WO2021129233A1 - Method for preparing natural ferulic acid by using oryzanol-containing saponin as raw material - Google Patents

Abstract

A method for preparing a natural ferulic acid by using oryzanol-containing saponin as a raw material, comprising the following steps to prepare a natural ferulic acid: hot-dissolving with alkali and alcohol and filtering, acid precipitation and separation, decolorizing with an organic solvent at normal temperature, hot reflux hydrolysis with alkali and alcohol, cold precipitation and separation, acidifying and cold standing desalination, refining with an ultrafiltration membrane, decolorizing with aluminum oxide, recovering the solvent, solid-liquid separation, drying and the like. In the present invention, the content of oryzanol in the raw material is first increased to 50-70%, and then the oryzanol is subjected to hot-dissolution, reflux and hydrolysis by using an alkali and alcohol solvent, and a pure white natural ferulic acid having a purity of 99% or more is obtained by means of synergistic effects of oryzanol purification and decoloration before hydrolysis and ferulic acid alcohol solution refining and decoloration after hydrolysis. The process of the present invention has the significant advantages of high yield, high purity and complete decolorization; compared with high-temperature concentrated alkali hydrolysis, the reaction is mild, the alkali concentration is low, the amount of alkali is small, and the conversion is complete; the production process is simple and low in cost; and the product meets the international requirements of natural vanillin on the natural degree of the raw material, creating obvious economic and social benefits.

Description

Method for preparing natural ferulic acid by using soapstock containing oryzanol as raw material Technical field

The invention belongs to the technical field of plant extraction and separation, and relates to a method for preparing natural ferulic acid by using soapstock containing oryzanol as a raw material.

Background technique

Oryzanol exists in rice bran oil and is a mixture of ferulic acid esters with triterpene alcohol as the main body. It mainly acts on the autonomic nervous system and endocrine center of the diencephalon, can adjust the autonomic nerve function, reduce endocrine balance disorders, and improve the symptoms of mental nerve disorders. It also has a variety of physiological functions such as lowering blood lipids, lowering liver lipids, preventing lipid oxidation, and anti-oxidation. In addition, it also has the effect of resisting arrhythmia, which can reduce the excitability of myocardium by regulating the function of autonomic nerves. The lipid-lowering effect of oryzanol can also improve the blood supply of the myocardium and play a role in improving sleep.

The chemical name of Ferulic Acid is 4-hydroxy-3-methoxycinnamic acid, which is one of the derivatives of cinnamic acid (also known as cinnamic acid, 3-phenyl-2-acrylic acid). Ferulic acid can scavenge free radicals, promote the production of enzymes that scavenge free radicals, increase the activity of glutathione transferase and quinone reductase, and inhibit the activity of tyrosinase to regulate human physiological functions. In addition, ferulic acid (sodium ferulate) has anti-platelet aggregation, inhibits the release of platelet serotonin, inhibits the production of platelet thromboxane A2 (TXA2), enhances prostaglandin activity, analgesia, and relieves vasospasm. It is a production It is the basic raw material of medicines for the treatment of cardiovascular and cerebrovascular diseases and leukopenia. At the same time, it can play the role of bodybuilding and skin protection in the human body.

Natural ferulic acid derived from rice bran is mainly used as the raw material for the production of natural vanillin, and is currently the only internationally recognized raw material for the production of natural vanillin by microbial methods.

Name: Ferulic Acid

Molecular formula: C ₁₀ H ₁₀ O ₄

Molecular weight: 194.18

CAS Number: 1135-24-6

Melting point: 169～173℃

Structural formula:

Physical properties: There are two types of ferulic acid, cis and trans. The cis is a yellow oil, and the trans is white to slightly yellow square crystals or fiber crystals. It is slightly soluble in cold water, soluble in hot water, and poor stability in aqueous solutions. , Easy to decompose when exposed to light; easily soluble in ethanol, methanol, acetone, ethyl acetate, etc., hardly soluble in benzene, petroleum ether, and good pH stability.

The raw material used in the present invention is soapstock containing oryzanol, preferably from rice bran oil soapstock with a certain oryzanol content obtained in the process of refining rice bran oil, commonly known as "oryzanol-containing soapstock" in the oil industry. The content of oryzanol in oryzanol-containing soapstock sold by Chinese rice bran oil refineries is generally 10-20%.

There are two methods for industrial production of ferulic acid: one is chemical synthesis, and the other is oryzanol hydrolysis. As for other methods, although there are reports, they have not been applied in actual production. At present, the large amount of ferulic acid exported in China is natural ferulic acid, mainly because China is the main rice producer in the world and has many large-scale rice bran oil plants, so it has an absolute advantage in oryzanol resources, and countries and regions such as Europe, America and Japan mainly use natural Ferulic acid is produced through microbial fermentation process to prepare the world's king of spices-natural vanillin, partly used in the pharmaceutical industry, and a small amount is used to prepare high-end cosmetics. Internationally, natural ferulic acid is strictly limited, that is, it must come from rice bran and can pass the naturalness test of isotope identification.

Industrial production of natural ferulic acid is obtained from a certain amount of oryzanol from rice bran as raw material, saponified and refined with high temperature concentrated alkali. The natural ferulic acid prepared in this way meets the export regulations, that is, the requirements of countries and regions such as Europe, America and Japan. Natural ferulic acid must come from rice bran to be considered natural.

