A method for preparing natural ferulic acid by using biological enzyme method

Abstract

The invention relates to the technical field of plant extraction and separation, and in particular to a method for preparing natural ferulic acid by using a biological enzyme method. The method has the following steps: step 1, preparing crude natural ferulic acid by enzymatic hydrolysis of oryzanol, and step 2, refining the crude natural ferulic acid into a qualified finished natural ferulic acid product. The method achieves a high content of ferulic acid in the prepared finished product, and no sodium ferulate intermediate is produced in the production process, so the naturalness is higher, and the demand of downstream customers for natural ferulic acid can be met from the process and process. In addition, the method has simple process steps, mild reaction conditions, can be co-produced with rice oil refining, has low production cost, does not use any solvent in the production process, has little environmental pollution, and is conducive to industrial application.

Description

Technical field:

[0001] The invention relates to the technical field of plant extraction and separation, and in particular to a method for preparing natural ferulic acid by utilizing a biological enzyme method. Background technology:

[0002] Ferulic acid is a type of phenolic acid and a derivative of cinnamic acid (i.e. cinnamic acid, 3-phenyl-2-propenoic acid). Its chemical name is 4-hydroxy-3-methoxycinnamic acid and its molecular formula is C 10 H 10 O4, molecular weight 194.18, CAS number: 1135-24-6, structural formula see the figure below. It has two structures, cis and trans. Cis ferulic acid is yellow oily liquid, and trans ferulic acid is white or slightly yellow crystal or powder.

[0003] The natural ferulic acid usually refers to trans-ferulic acid, which is soluble in hot water, slightly soluble in cold water, has poor stability in alkaline aqueous solution, can form sodium salt, and has good pH stability. It is easily soluble in methanol, ethanol, and acetone, but difficult to dissolve in benzene and petroleum ether.

[0004] Natural ferulic acid is an important pharmaceutical intermediate and raw material with antioxidant, antibacterial, anti-inflammatory and anti-platelet aggregation effects. It is also the only natural vanillin fermentation production raw material recognized internationally.

[0005]

[0006] Oryzanol is a lipid accompaniment mainly found in rice bran oil, mainly a mixture of triterpenoid alcohol ferulic acid esters, supplemented by a small amount of phytosterol ferulic acid esters. It has pharmacological effects such as regulating nerves, lowering blood lipids, and preventing arrhythmias. The molecular structure is shown in the figure above.

[0007] At present, there are two main sources of natural ferulic acid that can be used as raw materials for natural vanillin fermentation. One is to extract, separate and purify free ferulic acid from plant materials such as asafoetida, chuanxiong, angelica, straw, etc. Chinese patent CN202310784149.2 discloses a method for extracting ferulic acid from Echinacea, Chinese patent CN202110676552.4 discloses a method for extracting ferulic acid from waste liquid of corn husk dietary fiber preparation, Chinese patent CN201910799833.1 discloses a simple method for extracting and purifying ferulic acid from green wheat kernel bran, Chinese patent CN201710220313.1 discloses a method for extracting and purifying ferulic acid from chuanxiong stems and leaves, and Chinese patent CN201310695017.9 discloses a process for extracting and purifying ferulic acid from bone-edge angelica, etc. However, there are two significant disadvantages in extracting and isolating free natural ferulic acid from plant materials: (1) the free ferulic acid content in plant materials is low, which is not conducive to industrial application; (2) organic solvents are used in the extraction and purification process, which reduces the naturalness of the product.

[0008] The second is to use oryzanol-rich rice bran oil soap stock as a substrate, use concentrated alkali solution to hydrolyze oryzanol into sodium ferulate and sterols, and then use dilute sulfuric acid and other acidic substances to reduce sodium ferulate to ferulic acid, and then separate and purify the product. Chinese Patent 201911358319.0 discloses a method for preparing natural ferulic acid using oryzanol-containing soap stock as a raw material, Chinese Patent 202010289498.3 discloses a method for separating and purifying ferulic acid from rice bran oil refined soap stock, and Chinese Patent 202010824474.3 discloses a method for separating and extracting natural ferulic acid from oryzanol-containing rice bran oil soap stock, etc. Although the yield of ferulic acid in this scheme is higher than that of scheme one and the principle is simple, since the hydrolysis reaction process requires pressure, pressure reaction equipment needs to be customized, which is not conducive to the industrial application of small and medium-sized enterprises. At the same time, the reaction process produces sodium ferulate as an intermediate, which makes it difficult for downstream vanillin fermentation manufacturers and the EU market to accept the explanation of the naturalness of its production process. Summary of the invention:

[0009] The technical problem to be solved by the present invention is to provide a method for preparing natural ferulic acid by using a biological enzyme method. The method achieves high ferulic acid content in the prepared finished product, and no sodium ferulate intermediate is produced in the production process, so the naturalness is higher, and the demand of downstream customers for natural ferulic acid can be met from the perspective of technology and process. In addition, the method has simple process steps, mild reaction conditions, can be co-produced with rice oil refining, has low production cost, does not use any solvent in the production process, has little environmental pollution, and is conducive to industrial application.

