CN102115690B - Method for comprehensively utilizing rice bran - Google Patents

Abstract

The invention discloses a method for comprehensively utilizing rice bran, which can simultaneously prepare four kinds of products including rice bran oil, rice bran crude fiber, rice bran protein and rice bran peptide. The preparation process is as follows: using rice bran as raw material, first extract the oil in rice bran, then use the "alkali-soluble acid precipitation" method to separate rice bran crude fiber and rice bran protein, then add protease to the rice bran protein to hydrolyze the protein, and then go through ultrafiltration classification, filtration Anion and cation exchange resins are used to remove salt, and finally concentrated and dried to obtain rice bran bioactive peptides.

Description

A method for comprehensive utilization of rice bran

technical field

The invention relates to a method for comprehensively utilizing rice bran.

Background technique

Rice is the largest grain variety in my country. At present, the annual output is about 185 million tons, accounting for 42% of the country's total grain output. Paddy production accounts for 37% of the total food production in the world. In the process of processing rice into polished rice, the shell and the seed coat and embryo accounting for about 10% of the total weight must be removed. Rice bran is made from the seed coat and embryo and is the main by-product of rice processing. Research results and data at home and abroad show that rice bran is rich in various nutrients and physiologically active substances. Due to the different raw materials and processing techniques used in processing rice bran, the composition of rice bran is not exactly the same. Generally speaking, rice bran contains an average of 15% protein, 16%-22% fat, 3%-8% sugar, and 10% water.

At present, the processing methods of rice bran at home and abroad are relatively single, and there is no comprehensive utilization method. Either only extract rice bran oil or only extract rice bran dietary fiber, and the utilization of rice bran protein and rice bran peptide is less. There are three main preparation techniques of existing rice bran peptides: (1) genetic engineering method; (2) chemical synthesis method; (3) enzymatic hydrolysis method. In the current process of preparing rice bran peptides by enzymatic hydrolysis, a large amount of lye or acid solution is added to adjust the pH of the solution during the enzymatic hydrolysis reaction, and there is no desalination process, so that the salt content of the finished product is too high; and, The final product is not classified, and the molecular weight distribution of the final product is quite different, which affects the physiological activity of the product.

Contents of the invention

The problem to be solved by the present invention is to provide a method for comprehensive utilization of rice bran, which can produce four kinds of products: rice bran oil, rice bran crude fiber, rice bran protein and rice bran peptide.

In order to solve the above-mentioned technical problems, the comprehensive utilization method of rice bran provided by the present invention is as follows: using rice bran as raw material, first extracting the oil in rice bran, then using the "alkali-soluble acid precipitation" method to separate rice bran crude fiber and rice bran protein, and then adding rice bran protein Protease hydrolyzes the protein, then undergoes ultrafiltration classification, passes through anion and cation exchange resins to remove salt, and finally concentrates and dries to obtain rice bran bioactive peptides.

A method of comprehensively utilizing rice bran of the present invention may be as follows:

(1) Crush the rice bran, pass through a 60-80 mesh sieve, use Soxhlet extraction method, use 95% n-hexane solvent to extract at 50°C for 2 hours, then filter the n-hexane solution, and dry the rice bran until the n-hexane is completely Volatile, it is defatted rice bran; use the rotary evaporator to completely evaporate the n-hexane from the filtrate, and the rest is rice bran oil;

(2) Dissolve defatted rice bran and water in step (1) into water at a ratio of 1:5 to 1:10 (mass ratio), heat to 45 to 55°C, adjust the pH to 8.0 to 10.0 with NaOH reagent, and keep stirring for 15 minutes. Centrifuge for 15 minutes at a speed of 3000-4000r/min, take the supernatant, and dry the precipitate to obtain rice bran crude fiber;

(3) Heat the supernatant of step (2) to 70-90°C, adjust the pH to 3.0-5.0 with citric acid reagent, stir continuously for 10min, 3000-4000r/min, 15min, and centrifuge to collect the precipitate, which is rice bran protein , drying to obtain rice bran protein powder;