There are many researches on natural ferulic acid in China. There are patent reports on the extraction of natural ferulic acid from different plants, the waste or scraps of rice bran oil processing, and the extraction of natural ferulic acid from the waste liquid of corn husk dietary fiber preparation process. acid. The breakdown is as follows:

1. The patent application number CN201910799833.1 discloses a simple method for extracting and purifying ferulic acid from green wheat kernel bran. The method is: pulverizing the raw green wheat kernel bran, and then using a certain amount of material Liquid ratio (g/ml) and lye mass fraction, soak at room temperature for extraction; then the water extract is centrifuged, the pH is adjusted to acidity and suction filtered, and then repeated extraction with ethyl acetate, the organic phase is collected and evaporated to dryness for recovery Ethyl acetate: After dissolving ferulic acid in the dry matter in boiling distilled water, freeze-drying, crystallization and collection, in order to achieve the purpose of separation and purification to obtain higher purity ferulic acid. This patent uses lye soaked at room temperature, the extraction efficiency is low, and whether it can be extracted effectively has yet to be further verified; through simple extraction and distilled water crystallization, the purity of ferulic acid obtained is not high, which limits the application in the high-end market; and the cost of freeze-drying Very high, no economic feasibility.

2. The patent application number CN201310713194.5 relates to a method for extracting ferulic acid from the waste liquid produced during the preparation of corn husk dietary fiber. The method includes the following steps: centrifuging the waste liquid and then concentrating and steaming, using concentrated hydrochloric acid to adjust the pH value of the waste liquid after removing impurities and ethanol; using a macroporous adsorption resin to adsorb the acidified waste liquid; using ethanol to ferulate the saturated resin Acid elution; the eluate is concentrated and evaporated, and then extracted with ethyl acetate. The ester phase is concentrated under reduced pressure to volatilize ethyl acetate to obtain the product. This patent application uses simple macroporous adsorption resin adsorption and ethyl acetate extraction processes, and it is difficult to obtain high-purity ferulic acid products.

3. The patent with application number CN201310553863.7 discloses a process for purifying ferulic acid, which mainly includes preparing ferulic acid extract, removing solvent in solution, purifying lye, purifying ferulic acid, and preparing ferulic acid Crystallization and preparation of finished ferulic acid and other steps. In the present invention, the concomitant product in the process of producing rice fatty acid from rice bran or/and crude γ-oryzanol is used as raw materials to prepare ferulic acid extract, which is then purified by a membrane combination purification process to obtain ferulic acid finished product. This patent utilizes high-concentration waste alkali. Whether it can be realized by membrane process and whether the membrane can withstand concentrated alkali requires further verification; whether white ferulic acid with a content of 98% can be directly obtained through the membrane process, and the product recovery rate can reach How much, also needs further verification.

4. The patent with the application number CN201310508184.8 discloses a method for preparing natural ferulic acid derived from rice bran, including the following steps: extraction: defatted rice bran is used as a raw material, using cellulase, protease and aspergillus niger Enzymatic fermentation of the compound enzyme; filtration: After the enzymatic hydrolysis is completed, the enzymatic hydrolysate is subjected to preliminary solid-liquid separation, and the primary filtrate is finely filtered with an ultrafiltration instrument to obtain a fine filtrate for use; enrichment: the fine filtrate is passed through a reversed-phase resin Carry out enrichment, then elution with water-containing alcohol; collect the eluate, concentrate, and crystallize to obtain crude ferulic acid; Purification: add crude ferulic acid to activated carbon, reflux with hot water at 90-100 degrees, then filter, and let the filtrate cool Crystallize to obtain ferulic acid product. This patent uses rice bran as a raw material to prepare natural ferulic acid, but the content of natural ferulic acid in rice bran is extremely low, less than 0.3%; and the process steps are numerous, which ultimately leads to higher cost per unit weight of ferulic acid production. Industrial advantages.

5. The patent with the application number CN201310196719.2 discloses a method for preparing ferulic acid, which includes the following steps: extracting the fiber raw material with a low-concentration alkaline-alcohol-water mixed solution to obtain an alkaline hydrolysate containing ferulic acid, and then Ultrafiltration is used to remove soluble macromolecular impurities, and then nanofiltration is used to concentrate the ultrafiltration permeate, the concentrated liquid is acidified, and the product is obtained by standing at low temperature for crystallization or organic solvent extraction to obtain ferulic acid. This patent uses a low-concentration alkaline-alcohol-water mixed solution to extract ferulic acid. Whether it can be extracted and the conversion efficiency requires further verification; whether ultrafiltration and nanofiltration can withstand the pH value of the alkaline hydrolysis solution, and whether there is a model of this specification Membrane needs further verification; the final product contains only about 85% ferulic acid, which cannot meet the actual demand.

6. The patent application number CN201310191601.0 discloses a method for preparing ferulic acid. The method specifically includes the following steps: S1. Mix the fibrous raw material with NaOH-ethanol-water solution, stir, treat at 65-75°C for 1 to 3 hours, filter and concentrate to obtain the ferulic acid extract; S2. Use a molecular weight cut-off of 1000 Ultrafiltration equipment with a capacity of ~10,000 ultra-filters the ferulic acid extract in S1, and the filtrate after ultrafiltration is processed by nanofiltration. The conditions of nanofiltration are: molecular interception is 100-180, and effective interception area is 0.2-0.3m ² nanofiltration membrane; pressure 0.1～0.45MPa, temperature 15～45℃; S3. The retentate after S2 nanofiltration is crystallized under the conditions of pH 1.0～3.0 and 1～5℃, filtered by suction and washed Crystal and dry ferulic acid solid. This patent uses a low-concentration alkaline-alcohol-water mixed solution to extract ferulic acid. Whether it can be extracted and the conversion efficiency requires further verification; whether ultrafiltration and nanofiltration can withstand the pH value of the alkaline hydrolysis solution, and whether there is a model of this specification Membrane also needs further verification. The final product ferulic acid has a low purity and is difficult to enter the European and American high-end markets.

