KR101724118B1 - Method for preparing high purity protein concentrate from rice bran - Google Patents

Abstract

Disclosed is a method for preparing a new rice bran protein extract that can eliminate the repetitive treatment of acid and base in the preparation of rice bran protein extract, thereby solving the problem of purity lowering and protein structure denaturation. (A) preparing a defatted rice gruel in which a fat component has been removed by extracting a raw rice gruel; (b) extracting a water-soluble protein by adding a weak alkaline solution to the defatted rice goblet; (c) separating the precipitate and the supernatant by centrifuging the solution containing the extracted protein; (d) passing the supernatant through a microfilter membrane to recover rice protein; And (e) re-dispersing the recovered rice bran protein in a weakly alkaline solution and drying the rice bran protein extract to obtain a rice bran protein extract.

Description

TECHNICAL FIELD [0001] The present invention relates to a method for producing a high-purity rice bran protein extract,

The present invention relates to a method for preparing rice bran protein extract, and more particularly, to a method for extracting high-purity rice bran protein from defatted rice bran.

Rice bran is an outer shell of rice, which is the main food resource of our country. It contains a large amount of dietary fiber, vegetable protein and other useful ingredients. However, because it contains a large amount of fat in the rice husk layer, The quality of roasted rice was rapidly deteriorated and it was not suitable as a food material. In order to solve the problem of lipid rancidity, the lipase contained in the rice bran produced immediately after the ripening is heated to maintain the state of inactivation, or it is stabilized by removing the internal moisture, and after degreasing with hexane, the sufficient added value as a food material is increased .

In addition, it has been reported that rice bran is superior in blood cholesterol lowering effect, antioxidant effect, and blood pressure elevation inhibitory effect (Nicolsi et al., 1993; Capro et al., 1997), and tocopherol, , Oruzanol, and ferulic acid (Andreason et al., 1999; Kikuzaki et al., 2002).

In addition, the rice protein protein compared with animal protein provides other important nutrients such as soluble fibrin and magnesium ion, so there is no cholesterol, low saturated fat content, low energy density due to high dietary fiber, It has been attracting attention as a health food.

A method for preparing rice bran protein extracts as disclosed in Patent No. 10-0912054 is disclosed as a method for extracting such rice protein. In this patent, a technique for separating rice bran protein, which can replace whey protein or casein sodium, and producing it as an edible protein, extracting proteins by adding an alkaline solution of pH 9 or more to the defatted rice bran, centrifuging the extract, Protein is separated by precipitating the protein by adding strong acid to the supernatant by lowering the pH to about pH 4. The protein is then purified again by re-dispersing the protein at pH 7 by addition of acid again, followed by coagulation and sedimentation And then the powdery protein is obtained by a spray drying method through a sterilization process.

However, in the case of extracting rice bran protein by the above-mentioned method, it is difficult to obtain a purified protein having a high purity of 80% or more due to salt formation by repeated treatment of acid and base, and the protein is subjected to coagulation precipitation and redispersion, There is a problem that the finally produced protein is changed to be insoluble. As a result, the denatured protein is inferior in digestion and absorption rate and has a disadvantage as a food protein.

Disclosure of the Invention The present invention has been devised to solve the problems described above, and it is an object of the present invention to provide a method for preparing a new rice bran protein extract which can solve the problem of purity lowering and protein structure denaturation by eliminating repeated treatment of acid and base in preparation of rice bran protein extract .

In order to solve the above-described problems, the present invention provides a method for producing a defatted rice gruel, comprising the steps of: (a) (b) extracting a water-soluble protein by adding a weak alkaline solution to the defatted rice goblet; (c) separating the precipitate and the supernatant by centrifuging the solution containing the extracted protein; (d) passing the supernatant through a microfilter membrane to recover rice protein; And (e) re-dispersing the recovered rice bran protein in a weakly alkaline solution and drying the rice bran protein extract to obtain a rice bran protein extract.

And the weak alkaline solution of step (b) has a pH of 9 or less.

In addition, the microfiltration membrane has a micropore size of 0.1 to 10 mu m in diameter.

And the weak alkaline solution of step (e) has a pH of 7.5 to 8.5.

And the concentration of the redispersed solution in step (e) is in the range of 20 to 40 Brix on the basis of the reflex balance.

According to the present invention, a high-purity rice bran protein without protein denaturation is extracted using a one-time microfiltration membrane method instead of a repetitive precipitation coagulation method during extraction and extraction of a protein by adding an alkali solution to a defatted rice bran, By simplifying the whole process, manufacturing cost and time can be saved, and a more economical method of producing rice bran protein extract can be provided.

Hereinafter, preferred embodiments of the present invention will be described in detail. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, the present invention will be described in detail with reference to the accompanying drawings. Throughout the specification, when an element is referred to as "including " an element, it means that it can include other elements, not excluding other elements, unless specifically stated otherwise.