[0010] The technical solution adopted by the present invention is: a method for preparing natural ferulic acid by using a biological enzyme method, the steps of the method are as follows:

[0011] Step 1: Enzymatic hydrolysis of oryzanol to produce crude natural ferulic acid:

[0012] a. Pump oryzanol-rich intermediate II, lipase, and deionized water into the enzyme reaction tank, stir, heat, and mix to perform enzymolysis reaction;

[0013] b. After the enzymatic hydrolysis reaction is completed, the material is separated into a mother liquor by sedimentation, and the mother liquor is cooled to precipitate the crude natural ferulic acid;

[0014] c. After the cold separation is completed, the material is centrifuged and washed with deionized water to obtain a natural ferulic acid wet-base crude product;

[0015] Step 2: Refining crude natural ferulic acid into qualified natural ferulic acid finished product:

[0016] d. Add deionized water to the enamel kettle, heat it, add the crude dry ferulic acid, stir to dissolve, then add wood activated carbon, continue stirring, and filter;

[0017] e. Cooling the filtrate to precipitate natural ferulic acid;

[0018] f. After the cold analysis is completed, the material is centrifuged and washed with deionized water, and the material is unloaded to obtain the natural ferulic acid wet-base fine product, and dried to obtain the dry ferulic acid fine product;

[0019] g. Dry the ferulic acid product, crush it, mix it, and then package it inside and outside to obtain the finished natural ferulic acid product.

[0020] Furthermore, the preparation method of the oryzanol-rich intermediate II is as follows:

[0021] Step 1: Enrichment of oryzanol:

[0022] h. The crude rice oil is degummed, dewaxed, decolorized once, and physically deacidified to obtain deacidified oil;

[0023] i. Pumping the deacidified oil into a oryzanol adsorption tank for heating, adding sodium fatty acid, stirring and adsorbing, and centrifuging to obtain a rice oil intermediate product and a oryzanol-rich intermediate product I;

[0024] Step 2: Second enrichment of oryzanol:

[0025] The oryzanol-rich intermediate product I is mixed with food-grade citric acid, and then subjected to acid hydrolysis reaction, centrifugal separation, water washing centrifugal separation, and physical deacidification to obtain a further enriched oryzanol-rich intermediate product II.

[0026] Furthermore, in the step 1, the first enrichment of oryzanol is:

[0027] h. After heating the crude rice oil to 70-75° C. through a heater, the crude rice oil is metered and pumped into a degumming reactor, and a 10% concentration of citric acid solution is added at a ratio of 500ppm-550ppm. After the reaction is retained for 1-2h, the crude rice oil is pumped out and heated to 85-90° C. through a heater, and centrifugal degumming is performed to obtain degummed oil; the degummed oil is pumped into a dewaxing crystal growing tank, cooled to 20° C. and crystal grown for 24h, filtered to remove wax, and dewaxed oil is obtained; the dewaxed oil is heated to 95° C.-100° C., activated white clay is added at a ratio of 3% of the mass ratio of the feed liquid to perform a decolorization, and the decolorized oil is filtered to obtain a decolorized oil; the decolorized oil is preheated by a heat exchanger and directly enters a physical deacidification tower for physical deacidification, and the temperature of the deacidification tower is controlled at 225-235° C. The vacuum of the deacidification tower is ≤200pa, and the acid value of the deacidified oil output is controlled between 0.5-1.0mg(KOH) / g;

[0028] i. The deacidified oil is metered and pumped into a oryzanol adsorption tank and heated to 50-60° C. 50% concentration of sodium fatty acid is metered into the tank according to a mass ratio of 50% concentration sodium fatty acid: deacidified oil = 1:5, and the mixture is stirred and adsorbed for 15-20 minutes. After the adsorption is completed, the mixture is pumped into a centrifuge for centrifugal separation to obtain a rice oil intermediate product and a oryzanol-rich intermediate product I.

