Plant dietary fiber extraction process

Abstract

The invention relates to the technical field of fiber extraction, and discloses a plant dietary fiber extraction process which comprises the following steps: firstly, performing water vapor permeation steam explosion treatment and ozone oxidation modification on a rice husk raw material to obtain a porous dietary fiber material with high oil holding capacity; secondly, supercritical carbon dioxide is used as a carrying medium, functional components are loaded on the dietary fiber materials, and preliminary drying is conducted; thirdly, in the process stage of loading the functional components with the supercritical carbon dioxide, combined operation of dynamic disturbance and adsorption purification is adopted, so that the loading uniformity is improved, and impurities are removed; and finally, carrying out gas replacement deep drying treatment on the dietary fiber material loaded with the functional components. Through the process combination, the functional dietary fiber product which is high in oil holding capacity, stable in functional component loading, high in purity and good in slow release performance and sensory quality can be obtained.

Description

Technical Field

[0001] The present invention relates to the technical field of fiber extraction, and more specifically, to a process for extracting plant dietary fiber. Background Art

[0002] Rice husk, as a common agricultural by-product, contains rich dietary fiber resources. However, due to the limitations of its structure and surface properties, the oil-holding capacity of unmodified rice husk dietary fiber and its ability to act as an effective carrier for functional components are usually not high. In the prior art, when using rice husk to prepare dietary fiber products that can load functional components (especially fat-soluble functional components), the following technical challenges are generally faced: First, how to significantly increase the loading amount of functional components on the dietary fiber and ensure the chemical stability and biological activity of the functional components after loading; Second, during the loading and subsequent processing, how to effectively avoid or remove odor substances that may be generated due to raw materials, processing processes, or the functional components themselves, and ensure the sensory quality of the final product; Third, how to endow the loaded functional dietary fiber products with good controlled-release characteristics to adapt to their applications in foods or health products.

[0003] Traditional methods for dietary fiber extraction and modification, as well as technologies for loading functional components, often have deficiencies in simultaneously solving the above multiple problems, or the process flow is relatively cumbersome, the processing cost is relatively high, or it is not environmentally friendly enough. Summary of the Invention

[0004] To solve the above technical problems, the present invention provides a process for extracting plant dietary fiber, including the following steps: Step 1: Pretreat and modify the plant raw materials to obtain dietary fiber materials; The pretreatment and modification include sequentially performing chemical impregnation treatment, steam penetration explosion treatment, and ozone oxidation modification treatment on the plant raw materials; Step 2: Load functional components onto the dietary fiber materials using supercritical carbon dioxide and perform preliminary drying; Dissolve the functional components in supercritical carbon dioxide fluid to form a solution carrying the functional components, bring the solution into contact with the dietary fiber materials to load the functional components, and then deposit the functional components on or within the dietary fiber materials by rapid pressure reduction and complete the preliminary drying; Step 3: Strengthen the supercritical carbon dioxide loading process of the functional components and implement on-line purification; During the loading process in Step 2, apply dynamic physical perturbation to the supercritical carbon dioxide fluid carrying the functional components to strengthen the mass transfer and distribution of the functional components to the dietary fiber materials, and bring the supercritical carbon dioxide fluid into contact with a temporarily arranged adsorbent to on-line remove impurities in the fluid; Step 4: Perform gas displacement deep drying treatment on the dietary fiber material loaded with functional ingredients; After the preliminary drying in Step 2, introduce the pretreated inert gas or clean air into the equipment containing the dietary fiber material loaded with functional ingredients, and further remove the residual carbon dioxide, moisture and volatile odor compounds through gas purging.

[0005] Preferably: The chemical impregnation treatment in Step 1 uses a dilute alkali solution or a dilute sulfite aqueous solution, and is impregnated for 1 - 3 hours under the temperature condition of 50 - 90 °C.

[0006] Preferably: The process conditions of the steam penetration explosion treatment in Step 1 are: the pressure in the equipment is maintained at 1.0 - 2.5 MPa, and the pressure holding time is 1 - 5 minutes.

[0007] Preferably: The process conditions of the ozone oxidation modification treatment in Step 1 are: disperse the material after the steam penetration explosion treatment in water to form a suspension, introduce a gas containing an ozone concentration of 10 - 100 mg / L into the suspension, and react for 0.5 - 2 hours under the temperature of 20 - 50 °C and the pH value of 5 - 7.

[0008] Preferably: The operating conditions for loading the functional ingredients with supercritical carbon dioxide in Step 2 are: temperature 35 - 60 °C, pressure 10 - 30 MPa.

[0009] Preferably: The ways of applying dynamic physical disturbance in Step 3 include: periodically changing the instantaneous flow rate or operating pressure of the supercritical carbon dioxide fluid passing through the loading equipment, or intermittently introducing a small amount of food - grade co - solvent in the main supercritical carbon dioxide flow path.

[0010] Preferably: The ways of online removing impurities in the fluid in Step 3 include: making the supercritical carbon dioxide fluid carrying the functional ingredients flow through an adsorption device filled with food - grade adsorbent particles before discharging from the loading equipment or during the circulation process, and the adsorbent is selected from one or more of activated carbon, diatomaceous earth or molecular sieve.

[0011] Preferably: The gas used for gas displacement deep drying treatment in Step 4 is nitrogen or purified air.

[0012] Preferably: The operating conditions for gas displacement deep drying treatment in Step 4 are: the gauge pressure inside the equipment is maintained at 0.01 - 0.1 MPa higher than the atmospheric pressure, and the gas displacement time is 0.5 - 4 hours.

[0013] Preferably: The plant raw material is rice husk; the functional ingredient is a fat - soluble nutrient or an essential oil substance extracted from plants.

[0014] The beneficial effects of the present invention are as follows: Significant improvement in the performance of dietary fiber material carriers: Through the combined pretreatment process of the first-step steam penetration explosion (SPORL) treatment and ozone oxidation modification, the microscopic pore characteristics of rice husk dietary fiber can be effectively improved (such as increasing porosity and specific surface area), and its surface chemical properties can be regulated (such as enhancing surface hydrophobicity). As a result, when it is used as a carrier for subsequent loading of functional components, its oil-holding capacity (the adsorption and retention capacity for fat-soluble functional components) is greatly improved compared to rice husk dietary fiber that is untreated or only treated by a single traditional method, laying a good material foundation for the efficient loading of functional components.

[0015] Optimization and greening of the functional component loading process: In the second step, supercritical carbon dioxide (Sc-CO2) is used as the carrier medium and solvent for functional components. The process conditions are mild, avoiding the environmental pollution and solvent residue problems caused by the use of traditional organic solvents. At the same time, the characteristics of Sc-CO2 help to load the functional components into the interior of the dietary fiber material in a highly dispersed state and form a preliminary embedding structure that is conducive to subsequent controlled release. Combining the innovative "dynamic perturbation and adsorption purification combined operation" in the third step further improves the uniformity and total amount of functional component loading in the dietary fiber material and realizes the online purification of the loading system.