The method for preparing rice bran protein extract according to the present invention comprises the steps of: (a) preparing a defatted rice gruel having a fat component removed by extracting raw rice bran; (b) extracting a water-soluble protein by adding a weak alkaline solution to the defatted rice goblet; (c) separating the precipitate and the supernatant by centrifuging the solution containing the extracted protein; (d) passing the supernatant through a microfilter membrane to recover rice protein; And (e) re-dispersing the recovered rice bran protein in a weakly alkaline solution and drying to obtain a rice bran protein extract.

The step (a) is a step of pretreating and degreasing the rice bran. The rice bran oil is extracted and removed while minimizing the denaturation of the protein contained in the unstable rice bran, thereby lowering the residual oil content to a desired level and preparing a defatted rice bran suitable for use as a protein extraction raw material. . In the present invention, the step of pretreatment and degreasing of rice bran are not particularly limited as long as the method can minimize the residual oil content. For example, the method disclosed in Japanese Patent No. 10-0912054, -Hexane is added to recover the residual oil content until the residual oil content becomes 5% by weight or less, and the step of removing residual hexane at a temperature of 60 ° C or lower can be applied.

The step (b) is a step of extracting a water-soluble protein from the defatted rice goblet, and a method of extracting the defatted rice gob by adding a weak alkali solution is used. In this step, the method disclosed in the above patent may also be used. That is, 4 to 8 times as much water as the weight of the skimmed rice is hydrolyzed and dispersed by hydration and agitation for 30 to 60 minutes, and then 1 to 5 N sodium hydroxide solution is injected at a temperature of 20 to 50 ° C to give a final pH of 8 to 10 Can be carried out by maintaining the pH below 9 and extracting the protein for about 30 to 60 minutes.

In the step (c), the first step of purifying rice bran protein is performed by centrifuging a solution containing the extracted water-soluble protein to take up the supernatant. In this step, the method disclosed in the patent may also be used. That is, the solution containing the extracted water-soluble protein can be centrifuged at a temperature of 5,000 g or more at room temperature to separate the supernatant and the precipitate.

The step (d) is a step of recovering high purity rice bran protein from the supernatant separated from the precipitate, and performing the sterilization by passing the supernatant through a microfiltration membrane. In this step, a strong acid such as hydrochloric acid is added to the supernatant to lower the pH to about 4 to lower the solubility of the protein and precipitate. The protein is recovered, the alkali is re-dispersed by re-dispersing the alkali, And water washing process. According to the conventional method, there is a problem that salts neutralized with proteins are left as impurities due to repeated use of acid and base solutions, and acid and base wastewater generated during the process must be treated, There is a problem in that a sterilization process must be separately added to use for food.

In contrast, the present invention eliminates bacteria and the like by passing a supernatant through a microfiltration membrane, eliminates the need for an additional bactericidal process, and dramatically increases protein purity by 85% or more because there is no salt generation by acid or base repeated treatment, Since the processes required for the conventional acid and base repetitive processes reach at least three stages, the protein can be recovered through one-time passage through the filtration device, which is excellent in terms of process efficiency.

The microfiltration membrane used in the present invention may be selected from the group consisting of cellulose acetate, cellulose nitrate, polyacrylonitrile / polyvinyl chloride copolymer, polysulfone, polyethersulfone, polyvinylidene fluoride, aliphatic polyamide, aromatic polyamide, polyimide, poly Etherimide, polyether ether ketone, polypropylene, polytetrafluoroethylene, etc. In order to be able to replace casein sodium with bacteria and fine insoluble matter filtration, a weight average molecular weight of 30,000 or more The micropores have a diameter of 0.1 to 10 mu m, preferably 0.2 to 2 mu m, so as to selectively recover only the microporous proteins, preferably 30,000 to 300,000, more preferably 50,000 to 100,000, and most preferably 60,000 to 70,000. Mu] m, still more preferably 0.3 to 1 [mu] m, and most preferably 0.4 to 0.6 [mu] m And membranes can be used. When the micropore size is out of the above range, the purity of rice bran protein may be lowered due to the difference in the components (bacteria, cells, saccharides, proteins, etc.) to be filtered depending on the size, and the yield is also undesirable.

The step (e) is a post-treatment step of commercializing the purified rice bran protein extract. The rice bran protein extract that has passed through the microfiltration membrane is re-dispersed in a weak alkaline solution and dried.

In order to obtain a powder of uniform size without lowering the purity of the rice bran protein extract upon redispersion and drying, the weakly alkaline solution to be used is adjusted to a pH of 7.5 to 8.5, preferably a pH of 7.8 to 8.5, 8.2, and the concentration of the redispersed solution may be redispersed to 20 to 40 Brix, preferably 25 to 35 Brix, on the basis of the reflex balance, followed by spray drying.

Hereinafter, a specific embodiment of the present invention will be described.