[0029] Furthermore, in the step 2, the second enrichment of oryzanol is:

[0030] According to the mass ratio of oryzanol-enriched intermediate product I: 10% food-grade citric acid = 100:15, metering pump is introduced and mixed in a homogenizer, and the pH value is finely adjusted to 5.8-6.2. After acid hydrolysis reaction for 2 hours, the phase is pumped into a centrifuge for centrifugal separation; the separated fatty acid phase is washed with 5% deionized water at 90°C-95°C, and then centrifuged; the washed fatty acid phase is heat-exchanged in a heat exchanger and then enters a physical deacidification tower, and is physically deacidified at a temperature of 225-235°C and a residual pressure of ≤200 Pa under vacuum to obtain a further enriched oryzanol-enriched intermediate product II.

[0031] Furthermore, in the step a, the oryzanol-rich intermediate II is metered into the enzyme reaction tank, and at the same time, lipase with an enzyme concentration of 2.5% and deionized water are metered at a mass ratio of 2%-3%, followed by stirring and heating to 50-55° C., self-circulating homogenization mixing is started for 2 hours, and enzymatic hydrolysis reaction is carried out for 5 hours.

[0032] Furthermore, in the step b, the step of separating the mother liquor by sedimentation of the material is as follows: adding deionized water at 95±2°C of the same mass as the oryzanol-rich intermediate II to the material, and when the material in the tank is heated to 95±2°C again, stopping stirring, settling for 20-30 minutes, and releasing the lower mother liquor into a cold separation tank;

[0033] The mother liquor cold separation step is as follows: start the programmed temperature reduction control of the cold separation tank, and cool it to 20-25° C. within 12-15 hours to precipitate the crude natural ferulic acid.

[0034] Furthermore, in the step c, after the cold separation is completed, the material is placed in a three-legged centrifuge for centrifugal separation, and after the separation is completed, it is rinsed with deionized water for 15-20 minutes, and the material is discharged to obtain a natural ferulic acid wet-base crude product.

[0035] Furthermore, in the step d, 1000 parts by mass of deionized water is added to the enamel kettle, heated to 90-95° C., 20-22 parts by mass of crude ferulic acid is added, stirred and dissolved for 5-10 minutes, and after all dissolved, 5-6 parts by mass of measured wood activated carbon is added, stirred for 5 minutes, and pumped into a four-hole bag filter for filtration.

[0036] Furthermore, in the step e, the filtrate cold precipitation step is as follows: the filtrate is collected in a cold precipitation tank for refining, and the programmed temperature reduction control of the cold precipitation tank is started to cool to 20-25° C. within 12-15 hours to precipitate natural ferulic acid.

[0037] Furthermore, in the step f, after the cold separation is completed, the material is placed in a three-legged centrifuge for centrifugal separation, and after the separation is completed, it is rinsed with deionized water for 15-20 minutes, and the material is unloaded to obtain the natural ferulic acid wet-based fine product.

[0038] The beneficial effects of the present invention are:

[0039] 1. For the first time, the bio-enzyme hydrolysis method was creatively applied to the production of ferulic acid, opening up a new idea for the production of ferulic acid. At the same time, during the entire processing process, ferulic acid always exists in the form of ferulic acid after hydrolysis, and no sodium ferulate intermediate is produced. This effectively solves the problem that most of the downstream customers of fermented vanillin do not recognize sodium ferulate intermediates.

[0040] The present invention does not produce sodium ferulate intermediates during the production process, and directly hydrolyzes oryzanol into ferulic acid and cycloartanols, thereby better meeting the naturalness requirements of fermented vanillin. The specific reaction process is as follows:

[0041]

[0042] 2. The method is simple, with low investment and low cost, which is conducive to the application of small and medium-sized enterprises

[0043] The method has a simple principle and mild reaction conditions. It does not require the addition of high-pressure reaction equipment. The production of natural ferulic acid can be completed by adding a small amount of ordinary equipment to the vegetable oil refining equipment. It is very suitable for industrial application in small and medium-sized vegetable oil processing enterprises.

[0044] 3. Obvious effect, stable product, wide application and high added value

[0045] The invention can stably produce a natural ferulic acid product with a content of more than 98% without the generation of sodium ferulate intermediates, effectively meeting the dual naturalness requirements of downstream fermentation natural vanillin customers for natural ferulic acid raw materials. At the same time, the oryzanol resources in the rice oil are effectively utilized, and on the basis of maintaining the production of oryzanol-containing rice oil, the excess oryzanol is efficiently utilized to increase the added value of the deep processing of rice oil. Description of the drawings:

[0046] The present invention is further described in detail below with reference to the accompanying drawings and specific embodiments.

