Neutralized oil moderate refining method based on negative pressure-cavitation coupling assistance

Abstract

The invention discloses a method for moderately refining neutralized oil based on negative pressure-cavitation coupling assistance, and belongs to the technical field of refined vegetable oil. The method comprises the following steps: mixing a special spherical porous functional adsorbent with neutralizing oil, refining at 40-90 DEG C under a certain vacuum degree by adopting a three-stage gradient ultrasonic process, and then separating. The adsorbent is prepared by taking polylactic acid and polyethylene glycol as double templates, has a gradient pore structure, is modified by citric acid, and can selectively adsorb impurities. The ultrasonic technology follows the high-medium-low power dynamic change and is matched with the adsorption process. According to the method, refining is rapidly completed at low temperature, the acid value of the finished product oil is smaller than or equal to 0.2 mg KOH / g, the peroxide value is smaller than or equal to 0.02 g / 100g, the retention rate of vitamin E and the retention rate of phytosterol both exceed 97%, and unification of efficient impurity removal and extremely high nutrition retention is achieved.

Description

Technical Field

[0001] This invention belongs to the field of refined vegetable oil technology, specifically relating to a method for moderately refining neutralized oil based on negative pressure-cavitation coupling assistance. Background Technology

[0002] Vegetable oils are an essential food source for human survival. They generally exist in liquid form at room temperature and are one of the main sources of energy for humans. The industry generally refers to the crude oil obtained through methods such as hot pressing and cold pressing as crude oil. Crude oil has a complex composition, containing not only impurities such as water, protein, colloids, and pigments, but also contaminants introduced during the production process. These contaminants affect the appearance of the oil and negatively impact its storage. Therefore, in the production of vegetable oils, it is necessary to remove impurities while retaining as many beneficial components as possible. Refining processes can significantly improve the quality of crude oil and reduce its acid value and peroxide value.

[0003] In the oil processing industry, refining is a crucial step determining product quality. However, traditional over-refining, in pursuit of ultimate purity, leads to the loss of micronutrients, bland flavor, and may even produce harmful substances such as trans fatty acids. Furthermore, it is energy-intensive and emits high levels of pollutants, failing to meet environmental protection requirements. It is worth noting that both chemical and physical refining involve high-temperature decolorization and deodorization processes. Traditional oil decolorization processes primarily rely on adsorbents such as activated clay. These materials, limited by their inherent properties, are mostly single-use and difficult to regenerate, resulting in large amounts of waste containing residual oil. This not only incurs high processing costs but also exacerbates environmental pollution. Deodorization processes face the dual problems of excessive energy consumption and reduced quality. Physical deodorization requires high temperatures (200-260℃) and high vacuum, accounting for over 60% of total refining energy consumption. It causes oxidation of polyunsaturated fatty acids, loss of trace elements such as vitamin E, and the potential risk of trans fatty acid formation. Chemical deodorization is prone to solvent residue and presents challenges in wastewater treatment. Furthermore, the synergy between the decolorization and deodorization processes is poor. Residual metal ions after decolorization can accelerate the oxidation of oils during deodorization, while the high-temperature environment of deodorization may cause the removed pigments to regenerate, affecting the stability of the final product and fully highlighting the limitations of traditional processes.

[0004] For example, Chinese patent application CN201710258655.2 discloses a physical refining process for vegetable oil, which includes the following steps: step 1) citric acid chelation, step 2) acid treatment, step 3) centrifugation, step 4) secondary centrifugation, step 5) decolorization, step 6) dewaxing and deodorization, and step 7) preparation of feed additives.