Example

Raw cores having a moisture content of 12 to 16% by weight were pelletized to a size of 2 to 10 mm and dried to a moisture content of 10% by weight or less. The dried rice bran pellets were subjected to circulating oil extraction by adding n-hexane three times as much as the weight of the rice pellets to extract the rice bran oil until the residual oil content reached 3 wt%, and residual hexane was removed at a temperature of 60 ° C or lower And a degreased rice bran was prepared. Then, water was added 6 times as much as the weight of the degreased rice bran, and the mixture was hydrated with stirring for 40 minutes to disperse the particles evenly. The final pH was maintained at 8 to 9 while injecting 3N sodium hydroxide solution at 30 ° C, And extracted. Then, the solution containing the extracted protein was centrifuged under conditions of 5,000 g or more to separate the supernatant and the precipitate, and the separated supernatant was taken and passed through a membrane module equipped with polysulfone microfiltration membrane having a fine pore size of 0.5 μm in diameter, Proteins were recovered. Then, 1N sodium hydroxide solution was added to the recovered rice bran protein, and the final pH was adjusted to 8, redispersed to a concentration of 30 Brix, and then the redispersed solution was injected at an air temperature of 150 to 190 ° C. and an air temperature of 80 to 100 ° C. , And nozzle pressure of 1.2 ~ 1.8 bar to prepare dried rice bran protein extracts.

Comparative Example 1

Except for using an ultrafiltration membrane having a micropore size of 0.05 mu m in diameter instead of the microfiltration membrane in the examples, a rice bran protein extract was prepared in the same manner as in Example.

Comparative Example 2

In the examples, rice bran protein extracts were prepared in the same manner as in Example except for using a ceramic filter having a fine pore size of 20 mu m instead of a microfiltration membrane.

Comparative Example 3

Rice bran protein extracts were prepared by acid and base repeated treatment. That is, the supernatant obtained by centrifugation according to the above example was adjusted to pH 3.5 to 5 with 2N hydrochloric acid solution at a temperature of 20 ° C, reacted within 30 minutes to precipitate proteins in the supernatant, and centrifuged again under conditions of 5,000 g or more A precipitated protein was obtained. About three times as much water was added to the obtained precipitated protein, followed by centrifugation again to obtain a washed precipitated protein. To the precipitated protein which had been washed with water, about 1.5 times of water was added again to prepare a solution. Was neutralized to pH 6-7 with 1N sodium hydroxide solution. The neutralized protein solution was spray dried in the same manner as in Example to prepare a dried rice bran protein extract.

Experimental Example

The yield of rice bran protein extracts prepared according to the above Examples and Comparative Examples was measured and the protein content was analyzed using Kjeldahl quantitation method (SpeedDigester K-436). The results are shown in Table 1 below. The yield was measured as the weight ratio of the final dried bovine protein extract to the weight of the dry powder of the weak alkaline extract.

Table 1 shows that when a rice bran protein extract is prepared by using a microfiltration membrane having an appropriate micropore size excluding an acid and base repeating treatment according to the present invention, the purity can be improved to 80% or more, , It can be confirmed that a rice protein extract having a protein content of 85% or more and a high purity and having an excellent yield of 80% or more can be produced.

On the other hand, when the ultrafiltration membrane is used, it can be produced with a relatively high purity, but it can not be obtained when using a microfiltration membrane, and the micropores are excessively small in size and thus the yield is low. In addition, when using a ceramic filter, the pore size was excessively large, and both the yield and the purity were remarkably decreased.

The preferred embodiments of the present invention have been described in detail above. It will be understood by those of ordinary skill in the art that various changes in form and details may be made therein without departing from the spirit and scope of the invention as defined by the appended claims.

Accordingly, the scope of the present invention is defined by the appended claims rather than the foregoing detailed description, and all changes or modifications derived from the meaning, range, and equivalence of the claims are included in the scope of the present invention Should be interpreted.

Claims (5)

(a) extracting a raw material of rice bran to produce a degreased bran without a fat component;
(b) extracting a water-soluble protein by adding a weak alkaline solution to the defatted rice goblet;
(c) separating the precipitate and the supernatant by centrifuging the solution containing the extracted protein;
(d) passing the supernatant through a microfilter membrane to recover rice protein having a weight average molecular weight of 30,000 or more; And
(e) re-dispersing the recovered rice bran protein in a weakly alkaline solution and drying to obtain a rice bran protein extract;
Wherein the method comprises the steps of:
The rice bran protein extract
Wherein the protein content by the content analysis using Kjeldahl quantitation method (SpeedDigester K-436) is 80% or more. The method according to claim 1,
Wherein the weak alkaline solution of step (b) has a pH of 9 or less. The method according to claim 1,
Wherein the microfiltration membrane has a micropore size of 0.1 to 10 mu m in diameter. The method according to claim 1,
Wherein the weak alkaline solution of step (e) has a pH of 7.5 to 8.5. The method according to claim 1,
Wherein the concentration of the redispersed solution in step (e) is in the range of 20 to 40 Brix based on the refractive index.