[0016] Improvement in the purity, stability, and sensory quality of the final product: The online adsorption purification operation in the third step combined with the "gas displacement deep drying" treatment in the fourth step can effectively remove trace odor compounds, potential degradation products of functional components, residual carbon dioxide, and deep moisture that may exist in the final product and originate from raw materials or the processing process. These measures significantly improve the chemical stability (such as antioxidant capacity) and bioactivity retention rate of the loaded functional components, extend the storage period of the functional dietary fiber product, and improve its final sensory characteristics (such as smell and flavor).

[0017] Expansion of high-value utilization ways for agricultural and sideline products: In this embodiment, the widely sourced and low-value rice husk resources are transformed into high-value functional dietary fiber products with the ability to effectively load specific functional components and endow them with good slow-release characteristics, high purity, high stability, and excellent flavor through a series of innovative physical-chemical and green processing technologies. Such products can be widely applied in the fields of functional foods, dietary supplements, health foods, or food ingredients with special nutritional requirements, providing a new technical path for the high-value and refined utilization of agricultural and sideline products and having good industrial application prospects and economic and social benefits. Brief Description of the Drawings

[0018] Figure 1is the release curve of β-carotene in the in vitro digestive system of the present invention; Figure 2 is the common sense sustained release curve of β-carotene in the yogurt digestive system of the present invention; Figure 3 is the bar chart of the bioavailability comparison of the functional components of the present invention; Figure 4 is the storage stability curve of β-carotene in the food application of the present invention. Detailed implementation manners

[0019] The subject matter described herein will now be discussed with reference to example embodiments. It should be understood that the discussion of these embodiments is only to enable those skilled in the art to better understand and thus implement the subject matter described herein, and changes can be made to the functions and arrangements of the elements discussed without departing from the scope of protection of the content of this specification. Each example can omit, substitute or add various processes or components as needed. Additionally, the features described in some examples can also be combined in other examples.

[0020] Example 1

[0021] In this example, a plant dietary fiber extraction process is proposed, including the following steps: Step 1: Pretreat and modify the plant raw materials to obtain dietary fiber materials; The pretreatment and modification include sequentially performing chemical impregnation treatment, steam penetration explosion treatment, and ozone oxidation modification treatment on the plant raw materials; The plant raw materials are rice husks, and the functional component is a fat-soluble nutrient; The chemical impregnation treatment uses a dilute alkali solution and is impregnated at a temperature of 50°C for 1 hour; The process conditions for the steam penetration explosion treatment are: the pressure in the equipment is maintained at 1.0 MPa, and the pressure holding time is 1 minute; The process conditions for the ozone oxidation modification treatment are: the material after the steam penetration explosion treatment is dispersed in water to form a suspension, and a gas containing an ozone concentration of 10 mg / L is introduced into the suspension, and the reaction is carried out at a temperature of 20°C and a pH value of 5 for 0.5 hour Step 2: Load the functional component onto the dietary fiber material using supercritical carbon dioxide and perform preliminary drying; The functional component is dissolved in supercritical carbon dioxide fluid to form a solution carrying the functional component, the solution is brought into contact with the dietary fiber material to load the functional component, and then the functional component is deposited on or within the dietary fiber material by rapid pressure reduction and preliminary drying is completed; The operating conditions for loading the functional component with supercritical carbon dioxide are: temperature 35°C, pressure 10 MPa; Step 3: Strengthen the supercritical carbon dioxide loading process of the functional components and implement on-line purification; During the loading process in Step 2, apply dynamic physical perturbations to the supercritical carbon dioxide fluid carrying the functional components to enhance the mass transfer and distribution of the functional components to the dietary fiber material, and make the supercritical carbon dioxide fluid contact with the temporarily arranged adsorbent to remove impurities in the fluid on-line; The ways to apply dynamic physical perturbations include: periodically changing the instantaneous flow rate of the supercritical carbon dioxide fluid passing through the loading device; The ways to remove impurities in the fluid on-line include: making the supercritical carbon dioxide fluid carrying the functional components flow through an adsorption device filled with food-grade adsorbent particles before discharging from the loading device, and the adsorbent is selected from activated carbon; Step 4: Conduct gas displacement deep drying treatment on the dietary fiber material loaded with functional components; After the preliminary drying in Step 2, introduce the pretreated inert gas or clean air into the device containing the dietary fiber material loaded with functional components, and further remove the residual carbon dioxide, moisture and volatile odor compounds through gas purging; The gas used for gas displacement deep drying treatment is nitrogen; The operating conditions for gas displacement deep drying treatment are: the internal pressure of the device is maintained at a gauge pressure 0.01 MPa higher than the atmospheric pressure, and the gas displacement time is 0.5 hour.

[0022] Example 2

[0023] The difference between this example and Example 1 is: In Step 1: The functional component is an essential oil substance extracted from plants; The chemical impregnation treatment uses a dilute sulfite aqueous solution and is impregnated at a temperature of 70 °C for 2 hours; The process conditions for steam penetration explosion treatment are: the pressure inside the device is maintained at 1.8 MPa and the pressure holding time is 3 minutes; The process conditions for ozone oxidation modification treatment are: disperse the material after steam penetration explosion treatment in water to form a suspension, introduce a gas containing an ozone concentration of 55 mg / L into the suspension, and react at a temperature of 35 °C and a pH value of 6 for 1.2 hours In Step 2: The operating conditions for supercritical carbon dioxide loading of the functional component are: temperature 37 °C, pressure 20 MPa; In Step 3: The ways to apply dynamic physical perturbations include: periodically changing the operating pressure of the supercritical carbon dioxide fluid passing through the loading device; Online methods for removing impurities from fluids include: passing a supercritical carbon dioxide fluid carrying functional components through an adsorption device filled with food-grade adsorbent particles during circulation, where the adsorbent is selected from diatomaceous earth; In step 4: The gas used for gas displacement deep drying treatment is purified air; The operating conditions for gas displacement deep drying treatment are: the internal pressure of the equipment is maintained at a gauge pressure 0.06 MPa higher than atmospheric pressure, and the gas displacement time is 2.5 hours.