7. The patent with the application number CN201010169724.0 discloses a process for separating and extracting natural ferulic acid with a content of ≥98% from the waste of rice bran oil processing, which is characterized in that it is produced from the processing of rice bran oil Waste as raw material, through ethanol washing → saponification and filtration → acidification and filtration → ethanol dissolution and filtration → ion exchange resin refining → decolorization → concentration → suction filtration → vacuum drying to obtain a white powder product with natural ferulic acid content ≥98% . The patent application year was earlier, and the content of oryzanol in the raw materials used was much higher than that of soapstocks containing oryzanol on the market at this stage; the high-temperature concentrated alkali aqueous solution was used to hydrolyze oryzanol into ferulic acid in an insoluble state, and the reaction conditions were severe. The conversion effect is slightly poor; the ion exchange resin is used to refine ferulic acid. Ferulic acid is unstable under alkaline conditions and is easy to oxidize and deteriorate, and the treatment of resin produces more waste water, which pollutes the environment.

8. The patent application number CN201310531556.9 discloses a process for extracting ≥98% natural ferulic acid from the leftovers of processed rice bran oil, specifically using the leftovers of processed rice bran oil as the extraction raw material. Alkane degreasing and decolorization, 80% or more edible ethanol to deodorize; then saponify twice with a certain concentration and temperature of sodium hydroxide aqueous solution, naturally filter with stainless steel filter, then adjust the saponification liquid with dilute sulfuric acid, and filter with suction; adjust the precipitation with dilute alkali The pH is 9～10, refined by ion exchange resin, eluted impurities, desorbed with alkaline ethanol, decolorized and filtered; the filtrate is passed through the resin column to remove harmful metal ions; the effluent adopts pervaporation membrane technology to separate ethanol and product recrystallization , The crystalline product is obtained by washing with water, filtering with suction and drying in vacuum. The patent application year was earlier, and the content of oryzanol in the raw materials used was much higher than that of soapstocks containing oryzanol on the market at this stage; the high-temperature concentrated alkali aqueous solution was used to hydrolyze oryzanol into ferulic acid in an insoluble state, and the reaction conditions were severe. The conversion effect is slightly poor; the ion exchange resin is used to refine ferulic acid. Ferulic acid is unstable under alkaline conditions and is easy to oxidize and deteriorate. The resin is treated to produce more waste water and pollute the environment.

Summary of the invention

In order to overcome the disadvantages of inefficient extraction and preparation of natural ferulic acid in the prior art, low purity, pollution, complicated processing, etc., the present invention provides a method for preparing natural ferulic acid by using soapstocks containing oryzanol as raw materials, which is produced on an industrial scale. It produces white natural ferulic acid with a purity of more than 99%. Specifically, it is the process of first increasing the content of oryzanol in the raw material and then hydrolyzing oryzanol, which avoids the low conversion rate, low finished product yield, difficult decolorization, and high cost caused by direct hydrolysis with low content of oryzanol, and significantly improves the final product natural asafoetida The acid yield and the decolorization effect of the process can reduce the production cost; the use of strong alkali to make the oryzanol hydrolyze in the solvent-dissolved state, compared with the high-temperature concentrated alkali aqueous solution in the insoluble state of the hydrolysis process, the temperature is easy to control, the alkali concentration is low, and the conversion Sufficient and high yield; no toxic solvent is used in the production process, and the solvent residue of the product meets export requirements; the production process is simple and low in cost; the product meets the international natural vanillin requirements for the naturalness of raw materials, creating an obvious economy and society benefit.

The technical solution adopted by the present invention to solve its technical problems is as follows: A method for preparing natural ferulic acid by using soapstock containing oryzanol as a raw material, including the following steps:

(1) Alkali alcohol hot melt filtration: add a high concentration alcohol aqueous solution to the raw material containing oryzanol soapstock, heat up to 50-60°C, adjust the system to alkaline with dilute lye, and then filter while hot to obtain filtrate 1;

(2) Separation by acid precipitation: Use the dilute acid filtrate 1 to be neutral or weakly acidic, fully stir and stand to make the oryzanol precipitation complete, filter, and collect the precipitate;

(3) Decolorization: Add a low-polarity organic solvent of 2 to 4 times its weight (W/V) to the precipitate, fully stir and stand at room temperature, centrifuge, and collect the centrifuged precipitate;

(4) Reflux hydrolysis: add alkali-containing alcohol solution and heat it to reflux, keep heat and hydrolyze to obtain alkali alcohol hydrolysate;

(5) Cooling separation: pass water to cool the alkali-alcohol hydrolyzate to room temperature, leave it to stand still to fully analyze the alkali-alcohol insoluble matter, and filter to obtain the alkali-alcohol hydrolysis filtrate, that is, filtrate 2;

(6) Acidification and cold storage for desalination: adjust the filtrate 2 to be acidic with dilute sulfuric acid, refrigerate at low temperature, the salt becomes crystals and precipitate, and filter while cold to obtain the desalinated water solution filtrate, that is, filtrate 3;

(7) Ultrafiltration membrane refining: Pass the filtrate 3 through the ultrafiltration membrane system, and collect the downstream liquid of the membrane, that is, the permeate, to obtain the ultrafiltration membrane refined liquid;

(8) Alumina decolorization: Pass the ultrafiltration membrane refined liquid through a chromatography column containing acidic alumina, and collect the effluent; after feeding, add a high-concentration alcohol aqueous solution to wash the column, collect the column wash, and combine the effluent And wash column liquid, get decolorizing liquid.

(9) Solvent recovery and solid-liquid separation: Recover the alcohol in the decolorizing liquid under vacuum and reduce the pressure, concentrate until there is no alcohol smell, and white natural ferulic acid crystals out, cool to room temperature and stand for 3-6h, filter and collect Precipitation and drying give natural ferulic acid.