(4) Dissolve the rice bran protein and water in step (3) into water at a ratio of 1:5 to 1:10 (mass ratio), heat to 90 to 100°C, keep for 15 to 30 minutes, then cool to 35 to 50°C, and use NaOH reagent to adjust and maintain the pH at 6.0-8.0, add neutral protease As1.398 according to the E/S ratio of 3%-7%, enzymolysis for 2-4 hours, keep stirring during the enzymolysis process, and use NaOH solution to maintain the pH value at 6.0 ~8.0;

(5) After the enzymatic hydrolysis in step (4), quickly adjust the pH to 5.0-3.0 with HCl solution, centrifuge at a speed of 3000-4000r/min for 15min, take the supernatant, and obtain the crude rice bran peptide liquid;

(6) Inject the crude rice bran peptide solution obtained in step (5) into the storage tank, and the solution passes through the ultrafiltration membrane with a molecular weight cut-off of 1000Da after microfiltration, and the small molecular substances in the solution permeate out through the inner wall of the hollow fiber membrane to become The ultrafiltrate, collecting the ultrafiltrate, is the rice bran peptide ultrafiltrate; the protein and other macromolecular substances in the solution are preserved and concentrated, and the concentrated solution is recovered to step 4 for enzymatic hydrolysis again;

(7) The exchange resin was soaked in deionized water for 24 hours and then packed into a column, then it was soaked with 7.5% hydrochloric acid and 10% NaOH respectively, converted into H ⁺ type cation exchange resin and OH ^- type anion exchange resin, and then used Wash with deionized water until the pH is 7.0 for use;

The ultrafiltrate obtained in step (6) is passed through the H ⁺ type cation exchange resin at a flow rate of 5 to 10 times the column volume/h to remove cations, and the sample addition is stopped when the pH of the effluent=4.0, and then the The effluent is passed through the OH ^- type anion exchange resin at the same flow rate to remove anions, and the sample addition is stopped when the pH of the effluent is 7.0, and it is collected as rice bran peptide refined liquid;

(8) The rice bran peptide refined solution obtained in step 6 is concentrated under reduced pressure to a solid content of 20% to 30%;

(9) After the refined rice bran peptide solution is concentrated, it is spray-dried or freeze-dried to make a dry powder.

The purpose of the above step (1) is: the oil content in the rice bran is about 16%, and the oil in the rice bran is extracted by utilizing the property that the oil dissolves in n-hexane, and the n-hexane is completely evaporated by rotary evaporation to obtain rice bran oil.

The purpose of the above step (2) is to separate the rice bran protein from the alkali-insoluble matter by utilizing the property of protein dissolving under alkaline conditions, so as to increase the content of the rice bran protein; the alkali-insoluble component is rice bran crude fiber.

The purpose of the acid precipitation in the above step (3) is to separate the rice bran protein from acid-soluble substances by utilizing the property of protein precipitation under acidic isoelectric point conditions, so as to increase the content of rice bran protein.

The purpose of the above steps (2) and (3) is to separate rice bran crude fiber and rice bran protein in defatted rice bran. At the same time, the rice bran protein used for hydrolysis is purified. Generally, the protein content in defatted rice bran is about 20%. After the above-mentioned treatment, the protein content can reach more than 80%.

The purpose of the above step (4) enzymolysis is: enzymatically hydrolyze the macromolecular protein in the rice bran into small molecular protein and peptide;

The purpose of acid adjustment in the above step (5) is to inactivate the enzyme and stop the enzymolysis reaction; the purpose of centrifugation is to collect the enzymolysis solution for solid-liquid separation.

The purpose of the ultrafiltration in the above step (6) is to intercept the products with required molecular weight; the purpose of the secondary enzymatic hydrolysis is to hydrolyze the macromolecular protein with a molecular weight of 1000 Da or more into small molecules, so as to improve the utilization of raw materials.

