KR101848840B1 - Method for producing rice starch - Google Patents

Abstract

The present invention relates to a method for producing rice starch with a novel composition wherein rice starch with high purity can be produced at a high yield in a rapid manner, and the method is eco-friendly as an amount of waste water generation is significantly reduced compared to an existing method, and production costs are reduced, and rice protein can be reused as the rice protein is dissolved without deterioration. The method for producing rice starch comprises: (1) a first rice protein dissolving step of making suspension by inserting rice powder into water-containing butanol, adjusting pH to be 5.8-8.0 by adding an alkali aqueous solution, heating the same to maintain a temperature to be 50-55°C, and dissolving protein of rice starch particles for one hour and half to two hours; (2) a second rice protein dissolving step of adjusting pH of the suspension to be 8.5-9.5 by adding the alkali aqueous solution to the suspension having been processed by step (1) and dissolving rice protein remaining in deep layers of the rice starch particles for 40 minutes to one hour by heating the suspension to have a temperature of 56-58°C; (3) a step of separating and collecting the rice starch powder particles from the suspension processed by step (2); and a step of purifying the rice starch particles, processed in step (3), by washing and dehydrating the same.

Description

Method for producing rice starch [

The present invention relates to a method for producing rice starch, and more particularly, to a method for producing rice starch having a high purity and a high yield, The present invention relates to a new method for preparing rice starch, which is capable of recycling rice protein because the rice protein is eluted without denaturation.

 Rice starch has a gelatinization temperature of 65 ~ 70 ℃ which is relatively low compared to other starches. Starch particle size is 2 ~ 9㎛, which is the smallest starch in starch, so it has high permeability and adhesion. It has a higher viscosity than other starches, especially superior in moisture retention to maintain moisture, and has a high digestion and absorption rate. Therefore, rice starch is highly utilized for food processing auxiliaries, adhesives, fiber processing auxiliaries, diet foods, patient meal, infant formula for infants and young children.

However, since rice bran cells are arranged regularly on the outer surface of the cells, the separation of starch is considerably more difficult than other foods such as corn, wheat, and potato.

According to the general rice starch preparation method, the protein is dissolved and removed by immersing the rice flour in a large amount of 0.3-0.5% alkali aqueous solution which is 4-5 times the volume of the rice flour volume. The protein is regularly arranged on the outer side of the rice blast cell Therefore, unless the rice starch particles are heated by heating the rice flour, the aqueous alkali solution can not flow into the rice starch particles, so that the rice protein does not readily elute. However, since rice starch is easily gelled at a low temperature in an aqueous alkali solution, it is difficult to swell the rice starch particles by heating the rice starch by immersing the rice in an alkaline aqueous solution. In addition, even if heated, it is difficult to heat at 30 ° C or more, and deliquescence is delayed by using a delaying agent.

In such a conventional method for producing rice starch, the rice flour must be immersed in an aqueous 0.3 to 0.5% alkali solution for 18 to 24 hours for a long time because the rice flour can not be heated or heated only to a very small extent.

Further, the rice starch is immersed in an aqueous alkaline solution for about 18 to 24 hours to elute the protein on the outer periphery of the rice starch particles to further dehydrate the rice starch, and then the rice flour is further subdivided and immersed in the alkaline aqueous solution for 4 to 8 hours, The proteins in the central portion are eluted, followed by filtration and washing with water to obtain rice starch particles.

As described above, the conventional method for producing rice starch requires a long time to immerse the rice flour in an aqueous alkaline solution. Therefore, the production time is long and the productivity is low. When the rice starch is filtered and washed, the starch layer floats, Has a low disadvantage.

In addition, a large amount of alkaline aqueous solution, which is about 4 to 5 times the amount of rice, is used to dissolve and remove proteins. Therefore, many wastewater is generated. In particular, when a delaying agent is used, the amount of wastewater is further increased. It is generally known that at least 5 to 50 tons of wastewater is produced when 1 ton of starch is produced. Therefore, a large-scale wastewater treatment facility for wastewater treatment is required, and the cost of wastewater treatment is high, which increases the manufacturing cost of rice starch.

In order to produce high quality rice starch, the rice starch prepared by using the alkaline aqueous solution is subjected to a process of purifying the rice starch at least 4 to 5 times or more to obtain a high quality product. .

On the other hand, the rice protein is a relatively simple protein consisting of 10 amino acids, consisting of gliadin belonging to Oryzenin and Prolamin belonging to Glutelin. In particular, lysine, an essential amino acid, is contained in rice protein more than twice as much as grains such as wheat, corn, and crude. Therefore, it is quite uneconomical to just discard rice proteins isolated from rice during the production of rice starch.