[0005] While this process has some effect on reducing acid value, it still fails to eliminate the damage to nutrients caused by high-temperature deodorization and does not solve the pollution problem caused by waste bleaching clay. Therefore, the problem of "over-refining" in the oil refining process urgently needs attention. The excessive pursuit of sensory indicators and storage stability has led to negative impacts such as the loss of functional components and a decline in oil quality, contradicting the modern food industry's development philosophy of "nutrition and health." Therefore, breaking free from the constraints of the existing high-temperature refining model and developing new low-temperature, environmentally friendly refining technologies has become a key task in promoting the upgrading of the oil industry. Summary of the Invention

[0006] This invention addresses the problems existing in the prior art by providing a low-temperature, environmentally friendly oil refining method. It aims to achieve moderate refining of neutralized oil under mild conditions through negative pressure-cavitation coupling with an auxiliary functional adsorbent, thus solving the problems of nutrient loss, high energy consumption, large pollutant emissions, and low adsorbent utilization caused by high temperatures in traditional refining processes. The method of this invention mixes the functional adsorbent with the neutralized oil, utilizes a negative pressure environment to lower the system temperature, and avoids the destruction of beneficial components of the oil by high temperatures. Simultaneously, the local high-temperature and high-pressure microenvironment generated by cavitation, along with strong shearing and stirring effects, significantly enhances the mass transfer efficiency and interaction between the functional adsorbent and impurities in the oil, improving the adsorption and refining effect. The spherical porous composite functional adsorbent used has a rich pore structure and specific surface chemical morphology. After modification with citric acid solution, it exhibits excellent selective adsorption capacity for impurities such as pigments, trace metal ions, and residual colloids in the oil, and is easily separated from the oil, effectively reducing the amount of adsorbent used and simplifying subsequent separation. By precisely controlling parameters such as negative pressure, temperature, ultrasonic cavitation power, and time during the refining process, and by conducting rigorous quality testing and evaluation of the finished oils, it is possible to maximize the retention of natural vitamin E, phytosterols, and other functional components in the oils while ensuring that they meet the requirements for appropriate refining (such as meeting the relevant national standards for color, acid value, peroxide value, etc.). This enhances the nutritional value and flavor quality of the oils, while reducing production energy consumption and environmental impact, aligning with the development trend of modern green food processing.

[0007] To achieve the above-mentioned technical objectives, the technical solution adopted by the present invention is as follows: A method for moderately refining neutralized oil based on negative pressure-cavitation coupling includes the following steps: (1) Mix the functional adsorbent with the neutralizing oil in a certain proportion; (2) Refine the homogeneous system in a negative pressure-cavitation environment; (3) Separate the functional adsorbent and refined oil to obtain a moderately refined finished oil; (4) Conduct quality testing and evaluation of the finished oil products, and then fill and store them.

[0008] The neutralized oil is one or more of the following: rapeseed oil, soybean oil, tea seed oil, camellia seed oil, olive oil, corn oil, and sunflower seed oil, which have undergone degumming and deacidification. Degumming and deacidification can be carried out with reference to existing technical methods. For example, degumming can be carried out by hydration degumming or acid degumming, and deacidification can be carried out by physical distillation or chemical alkali refining to ensure the effective removal of major impurities such as phospholipids and free fatty acids.

[0009] Furthermore, the neutralizing oil is rapeseed oil or soybean oil that has undergone degumming and deacidification.

[0010] Furthermore, the functional adsorbent is a spherical porous composite adsorbent, and its preparation method is as follows: (a) The porous material, the first template agent, the second template agent and deionized water are mixed in a mass ratio of (6-8):(0.5-2):(0.3-1.5):(3-5) and ball-milled to form a uniform slurry; (b) The slurry is spray-dried to form spherical precursor particles; (c) The spherical precursor particles are subjected to programmed temperature-controlled calcination, and successively undergo the first template agent decomposition and pore-forming stage, the second template agent decomposition and pore-forming stage, and the high-temperature stabilization stage to obtain the spherical porous functional adsorbent; before use, the spherical porous functional adsorbent is impregnated with a 0.5-5 wt% citric acid solution and dried at 100-120℃.

[0011] Furthermore, the porous material is one or more of activated clay, activated carbon, diatomaceous earth, attapulgite, zeolite, and sepiolite.

[0012] Furthermore, the first template agent is polylactic acid, and the second template agent is polyethylene glycol; the programmed temperature-controlled calcination specifically involves: under an inert atmosphere, first heating to 200-240℃ and holding for 1-2 hours to decompose polyethylene glycol; then heating to 300-350℃ and holding for 1.5-2.5 hours to pyrolyze and carbonize polylactic acid; finally, calcining at 450-550℃ for 2-3 hours in air to remove residual carbon.