In the preferred technical solution of the present invention:

In step (1), use dilute lye to adjust the pH of the system to 9.0 to 10.0; and/or use dilute acid to adjust the pH of the dissolved filtrate to 6.0 to 7.0 in step (2); and/or use dilute sulfuric acid to adjust in step (6) The pH of the alkali alcohol hydrolysis filtrate is 3.0 to 4.0.

In step (1), the high-concentration alcohol solution is an alcohol aqueous solution with a concentration of 85-98wt%, and the alcohol is a low-carbon alcohol, specifically ethanol, propanol, propylene glycol, preferably ethanol; the alcohol aqueous solution and oryzanol-containing soapstock The volume-to-mass ratio of the raw materials is 4-8 (L/kg), and the volume-to-mass ratio of the alcohol aqueous solution and the raw materials containing oryzanol-containing soapstock is preferably 5-6 (L/kg).

In step (1), the method of adding the alcohol aqueous solution is not particularly limited, and it can be added together or added in batches, preferably divided into 2-3 times uniformly, which can more effectively extract the oryzanol.

In step (1), the lye is not particularly limited, and dilute sodium hydroxide or potassium hydroxide aqueous solution is generally used, and the corresponding concentration is 5-10% by weight.

In step (2), the dilute acid is not particularly limited. Generally, dilute hydrochloric acid or dilute sulfuric acid is used, and the corresponding concentration is 5-10% by weight; the filtration method is three-legged bag centrifugation or three-legged sedimentation centrifugation;

In step (3), the low-polarity organic solvent is selected from at least one of n-hexane, mineral spirits No. 6 and petroleum ether, and the volume-to-mass ratio of the precipitate obtained in step (2) is 2-4 (L/ kg).

The purpose of steps (1)-(3) is to increase the content of oryzanol in the centrifugal precipitation from 10-20wt% in the raw material to 50-70wt% through the steps of alkali alcohol hot melt filtration, acid precipitation separation, and room temperature organic solvent decolorization. , And then proceed to hydrolysis (saponification) reaction.

In the present invention, after steps (1)-(3), the content of oryzanol in the centrifugal precipitation is increased to 50-70wt%, which has a vital influence on the realization of the purpose of the present invention. The reasons are: 1. Improve the hydrolysis and conversion of oryzanol Efficiency, avoid the low conversion rate caused by direct hydrolysis of low-content oryzanol; 2. Improve the decolorization effect, remove most of the pigment in the oryzanol stage, and synergize with the refining and decolorization of steps (7) and (8) to obtain pure white The product solves the problem that natural ferulic acid is not easy to decolor; 3. Improve the yield of finished products. By purifying and decolorizing oryzanol, the loss of oryzanol is low, and the subsequent decolorization steps of natural ferulic acid are reduced. The decolorization of natural ferulic acid causes greater product loss; 4. Reduce production costs. By purifying oryzanol, the amount of alkali and alcohol during the hydrolysis of alkali alcohol can be reduced, the production efficiency can be improved, and the production cost can be reduced synergistically by increasing the yield of the finished product.

The purpose of step (4) is to convert oryzanol into sodium ferulate, triterpene alcohol and sterol under suitable conditions. The alkali-containing alcohol solution is made by adding sodium hydroxide and/or potassium hydroxide to the high-concentration alcohol aqueous solution, and the final alkali-containing alcohol solution alkali, the concentration of the alkali is 10-15% by weight, and the concentration of the alcohol is 70- 80wt%, the balance is water.

In step (4), the volume-to-mass ratio of the alkali-containing alcohol solution to the centrifugal precipitate obtained in step (3) is 6-10 (L/kg); the reflux temperature of the solvent is 90-95°C, which is required during the whole process of oryzanol hydrolysis Keep this temperature range; the hydrolysis time of the oryzanol is 6.5-8.5h.

In step (5), the standing time is 3-6h.

In step (6), the dilute sulfuric acid has a corresponding concentration of 15-30%.

In step (6), only dilute sulfuric acid can be used to generate sodium sulfate with the sodium hydroxide in the previous step, and then most of the sodium sulfate is removed through the process steps of the present invention. If dilute hydrochloric acid is used, it will generate sodium chloride with the sodium hydroxide in the previous step, and it is difficult for sodium chloride to precipitate crystals in the process steps of the present invention, which is not conducive to removal. Here, the concentration of dilute sulfuric acid is 15-30% by weight in order to reduce the volume of dilute sulfuric acid used by increasing the concentration, thereby reducing the total volume of the solution after the final pH is adjusted to acidity. Conducive to the subsequent crystallization step.

In step (6), the refrigeration at low temperature is to cool down to 0-4°C and refrigerate for 6-12 hours to make the salt crystallize out. Finally, while keeping it cold, the salt and the alcohol solution containing natural ferulic acid are filtered Separate.

In step (7), the molecular weight cut-off of the ultrafiltration membrane is 5000-8000, the material is polyethersulfone, the operating pressure is 1.0-2.0 MPa, and the collected part is the membrane downstream liquid, that is, the permeate;

In step (8), the added amount of acidic alumina is 2 to 4 wt% of the raw material of soapstock containing oryzanol;

In step (9), the filtering operation is to first pass the material through the bag centrifuge, and then add 40-45°C warm water to the centrifuge for 2 to 4 times; the drying method is air drying or vacuum drying , Or microwave vacuum drying, the drying temperature is 55～65℃.