However, when rice starch is prepared by the conventional method as described above, the rice protein is less likely to be recycled because it is likely to be denatured by the influence of alkali.

Korean Patent No. 10-1461639 (Apr. Korean Patent No. 10-1535061 (2015. 07.02)

SUMMARY OF THE INVENTION The present invention has been made in view of the above problems, and it is an object of the present invention to provide a method of producing rice starch of high purity at a high yield by using an optimal solvent for dissolving rice protein, The present invention relates to a novel method for producing rice starch which is capable of recovering eluted rice proteins and recycling them because the amount of waste water generated is remarkably reduced compared with that of conventional rice starches.

According to a feature of the present invention, (1) a rice flour is added to a functional butanol having a weight of 1.5 to 2 times the weight of the rice flour to prepare a suspension, the pH is adjusted to 5.8 to 8.0 by adding an aqueous alkali solution, A first rice protein elution step in which the protein of rice starch particles is eluted for 1 hour and a half to 2 hours by heating; (2) The pH of the suspension is adjusted to 8.5 to 9.5 by addition of an aqueous alkali solution to the suspension after completion of the step (1), and the rice starch particles are heated for 40 minutes to 1 hour by heating to maintain the temperature at 56 to 58 ° C. A second rice protein elution step of eluting the rice protein remaining in the deep layer; (3) separating the rice starch particles from the suspension after the step (2); And (4) washing, dehydrating and purifying the rice starch particles separated in the step (3).

The present invention having the above-described configuration has the following effects.

First, the amount of waste water generated is reduced.

Since the present invention utilizes a functional butanol having a high solubilizing capacity for rice protein as a solvent for rice protein, the rice protein contained in the rice starch particles can be effectively eluted even when only about 1.5 to 2 times the weight of the rice flour is used. The amount of wastewater generated is remarkably reduced compared with the method using 4 to 5 times more than the rice flour.

In addition, since functional butanol is hydrophilic, it is mixed well with an aqueous alkali solution used as a protein separation assisting agent in the present invention. Therefore, it is not necessary to use a separate emulsifier. Also, since functional butanol is used as a solvent for rice protein, It is not necessary to use a separate delaying agent because the rice starch does not easily age when heated. When an emulsifier or a delaying agent is used, a large amount of washing water is required to remove these agents when washing rice starch, thereby increasing the amount of waste water generated. In the present invention, an emulsifier or a delaying agent is not used. The amount of waste water generated is also reduced.

Second, high purity rice starch can be economically produced.

In the first protein elution step, the pH of the suspension is adjusted to 5.8 to 8.0 and the temperature to 50 to 55 ° C to relax the fiber bundles in the amorphous region of the rice starch particles to restrict the swelling of the rice starch particles, The protein is efficiently eluted by allowing the solvent to flow into the amorphous region of the rice starch particles without being enriched. In the second protein elution step, the fiber bundles of the crystal region constituting the deep part of the rice starch particles are relaxed, Layer, so that high purity rice starch can be prepared by further eluting the rice protein remaining in the deep layer without being eluted in the primary protein elution step.

In addition, unlike conventional rice starch production methods, since functional butanol is used as a solvent, rice starch is not degraded even when it is heated to a relatively higher temperature than conventional ones without using a delaying agent, so that in the first and second protein elution steps By heating to increase protein elution rate, the production time of rice starch is shortened and productivity is improved.

Third, the rice protein can not be denatured and it is possible to recycle the separated rice protein.

By controlling the temperature and pH so that the rice protein is not denatured in the leaching step of the rice protein, the protein can be recovered and recycled because the rice protein is not denatured and eluted. In particular, since lysine, which is an essential amino acid, is contained twice as much as rice in comparison with other grains, it is quite useful to recover and use the lysine eluted in the production of rice starch.

Fourth, the recovery rate of rice starch is high.

The Kollung drag force between the rice starch particles is increased to cause the aggregation of the rice starch particles so that the loss of the rice starch particles is prevented during the separation step of the rice starch particles after the elution of the rice protein is completed and thus the recovery rate of the rice starch is improved .

1 is a schematic diagram of a process according to a preferred embodiment of the present invention.
FIG. 2 is a graph showing the solubility of rice protein

Hereinafter, the present invention will be described in more detail with reference to the drawings.

FIG. 1 is a schematic view of a manufacturing process according to a preferred embodiment of the present invention, and the present invention comprises the following processes.