[0013] Furthermore, the amount of adsorbent added is 1.0 - 3.0 wt% of the neutralized oil mass.

[0014] Furthermore, the negative pressure-cavitation environment refers to placing a mixture containing a functional adsorbent and neutralizing oil in a container and evacuating it to a specified vacuum level, maintaining the vacuum level, keeping the system temperature, and applying ultrasonic waves to induce cavitation; wherein, the vacuum level is controlled at ≤-0.1 MPa and the temperature is 40-90℃.

[0015] Furthermore, the ultrasound employs a gradient ultrasound process, specifically: the first stage has a power of 700-750W and an ultrasound time of 1-3 minutes; the second stage has a power of 550-600W and a time of 10-15 minutes; and the third stage has a power of 450-500W and a time of 20-30 minutes.

[0016] Further, in step (3) the separation method is as follows: after the reaction is completed, the reaction system is cooled to room temperature, the vacuum is slowly broken, the mixture is transferred to a centrifuge for centrifugation, the supernatant is collected, filtered through a filter membrane, and then placed in a refrigerator at 4°C for testing.

[0017] Furthermore, step (4) of the quality evaluation of moderately refined oils includes the detection of acid value, peroxide value, and oxidative stability of refined oils, as well as the retention rate of relevant major micronutrient components. Among them, acid value, peroxide value, and oxidative stability are tested according to national standards GB 5009.229-2025 "National Food Safety Standard - Determination of Acid Value in Food", GB 5009.227-2023 "National Food Safety Standard - Determination of Peroxide Value in Food", and GB / T 21121-2024 "Determination of Oxidative Stability of Animal and Vegetable Oils (Accelerated Oxidation Test)", respectively. The detection of micronutrients is carried out according to the methods specified in the national standards.

[0018] Furthermore, the quality of the resulting finished oil meets the physicochemical indicators of edible vegetable oils in the national standard GB 2716-2018 "National Food Safety Standard for Vegetable Oils".

[0019] The core of this invention lies in two synergistically innovative technical features: first, the creative use of a dual-template agent synergistic pore-forming technology to prepare spherical porous composite functional adsorbents; and second, the matching application of a three-stage gradient ultrasonic process. The organic combination of these two features enables highly efficient and selective refining of neutralized oils under mild conditions.

[0020] 1. Spherical morphology and easy separation: Through spray drying and template agent shaping, the adsorbent is a regular spherical particle (particle size controllable). Its good flowability and large size (compared to nanoparticles) make it possible to achieve efficient and rapid separation from oil after refining through simple sieving or low-speed centrifugation. This completely solves the industry problems of difficult filtration of traditional powdered activated clay, high oil content in waste residue, and easy caking, reducing subsequent processing costs and environmental burden.

[0021] 2. A gradient porous structure is constructed using dual template agents, resulting in a doubling of adsorption capacity and mass transfer efficiency. The key material innovation of this invention lies in the use of polylactic acid (PLA) and polyethylene glycol (PEG) as dual template agents. Through precisely controlled programmed temperature rise, PEG decomposes at a relatively low temperature (~220°C), primarily creating abundant mesopores (2-50 nm) within the porous adsorbent matrix. Subsequently, PLA undergoes pyrolysis and carbonization at a higher temperature (~320°C) and is ultimately removed, forming a continuous macroporous (50-300 nm) framework. This unique "macropore-mesopore" gradient pore structure provides hierarchical diffusion pathways and matching adsorption spaces for impurities of different molecular sizes in oils (such as macromolecular pigments, colloids, and small-molecule polar oxides). Macropores facilitate the rapid transport of impurity molecules to the adsorbent interior, while mesopores provide a large specific surface area (up to 350 m²). 2 Deep adsorption of impurities (above / g) was achieved, thus simultaneously optimizing adsorption capacity and adsorption kinetics. Finally, post-treatment with citric acid solution introduced polar functional groups such as carboxyl groups onto the adsorbent surface. These functional groups exhibit stronger affinity and selective adsorption capacity for polar impurities in oils (such as phospholipids, trace metal ions, and free fatty acids), while showing weaker adsorption for neutral triglyceride molecules. This significantly reduced the entrainment loss of neutral oils (i.e., active ingredients) while efficiently removing impurities.

