on the wall surface of the tank, and similarly, immediately after that, the plastic bag Even if it is wrapped in a bag or the like, condensation does not occur on the inside of the bag. In addition, when the amount of water to be added is increased by the amount of increase in water content for conditioning, when the water is discharged from the chute 40, the added water is used as a coating layer on the surface of the rice grain or the rice grain. Although it remains in a state that it has penetrated to the very surface layer, the amount is only 0.4% by weight or less of the polished rice, and the temperature of the polished rice has already dropped, so the rice grains rapidly Since it does not penetrate into rice or dry on the contrary, it does not cause cracks, and if it is put into the tank as it is or wrapped in a plastic bag, it gradually penetrates into the rice grain. Then
The water content of the whole rice grain shifts to an equilibrium state.

As the above-mentioned experiments by the present inventor, the water content of the polished rice immediately after the milled rice processing is hardly reduced as compared with that of brown rice, and in the present invention, the polished rice can be cooled without being evaporated. Therefore, it will be possible to obtain milled rice whose moisture content is almost the same as that of brown rice and whose temperature is almost the same as the temperature. Furthermore, if necessary, it is possible to temper it within 0.4%. Is approximately 14.5 to 15 with an upper limit of 16%.
Today, in the range of 5%, it is possible to obtain milled rice with a water content of about 15%, which is preferable for cooking rice.

FIG. 3 shows an automatic controller for the device of the present invention.
C is a control device having a microcomputer and the like built therein. When the operation is started and each measured value from the flow rate sensor S of milled rice, the temperature sensor T1 of milled rice on the supply side, and the temperature sensor T3 is input to the control device C, a preset calculation formula is used. When the plunger pump 27 is controlled so that the amount of water to be added is optimum and the measured value by the temperature sensor T2 of the milled rice on the discharge side is input to the control device C, the optimum value is obtained by comparison with the temperature. The number of rotations of the main motor 34 is controlled so that the evaporation time becomes. By performing such automatic control, each part is automatically adjusted to follow changes in the flow rate, temperature, and temperature of the milled rice during operation, so that operation can always be performed in an optimum state. In addition, the type of brown rice and the degree of polished rice (whiteness of polished rice) can be set in the controller C before operation, and the temperature and the relative humidity of the atmosphere can be set automatically or by manual input. It is also conceivable that the control device C selects an appropriate amount of water or evaporation time based on such information and programs it so as to automatically preset.

In this embodiment, the amount of evaporation of water from the polished rice is adjusted by the evaporation time. However, the evaporation time is kept constant and the suction air volume of the intake blower 43 is changed. It is possible to adjust,
Further, it is possible to change the evaporation time and the suction air volume at the same time.

In the present invention, the temperature of milled rice is expressed as "around the temperature" or "approximately the same as the temperature". However, even if the temperature of the milled rice is not exactly the same as the temperature, the temperature or the temperature may be the same. If it is within the range of plus 2 to 3 ° C., no problem actually occurs.

Further, in the present invention, "immediately after rice polishing"
Means that the milled rice after milling does not pass through a post-treatment device such as another milled rice refining device that extremely lowers the temperature of milled rice, and it is stored in the tank for the purpose of cooling and storage. It refers to a state that has not been stored for a while, such as equipment that does not significantly lower the temperature of polished rice such as elevators and sorters of some sort, and an adjustment tank for smoothing the flow rate of polished rice. When intervening between the machine and the device of the present invention,
Included in "immediately after processing rice".

[0017]

EFFECT OF THE INVENTION According to the method and apparatus for cooling and refining polished rice according to the present invention, it is possible to rapidly cool the refined rice which has been heated to a high temperature by processing the polished rice. Does not oxidize or denature protein, and it does not crack the polished rice,
Polished rice has a good taste when cooked. In addition, since the polished rice is cooled, it is not necessary to take measures against dew condensation on the tank, etc., and it can be immediately packaged in a plastic bag or the like and shipped in an extremely short time of about 1 minute after the rice processing. Work efficiency is greatly improved. Furthermore, the water content can be adjusted to a certain water content that is suitable for cooking rice, and the amount of water added during the cooking operation can be facilitated. Further, since the present apparatus can be made small in processing capacity, it can be installed in a narrow rice mill, and has a feature that it can be suitably implemented, such as facility cost reduction, due to its simple structure.

[Brief description of drawings]

FIG. 1 is a cross-sectional view showing a cooling and refining device according to an embodiment of the present invention.

FIG. 2 is a plan view showing an evaporation means.

FIG. 3 is an explanatory diagram showing an automatic control device.

FIG. 4 is a schematic diagram showing an apparatus used in Experiment 2.

[Explanation of symbols]

 20 Water Mixing Means 23 Screw Feeder 26 Water Supply Port 30 Evaporating Means 33 Net 38 Discharge Port 41 Receiving Cylinder 43 Intake Blower S Flow Rate Sensor T1 Temperature Sensor T2 Temperature Sensor T3 Temperature Sensor C Controller

Claims (5)

[Claims] 1. 0.4 to 1.5 for milled rice immediately after milling.
A cooling and conditioning method for milled rice, which comprises adding water in an amount of wt% and mixing the mixture, and then immediately blowing air to lower the temperature of the milled rice to near the temperature while evaporating the added water. 2. The method for cooling and refining polished rice according to claim 1, wherein the treatment time from the start of addition of water to the end of evaporation by wind is within about 1 minute. 3. The cooled temper of polished rice according to claim 1, wherein the water content of the milled rice after the treatment is increased by 0 to 0.4% from the water content of the unpolished rice before the milled rice processing. Method. 4. 0.4 to 1.5 for polished rice immediately after the processing of rice.
It is characterized by comprising water mixing means for adding water by weight% and mixing, and evaporating means for spreading polished rice on a net and blowing air to evaporate the water added in the water mixing means. Cooling and refining equipment for polished rice. 5. A milled rice flow rate, milled rice temperature, and air temperature sensor are provided, and the amount of water added is adjusted based on the measured values of these sensors, and the evaporation time and evaporation The cooling and refining device for milled rice according to claim 4, further comprising an automatic control device for adjusting at least one of the air volumes.