1) Primary rice protein elution step

The pH of the suspension was adjusted to 5.8 to 8.0 by adding an aqueous alkaline solution to the rice flour at a ratio of 1.5 to 2 times the weight of the rice flour, and the mixture was heated to maintain the temperature at 50 to 55 ° C for 1 hour and a half For 2 hours. At this time, the rice flour is allowed to react while stirring to maintain the dispersed state without sinking.

Functional butanol is a solvent for the separation of protein from rice flour, which solubilizes almost all the proteins that make up the rice protein. In particular, since functional butanol has a hydrophilic property, it has an advantage of being well mixed with an aqueous alkali solution even without a separate emulsifier, and has a solubility parameter of 11.0 and a higher solubility constant than other hydrophilic solvents. The addition reaction with the aqueous alkaline solution is not caused.

In addition, in the present invention, since water and a functional butanol as a solvent are mixed in the suspension, the coulomb drag of the solvent in the suspension is lowered, and the coulomb force between the rice starch particles is relatively increased, so that the rice starch particles are agglomerated The effect of preventing suspension of rice starch particles can be obtained, and thus the recovery rate of rice starch is improved.

Functional butanol is used at about 1.5 to 2 times the weight of the rice flour. Even if the functional butanol is used only in the above amount, the protein contained in the rice starch particles is sufficiently dissolved. Even if the amount is more than the above amount, It is not economically advantageous to use the functional butanol more than the above amount.

In this step, the pH of the suspension is adjusted to 5.8 to 8.0 by adding an aqueous alkali solution to relax the fiber bundles in the amorphous region of the rice starch particles so that the starch particles of rice are not swollen properly, and the reaction temperature is adjusted to 50 to 55 ≪ / RTI >

Generally, if the swelling of the rice starch particles does not occur, the solvent will not penetrate into the amorphous region and the crystalline region of the rice starch particles, and the rice protein will not be properly eluted, resulting in a failure to obtain high purity rice starch. It takes time. However, since rice starch gels when rice starch particles are excessively swollen, it is necessary to swell the rice starch particles to a minimum so that rice starch does not become luxurious.

When the rice starch particles are properly swollen by the aqueous alkali solution, the elution rate of the rice protein is improved, so that the aqueous alkali solution functions as a protein separation assisting agent. Particularly, in the present invention, since functional butanol is used as a solvent for protein elution and a small amount of an aqueous alkali solution is used as a protein separation assisting agent, the temperature of the suspension is raised to a relatively high level of about 50 to 55 ° C Rice starch particles are not luxurious even when put up.

As can be seen from the graph of 'solubility of rice protein according to pH change' shown in FIG. 2, since the solubility of rice protein rapidly increases at pH 5.8, the pH of the suspension is increased to 5.8 or more . When the pH is more than 8.0, the solubility of the rice protein is increased. However, since the possibility that the rice starch becomes luxurious by heating is remarkably increased, it is preferable to adjust the added amount of the alkaline aqueous solution so as not to exceed the pH 8.0.

As the aqueous alkali solution, at least one of aqueous solution of sodium carbonate, aqueous solution of sodium hydroxide, aqueous solution of potassium hydroxide and aqueous solution of potassium carbonate is used.

Further, the higher the temperature, the higher the dissolution rate of the protein. Therefore, in order to increase the dissolution rate of the protein, it is necessary to heat the suspension. For example, the oryzenin, the main axis of rice protein, increases the elution rate by 2 to 3 times as the temperature rises by 10 ° C. However, since the protein should not be denatured by heat, the heating temperature of the suspension should be controlled.

Since the rice protein is denatured from 60 ° C, the temperature of the suspension may be maintained below 60 ° C. However, if the temperature of the suspension is higher than 55 ° C, the denatured protein may be induced as the reaction progresses and the rice starch particles may become luxurious. It is preferable to adjust the temperature to 50 to 55 占 폚.

 Thus, in this step, the swelling of the rice starch particles is suitably induced by adjusting the pH of the suspension to 5.8 to 8.0 and the reaction temperature to 50 to 55 ° C, so that the rice starch particles do not gel and rapidly dissolve without denaturation of the rice protein .

2) Second rice protein elution step

In this step, the pH of the suspension is adjusted to about 8.5 to 9.5 by adding an alkali aqueous solution to the suspension subjected to the primary rice protein elution step, and the suspension is heated for about 40 minutes to 1 hour while heating to maintain the temperature of 56 to 58 ° C . In this step, the rice flour is allowed to react with stirring to prevent sinking.