[0022] 3. Precise matching of gradient ultrasonic technology with the adsorption process to achieve process enhancement and protection: This invention abandons fixed ultrasonic power and innovatively adopts a three-stage gradient power of "high-medium-low". The first stage, high power (700-750W), generates a strong cavitation effect in the initial 1-3 minutes. The generated microjets and shock waves can instantly break the agglomeration of impurities (such as pigment polymers and micelles) in the oil and strongly disperse the spherical adsorbent, fully exposing its surface and creating optimal initial conditions for rapid adsorption. The second stage, medium power (550-600W), maintains a moderate cavitation intensity in the following 10-15 minutes, continuously providing mass transfer driving force and promoting the diffusion of dispersed impurity molecules to the surface and internal gradient channels of the adsorbent. This is the main body of the adsorption process and the guarantee of efficiency. The third stage, with low power (450-500W), provides a gentle cavitation environment in the final stage (total time 20-30 minutes), aiming to complete the "finishing touches" of deep adsorption while avoiding two negative impacts that may result from continuous high energy input: first, impurities and other components already adsorbed within the pores of the adsorbent (especially within mesopores) may desorb due to severe disturbance; second, spherical adsorbent particles may experience mechanical wear or breakage due to prolonged high-intensity cavitation impact. This dynamically matched power strategy achieves an optimal balance between refining efficiency and product quality (nutrient retention, adsorbent integrity).

[0023] In summary, the beneficial effects of the technical solution of this invention are as follows: The spherical gradient porous adsorbent prepared in this invention provides an ideal target for gradient ultrasound processes. Its spherical structure and high mechanical strength enable it to withstand the impact of high-power ultrasound in the first stage without easily pulverizing; its abundant internal pores provide a large working space for continuous cavitation microfluidics in the medium and low power stages, enhancing mass transfer within the pores. The porous microstructure on the surface further increases the contact area with oils and significantly improves mass transfer efficiency.

[0024] Under negative pressure (≤-0.1MPa), the boiling point of the system decreases, which helps to remove low-boiling-point odor substances. At the same time, negative pressure lowers the cavitation threshold of the liquid, which allows for a more significant cavitation effect under the same ultrasonic power. This, combined with gradient ultrasound, forms a dual enhancement of "negative pressure-cavitation", further improving refining efficiency.

[0025] Through the aforementioned synergistic effect, the method of this invention, using only 1.0-3.0 wt% adsorbent at a low temperature of 40-90℃, can quickly bring refined oil to meet national standards. Particularly noteworthy is the high retention rate of Vitamin E (over 98%) and phytosterols (over 97%) in the finished oil, significantly higher than traditional high-temperature processes (typically below 85%), with excellent reductions in acid value and peroxide value. The entire process features low energy consumption, no harmful solvent addition, easily separable and potentially regenerable adsorbent, achieving a green, efficient, and highly nutrient-retaining refined oil product. Attached Figure Description

[0026] Figure 1 These are electron microscope images of the spherical porous composite adsorbent of Example 1 of the present invention at different magnifications; Figure 2 This is a pore distribution diagram of the spherical porous composite adsorbent obtained in Example 1 of the present invention; Figure 3 Electron micrographs of the surface morphology of the porous composite adsorbents in Comparative Examples 1-3. Detailed Implementation

[0027] The technical solution of the present invention will be further described below with reference to specific embodiments, but it is not limited thereto.

[0028] Example 1 A method for moderately refining neutralized oil based on negative pressure-cavitation coupling includes the following steps: (1) Mix the functional adsorbent with the neutralizing oil in a certain proportion; (2) Refine the homogeneous system in a negative pressure-cavitation environment; (3) Separate the functional adsorbent and refined oil to obtain a moderately refined finished oil; (4) Conduct quality testing and evaluation of the finished oil products, and then fill and store them.