The purpose of desalting in the above step (7) is to remove the salt ions in the enzymolysis solution due to the constant adjustment of pH during the enzymolysis process. The salt content of products that have not undergone desalination treatment is greater than 8%, and the salt content of products that have undergone desalination treatment is less than 2%;

Compared with the prior art, the present invention has the following advantages and effects:

(1) This method provides a method for comprehensive utilization of rice bran, which can simultaneously prepare four products of rice bran oil, rice bran crude fiber, rice bran protein, and rice bran peptide;

(2) Extract oil and fat components in rice bran by leaching method, and prepare about 10 g of rice bran oil per 100 g of rice bran.

(3) Separating rice bran crude fiber and rice bran protein by alkali-soluble acid precipitation method, the crude protein content in the extracted rice bran protein is about 70%, and the dietary fiber content in the rice bran crude fiber is about 40%;

(4) The ultrafiltration method is used to classify the rice bran peptide to ensure that 100% of the rice bran peptide has a molecular weight below 1000Da, and the rice bran peptide with a molecular weight above 1000Da is subjected to secondary enzymatic hydrolysis, so that the molecular weight distribution of the final product is all below 1000Da;

(5) Desalting the crude rice bran peptide by using an anion-yang exchange resin, the salt content of the product that has not been desalted is greater than 8%, and the salt content of the product desalted by this method is less than 2%;

Description of drawings

The present invention will be described in further detail below in conjunction with the accompanying drawings and specific embodiments.

Fig. 1 is the process flow chart of the method for comprehensive utilization of rice bran of the present invention.

Detailed ways

The E/S ratio described in the present invention refers to the mass ratio of the consumption of enzyme and rice bran protein; The enzymatic activity of neutral protease As1.398 described in the present invention is 130000U/g; The description refers to the mass ratio.

Example 1

A method for comprehensively utilizing rice bran, the method comprising the steps of:

(1) Weigh 100g of rice bran, crush it through a 60-mesh sieve, use Soxhlet extraction method, use 95% n-hexane solvent to extract at 50°C for 2 hours, then filter the n-hexane solution, and dry the rice bran until the n-hexane is completely Volatility is defatted rice bran; the filtrate is completely evaporated with n-hexane with a rotary evaporator, and the rest is rice bran oil, weighing 11.3g;

(2) Pour the defatted rice bran in step (1) into 600mL water, heat to 45°C, adjust the pH to 9.0 with NaOH reagent, stir continuously for 15min, centrifuge at 3000r/min for 15min, and take the supernatant; Precipitated and dried, it was rice bran crude fiber, weighing 53.2g;

(3) Heat the supernatant of step (2) to 80°C, adjust the pH to 3.5 with citric acid reagent, stir continuously for 10 minutes, 3000r/min, 15 minutes, centrifuge to collect the precipitate, which is rice bran protein, and dry it to get rice bran Protein powder, weighing 26.5g;

(4) Add the precipitate of step (3) to 200mL water, heat to 90°C, keep for 20min, then cool to 45°C, adjust and keep the pH at 7.0 with NaOH reagent, add neutral protease As1.398 (enzyme activity is 130000U /g) 1.5g, enzymatic hydrolysis for 2h, stirring continuously during the enzymolysis process, and keeping the pH value at 7.0 with NaOH solution;

(5) After the enzymatic hydrolysis in step (4), quickly adjust the pH to 4.0 with HCl solution, centrifuge for 15 minutes at a speed of 3000r/min, take the supernatant, and obtain the crude rice bran peptide liquid;

(6) Inject the crude rice bran peptide solution obtained in step (5) into the storage tank, and the solution passes through the ultrafiltration membrane with a molecular weight cut-off of 1000Da after microfiltration, and the small molecular substances in the solution permeate out through the inner wall of the hollow fiber membrane to become The ultrafiltrate, collecting the ultrafiltrate, is the rice bran peptide ultrafiltrate; the protein and other macromolecular substances in the solution are preserved and concentrated, and the concentrated solution is recovered to step 4 for enzymatic hydrolysis again;