[0047] Figure 1 This is a process flow chart for the first enrichment of oryzanol.

[0048] Figure 2 This is a process flow chart for the secondary enrichment of oryzanol.

[0049] Figure 3 This is a process flow chart for preparing crude natural ferulic acid by enzymatic hydrolysis of oryzanol.

[0050] Figure 4 The present invention is a process flow chart for refining crude natural ferulic acid into qualified natural ferulic acid finished products. Specific implementation method:

[0051] Example 1

[0052] During the pilot production process, due to the relationship between material quantity and energy consumption cost, one or more work sections will be repeated or combined for production and processing as needed.

[0053] like Figure 1 As shown, the first enrichment of oryzanol:

[0054] 650 tons of food-grade rice bran crude oil raw materials (crude oil acid value 18.42mg (KOH) / g, oryzanol content 2.19%, water and volatile matter 0.23%) are allocated for processing refined rice oil, heated to 75 ° C by a heater, and 10% concentration of citric acid solution is added at a ratio of 0.05% of the oil weight, mixed by a homogenizer, and then put into a delay tank for delayed reaction for 2 hours. After being pumped out and heated to 90 ° C by a heater, a degumming centrifuge is used for centrifugal separation to obtain degummed oil.

[0055] The degummed oil enters the dewaxing crystal growing tank, and the circulating water cooling control program is started. The temperature is stirred and cooled to 20°C within 24 hours. Then the plate and frame dewaxing filter is used for dewaxing filtration to obtain dewaxed oil.

[0056] The dewaxed oil is heated to 95°C by a heater and then enters a decolorization tower. At the same time, activated white clay is added at a ratio of 3% of the oil weight for decolorization. After stirring and decolorizing for 20 minutes, it is decolorized and filtered using a closed bottom-discharging plate and frame filter to obtain a primary decolorized oil.

[0057] The primary decolorized oil is preheated and then enters the deacidification tower for physical deacidification to obtain deacidified oil. The temperature of the deacidification tower is 235°C, the vacuum of the deacidification tower is 120pa, the retention time is 10min, and the output deacidified oil has an acid value of 0.57mg(KOH) / g and an oryzanol content of 2.51%.

[0058] The deacidified oil produced is heated to 52° C. in a heat exchanger, mixed in a mixer at a ratio of deacidified oil: 50% fatty acid sodium = 5:1, and then pumped into a oryzanol adsorption tank, heated to maintain a temperature of 56° C., stirred and adsorbed for 20 minutes, and then pumped into a centrifuge for centrifugal separation. Rice oil intermediate (detected acid value 0.48 mg (KOH) / g, oryzanol content 0.88%) and oryzanol-rich intermediate I (water content 50.3%, oryzanol content 11.5%) are obtained.

[0059] like Figure 2 As shown, the second enrichment of oryzanol:

[0060] 4.5 tons of oryzanol-rich intermediate I on a dry basis were metered into an acidification reaction tank, 675 kg of 10% food-grade citric acid solution was added, and the mixture was stirred and mixed while circulating with a homogenizer, and the pH was adjusted to 6. After acid hydrolysis for 2 hours, the mixture was pumped into a centrifuge for centrifugal separation to obtain a light phase fatty acid mixture, and the fatty acid mixture was washed with 5% deionized hot water and centrifuged for a second time.

[0061] The fatty acid mixed oil separated by washing was heat exchanged in a heat exchanger and then entered a physical deacidification tower for physical deacidification (deacidification temperature 232° C., vacuum degree of deacidification tower 170 Pa) to obtain 17.8 tons of oryzanol-rich intermediate II, and the oryzanol content was detected to be 36.75%.

[0062] like Figure 3 As shown, crude natural ferulic acid is prepared by enzymatic hydrolysis of oryzanol:

[0063] 4.5 tons of oryzanol-rich intermediate II, 90 kg of 2.5% concentration lipase, and 225 kg of deionized water were added in a metered amount, mixed in a homogenizer, and then put into an enzymatic hydrolysis reactor. The mixture was stirred and heated to 55° C. The homogenizer was turned on for self-circulation for 2 hours, and then the enzymatic hydrolysis reaction was stirred for 5 hours.