In this step, an aqueous alkaline solution is further added to raise the pH of the suspension, so that the fibrous bundle in the crystalline region forming the deep layer of the rice starch particles is further relaxed so that the solvent flows into the deep layer of the rice starch particles, The rice protein remaining in the layer is further eluted.

The isoelectric point (PI) of the lysine, which is the most important protein among the ten amino acids constituting the rice protein, is 9.7. At this isoelectric point, the coagulation action of lysine occurs and the dissolution of lysine becomes difficult. Therefore, the pH of the suspension is adjusted to 8.5 to 9.5 . Also, the temperature of the suspension is increased to 56 ~ 58 ° C, which is the maximum temperature at which the protein is not denatured, to maximally increase the elution rate of the residual protein of the rice starch particles.

In this step, when the reaction is carried out at the above pH and temperature conditions for about 40 minutes to 1 hour, the rice protein remaining in the deep layer of the rice starch particles is mostly eluted, so that high purity rice starch having a purity of 98% or more can be obtained.

3) Separation of rice starch

After the second protein separation step, the suspension is dehydrated with a centrifuge to separate the rice starch and the liquid containing the rice protein. When centrifuged in this manner, rice starch is obtained in the form of a solid.

At this time, as described above, since the coulomb force between the rice starch particles is relatively high, the rice starch particles are clumped to prevent the suspension, thereby improving the separation efficiency of the rice starch particles.

4) Rice starch purification step

The rice starch separated in the above step is washed, concentrated, dehydrated and purified to obtain the final rice starch. This step is performed in the same manner as the conventional rice starch purification step.

If necessary, the modified rice starch may be transformed into alpha to produce modified starch. In this case, water is added so that the moisture content of the purified rice starch is 22 to 25%, and the mixture is heated to 50 to 55 ° C under a reduced pressure of 100 torr to obtain rice starch. Preferably, this step is carried out using a vertical kneader. Then, the heated starch is dried by heating. In this drying step, the α-starch of rice starch is fixed.

In the present invention having the above-described structure, since functional butanol is used as a rice protein solvent and an aqueous alkaline solution is used as a protein separation assisting agent, the rice starch is not agglomerated even when heated to a relatively higher temperature than conventional rice starch preparation methods Therefore, it is possible to elute almost all of the rice protein relatively quickly, and there is an advantage that the amount of wastewater can be reduced compared with the conventional method using a large amount of alkali aqueous solution of about 4 to 5 times of the rice flour.

In addition, since rice protein is not denatured but eluted, rice protein can be recycled. The rice protein eluted in the present invention is recovered and recycled by a known method.

Experimental Example  One

100 Kg of rice flour and 200 L of functional butanol (160 Kg) were added to a 500 L reactor to prepare a suspension. The pH of the suspension was adjusted to 7.0 by adding an aqueous alkali solution, followed by heating at 52 캜 for 2 hours while stirring. Was adjusted to 9.0, and the mixture was heated to 58 DEG C and reacted for 1 hour to elute the rice protein.

After the reaction, the suspension was centrifuged to separate the rice starch particles from the solution, washed, concentrated, and dehydrated to obtain 68 kg of rice starch.

The pH of the solution was adjusted to 6.45, which is the isoelectric point of Oryzenin, by adding 1N-hydrochloric acid to the solution containing rice protein, which was separated from the suspension of rice starch. The pH of the solution was adjusted to 30 to 40 ° C After the mixture was allowed to stand, the mixture was purified, concentrated, and dehydrated in a disk-separating centrifugal concentrator, dried in a hot-air drier at 50 DEG C and pulverized to 80 mesh to obtain 6.8 kg of protein.

Claims (1)

(1) The rice flour was added to the boiling water of 1.5 to 2 times the weight of the rice flour to prepare a suspension. The pH was adjusted to 5.8 to 8.0 by adding an aqueous alkali solution and heated to maintain the temperature at 50 to 55 ° C. A first rice protein elution step of eluting proteins of rice starch particles over a period of time;
(2) The pH of the suspension is adjusted to 8.5 to 9.5 by addition of an aqueous alkali solution to the suspension having been subjected to the step (1), and the rice starch particles are heated for 40 minutes to 1 hour by heating to maintain the temperature at 56 to 58 ° C. A second rice protein elution step of eluting the rice protein remaining in the deep layer;
(3) separating the rice starch particles from the suspension after the step (2); And
(4) washing, dehydrating and purifying the rice starch particles separated in the step (3).

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