(7) The exchange resin was soaked in deionized water for 24 hours and then packed into a column, then it was soaked with 7.5% hydrochloric acid and 10% NaOH respectively, converted into H ⁺ type cation exchange resin and OH ^- type anion exchange resin, and then used Wash with deionized water until the pH is 7.0 for use;

The ultrafiltrate obtained in step (6) is passed through the H ⁺ type cation exchange resin at a flow rate of 10 times column volume/h to remove cations, and the sample addition is stopped when the pH of the effluent is about 4.0, and then the effluent is Remove anions by passing through OH ^- type anion exchange resin at the same flow rate, stop adding samples when the pH of the effluent is 7.0, and collect it as rice bran peptide refined solution;

(8) The rice bran peptide refined solution obtained in step 6 is concentrated under reduced pressure to a solid content of 30%;

(9) After the refined rice bran peptide solution is concentrated, it is spray-dried or freeze-dried to make a dry powder, weighing 15.3 g.

The rice bran peptide obtained by the above method has a total nitrogen content (on a dry basis) of 85.2% and a peptide content (on a dry basis) ≥ 80.4% after testing. The relative molecular weights obtained are all below 1000 Da and the moisture content is 5.7%. Ash content (on dry basis) ≤ 1.6%, crude fat content (on dry basis) ≤ 0.8%.

Example 2

A method for comprehensively utilizing rice bran, the method comprising the steps of:

(1) Weigh 500g of rice bran, crush it through a 60-mesh sieve, use Soxhlet extraction method, extract it with 95% n-hexane solvent at 50°C for 2 hours, then filter the n-hexane solution, and air-dry the rice bran until the n-hexane is completely Volatility is defatted rice bran; the filtrate is completely evaporated with n-hexane with a rotary evaporator, and the rest is rice bran oil, weighing 58.9g;

(2) Pour the defatted rice bran in step (1) into 2.5L of water, heat to 50°C, adjust the pH to 8.5 with NaOH reagent, stir continuously for 15min, centrifuge at 3000r/min for 15min, and take the supernatant; The precipitate was dried, and it was rice bran crude fiber, weighing 247.3g;

(3) Heat the supernatant of step (2) to 90°C, adjust the pH to 3.0 with citric acid reagent, stir continuously for 10 minutes, 3000r/min, 15 minutes, centrifuge to collect the precipitate, which is rice bran protein, and dry it to get rice bran Protein powder, weighing 105.6g;

(4) Add the precipitate of step (3) into 1L of water, heat to 90°C, keep for 20min, then cool to 40°C, adjust with NaOH reagent and keep the pH at 7.5, add neutral protease As1.398 (enzyme activity is 130000U /g) 5g, enzymolysis for 3h, stirring constantly during the enzymolysis process, and keeping the pH value at 7.5 with NaOH solution;

(5) After the enzymatic hydrolysis in step (4), quickly adjust the pH to 4.0 with HCl solution, centrifuge for 15 minutes at a speed of 3000r/min, take the supernatant, and obtain the crude rice bran peptide liquid;

(6) Inject the crude rice bran peptide solution obtained in step (5) into the storage tank, and the solution passes through the ultrafiltration membrane with a molecular weight cut-off of 1000Da after microfiltration, and the small molecular substances in the solution permeate out through the inner wall of the hollow fiber membrane to become The ultrafiltrate, collecting the ultrafiltrate, is the rice bran peptide ultrafiltrate; the protein and other macromolecular substances in the solution are preserved and concentrated, and the concentrated solution is recovered to step 4 for enzymatic hydrolysis again;

(7) The exchange resin was soaked in deionized water for 24 hours and then packed into a column, then it was soaked with 7.5% hydrochloric acid and 10% NaOH respectively, converted into H ⁺ type cation exchange resin and OH ^- type anion exchange resin, and then used Wash with deionized water until the pH is 7.0 for use;