[0029] The neutralized oil is soybean oil that has undergone degumming and deacidification. Degumming and deacidification can be carried out using existing technical methods, such as hydration degumming or acid degumming, and physical distillation or chemical alkali refining, to ensure the effective removal of major impurities such as phospholipids and free fatty acids.

[0030] The functional adsorbent is a spherical porous composite adsorbent, and its preparation method is as follows: (a) The porous material, the first template agent, the second template agent and deionized water are mixed in a mass ratio of 6:0.5:0.3:3 and ball-milled to form a uniform slurry; (b) The slurry is spray-dried to form spherical precursor particles; (c) The spherical precursor particles are subjected to programmed temperature-controlled calcination, and successively undergo the first template agent decomposition and pore-forming stage, the second template agent decomposition and pore-forming stage, and the high-temperature stabilization stage to obtain the spherical porous functional adsorbent; before use, the spherical porous functional adsorbent is impregnated with a 0.5wt% citric acid solution and dried at 100-120℃.

[0031] The porous material is activated clay.

[0032] The first template agent is polylactic acid, and the second template agent is polyethylene glycol. The programmed temperature-controlled calcination is specifically as follows: under an inert atmosphere, the temperature is first raised to 200-240℃ and held for 1 hour to decompose the polyethylene glycol; then the temperature is raised to 300-350℃ and held for 1.5 hours to pyrolyze and carbonize the polylactic acid; finally, in an air atmosphere, it is calcined at 450-550℃ for 2 hours to remove residual carbon.

[0033] The amount of adsorbent added is 3.0 wt% of the weight of the neutralized oil.

[0034] A negative pressure-cavitation environment refers to placing a mixture of functional adsorbent and neutralizing oil in a container and evacuating it to a specified vacuum level, maintaining the vacuum level, keeping the system temperature constant, and applying ultrasonic waves to induce cavitation; wherein the vacuum level is controlled at ≤-0.1MPa and the temperature is 40℃.

[0035] The ultrasound employs a gradient ultrasound process, specifically: the first stage has a power of 700-750W and an ultrasound time of 3 minutes; the second stage has a power of 550-600W and a time of 15 minutes; and the third stage has a power of 450-500W and a time of 30 minutes.

[0036] Step (3) separation method is as follows: after the reaction is completed, the reaction system is cooled to room temperature, the vacuum is slowly broken, the mixture is transferred to a centrifuge for centrifugation, the supernatant is collected, filtered through a filter membrane, and then placed in a refrigerator at 4°C for testing.

[0037] Example 2 A method for moderately refining neutralized oil based on negative pressure-cavitation coupling includes the following steps: (1) Mix the functional adsorbent with the neutralizing oil in a certain proportion; (2) Refine the homogeneous system in a negative pressure-cavitation environment; (3) Separate the functional adsorbent and refined oil to obtain a moderately refined finished oil; (4) Conduct quality testing and evaluation of the finished oil products, and then fill and store them.

[0038] The neutralized oil is rapeseed oil that has undergone degumming and deacidification. Degumming and deacidification can be carried out using existing technical methods, such as hydration degumming or acid degumming, and physical distillation or chemical alkali refining, to ensure the effective removal of major impurities such as phospholipids and free fatty acids.

[0039] The functional adsorbent is a spherical porous composite adsorbent, and its preparation method is as follows: (a) The porous material, the first template agent, the second template agent and deionized water are mixed in a mass ratio of 7:1:1:4 and ball-milled to form a uniform slurry; (b) The slurry is spray-dried to form spherical precursor particles; (c) The spherical precursor particles are subjected to programmed temperature-controlled calcination, and successively undergo the first template agent decomposition and pore-forming stage, the second template agent decomposition and pore-forming stage, and the high-temperature stabilization stage to obtain the spherical porous functional adsorbent; before use, the spherical porous functional adsorbent is impregnated with a 3 wt% citric acid solution and dried at 100-120℃.

[0040] The porous material is activated carbon.