[0064] After the reaction is completed, 4.5 tons of 95°C deionized water is quickly added to the enzymatic hydrolysis reactor. When the temperature is raised to 95°C while stirring, the stirring is stopped, and the mixture is allowed to settle for 20 minutes. The mother liquor at the bottom is discharged into a cold precipitation tank.

[0065] After the lower mother liquor is drained, the cooling water of the cold precipitation tank is started, and the temperature is lowered to 24° C. within 12 hours to precipitate the crude natural ferulic acid. After the cold precipitation is completed, the material is centrifuged and rinsed with deionized water to obtain the crude natural ferulic acid wet basis product. The ferulic acid content is 92.31% and the water content is 27.65%.

[0066] like Figure 4 As shown, crude natural ferulic acid is refined into qualified natural ferulic acid finished product:

[0067] Add 1000 kg of deionized water to the hot melt refining tank, heat to 95°C, quickly add 21.5 kg of natural ferulic acid crude product on a dry basis, stir until fully dissolved, add 6 kg of activated carbon, then stir to remove impurities for 5 minutes, filter with a four-hole filter bag filter while hot, and obtain a clear liquid to remove the fines and place in a cold analysis tank.

[0068] When the cold analysis tank reaches the appropriate liquid level, start the cooling control program and cool it to 22°C within 12 hours. Then use a three-legged centrifuge for centrifugal separation. After the centrifugation, rinse with deionized water for 15 minutes and unload for drying.

[0069] The material to be dried was pinched into small pieces and spread flat on a drying tray padded with gauze to keep the thickness about 3 cm. 24 trays were placed on each drying rack and 4 drying racks were placed on each drying oven. The temperature was raised to 105°C and maintained for 15 hours. Samples were taken for testing and the content of dried ferulic acid was 99.08% and the loss on drying was 0.1%.

[0070] After all the ferulic acid in this batch is dried, it is combined, crushed, mixed, weighed, and packaged inside and outside to obtain 1201.5 kg of natural ferulic acid product with a ferulic acid content of 99.27% ​​and a drying loss of 0.11%.

[0071] As shown in Example 1, the finished product prepared by the present invention has a high ferulic acid content, and no sodium ferulate intermediate is produced in the production process, so the product is more natural and can meet the needs of downstream customers for natural ferulic acid in terms of both technology and process. In addition, the method has simple process steps, mild reaction conditions, can be co-produced with rice oil refining, has low production cost, does not use any solvent in the production process, has little environmental pollution, and is conducive to industrial application.

[0072] It can be understood that the above specific description of the present invention is only used to illustrate the present invention and is not limited to the technical solutions described in the embodiments of the present invention. Those skilled in the art should understand that the present invention can still be modified or replaced by equivalents to achieve the same technical effects; as long as the use requirements are met, they are within the protection scope of the present invention.

Claims

1. A method for preparing natural ferulic acid by bioenzymatic method, characterized in that: The steps of this method are as follows: Step 1: Enzymatic hydrolysis of oryzanol to produce crude natural ferulic acid: a. Pump the oryzanol-rich intermediate II into the enzyme reaction tank, and at the same time pump lipase with an enzyme concentration of 2.5% at a mass ratio of 2%-3%, and deionized water at a mass ratio of 4%-5%, then stir, heat to 50-55°C, start self-circulation homogenization mixing for 2 hours, and perform enzymolysis reaction for 5 hours; b. After the enzymatic hydrolysis reaction is completed, the material is separated into a mother liquor by sedimentation, and the mother liquor is cooled to precipitate the crude natural ferulic acid; c. After the cold separation is completed, the material is centrifuged and washed with deionized water to obtain a natural ferulic acid wet-base crude product; Step 2: Refining crude natural ferulic acid into qualified natural ferulic acid finished product: d. Add deionized water to the enamel kettle, heat it, add the crude dry ferulic acid, stir to dissolve, then add wood activated carbon, continue stirring, and filter; e. Cooling the filtrate to precipitate natural ferulic acid; f. After the cold analysis is completed, the material is centrifuged and washed with deionized water, and the material is unloaded to obtain the natural ferulic acid wet-base fine product, and then dried to obtain the dry ferulic acid fine product; g. Drying the ferulic acid product, crushing, mixing, inner packaging, and outer packaging to obtain a natural ferulic acid product; The preparation method of the oryzanol-rich intermediate II is as follows: Step ①, primary enrichment of oryzanol: h. The crude rice oil is degummed, dewaxed, decolorized once, and physically deacidified to obtain deacidified oil; i. Pump the deacidified oil into the oryzanol adsorption tank and heat it to 50-60°C, add 50% fatty acid sodium at a mass ratio of 50% fatty acid sodium: deacidified oil = 1:5, and stir and adsorb for 15-20 minutes; After the adsorption is completed, the mixture is pumped into a centrifuge for centrifugal separation to obtain a rice oil intermediate and a oryzanol-rich intermediate I; Step ②, secondary enrichment of oryzanol: According to the mass ratio of oryzanol-rich intermediate product I: 10% food-grade citric acid = 100:15, metering pump is added and mixed in a homogenizer, and the pH value is finely adjusted to 5.8-6.