The ultrafiltrate obtained in step (6) is passed through the H ⁺ type cation exchange resin at a flow rate of 10 times column volume/h to remove cations, and the sample addition is stopped when the pH of the effluent is about 4.0, and then the effluent is Remove anions by passing through OH ^- type anion exchange resin at the same flow rate, stop adding samples when the pH of the effluent is 7.0, and collect it as rice bran peptide refined solution;

(8) The rice bran peptide refined solution obtained in step 6 is concentrated under reduced pressure to a solid content of 30%;

(9) After the refined rice bran peptide solution is concentrated, it is spray-dried or freeze-dried to make a dry powder, weighing 67.6 g.

The rice bran peptide obtained by the above method has a total nitrogen content of rice bran peptide (on a dry basis) of 84.1% and a peptide content (on a dry basis) of ≥79.5%. Ash content (on dry basis) ≤ 1.9%, crude fat content (on dry basis) ≤ 0.9%.

Example 3

A method for comprehensively utilizing rice bran, the method comprising the steps of:

(1) Weigh 1000g of rice bran, crush it through a 80-mesh sieve, use Soxhlet extraction method, use 95% n-hexane solvent to extract at 50°C for 2 hours, then filter the n-hexane solution, and dry the rice bran until the n-hexane is completely Volatility is defatted rice bran; the filtrate is completely evaporated with n-hexane with a rotary evaporator, and the rest is rice bran oil, weighing 110.2g;

(2) Pour the defatted rice bran in step (1) into 7L water, heat to 45°C, adjust the pH to 9.0 with NaOH reagent, stir continuously for 15min, centrifuge for 15min at a speed of 3000r/min, and take the supernatant; Precipitated and dried, it was rice bran crude fiber, weighing 537.6g;

(3) Heat the supernatant of step (2) to 90°C, adjust the pH to 3.0 with citric acid reagent, stir continuously for 10 minutes, 3000r/min, 15 minutes, centrifuge to collect the precipitate, which is rice bran protein, and dry it to get rice bran Protein powder, weighing 206.8g;

(4) Add the precipitate of step (3) into 1500mL water, heat to 90°C, keep for 20min, then cool to 45°C, adjust and keep the pH at 7.0 with NaOH reagent, add neutral protease As1.398 (enzyme activity is 130000U /g) 10g, enzymolysis for 4h, stirring constantly during the enzymolysis process, and keeping the pH value at 7.5 with NaOH solution;

(5) After the enzymatic hydrolysis in step (4), quickly adjust the pH to 4.0 with HCl solution, centrifuge for 15 minutes at a speed of 3000r/min, take the supernatant, and obtain the crude rice bran peptide liquid;

(6) Inject the crude rice bran peptide solution obtained in step (5) into the storage tank, and the solution passes through the ultrafiltration membrane with a molecular weight cut-off of 1000Da after microfiltration, and the small molecular substances in the solution permeate out through the inner wall of the hollow fiber membrane to become The ultrafiltrate, collecting the ultrafiltrate, is the rice bran peptide ultrafiltrate; the protein and other macromolecular substances in the solution are preserved and concentrated, and the concentrated solution is recovered to step 4 for enzymatic hydrolysis again;

(7) The exchange resin was soaked in deionized water for 24 hours and then packed into a column, then it was soaked with 7.5% hydrochloric acid and 10% NaOH respectively, converted into H ⁺ type cation exchange resin and OH ^- type anion exchange resin, and then used Wash with deionized water until the pH is 7.0 for use;

The ultrafiltrate obtained in step (6) is passed through the H ⁺ type cation exchange resin at a flow rate of 10 times column volume/h to remove cations, and when the effluent pH=4.0, the sample addition is stopped, and the effluent is then Remove anions by passing through OH ^- type anion exchange resin at the same flow rate, stop adding samples when the pH of the effluent is 7.0, and collect it as rice bran peptide refined solution;

(8) The rice bran peptide refined solution obtained in step 6 is concentrated under reduced pressure to a solid content of 30%;

(9) After the refined rice bran peptide solution is concentrated, it is spray-dried or freeze-dried to make a dry powder, weighing 158.9 g.