[0041] The first template agent is polylactic acid, and the second template agent is polyethylene glycol. The programmed temperature-controlled calcination is specifically as follows: under an inert atmosphere, the temperature is first raised to 200-240℃ and held for 1 hour to decompose the polyethylene glycol; then the temperature is raised to 300-350℃ and held for 2 hours to pyrolyze and carbonize the polylactic acid; finally, in an air atmosphere, it is calcined at 450-550℃ for 2 hours to remove residual carbon.

[0042] The amount of adsorbent added is 1 wt% of the mass of the neutralized oil.

[0043] A negative pressure cavitation environment refers to placing a mixture of functional adsorbent and neutralizing oil in a container and evacuating it to a specified vacuum level, maintaining the vacuum level, keeping the system temperature constant, and applying ultrasonic waves to induce cavitation; wherein, the vacuum level is ≤-0.1MPa and the temperature is 90℃.

[0044] The ultrasound employs a gradient ultrasound process, specifically: the first stage has a power of 700-750W and an ultrasound time of 3 minutes; the second stage has a power of 550-600W and a time of 10 minutes; and the third stage has a power of 450-500W and a time of 20 minutes.

[0045] Step (3) separation method is as follows: after the reaction is completed, the reaction system is cooled to room temperature, the vacuum is slowly broken, the mixture is transferred to a centrifuge for centrifugation, the supernatant is collected, filtered through a filter membrane, and then placed in a refrigerator at 4°C for testing.

[0046] Example 3 A method for moderately refining neutralized oil based on negative pressure-cavitation coupling includes the following steps: (1) Mix the functional adsorbent with the neutralizing oil in a certain proportion; (2) Refine the homogeneous system in a negative pressure-cavitation environment; (3) Separate the functional adsorbent and refined oil to obtain a moderately refined finished oil; (4) Conduct quality testing and evaluation of the finished oil products, and then fill and store them.

[0047] The neutralized oil is soybean oil that has undergone degumming and deacidification. Degumming and deacidification can be carried out using existing technical methods, such as hydration degumming or acid degumming, and physical distillation or chemical alkali refining, to ensure the effective removal of major impurities such as phospholipids and free fatty acids.

[0048] The functional adsorbent is a spherical porous composite adsorbent, and its preparation method is as follows: (a) The porous material, the first template agent, the second template agent and deionized water are mixed in a mass ratio of 8:2:1.5:5 and ball-milled to form a uniform slurry; (b) The slurry is spray-dried to form spherical precursor particles; (c) The spherical precursor particles are subjected to programmed temperature-controlled calcination, and successively undergo the first template agent decomposition and pore-forming stage, the second template agent decomposition and pore-forming stage, and the high-temperature stabilization stage to obtain the spherical porous functional adsorbent; before use, the spherical porous functional adsorbent is impregnated with a 5 wt% citric acid solution and dried at 100-120℃.

[0049] The porous material is diatomaceous earth.

[0050] The first template agent is polylactic acid, and the second template agent is polyethylene glycol. The programmed temperature-controlled calcination is specifically as follows: under an inert atmosphere, the temperature is first raised to 200-240℃ and held for 2 hours to decompose the polyethylene glycol; then the temperature is raised to 300-350℃ and held for 2.5 hours to pyrolyze and carbonize the polylactic acid; finally, in an air atmosphere, it is calcined at 450-550℃ for 3 hours to remove residual carbon.

[0051] The amount of adsorbent added is 2.0 wt% of the neutralized oil mass.

[0052] A negative pressure-cavitation environment refers to placing a mixture of functional adsorbent and neutralizing oil in a container and evacuating it to a specified vacuum level, maintaining the vacuum level, keeping the system temperature constant, and applying ultrasonic waves to induce cavitation; wherein, the vacuum level is ≤-0.1MPa and the temperature is 65℃.

[0053] The ultrasound employs a gradient ultrasound process, specifically: the first stage has a power of 700-750W and an ultrasound time of 3 minutes; the second stage has a power of 550-600W and a time of 15 minutes; and the third stage has a power of 450-500W and a time of 30 minutes.

[0054] Step (3) separation method is as follows: after the reaction is completed, the reaction system is cooled to room temperature, the vacuum is slowly broken, the mixture is transferred to a centrifuge for centrifugation, the supernatant is collected, filtered through a filter membrane, and then placed in a refrigerator at 4°C for testing.