[0024] Example 3

[0025] The difference between this example and Example 1 lies in: In step 1: The chemical impregnation treatment uses a dilute alkali solution and is carried out at a temperature of 90 °C for 3 hours; The process conditions for steam penetration explosion treatment are: the pressure inside the equipment is maintained at 2.5 MPa, and the pressure holding time is 5 minutes; The process conditions for ozone oxidation modification treatment are: dispersing the material after steam penetration explosion treatment in water to form a suspension, introducing a gas with an ozone concentration of 100 mg / L into the suspension, and reacting at a temperature of 50 °C and a pH value of 7 for 2 hours In step 2: The operating conditions for loading functional components with supercritical carbon dioxide are: temperature 60 °C, pressure 30 MPa; In step 3: The method of applying dynamic physical disturbance includes: intermittently introducing a small amount of food-grade co-solvent into the main supercritical carbon dioxide flow path; Online methods for removing impurities from fluids include: passing a supercritical carbon dioxide fluid carrying functional components through an adsorption device filled with food-grade adsorbent particles before discharging from the loading equipment, where the adsorbent is selected from activated carbon, diatomaceous earth, and molecular sieve; In step 4: The operating conditions for gas displacement deep drying treatment are: the internal pressure of the equipment is maintained at a gauge pressure 0.1 MPa higher than atmospheric pressure, and the gas displacement time is 4 hours.

[0026] Example 4

[0027] In this example, a plant dietary fiber extraction process is proposed, and the specific steps are as follows: The first step: Pretreat and modify the rice husk raw material to obtain a dietary fiber material with high oil-holding capacity. This step aims to treat the rice husk raw material through a combination of physical and chemical methods to break its tight lignocellulose structure, increase its specific surface area and porosity, and regulate its surface chemical properties, so as to prepare a dietary fiber material with excellent adsorption capacity for subsequent loading of functional components.

[0028] This step specifically includes the following operations: (1) Chemically impregnate the rice husk raw material: Place the dry and clean rice husk raw material in a dilute alkali solution (an aqueous sodium hydroxide solution with a mass fraction of 1.2%) and impregnate it at a temperature of 70 °C for 2 hours. This chemical impregnation treatment is a conventional pretreatment method in the art, and its function is to preliminarily swell the cellulose in the rice husk and cause partial degradation of hemicellulose and lignin, resulting in the initial loosening of the overall structure of the rice husk.

[0029] (2) Perform steam penetration explosion (SPORL) treatment on the chemically impregnated rice husk: Put the rice husk material that has undergone the above chemical impregnation treatment and solid-liquid separation into a steam penetration explosion device and process it under preset process conditions (using saturated steam to maintain the pressure in the device at 1.8 MPa and holding it at this pressure for 4 minutes). This SPORL treatment is a well-known physical and chemical combined pretreatment technology in the art. Through the penetration of high-temperature and high-pressure water vapor and subsequent rapid pressure release, it can effectively destroy the cell wall structure of the rice husk and the complex network structure formed between cellulose, hemicellulose, and lignin, laying a foundation for subsequent modification treatment.

[0030] (3) Perform ozone oxidation modification on the rice husk material after SPORL treatment: Wash the rice husk material after SPORL treatment with water until the pH is neutral, and then disperse it in deionized water according to a predetermined solid-liquid ratio to make a suspension. Under stirring, continuously introduce a gas containing ozone (the concentration of ozone in the gas is 60 mg / L) into this suspension, and carry out an oxidation reaction for 1.2 hours at a temperature of 35 °C and a neutral pH environment. As a strong oxidant, ozone can selectively oxidize the residual lignin in the material after SPORL treatment and some chemical groups on the surface of cellulose (such as oxidizing hydroxyl groups to oxygen-containing functional groups such as carboxyl or carbonyl groups), and at the same time etch the fiber surface to a certain extent, thereby increasing the pore number and specific surface area of the dietary fiber material and changing its surface charge state and hydrophobicity. This ozone oxidation modification step combined with the aforementioned SPORL treatment synergistically improves the oil-holding capacity of the finally obtained dietary fiber material and its suitability as a carrier for functional components, and its modification effect is better than that of using SPORL treatment or conventional chemical oxidation methods alone.

[0031] The second step: Load functional components onto the dietary fiber material using supercritical carbon dioxide (Sc-CO2) and perform preliminary drying. The purpose of this step is to introduce the target functional components (such as fat-soluble compounds such as vitamin E and β-carotene, or essential oil substances extracted from plants) into the pore structure of the dietary fiber material with high oil-holding capacity prepared in the previous step, and use the characteristics of Sc-CO2 to complete preliminary drying.

[0032] This step specifically includes the following operations: (1) Dissolve the functional component in supercritical carbon dioxide: Thoroughly contact the functional component to be loaded with supercritical carbon dioxide (Sc-CO2) in a mixing device (such as an extraction kettle with a stirring device). By regulating the operating conditions of Sc-CO2, maintain the temperature in the range of 50 °C and the pressure in the range of 20 MPa, so that the functional component dissolves in the Sc-CO2 fluid, forming a Sc-CO2 solution carrying the functional component. Sc-CO2 serves as an environmentally friendly solvent and a carrier tool for the functional component here.

[0033] (2) Contact the Sc-CO2 solution carrying the functional component with the dietary fiber material to complete the loading: Pre-load the high oil-holding dietary fiber material, which is dry or contains only a small amount of bound water, prepared in the first step, into a pressure-bearing loading device (loading kettle). Then, continuously or batchwise introduce the previously prepared Sc-CO2 solution carrying the functional component into this loading kettle to ensure sufficient contact between the Sc-CO2 solution and the dietary fiber material. By setting the flow rate of the Sc-CO2 solution and the total contact time (the contact time is 2 hours), relying on the high penetration ability of the Sc-CO2 fluid and the porous structure and high oil-holding characteristics of the dietary fiber material, promote the functional component dissolved in Sc-CO2 to penetrate and distribute in the pore network of the dietary fiber material, and be retained on or within the fiber material due to adsorption or subsequent pressure changes.

[0034] (3) Complete the deposition and fixation of the functional component and the preliminary drying of the dietary fiber material by rapid depressurization: After the functional component and the dietary fiber material are in sufficient contact to reach the predetermined loading degree, quickly reduce the pressure in the loading kettle to a level close to atmospheric pressure. Due to the sharp drop in pressure, the density of Sc-CO2 and its ability to dissolve the functional component decrease rapidly, resulting in the previously dissolved functional component precipitating from Sc-CO2 in the form of fine particles or thin films and depositing, crystallizing, or depositing on the inner wall and surface of the pores of the dietary fiber material. At the same time, during this rapid depressurization process, the gasified CO2 will carry away some free water in the dietary fiber material and Sc-CO2 itself (if it exists in a liquid or high-density state in the pores before depressurization), thereby realizing the preliminary drying of the dietary fiber material loaded with the functional component. This step helps to fix the functional component in the fiber material with a high degree of dispersion and form a preliminary micro-embedding structure.