Principle of the method of the invention

The present invention uses soapstock containing oryzanol as a raw material. The content of oryzanol in the raw materials is only 10-20%, and the rest are mainly fat-soluble impurities and pigments. Since the oryzanol-containing soaps are derived from rice bran oil, and the oryzanol in it can be dissolved in hot alkaline ethanol, the oryzanol in the raw materials can be dissolved with a high-concentration ethanol alkaline solution under heating conditions and control a certain temperature range. Without destroying the oryzanol, the oryzanol dissolved in the solution is separated from the hot alkali alcohol insoluble impurities by filtration; the oryzanol is insoluble in acid alcohol, but some impurities and pigments can be dissolved in acid alcohol. Therefore, adjust the pH of the alkali alcohol solution to The acidity is in the neutral range, and the oryzanol is precipitated and separated from the acid ethanol insoluble impurities by filtration; oryzanol is hardly soluble in lipophilic organic solvents such as n-hexane, mineral spirits, petroleum ether, etc. under normal temperature conditions, and a large amount of fat-soluble impurities And pigments can be dissolved in these lipophilic organic solvents. Therefore, by dissolving impurities and pigments in lipophilic organic solvents at room temperature and removing them by filtration, the content of oryzanol can be increased to 50-70%, and the color will change from brown to yellow. Yellowish white.

In order to ensure that oryzanol can be completely converted into natural ferulic acid and reduce the damage of hot alkali, it is necessary to hydrolyze oryzanol in an alkali alcohol solution at a certain temperature. By controlling the concentration of alkali and alcohol, and heating to a certain temperature, oryzanol can be made Dissolve in alkali alcohol and achieve high-efficiency hydrolysis and mild hydrolysis, thus achieving temperature control. By hydrolyzing to a specified time, oryzanol is hydrolyzed into natural ferulic acid salts; some impurities and pigments are only soluble in hot alkali Alcohol but hardly soluble in cold alkali alcohol. Natural ferulic acid salts are easily soluble in a certain concentration of alkali alcohol solution. Therefore, by cooling and filtering, the insoluble impurities in alkali alcohol can be further removed; alkali alcohol Because the solution has a high alkali concentration, it is not conducive to the refining operation, and natural ferulic acid still exists in the form of salt. To make natural ferulic acid into free natural ferulic acid and improve the purity, it is necessary to neutralize the alkali and increase the purity. Remove the salt produced by neutralization. Since free natural ferulic acid is easily soluble in high alcohol, the salt produced by neutralization has less solubility in high alcohol, and will crystallize out with the decrease of temperature and standing for a certain period of time. Therefore, it can be removed by filtration. The salt obtains an alcohol solution that mainly dissolves free natural ferulic acid. The separation and refining are achieved through the poor cold and hot solubility of natural ferulic acid, impurities, and pigments in the same solvent system, and the poor solubility of the same solvent system under different conditions.

The highly alcoholic solution of natural ferulic acid still contains a certain amount of pigments. Because of the difference in molecular weight and molecular structure between these pigments and ferulic acid, these impurities and pigments can be removed by ultrafiltration membranes with a certain molecular weight cut-off. However, pigments with similar molecular weight and structure to ferulic acid still exist in the alcohol solution, but these pigments can be adsorbed by acidic alumina, while natural ferulic acid is not adsorbed. Therefore, through membrane separation and alumina decolorization, it can be obtained Nearly colorless decolorizing liquid.

Although natural ferulic acid is easily soluble in high-concentration alcohol, it is difficult to dissolve in water. By recovering and removing the alcohol, natural ferulic acid will precipitate out in large amounts due to reduced solubility. The natural ferulic acid can be separated from water by centrifugation. The water is further removed by drying to obtain a dry natural ferulic acid product.

Beneficial effects of the method of the invention

1. The present invention provides a natural ferulic acid derived from rice bran oryzanol. The corresponding product has been sold stably, creating obvious economic and social benefits. The purity of the natural ferulic acid obtained according to the method of the present invention is as high as 99%, and the color is white. The naturalness of the product determined by the internationally recognized isotope detection method is in line with the raw materials of large-scale enterprises producing natural vanillin in Europe, America, and Japan. Requirements for natural ferulic acid.

2. According to the method of the present invention, the production efficiency of natural ferulic acid is high, the loss is small, and the final yield is over 80%, which has obvious advantages in cost control.

3. No toxic solvent is used in the production process, and the solvent residue of the product meets export requirements.

4. A relatively simple production process suitable for plant extract factories has been established, which can produce high-quality natural ferulic acid industrial products on a large scale. The process of the invention has the remarkable advantages of complete decolorization and good effect; compared with high-temperature concentrated alkali hydrolysis, the temperature is easy to control, the alkali concentration is low, the conversion is sufficient, and the yield is high.

Detailed ways

In the following, the present invention will be further described in conjunction with embodiments.

The raw material used in the examples of the present invention contains oryzanol-containing soapstock (oryzanol-containing soapstock) was purchased from Yueyang, Hunan, China, and the content of oryzanol was 13.65%. The solvent used in the present invention is n-hexane, No. 6 solvent, and petroleum ether with a purity of 99%, acidic alumina is a commercially available common specification, and pure water is prepared by secondary pure water equipment in the production workshop. The chemical reagents and raw and auxiliary materials used in the embodiments of the present invention, unless otherwise specified, are all obtained through conventional commercial channels.

In the embodiment of the present invention, ultraviolet-visible spectroscopic absorption chromatography (UV) is used to detect the content of oryzanol, and high performance liquid chromatography (HPLC) is used to detect the content of natural ferulic acid.

Naturalness verification standard of natural ferulic acid: 1. ¹⁴ C specific activity: >14D PM/gc; 2. Hydrogen isotope ² H/ ¹ Hδ<-156; 3. Carbon isotope ¹³ C/ ¹² Cδ<-35.

Example 1

1. Alkaline alcohol hot melt filtration. First, add 1200L of edible ethanol with a concentration of 89% to a 3m ³ extraction tank, put 400kg of oryzanol-containing soapstock raw materials into the extraction tank under constant stirring, continue to add 1200L of edible ethanol with a concentration of 89%, keep continuous stirring, heating, and heating At 52°C, adjust the pH of the system to 9.0 with a 6% dilute aqueous sodium hydroxide solution to dissolve the raw materials, pass the raw materials through a disc centrifuge while hot, and collect the filtrate to obtain 2650L of dissolved filtrate.