[0055] Comparative Example 1 Compared to Example 1, this comparative example is identical to Example 1 in all preparation conditions and application parameters except that polyethylene glycol is used as the template agent in the adsorbent preparation process, without the addition of polylactic acid. That is: The functional adsorbent is a spherical porous composite adsorbent, and its preparation method is as follows: (a) The porous material, template agent and deionized water are mixed in a mass ratio of 6:0.3:3 and ball-milled to form a uniform slurry; (b) The slurry is spray-dried to form spherical precursor particles; (c) The spherical precursor particles are subjected to programmed temperature-controlled calcination to obtain the spherical porous functional adsorbent; before use, the spherical porous functional adsorbent is impregnated with a 0.5wt% citric acid solution and dried at 100-120℃.

[0056] The porous material is activated clay.

[0057] The template agent is polyethylene glycol; the programmed temperature-controlled calcination is as follows: under an inert atmosphere, the temperature is first raised to 200-240℃ and held for 1 hour; then the temperature is raised to 300-350℃ and held for 1.5 hours; finally, in an air atmosphere, it is calcined at 450-550℃ for 2 hours to remove residual carbon.

[0058] Comparative Example 2 Compared to Example 1, this comparative example is identical to Example 1 in all preparation conditions and application parameters except that polylactic acid is used as the template agent in the adsorbent preparation process, without the addition of polyethylene glycol. That is: The functional adsorbent is a spherical porous composite adsorbent, and its preparation method is as follows: (a) The porous material, template agent and deionized water are mixed in a mass ratio of 6:0.5:3 and ball-milled to form a uniform slurry; (b) The slurry is spray-dried to form spherical precursor particles; (c) The spherical precursor particles are subjected to programmed temperature-controlled calcination to obtain the spherical porous functional adsorbent; before use, the spherical porous functional adsorbent is impregnated with a 0.5wt% citric acid solution and dried at 100-120℃.

[0059] The porous material is activated clay.

[0060] The template agent is polylactic acid; the programmed temperature-controlled calcination is specifically as follows: under an inert atmosphere, the temperature is first raised to 200-240℃ and held for 1 hour; then the temperature is raised to 300-350℃ and held for 1.5 hours; finally, in an air atmosphere, it is calcined at 450-550℃ for 2 hours to remove residual carbon.

[0061] Comparative Example 3 Compared to Example 1, this comparative example is identical to Example 1 in all preparation conditions and application parameters except that no template agent is used in the adsorbent preparation process. That is: The functional adsorbent is a spherical porous composite adsorbent, and its preparation method is as follows: (a) The porous material and deionized water are mixed at a mass ratio of 6:3 and ball-milled to form a uniform slurry; (b) The slurry is spray-dried to form spherical precursor particles; (c) The spherical precursor particles are subjected to programmed temperature-controlled calcination to obtain the spherical porous functional adsorbent; before use, the spherical porous functional adsorbent is impregnated with a 0.5wt% citric acid solution and dried at 100-120℃.

[0062] The porous material is activated clay.

[0063] The specific process of temperature-controlled calcination is as follows: under an inert atmosphere, the temperature is first raised to 200-240℃ and held for 1 hour; then the temperature is raised to 300-350℃ and held for 1.5 hours; finally, in an air atmosphere, it is calcined at 450-550℃ for 2 hours.

[0064] Comparative Example 4 This comparative example is identical to Example 1 in all conditions except for the use of a single ultrasonic power. That is: A method for moderately refining neutralized oil based on negative pressure-cavitation coupling includes the following steps: (1) Mix the functional adsorbent with the neutralizing oil in a certain proportion; (2) Refine the homogeneous system in a negative pressure-cavitation environment; (3) Separate the functional adsorbent and refined oil to obtain a moderately refined finished oil; (4) Conduct quality testing and evaluation of the finished oil products, and then fill and store them.