[0035] Step 3: Strengthen the supercritical carbon dioxide loading process of the functional components and implement on-line purification. This step is a key technical feature of the present invention, aiming to improve the loading uniformity and total amount of the functional components in the dietary fiber material, and simultaneously remove trace odor compounds or potential degradation products of the functional components that may exist in the loading system, thereby enhancing the purity and stability of the final product. This step introduces a "combined operation of dynamic perturbation and adsorption purification" in the main process flow of loading the functional components using Sc-CO2 in Step 2.

[0036] This combined operation may specifically include one or two of the following series or parallel sub-operations: (1) Strengthen the mass transfer process by applying dynamic perturbation to the Sc-CO2 fluid: During the loading process in Step 2, instead of the continuous loading method of Sc-CO2 with a constant flow rate or constant pressure, the process conditions of periodically changing the state of the Sc-CO2 fluid in the loading autoclave are adopted. The instantaneous flow rate of the Sc-CO2 fluid passing through the loading autoclave can be adjusted periodically (perturbation is performed every 20 minutes). Such dynamic perturbation operations can enhance the microscopic mass transfer of the functional components in the Sc-CO2 fluid by actively introducing an unsteady flow and dissolution environment, helping to overcome the concentration boundary layer that may form under static or laminar conditions, thereby promoting the more rapid and uniform penetration of the functional components from the Sc-CO2 mainstream fluid into the internal pores of the dietary fiber material and strengthening their adsorption or deposition effect on the fiber surface. Compared with the traditional static or uniform-speed Sc-CO2 loading process using constant conditions, this method can more effectively improve the loading amount and distribution uniformity.

[0037] (2)Purify the loading system by means of on-line adsorption: While performing the aforementioned dynamic perturbation enhanced mass transfer operation, or setting up an independent purification stage in the loading process, temporarily or periodically connect the outlet pipeline of the loading kettle or set up a bypass circulation pipeline to an adsorption device (such as a small adsorption column) filled with adsorbent. A small amount (0.6% relative to the mass of the dietary fiber material) of pre-treated food-grade adsorbent particles (medical-grade activated carbon with an average particle size of 50 microns) is pre-filled in this adsorption device. The Sc-CO2 fluid carrying functional components and having flowed through part of the dietary fiber material bed (or completed a cycle) flows through this adsorption device before being discharged from the loading kettle or during the circulation process. At this time, trace odor precursors contained in the Sc-CO2 fluid, tiny impurities not completely removed from the raw materials, or trace degradation by-products that may be generated by functional components in the Sc-CO2 environment, etc., will be selectively adsorbed and removed by the adsorbent. The adsorbent in this adsorption device can be designed to be replaced after single use, or regenerated after processing several batches of materials. Alternatively, a temporary solid-phase extraction material that has a certain solubility in Sc-CO2 but can be effectively separated from the dietary fiber material and functional components when depressurizing to remove CO2 subsequently can be used in a small amount by premixing it with the dietary fiber material or setting it in the Sc-CO2 flow path. These materials adsorb impurities under supercritical conditions and precipitate or are separated from the product through subsequent steps when depressurizing to remove CO2. This process of on-line and in-situ removing trace unwanted components in the system can better protect the activity of functional components sensitive to subsequent processing and avoid the risk of secondary pollution that may be introduced during the purification process compared with the traditional method of first completing the loading and then performing subsequent purification treatments (such as deodorization, refining) on the product. Through the combined application of the above sub-operations (1) and (2) or selective execution according to actual needs, this step can effectively enhance the functional component loading process without significantly increasing the overall complexity of the process flow, and actively regulate the product purity on-line.

[0038] Step 4: Perform gas displacement deep drying and stabilization treatment on the dietary fiber material loaded with functional components. It is carried out after the rapid depressurization of Sc-CO2 in Step 2 (3) to complete the preliminary drying. Its purpose is to further remove the carbon dioxide that may remain in the product, the tightly bound trace moisture, and the low-boiling volatile odor compounds that were not completely removed in the previous steps, thereby significantly improving the long-term storage stability of the loaded functional components and optimizing the sensory acceptance of the final dietary fiber product.

[0039] This step specifically includes the following operations: After the second-step treatment, most of the CO2 has been vaporized and escaped, the functional components have been deposited and fixed on the dietary fiber material, and the dietary fiber material has reached a preliminary drying state, the product is not immediately removed from the loading device (loading kettle), or the preliminarily dried material is quickly transferred to a closed device dedicated to gas replacement drying for the following "gas replacement deep drying" treatment: (1) Selection and pretreatment of the drying gas: According to product requirements and economic considerations, select one or a combination of several pretreated gases as the replacement and drying medium. In this embodiment, high-purity nitrogen (food-grade nitrogen with a purity of not less than 99.9%) is selected as the inert protective gas. In some cases, if the product characteristics permit and there are special requirements for the flavor of the final product, clean air that has been efficiently filtered (removing dust particles and oil mist) and humidity-adjusted (controlling the relative humidity below 20%) can also be selected, or air with a light natural fragrance obtained by passing such clean air through an aroma generating device equipped with dried natural spices (such as dehydrated flower petals, vanilla pods, etc.). Before use, the selected gas can be adjusted to a temperature of, for example, 35°C according to process needs.

[0040] (2) Operating process of gas replacement drying: Continuously and slowly introduce the selected and pretreated drying gas into the device containing the preliminarily dried dietary fiber material loaded with functional components at a preset flow rate (this flow rate should ensure several effective replacements of the gas volume inside the device within 2 hours). During the ventilation operation, maintain the internal pressure of the device slightly higher than the atmospheric pressure (gauge pressure of 0.5 MPa) to promote the uniform flow and penetration of the gas in the material bed. The drying gas is introduced from one end of the device and discharged from the other end. The discharged gas carries residual CO2 desorbed or evaporated from the dietary fiber material (possibly dissolved in trace amounts of residual moisture or physically adsorbed on the fiber surface), deeper bound water (removed by continuous air flow blowing and diffusion), and low-boiling organic odor compounds that were not completely removed in the previous process steps. The duration of this gas replacement drying process depends on the quantity of the dietary fiber material being processed, its stacking state, the flow rate of the gas used, and the specific requirements for the drying degree and purity of the final product, and usually lasts for 3 hours.