2. Acid precipitation separation. Adjust the pH of the dissolving filtrate to 6.5 with dilute sulfuric acid with a concentration of 5%, stir well, and let stand for 6 hours to make the oryzanol precipitation complete. Collect the centrifugal precipitation through a tripod centrifuge to obtain 261 kg of the centrifugal precipitation.

3. Decolorization of organic solvents at room temperature. Add 650L of n-hexane to 261kg of centrifugal sediment, stir well under normal temperature conditions, let it stand for 1h, and collect the centrifugal sediment through a three-foot bag centrifuge to obtain 137kg of centrifugal sediment.

4. Alcohol hydrolysis under hot reflux. Add 1000L alkaline ethanol (sodium hydroxide 13%, ethanol 71%) solution into a 2m ³ extraction tank, keep stirring continuously, add 137kg centrifugal precipitation, heat to 92℃, make the solvent reflux, heat preservation and hydrolyze for 7.5h to make oryzanol It is transformed into sodium ferulate, triterpene alcohol and sterol.

5. Cold analysis and separation. Cool the alkaline alcohol hydrolysate to room temperature through tap water and let it stand for 4 hours to fully analyze the alkaline alcohol insoluble matter. Collect the precipitate and the filtrate separately through a three-foot sedimentation centrifuge. The precipitate is used for post-processing. The filtrate is the alkaline alcohol hydrolysis filtrate. 800L alkali alcohol hydrolysis filtrate.

6. Desalting by acidification and cold storage. Use 20% dilute sulfuric acid to adjust the pH of the alkali alcohol hydrolysis filtrate to 3.0, put the solution in a freezer, refrigerate at 2°C for 8 hours, to allow sodium sulfate to crystallize out, and pass through a three-foot bag centrifuge while it is cold to collect the precipitate and the filtrate. , Precipitation is used for post-treatment, and the filtrate is desalinated hydrolysis filtrate containing free natural ferulic acid.

7. Ultrafiltration membrane refining. Pass the desalted water solution filtrate through an ultrafiltration membrane system with a molecular weight cut-off of 5000, and collect the downstream fluid of the membrane, that is, the permeate, to obtain the ultrafiltration membrane refined fluid; after the material is fed, the upstream fluid is diluted with purified water for a total of 2 times, each time Add 100L of purified water; combine the ultrafiltration membrane permeate to obtain 850L of ultrafiltration membrane refined solution.

8. Decolorization of alumina. Pack 10kg of acidic alumina in the chromatography column in advance, then pass the ultrafiltration membrane refined liquid through the acidic alumina chromatography column, and collect the effluent; after feeding, add 15L of edible ethanol with a concentration of 89% to wash the column, and collect the column washing liquid . Combine the effluent and the washing liquid to obtain a decolorizing liquid.

9. Solvent recovery and solid-liquid separation. The edible ethanol in the decolorizing liquid is recovered under vacuum and reduced pressure, the vacuum degree is controlled to be greater than -0.085MPa and the temperature is 62°C, and the concentration is concentrated to no alcohol taste, so that a large amount of white natural ferulic acid crystals are precipitated. Discharge the material to the high tank while it is hot, cool it to room temperature with tap water and let it stand for 3 hours. Pass through the bag centrifuge. After the material has been fed, add 40℃ warm water into the centrifuge, divided into 2 times, 60L each time, and collect the centrifugal sediment.

10. Dry. The precipitate was dried by blowing at 63°C to obtain 14.81 kg of natural ferulic acid.

After testing, the finished product has a natural ferulic acid content of 99.16%, visually pure white, and the product yield is 84.22%. The product has passed the European and American isotope method to test the ^{naturalness verification standard of natural ferulic acid: 1. 14} C specific activity: 14.5D PM/gc; 2. Hydrogen isotope ² H/ ¹ Hδ is -159; 3. Carbon isotope ¹³ C/ ¹² Cδ is -35.9.

Example 2

1. Alkaline alcohol hot melt filtration. First, add 1000L of 92% edible ethanol to the 3m ³ extraction tank, put 300kg of oryzanol-containing soapstock raw materials into the extraction tank under constant stirring, continue to add 1000L of 92% edible ethanol, keep continuous stirring and heating, and increase the temperature. At 55°C, adjust the pH of the system to 10.0 with a 5% concentration of dilute sodium hydroxide aqueous solution to dissolve the raw materials, pass the raw materials through a three-foot sedimentation centrifuge while they are hot, and collect the filtrate to obtain 2160L of dissolved filtrate.

2. Acid precipitation separation. Adjust the pH of the dissolved filtrate to 7.0 with a concentration of 8% dilute hydrochloric acid, stir well, stand for 5 hours to make the oryzanol precipitation complete, collect the centrifugal precipitation through a three-legged sedimentation centrifuge, and obtain 186 kg of the centrifugal precipitation.

3. Decolorization of organic solvents at room temperature. Add 550L of No. 6 mineral spirits to 186kg of centrifugal sediment, stir well under normal temperature conditions, let it stand for 2h, and collect centrifugal sediment through a three-foot bag centrifuge to obtain 101kg of centrifugal sediment.

4. Alcohol hydrolysis under hot reflux. Add 900L alkaline ethanol (sodium hydroxide 15%, ethanol 67%) solution into a 2m ³ extraction tank, keep continuous stirring, add 101kg centrifugal precipitation, heat up to 94℃, make the solvent reflux, heat preservation and hydrolysis for 7.0h to make oryzanol It is transformed into sodium ferulate, triterpene alcohol and sterol.