2. After acid hydrolysis reaction for 2 hours, it is pumped into a centrifuge for centrifugal separation; the separated fatty acid phase is added with 5% deionized water at 90°C-95°C for water washing, and then centrifugal separation is performed; the washed fatty acid phase is heat-exchanged in a heat exchanger and then enters a physical deacidification tower, and is physically deacidified at a temperature of 225-235°C, ≤200 Pa and vacuum to obtain a further enriched oryzanol-rich intermediate product II.

2. The method for preparing natural ferulic acid by bioenzyme method according to claim 1, characterized in that: In the step h, the crude rice oil is heated to 70-75° C. by a heater, and then metered and pumped into a degumming reactor, and a 10% concentration of citric acid solution is added at a ratio of 500ppm-550ppm. After retention reaction for 1-2h, the crude rice oil is pumped out and heated to 85-90° C. by a heater, and centrifugal degumming is performed to obtain degummed oil; the degummed oil is pumped into a dewaxing crystal growing tank, cooled to 20° C. and crystal grown for 24h, filtered to remove wax, and dewaxed oil is obtained; the dewaxed oil is heated to 95° C.-100° C., and activated white clay is added at a ratio of 3% of the mass ratio of the feed to the liquid for a primary decolorization, and filtered to obtain a primary decolorized oil; the primary decolorized oil is preheated by a heat exchanger and directly enters a physical deacidification tower for physical deacidification, and the temperature of the deacidification tower is controlled at 225-235° C., the vacuum of the deacidification tower is ≤200pa, and the acid value of the output deacidified oil is controlled between 0.5-1.0mg(KOH) / g.

3. The method for preparing natural ferulic acid by bioenzyme method according to claim 1, characterized in that: In the step b, the step of separating the mother liquor by sedimentation of the material is as follows: adding deionized water at 95±2°C of the same mass as the oryzanol-rich intermediate II to the material, and when the material in the tank is heated to 95±2°C again, stopping stirring, settling for 20-30 minutes, and releasing the lower mother liquor into a cold separation tank; The mother liquor cold separation step is as follows: start the programmed temperature reduction control of the cold separation tank, and cool it to 20-25° C. within 12-15 hours to precipitate the crude natural ferulic acid.

4. The method for preparing natural ferulic acid by bioenzyme method according to claim 1, characterized in that: In the step c, after the cold separation is completed, the material is placed in a three-legged centrifuge for centrifugal separation, and after the separation is completed, it is rinsed with deionized water for 15-20 minutes, and the material is discharged to obtain a natural ferulic acid wet-base crude product.

5. The method for preparing natural ferulic acid by bioenzyme method according to claim 1, characterized in that: In the step d, 1000 parts by mass of deionized water is added to the enamel kettle, heated to 90-95° C., 20-22 parts by mass of crude ferulic acid on a dry basis is added, stirred and dissolved for 5-10 minutes, and after all dissolved, 5-6 parts by mass of measured wood activated carbon is added, stirred for 5 minutes, and pumped into a four-hole filter bag filter for filtration.

6. The method for preparing natural ferulic acid by bioenzyme method according to claim 1, characterized in that: In the step e, the filtrate cold precipitation step is as follows: the filtrate is collected in a cold precipitation tank for refining, and the programmed temperature reduction control of the cold precipitation tank is started to cool to 20-25° C. within 12-15 hours to precipitate natural ferulic acid.

7. The method for preparing natural ferulic acid by bioenzyme method according to claim 1, characterized in that: In the step f, after the cold separation is completed, the material is placed in a three-legged centrifuge for centrifugal separation, and after the separation is completed, it is rinsed with deionized water for 15-20 minutes, and the material is unloaded to obtain the wet-based fine product of natural ferulic acid.

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