[0041] (3)Drying end judgment and subsequent processing: When the gas displacement drying reaches the preset processing time, or it is determined that the desired drying and purification effects have been achieved by online parameter monitoring of the gas at the equipment outlet (monitoring whether the humidity of the outlet gas reaches the preset low point, or whether the concentration of specific odor compounds drops to a trace level), the gas for drying is stopped. If the material or gas is heated during the gas displacement drying process, after stopping the ventilation, or while gradually reducing the ventilation flow rate, the product is naturally cooled to room temperature or the predetermined discharge temperature in the atmosphere of the drying gas, and then the functional dietary fiber product can be taken out of the equipment and subjected to subsequent weighing and sealed packaging. This "gas displacement deep drying" step, based on preliminary drying, further removes trace volatiles through the gentle and continuous purging effect of a specific atmosphere, which is an effective supplement and improvement to conventional drying methods. It is particularly effective in enhancing the long-term stability of dietary fiber products with load-sensitive functional ingredients and improving their final sensory quality. Compared with drying completed only by reducing the pressure of Sc-CO2, this step can remove residual CO2 and moisture affecting product stability, as well as trace odor substances affecting product flavor, more deeply and thoroughly, thus endowing the final product with better storage performance and broader market application potential.

[0042] Experimental verification To verify the technical effects of the various process steps of the present invention, a series of experimental comparative tests are carried out below to prove the technical effects of the present invention in a quantitative and qualitative manner.

[0043] Experiment 1: Performance test of dietary fiber material carrier 1.1 Experimental purpose Evaluate the effects of different treatment methods on the oil-holding capacity, pore structure characteristics, and surface properties of rice husk dietary fiber, and verify the synergistic effect of the combined pretreatment process of SPORL treatment and ozone oxidation modification.

[0044] 1.2 Experimental method 1.2.1 Sample preparation Control group A: Untreated original rice husk powder; Control group B: Rice husk dietary fiber treated only with SPORL; Control group C: Rice husk dietary fiber treated only with ozone oxidation; Experimental group: Rice husk dietary fiber material pretreated by the combined process of SPORL treatment and ozone oxidation modification according to the method of the present invention.

[0045] 1.2.2 Determination of the oil-holding capacity of dietary fiber Take 5 g of the dried sample and place it in a centrifuge tube; Add soybean oil of known weight (initial weight W0), and mix well for 30 minutes; Centrifuge at 3000 rpm for 10 minutes, and pour out the unabsorbed grease; Weigh the weight of the remaining sample (W1); Oil holding capacity (g / g) = (W1 - 5) / 5; 1.2.3 Analysis of micro-pore characteristics The specific surface area, pore volume and pore size distribution of each sample were measured by nitrogen adsorption method: (1) Sample pretreatment: Vacuum drying at 105 °C for 24 hours (2) Measured by a specific surface area analyzer, and the specific surface area was calculated using the BET equation (3) The pore size distribution was analyzed by the BJH method.

[0046] 1.2.4 Measurement of surface hydrophobicity The surface hydrophobicity of the sample was evaluated by the water droplet contact angle measurement method: (1) Press the sample into a flat sheet (2) At room temperature, use a contact angle measuring instrument to measure the static contact angle of the water droplet on the surface of the sample (3) Each sample was measured 5 times and the average value was taken.

[0047] 1.3 Experimental results 1.3.1 The test results of oil holding capacity are shown in the following table:

[0048] 1.3.2 The results of micro-pore characteristics are shown in the following table:

[0049] 1.3.3 The results of surface hydrophobicity are shown in the following table:

[0050] 1.4 Conclusions The experimental results show that the rice husk dietary fiber material (experimental group) pretreated by the combination of SPORL treatment and ozone oxidation modification shows significantly superior carrier performance compared with other treatment methods: Oil holding capacity: The oil holding capacity of the experimental group reached 4.65 g / g, which was 244% higher than that of the untreated group, 62% higher than that of the single SPORL treatment, and 92% higher than that of the single ozone treatment, proving that the combined pretreatment produced an obvious synergistic effect.

[0051] Micro-pore characteristics: The experimental group had the highest specific surface area (46.8 m² / g) and total pore volume (0.158 cm³ / g), and the pore size distribution tended to be in the medium and small pore size range (5 - 60 nm). This pore structure characteristic was beneficial to the deep adsorption and uniform distribution of functional components.

[0052] Surface hydrophobicity: The water droplet contact angle of the experimental group (98.7°) was significantly higher than that of other groups, indicating that its surface had stronger hydrophobic properties, which was extremely beneficial for loading lipophilic functional components.

[0053] The above results fully verified that the combined pretreatment process of SPORL treatment and ozone oxidation modification adopted in the present invention could synergistically improve the microscopic pore structure and surface chemical properties of rice husk dietary fiber, significantly enhance its oil-holding capacity as a carrier of functional components, and lay a good foundation for subsequent efficient loading of functional components.

[0054] Experiment 2: Test on the loading effect of functional components 2.1 Experimental purpose To evaluate the comparative effect of the supercritical CO2 loading method and the traditional solvent loading method, and verify the influence of the combined operation of dynamic perturbation and adsorption purification on the loading uniformity and purity of functional components.

[0055] 2.2 Experimental method 2.2.1 Samples and materials Dietary fiber material: The rice husk dietary fiber material pretreated by the combined process of SPORL treatment and ozone oxidation modification in Experiment 1 was used; Functional component: β-carotene was selected as a representative lipophilic functional component; Control solvent: A mixed solvent of analytical pure ethanol and n-hexane (volume ratio 1:1).

[0056] 2.2.2 Comparison of loading methods Control group A: Traditional solvent loading method; Dissolve β-carotene in the ethanol-n-hexane mixed solvent (concentration 5 mg / mL); Soak the dietary fiber material in the above solution, and the solid-liquid ratio is 1:10 (g / mL); Soak at room temperature for 4 hours, and stir every 30 minutes during this period; After vacuum filtration, dry at 50 °C under vacuum for 12 hours; Record the loading amount of β-carotene; Control group B: Static supercritical CO2 loading method; Layer the dietary fiber material and β-carotene (mass ratio 10:1) in the supercritical extraction tank; Maintain at 45 °C and 20 MPa for 2 hours; Slowly depressurize at a rate of 5 MPa / min; Record the loading amount of β-carotene; Experimental group: Dynamic perturbation supercritical CO2 loading method (the method of the present invention); Layer the dietary fiber material and β-carotene (in a mass ratio of 10:1) in the supercritical extraction tank; Under the basic conditions of 45 °C and 20 MPa, adjust the pressure every 30 minutes (with a fluctuation of ±1 MPa); Introduce 0.5% by volume of food-grade ethanol as a co-solvent every 60 minutes; Set up an on-line adsorption device (filled with activated carbon, 0.5% of the mass of the dietary fiber material) during the loading process; After 2 hours of loading, rapidly depressurize at a rate of 10 MPa / min; Record the loading amount of β-carotene.

[0057] 2.2.3 Determination of Loading Effect Determination of Loading Amount: Take 0.5 g of the dietary fiber material loaded with β-carotene; Add 10 mL of n-hexane extraction solution; Extract by ultrasound for 30 minutes and filter; Measure the absorbance at a wavelength of 450 nm using a spectrophotometer; Calculate the loading amount (mg / g) according to the β-carotene standard curve.