5. Cold analysis and separation. Cool the alkaline alcohol hydrolysate to room temperature through tap water and let it stand for 5 hours to fully analyze the alkaline alcohol insoluble matter. Collect the precipitate and the filtrate separately through a three-foot sedimentation centrifuge. The precipitate is used for post-processing. The filtrate is the alkaline alcohol hydrolysis filtrate. 630L alkali alcohol hydrolysis filtrate.

6. Desalting by acidification and cold storage. Adjust the pH of the alkaline alcohol hydrolysis filtrate to 4.0 with 25% dilute sulfuric acid, put the solution in the freezer, refrigerate at 1℃ for 9h, so that the sodium sulfate crystals can be fully analyzed, and pass through a three-foot sedimentation centrifuge while it is cold, and collect the precipitate and the filtrate separately , Precipitation is used for post-treatment, and the filtrate is desalinated hydrolysis filtrate containing free natural ferulic acid.

7. Ultrafiltration membrane refining. Pass the demineralized water solution filtrate through an ultrafiltration membrane system with a molecular weight cutoff of 8000, and collect the downstream liquid of the membrane, that is, the permeate, to obtain the ultrafiltration membrane refined liquid; after the material is fed, the upstream liquid is diluted with purified water for a total of 2 times, each time Add 100L of purified water; combine the ultrafiltration membrane permeate to obtain 700L of ultrafiltration membrane refined solution.

8. Decolorization of alumina. Pack 11kg of acidic alumina in the chromatography column in advance, then pass the ultrafiltration membrane refined liquid through the acidic alumina chromatography column, and collect the effluent; after feeding, add 16L of 92% edible ethanol to wash the column, and collect the wash column. . Combine the effluent and the washing liquid to obtain a decolorizing liquid.

9. Solvent recovery and solid-liquid separation. The edible ethanol in the decolorizing liquid is recovered under vacuum and reduced pressure, the vacuum degree is controlled to be greater than -0.085MPa and the temperature is 64°C, and the concentration is concentrated to no alcohol taste, so that a large amount of white natural ferulic acid crystals are precipitated. Discharge the material to a high tank while it is hot, cool it to room temperature with tap water and let it stand for 4 hours. Pass through a bag centrifuge. After the material has been fed, add 43℃ warm water to the centrifuge, 3 times, 50L each time, and collect the centrifugal sediment.

10. Dry. The precipitate was vacuum dried at 62°C, and the vacuum degree was controlled -0.09MPa to obtain 11.02kg of natural ferulic acid.

After testing, the finished product has a natural ferulic acid content of 99.25%, visually pure white, and the product yield is 83.56%.

Example 3

Others are the same as Example 1, except that in step (1), the pH of the system is adjusted to 9.0 with dilute lye; and/or the pH of the dissolved filtrate is adjusted to 8.0 with dilute acid in step (2); and/or in step (6) Adjust the pH of the alkali alcohol hydrolysis filtrate to 4.0 with dilute sulfuric acid. After testing, the finished product has a natural ferulic acid content of 97.73%, visually pure white, and the product yield is 82.31%.

Example 4

Others are the same as in Example 1, except that in step (1), the pH of the system is adjusted to 7.0 with dilute lye; and/or the pH of the dissolved filtrate is adjusted to 8.0 with dilute acid in step (2); and/or in step (6) Adjust the pH of the alkali alcohol hydrolysis filtrate to 2.5 with dilute sulfuric acid. After testing, the finished product has a natural ferulic acid content of 97.22%, visually pure white, and the product yield is 82.16%.

Example 5

Others are the same as in Example 1, except that in step (1), the pH of the system is adjusted to 7.0 with dilute lye; and/or the pH of the dissolved filtrate is adjusted to 8.0 with dilute acid in step (2); and/or in step (6) Adjust the pH of the alkali alcohol hydrolysis filtrate to 2.5 with dilute sulfuric acid. After testing, the finished product has a natural ferulic acid content of 98.41%, visually pure white, and the product yield is 81.40%.

Example 6

Others are the same as in Example 1, except that in step (1), the pH of the system is adjusted to 7.0 with dilute lye; and/or the pH of the dissolved filtrate is adjusted to 8.0 with dilute acid in step (2); and/or in step (6) Adjust the pH of the alkali alcohol hydrolysis filtrate to 2.5 with dilute sulfuric acid. After testing, the finished product has a natural ferulic acid content of 98.41%, visually pure white, and the product yield is 81.40%.

Example 7

Others are the same as in Example 1, the difference is that the alkaline ethanol used in step (4) is 16 wt% of sodium hydroxide and 65 wt% of ethanol. After testing, the finished product has a natural ferulic acid content of 94.38%, visually white, and the product yield is 78.40%.

Example 8

Others are the same as in Example 1, except that in step (4), the alkaline ethanol used is 8wt% of sodium hydroxide and 85wt% of ethanol. After testing, the finished product has a natural ferulic acid content of 88.63%, visually white, and the product yield is 83.91%.

Example 9

Others are the same as in Example 1, the difference is that the heating reflux temperature in step (4) is 98°C, and the hydrolysis is kept for 5 hours. After testing, the finished product has a natural ferulic acid content of 93.35%, visually white, and the product yield is 84.68%.

Example 10

Others are the same as in Example 1, the difference is that step (4) heating and reflux temperature is 85°C, and hydrolysis is kept for 8.5 hours. After testing, the finished product has a natural ferulic acid content of 95.17%, visually white, and the product yield is 81.50%.

Comparative example 1

Others are the same as in Example 1, except that in step (6), 30% hydrochloric acid is used to replace 20% dilute sulfuric acid, and the pH of the alkaline alcohol hydrolysis filtrate is also adjusted to 3.0. The finished product was finally obtained. After testing, the content of ferulic acid in the finished product was 87.63%, and the yield was 71.53%.