The rice bran peptide obtained by the above method has a total nitrogen content of rice bran peptide (on a dry basis) of 81.8% and a peptide content (on a dry basis) ≥ 76.2%. Ash content (on dry basis) ≤ 1.9%, crude fat content (on dry basis) ≤ 1.0%.

Claims (1)

1. a method that fully utilizes rice bran, is characterized in that the method comprises the steps:

(1) rice bran is pulverized, crossed 60～80 mesh sieves, adopt the Soxhlet extraction process, with 95% normal hexane solvent lixiviate 2h under 50 ℃ of conditions, then hexane solution is filtered, rice bran airing to normal hexane is volatilized fully, be defatted rice bran; Filtrate is evaporated normal hexane fully with rotatory evaporator, and remaining is Rice pollard oil;

(2) step (1) defatted rice bran and the water mass ratio by 1: 5～1: 10 is dissolved in water, be heated to 45～55 ℃, regulate pH to 8.0～10.0 with NaOH reagent, do not stop to stir 15min, under the rotating speed of 3000～4000r/min, centrifugal 15min gets supernatant liquor, to precipitate oven dry, be the rice-bran crude fiber;

(3) supernatant liquor with step (2) is heated to 70～90 ℃, regulates pH to 3.0～5.0 with citric acid reagent, does not stop to stir 10min, 3000～4000r/min, and 15min, centrifugal collecting precipitation is rice bran protein, dries to get the rice bran protein powder;

(4) rice bran protein of step (3) and the water mass ratio by 1: 5～1: 10 is dissolved in water, be heated to 90～100 ℃, keep 15～30min, then be cooled to 35～50 ℃, regulate and keep pH 6.0～8.0 with NaOH reagent, adding neutral protease As1.398 by E/S than 3%～7%, enzymolysis 2～4h, constantly stir in enzymolysis process, and keep the pH value 6.0～8.0 with NaOH solution;

(5) after step (4) enzymolysis finishes, regulate pH to 5.0～3.0 with HCl solution rapidly, under the rotating speed of 3000～4000r/min, centrifugal 15min gets supernatant liquor, and gained is the rough liquid of rice bran peptide;

(6) the rough liquid of the rice bran peptide of step (5) gained is injected storage tank, solution is the 1000Da ultra-filtration membrane by the molecular weight interception after micro-filtration, small-molecule substance in solution infiltrates through the inwall of hollow-fibre membrane becomes ultrafiltrated, collects ultrafiltrated, is rice bran peptide ultrafiltrated; Solution comprises that albumen is kept and concentrated at interior macromolecular substance, and concentrated solution is recycled in step (4) enzymolysis again;

(7) exchange resin immersion treatment in deionized water filled post after 24 hours, then with 7.5% hydrochloric acid and 10%NaOH, it was soaked respectively, was converted into H ⁺Type Zeo-karb and OH ^-Type anionite-exchange resin, then be 7.0 stand-by with washed with de-ionized water to pH;

With the ultrafiltrated of gained in step (6), pass through H with the flow velocity of 5～10 times of column volume/h ⁺The type Zeo-karb removes positively charged ion, stops application of sample when effluent liquid pH=4.0, afterwards this effluent liquid is passed through OH with same flow velocity ^-Type anionite-exchange resin removes negatively charged ion, is pH to effluent liquid and stops application of sample at 7.0 o'clock, is collected as rice bran peptide refined liquid;

(8) by the rice bran peptide refined liquid that obtains in step 6, be evaporated to solid content 20%～30%;

(9) after refining rice bran peptide liquid concentrated, dry powder was made in spray-dried or lyophilize.

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