[0058] Determination of Loading Uniformity: Randomly take 10 small samples (each 50 mg) from different positions of each sample; Measure the β-carotene content of each small sample separately; Calculate the relative standard deviation (RSD%) as the uniformity index.

[0059] Determination of Purity of Loaded Product: Use high performance liquid chromatography (HPLC) to detect possible degradation products in the sample; Chromatographic conditions: C18 reverse phase column, acetonitrile-water mobile phase, detection wavelength of 450 nm; Calculate the purity percentage of β-carotene.

[0060] 2.3 Experimental Results 2.3.1 Comparison of Loading Effects of Functional Components, as shown in the following table:

[0061] 2.3.2 Comparison of Energy Consumption and Time during Loading Process, as shown in the following table:

[0062] 2.4 Conclusion The experimental results show that the dynamic perturbation supercritical CO2 loading method adopted in the present invention has significant advantages compared with the traditional solvent loading method and the static supercritical CO2 loading method: Loading efficiency: The loading amount of functional components by the dynamic perturbation supercritical CO2 method reaches 7.65 mg / g, which is 79% higher than that of the traditional solvent method and 31% higher than that of the static supercritical CO2 method, proving that dynamic perturbation can effectively enhance the mass transfer process and improve the penetration and retention of functional components in dietary fiber materials.

[0063] Loading uniformity: The loading uniformity of the dynamic perturbation supercritical CO2 method is excellent, with a relative standard deviation of only 6.3%, far lower than that of the traditional solvent method (18.7%) and the static supercritical CO2 method (12.4%), indicating that the method of the present invention can distribute functional components more uniformly in dietary fiber materials.

[0064] Product purity: Through online adsorption purification, the purity of β-carotene in the product prepared by the dynamic perturbation supercritical CO2 method is as high as 99.2%, and the solvent residue is extremely low (<2 ppm), indicating that this method has excellent green environmental protection characteristics.

[0065] Process efficiency: Although the energy consumption of the dynamic perturbation supercritical CO2 method is slightly higher, its total processing time is significantly shortened, and no subsequent purification treatment steps are required, so it has higher production efficiency and lower environmental impact from the overall process perspective.

[0066] In summary, the supercritical CO2 loading method combining dynamic perturbation and adsorption purification of the present invention shows obvious advantages in terms of functional component loading efficiency, uniformity, product purity and process greenness, providing efficient and reliable technical support for the preparation of high-quality functional dietary fiber products.

[0067] Experiment 3: Testing of product purity, stability and sensory quality 3.1 Experimental purpose Evaluate the effects of the "online adsorption purification" and "gas replacement deep drying" processes in the present invention on the purity, stability and sensory quality of functional dietary fiber products.

[0068] 3.2 Experimental method 3.2.1 Sample preparation Control group A: β-carotene-loaded dietary fiber prepared by the traditional solvent loading method; Control group B: β-carotene-loaded dietary fiber prepared by static supercritical CO2 loading without gas replacement deep drying; Experimental group: β-carotene-loaded dietary fiber prepared by the method of the present invention (dynamic perturbation supercritical CO2 loading + online adsorption purification + gas replacement deep drying); 3.2.2 Determination of Residual Substance Content Analysis of solvent residue: The content of residual organic solvents in the sample was determined by headspace gas chromatography; Chromatographic conditions: HP-VOC chromatographic column, programmed temperature rise, FID detector; Detection targets: ethanol, n-hexane, carbon dioxide.

[0069] Analysis of off-odor substances: Solid-phase microextraction-gas chromatography-mass spectrometry (SPME-GC-MS) was used; Main detection targets: low molecular weight aldehydes and ketones, sulfur-containing compounds, degradation products of terpenes, etc.

[0070] 3.2.3 Stability Test Accelerated storage stability experiment: Three groups of samples were stored in an environment of 45 °C and relative humidity of 75%; Samples were taken for analysis at 0, 7, 14, 21, and 28 days; The retention rate of β-carotene content was determined; The antioxidant activity (DPPH radical scavenging ability) of the sample was determined.

[0071] Light stability experiment: Three groups of samples were placed under simulated fluorescent lamp irradiation (4500 ± 500 lux); Samples were taken for analysis after irradiation for 0, 6, 12, 24, and 48 hours; The retention rate of β-carotene content was determined; The color change of the sample was observed (Lab* value was measured using a color difference meter).

[0072] 3.2.4 Sensory Quality Evaluation Electronic nose analysis: An electronic nose instrument was used to analyze the odor characteristic spectrum of the sample; The odor characteristic differences of different samples were distinguished according to principal component analysis (PCA).

[0073] Expert sensory evaluation: Ten trained sensory evaluation experts were invited; Evaluation indicators: odor intensity, off-odor degree, overall odor acceptance; The scoring used a 9-point system (1 = extremely poor, 9 = extremely good).

[0074] Application simulation test: Each sample was added to yogurt and biscuits (the addition amount was 1%); Sensory evaluation was carried out after production and after storage for 7 days; Evaluation indicators: flavor coordination, overall acceptance.

[0075] 3.3 Experimental results 3.3.1 Test results of residual substance content are shown in the following table:

[0076] 3.3.2 Test results of accelerated storage stability are shown in the following table:

[0077] 3.3.3 Test results of light stability are shown in the following table:

[0078] 3.3.4 Sensory quality evaluation results are shown in the following table:

[0079] 3.4 Conclusions The experimental results show that the functional dietary fiber product processed by the "online adsorption and purification" and "gas displacement and deep drying" processes of the present invention has significant advantages in terms of purity, stability and sensory quality: Product purity: The total residual solvent amount (2.8 ppm) and the total concentration of off-flavor substances (24.6 ppb) in the experimental group samples are significantly lower than those in control group A (248.5 ppm and 673.4 ppb) and control group B (36.7 ppm and 189.5 ppb), indicating that the process of the present invention can effectively remove residual organic solvents, carbon dioxide and off-flavor compounds in the product, and significantly improve the product purity.

[0080] Product stability: Under accelerated storage conditions, the retention rate of β-carotene in the experimental group still reached 87.5% after 28 days, which is much higher than that in control group A (51.7%) and control group B (65.8%) Under light conditions, the retention rate of β-carotene in the experimental group still had 68.4% after 48 hours, while that in control group A was only 25.7%, and that in control group B was 41.3% The retention rate of antioxidant activity is positively correlated with the β-carotene content, indicating that the process of the present invention can better protect the biological activity of functional components Sensory quality: The experimental group samples are superior to the control group in sensory indicators such as odor intensity, off-flavor degree, overall odor acceptance, etc. Especially in actual food applications (yogurt and biscuits), they show better flavor coordination, with scores as high as 8.4 - 8.6 points (out of 9 points).