Comparative example 2

Others are the same as in Example 1, the difference is that the decolorization method in step (3) is changed to n-butanol, heated and stirred at 60° C., and the finished product is finally obtained. After testing, the ferulic acid content in the finished product is 82.6%, and the yield is 74.17%.

Comparative example 3

Others are the same as in Example 1, the difference is that after adjusting the pH to 3.0 with dilute sulfuric acid in step (6), the solution is placed at 10° C. overnight to fill the analytical crystals. The finished product was finally obtained. After testing, the content of ferulic acid in the finished product was 91.86%, and the yield was 76.75%.

Comparative example 4

Others are the same as in Example 1, except that the step (7) of ultrafiltration membrane crystal refining is omitted. In step (6), the desalinated hydrolysis filtrate directly enters the acidic alumina chromatography column of step (8). The final product is obtained. After testing, the content of ferulic acid in the product is 75.83%, and the yield is 85.21%.

Comparative example 5

Others are the same as in Example 1, the difference is that the acidic alumina chromatography column that omits step (8) is replaced with a silica gel chromatography column. The finished product was finally obtained. After testing, the content of ferulic acid in the finished product was 91.30%, the yield was 77.25%, and the product was yellow.

The above detailed description is a specific description of one of the possible embodiments of the present invention. This embodiment is not intended to limit the patent scope of the present invention. Any equivalent implementation or modification that does not deviate from the present invention should be included in the present invention. Within the scope of technical solutions.

Claims (10)

1. A method for preparing natural ferulic acid by using soapstock containing oryzanol as a raw material, including the following steps:

   (1) Alkali alcohol hot melt filtration: add a high concentration alcohol aqueous solution to the raw material containing oryzanol soapstock, heat up to 50-60°C, adjust the system to alkaline with dilute lye, and then filter while hot to obtain filtrate 1;

   (2) Acid precipitation separation: adjust the filtrate 1 to be neutral or weakly acidic with dilute acid, stir and let it stand to make the oryzanol precipitation complete, filter, and collect the precipitate;

   (3) Decolorization: Add a low-polarity organic solvent of 2 to 4 times its weight (W/V) to the precipitate, fully stir and stand at room temperature, centrifuge, and collect the centrifuged precipitate;

   (4) Reflux hydrolysis: add alkali-containing alcohol solution and heat it to reflux, keep heat and hydrolyze to obtain alkali alcohol hydrolysate;

   (5) Cooling separation: pass water to cool the alkali-alcohol hydrolyzate to room temperature, leave it to stand still to fully analyze the alkali-alcohol insoluble matter, and filter to obtain the alkali-alcohol hydrolysis filtrate, that is, filtrate 2;

   (6) Acidification and cold storage for desalination: adjust the filtrate 2 to be acidic with dilute sulfuric acid, refrigerate at low temperature, the salt becomes crystals and precipitate, and filter while cold to obtain the desalinated water solution filtrate, that is, filtrate 3;

   (7) Ultrafiltration membrane refining: Pass the filtrate 3 through the ultrafiltration membrane system, and collect the downstream liquid of the membrane, that is, the permeate, to obtain the ultrafiltration membrane refined liquid;

   (8) Alumina decolorization: Pass the ultrafiltration membrane refined liquid through a chromatography column containing acidic alumina, and collect the effluent; after feeding, add a high-concentration alcohol aqueous solution to wash the column, collect the column wash, and combine the effluent And wash column liquid, get decolorizing liquid.

   (9) Solvent recovery and solid-liquid separation: Recover the alcohol in the decolorizing liquid under vacuum and decompression, concentrate until there is no alcohol smell, and white natural ferulic acid crystals out, cool to room temperature and stand for 3-6h, filter and collect Precipitation and drying give natural ferulic acid.
2. The method according to claim 1, characterized in that in step (1), the pH of the system is adjusted to 9.0 to 10.0 with dilute lye; and/or the pH of the filtrate 1 is adjusted to 6.0 to 7.0 with dilute acid in step (2). And/or in step (6), dilute sulfuric acid is used to adjust the pH of the filtrate 2 to 3.0-4.0.
3. The method of claim 1, wherein the volume mass ratio of the alcohol aqueous solution and the raw material of the oryzanol-containing soapstock is 4-8 (L/kg), preferably 5-6 (L/kg).
4. The method of claim 1, wherein the low-polarity organic solvent is selected from at least one of n-hexane, mineral spirits No. 6 and petroleum ether, and the volume-to-mass ratio of the precipitate obtained in step (2) It is 2-4 (L/kg).
5. The method according to claim 1, wherein in the alkali-containing alcohol solution, the concentration of the alkali is 10-15% by weight, the concentration of the alcohol is 70-80% by weight, and the balance is water.
6. The method according to claim 1, wherein, in step (4), the volume-to-mass ratio of the alkali-containing alcohol solution to the centrifugal precipitate obtained in step (3) is 6-10 (L/kg); the solvent is refluxed The temperature is 90-95° C., and the temperature range is maintained during the entire process of oryzanol hydrolysis; the hydrolysis time of the oryzanol is 6.5-8.5 h.
7. The method according to claim 1, wherein in step (6), the concentration of the dilute sulfuric acid is 15-30%.
8. The method according to claim 1, characterized in that, in step (6), the refrigeration at low temperature is to cool to 0-4°C and refrigerate for 6-12 hours.
9. The method according to claim 1, wherein in step (7), the molecular weight cut-off of the ultrafiltration membrane is 5000-8000, the material is polyethersulfone, and the operating pressure is 1.0-2.0 MPa.
10. The method according to claim 1, characterized in that, in step (8), the added amount of acidic alumina is 2 to 4 wt% of the raw material of soapstock containing oryzanol.