[0081] The analysis results of the electronic nose show that the products processed by the technology of the present invention have a lighter and more neutral odor characteristic spectrum, reducing the odor interference generated during the raw material and processing processes, and being more conducive to the application of functional dietary fiber in various foods.

[0082] In summary, the process combination of "online adsorption and purification" and "gas displacement and deep drying" in the present invention can significantly improve the purity, stability and sensory quality of functional dietary fiber products, especially showing outstanding effects in improving the long-term storage stability and sensory acceptance of products, laying a technical foundation for the wide application of functional dietary fiber products in the food industry.

[0083] Experiment 4: Application performance test of functional dietary fiber products 4.1 Experimental purpose Evaluate the sustained-release performance, bioavailability and the impact on food quality of the functional dietary fiber products prepared by the present invention in actual food applications.

[0084] 4.2 Experimental method 4.2.1 Sample preparation Use the three groups of samples in Experiment 3: (1) Control group A: β-carotene-loaded dietary fiber prepared by the traditional solvent loading method; (2) Control group B: β-carotene-loaded dietary fiber prepared by static supercritical CO2 loading without gas displacement and deep drying; (3) Experimental group: β-carotene-loaded dietary fiber prepared by the method of the present invention (dynamic perturbation supercritical CO2 loading + online adsorption and purification + gas displacement and deep drying).

[0085] 4.2.2 Test of the sustained-release performance of functional components In vitro digestion simulation experiment: Adopt a continuous three-stage in vitro digestion model (oral cavity, stomach, small intestine); Oral cavity stage: The sample is treated in artificial saliva for 10 minutes (pH 7.0, containing α-amylase); Stomach stage: The pH is adjusted to 2.0, pepsin is added, and the treatment is carried out at 37°C for 2 hours; Small intestine stage: The pH is adjusted to 6.8, trypsin, bile salts and lipase are added, and the treatment is carried out at 37°C for 4 hours; Samples are taken at different time points to measure the release amount of β-carotene (expressed as the release percentage).

[0086] Test of long-term sustained-release behavior: Add the samples to the simulated food matrix (at an addition amount of 1%); Simulated food matrix A: Yogurt system with 20% oil content (pH 4.5); Simulated food matrix B: Mixture of biscuit powder and water (pH 6.8); Store at 37°C and take samples at 0, 4, 8, 12, 24, 48, and 72 hours. Determine the cumulative release amount of β-carotene.

[0087] 4.2.3 Bioavailability assessment β-carotene absorption experiment in bilayer vesicles after simulated digestion: Contact the supernatant of the in vitro digested sample with in vitro bilayer liposomes; After incubating at 37°C for 2 hours, determine the content of β-carotene in the liposomes; Calculate the bioavailability index.

[0088] Caco-2 cell absorption experiment: Co-culture the in vitro digestion products of the three groups of samples with a monolayer of Caco-2 cells; After incubating for 4 hours, determine the content of β-carotene in the cells; Calculate the absorption efficiency (%).

[0089] 4.2.4 Food application impact test Impact on food physical properties: Add the three groups of samples to bread, cookies, and yogurt respectively (the addition amount is 0.5%); Determine the physical indexes such as the texture characteristics, volume, and pH value of the food before and after addition; Use a texture analyzer to measure indexes such as hardness, elasticity, and chewiness.

[0090] Impact on food storage stability: Prepare functional bread and yogurt added with the three groups of samples; Store under normal storage conditions (bread: room temperature, yogurt: 4°C); Monitor the changes in the β-carotene content and product quality of the samples at 0, 3, 7, 14, and 21 days.

[0091] 4.3 Experimental results 4.3.1 Release characteristics of functional components in the in vitro digestive system, as shown in the following table and Figure 1 as follows:

[0092] 4.3.2 Long-term sustained release characteristics in the simulated food system, as shown in the following table and Figure 2 as follows:

[0093] 4.3.3 Bioavailability assessment results, as shown in the following table and Figure 3 as follows:

[0094] 4.3.4 The food application impact test results are as follows in the table and Figure 4 shown as follows:

[0095] 4.4 Conclusions The experimental results show that the functional dietary fiber product prepared by the present invention has significant advantages in application performance: Controlled release characteristics: In the simulated digestive system, the experimental group samples showed obvious sustained and controlled release characteristics. The total digestion rate at 6 hours was 85.6%, lower than that of control group A (95.8%) and control group B (92.3%), indicating that the process of the present invention can form a more stable carrier-functional ingredient composite structure.

[0096] In the simulated food systems (yogurt and biscuits), the experimental group samples also showed a more gentle release curve. The release rates after 72 hours were 81.2% and 77.4% respectively, while the control groups were basically released within 48 hours. This slow release characteristic is beneficial to the stability of functional ingredients during food processing, storage and digestion, and prolongs their effective action time.

[0097] Improved bioavailability: Although the total release rate of the experimental group samples in the simulated digestive system was slightly lower, their bioavailability index (0.75) was significantly higher than that of control group A (0.42) and control group B (0.58).

[0098] In the double-layer vesicle absorption experiment and Caco-2 cell absorption experiment, the absorption rates of the experimental group samples reached 52.8% and 34.6% respectively, both significantly higher than those of the two control groups. This indicates that the process of the present invention improves the bioaccessibility of β-carotene by optimizing the microstructure and surface properties of the dietary fiber carrier, enabling it to be more effectively absorbed and utilized by the human body.

[0099] Food application impact: After adding the three groups of samples to bread and yogurt, the impact on the basic physical properties (specific volume, hardness, pH value, viscosity, etc.) of the products was minimal, and the impact of the experimental group was the smallest, indicating that the functional dietary fiber product prepared by the present invention has good food ingredient compatibility.

[0100] During food storage, the retention rate of β-carotene in the experimental group samples was significantly higher than that of the control groups. The retention rates of bread and yogurt after 21 days of storage reached 78.3% and 83.7% respectively. This excellent storage stability is of great significance for extending the shelf life of functional foods and maintaining their nutritional value.

[0101] Comprehensive application value: The functional dietary fiber product prepared by the present invention provides a solid foundation for its application in high-value-added products such as functional foods and dietary supplements through the excellent performance combination of "controlled release - high bioavailability - low-impact addition".

[0102] This product can not only play its original physiological function as dietary fiber, but also serve as a carrier for functional ingredients to provide stable and long-lasting nutrient delivery, realizing double functional values.

[0103] In summary, the functional dietary fiber product prepared based on the process combination of dynamic perturbation supercritical CO2 loading, online adsorption purification and gas displacement deep drying shows excellent slow-release characteristics, bioavailability and stability in actual food applications, fully verifying the practicality and innovation of the process of the present invention in developing high-value functional food raw materials.

[0104] Comprehensive analysis of experimental results Through the above four groups of systematic experimental verifications, the technical effects of the present invention were comprehensively evaluated from multiple dimensions such as carrier performance, loading efficiency, product quality and application characteristics. The experimental results show that: 1. Regarding the improvement of the carrier performance of dietary fiber materials The combined pretreatment process of SPORL treatment and ozone oxidation modification can synergistically optimize the microstructure and surface properties of rice husk dietary fiber, increasing its oil-holding capacity by 244% (compared with the untreated group), with a specific surface area of 46.8 m² / g and the water droplet contact angle increased to 98.7°, forming an ideal carrier for functional ingredients. The significant improvement of this series of parameter indicators is the basic guarantee for subsequent efficient loading.

[0105] 2. Regarding the optimization and greening of the functional ingredient loading process Compared with the traditional solvent method and static supercritical CO2 method, the combined operation of dynamic perturbation supercritical CO2 loading and online adsorption purification has significant advantages in loading efficiency and uniformity (the loading amount is increased by 31 - 79%, and the uniformity RSD is reduced to 6.3%). At the same time, this method hardly produces solvent residues (<2 ppm, only 1 / 124 of the traditional method), and the processing time is shortened (3.6 hours, only 1 / 4.6 of the traditional method), reflecting the "high efficiency" and "greenness" of the process.

[0106] 3. Regarding the improvement of product purity, stability and sensory quality For products processed by the processes of "online adsorption and purification" and "gas displacement and deep drying", the total residual solvent and the total concentration of odor substances are reduced to 2.8 ppm and 24.6 ppb respectively, which are significantly lower than those of the control group. The retention rates of β-carotene under accelerated storage and light conditions are increased by 35.8% and 42.7% respectively, and the overall acceptance in the sensory evaluation reaches 8.2 points (on a 9-point scale), fully demonstrating the remarkable effects of the process of the present invention in ensuring the product stability and sensory quality.

[0107] 4. Regarding the improvement of the application performance and value of the product The functional dietary fiber product prepared by the present invention exhibits ideal sustained-release characteristics in simulated digestion and food systems, and the bioavailability index is increased to 0.75. It has excellent stability (retention rate of 78.3% - 83.7% after 21 days) and good ingredient compatibility in practical food applications such as bread and yogurt. This performance combination of "controlled release - high bioavailability - low-impact addition" provides new application ideas for the development of functional foods.

[0108] The above embodiments of the present invention have been described, but the embodiments are not limited to the above specific implementation manners. The above specific implementation manners are merely illustrative rather than restrictive. Under the inspiration of the present embodiment, those of ordinary skill in the art can also make more equivalent embodiments in various forms, all of which fall within the protection scope of the present embodiment.

Claims

1. A plant dietary fiber extraction process, characterized in that, It includes the following steps: Step 1: Pretreat and modify the plant raw materials to obtain dietary fiber materials; The pretreatment and modification include sequentially performing chemical impregnation treatment, steam penetration explosion treatment, and ozone oxidation modification treatment on the plant raw materials; Step 2: Load functional components onto the dietary fiber materials using supercritical carbon dioxide and perform preliminary drying; Dissolve the functional components in the supercritical carbon dioxide fluid to form a solution carrying the functional components, bring the solution into contact with the dietary fiber materials to load the functional components, and then deposit the functional components on or within the dietary fiber materials by rapid pressure reduction and complete preliminary drying; Step 3: Strengthen the supercritical carbon dioxide loading process of the functional components and implement on-line purification; During the loading process in Step 2, apply dynamic physical disturbance to the supercritical carbon dioxide fluid carrying the functional components to strengthen the mass transfer and distribution of the functional components to the dietary fiber materials, and make the supercritical carbon dioxide fluid contact with a temporarily arranged adsorbent to remove impurities in the fluid on-line; Step 4: Perform gas displacement deep drying treatment on the dietary fiber materials loaded with functional components; After the preliminary drying in Step 2, introduce the pretreated inert gas or clean air into the equipment containing the dietary fiber materials loaded with functional components, and further remove the residual carbon dioxide, moisture, and volatile odor compounds through gas purging.

2. The extraction process of a plant dietary fiber according to claim 1, wherein, The chemical impregnation treatment in Step 1 uses a dilute alkali solution or a dilute sulfite aqueous solution and is impregnated for 1 - 3 hours under the temperature condition of 50 - 90°C.

3. The plant dietary fiber extraction process according to claim 1, characterized in that, The process conditions for the steam penetration explosion treatment in Step 1 are: the pressure in the equipment is maintained at 1.0 - 2.5 MPa, and the pressure holding time is 1 - 5 minutes.

4. A plant dietary fiber extraction process according to claim 1, characterized in that, The process conditions for the ozone oxidation modification treatment in Step 1 are: disperse the materials after the steam penetration explosion treatment in water to form a suspension, introduce a gas containing an ozone concentration of 10 - 100 mg / L into the suspension, and react for 0.5 - 2 hours under the temperature of 20 - 50°C and the pH value of 5 - 7.

5. A plant dietary fiber extraction process according to claim 1, characterized in that, The operating conditions for loading the functional components with supercritical carbon dioxide in Step 2 are: temperature 35 - 60°C, pressure 10 - 30 MPa.

6. A plant dietary fiber extraction process according to claim 1 or 5, characterized in that, The ways to apply dynamic physical disturbance in Step 3 include: periodically changing the instantaneous flow rate or operating pressure of the supercritical carbon dioxide fluid passing through the loading equipment, or intermittently introducing a food-grade co-solvent in the main supercritical carbon dioxide flow path.

7. A process for extracting plant dietary fiber according to claim 1, characterized in that, The ways to remove impurities in the fluid on-line in Step 3 include: making the supercritical carbon dioxide fluid carrying the functional components flow through an adsorption device filled with food-grade adsorbent particles before discharging from the loading equipment or during the circulation process, and the adsorbent is selected from one or more of activated carbon, diatomaceous earth, or molecular sieve.

8. A process for extracting plant dietary fiber according to claim 1, characterized in that, The gas used for gas displacement deep drying treatment in Step 4 is nitrogen or purified air.

9. A process for extracting plant dietary fiber according to claim 1, characterized in that, The operating conditions for gas displacement deep drying treatment in Step 4 are: the internal pressure of the equipment is maintained at a gauge pressure higher than the atmospheric pressure by 0.01 - 0.1 MPa, and the gas displacement time is 0.5 - 4 hours.

10. A process for extracting plant dietary fiber according to claim 1, characterized in that, The plant raw material is rice husk; the functional components are fat-soluble nutrients or essential oil substances extracted from plants.

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