[0065] A negative pressure-cavitation environment refers to placing a mixture of functional adsorbent and neutralizing oil in a container and evacuating it to a specified vacuum level, maintaining the vacuum level, keeping the system temperature constant, and applying ultrasonic waves to induce cavitation; wherein the vacuum level is controlled at ≤-0.1MPa and the temperature is 40℃.

[0066] Ultrasonic process parameters: power 700-750W, ultrasonic time 48min.

[0067] Comparative Example 5 This comparative example is identical to Example 1 in all conditions except for the use of a single ultrasonic power. That is: A method for moderately refining neutralized oil based on negative pressure-cavitation coupling includes the following steps: (1) Mix the functional adsorbent with the neutralizing oil in a certain proportion; (2) Refine the homogeneous system in a negative pressure-cavitation environment; (3) Separate the functional adsorbent and refined oil to obtain a moderately refined finished oil; (4) Conduct quality testing and evaluation of the finished oil products, and then fill and store them.

[0068] A negative pressure-cavitation environment refers to placing a mixture of functional adsorbent and neutralizing oil in a container and evacuating it to a specified vacuum level, maintaining the vacuum level, keeping the system temperature constant, and applying ultrasonic waves to induce cavitation; wherein the vacuum level is controlled at ≤-0.1MPa and the temperature is 40℃.

[0069] The ultrasonic process parameters are: power 550-600W, time 48min.

[0070] Comparative Example 6 This comparative example is identical to Example 1 in all conditions except for the use of a single ultrasonic power. That is: A method for moderately refining neutralized oil based on negative pressure-cavitation coupling includes the following steps: (1) Mix the functional adsorbent with the neutralizing oil in a certain proportion; (2) Refine the homogeneous system in a negative pressure-cavitation environment; (3) Separate the functional adsorbent and refined oil to obtain a moderately refined finished oil; (4) Conduct quality testing and evaluation of the finished oil products, and then fill and store them.

[0071] A negative pressure-cavitation environment refers to placing a mixture of functional adsorbent and neutralizing oil in a container and evacuating it to a specified vacuum level, maintaining the vacuum level, keeping the system temperature constant, and applying ultrasonic waves to induce cavitation; wherein the vacuum level is controlled at ≤-0.1MPa and the temperature is 40℃.

[0072] The ultrasonic process is as follows: power 450-500W, time 48min.

[0073] Performance testing The morphology of the experimentally prepared spherical porous composite adsorbent was analyzed using a scanning electron microscope (SEM) with cold field emission. The operating conditions were: accelerating voltage 15 kV, magnification 10⁻¹⁰–10⁻¹⁰ kx. The pore size distribution was characterized using a Micromeritics ASAP 2460 surface area and porosity analyzer (USA).

[0074] In the examples and comparative examples, the neutralized oil used was crude oil obtained after degumming and deacidification. The acid value, peroxide value, and oxidative stability of the oil before and after refining were tested according to national standards GB 5009.229-2025 "National Food Safety Standard - Determination of Acid Value in Food", GB 5009.227-2023 "National Food Safety Standard - Determination of Peroxide Value in Food", and GB / T 21121-2024 "Determination of Oxidative Stability of Animal and Vegetable Oils (Accelerated Oxidation Test)". The detection of tocopherols, polyphenols, and phytosterols was performed according to GB / T 26635-2011 "Determination of Tocopherol and Tocotrienol Content in Animal and Vegetable Oils - High Performance Liquid Chromatography", LS / T 6119-2017 "Grain and Oil Inspection - Determination of Polyphenols in Vegetable Oils - Spectrophotometric Method", and GB / T25223-2024 "Determination of Sterol Composition and Total Sterols in Animal and Vegetable Oils - Gas Chromatography". Each experiment was repeated three times, and the average value was taken as the final result.

[0075] Table 1. Refined oil indicators for the examples and comparative examples. Table 2. Refined oil indicators for the examples and comparative examples. The formula for calculating the tocopherol retention rate is (tocopherol retention rate %) = tocopherol content in refined oil / tocopherol content in unrefined oil × 100%. The calculation methods for polyphenol retention rate and sterol retention rate are similar.

[0076] As can be seen from the data in Table 1-2, the refined oils prepared in Examples 1-3 exhibit significant advantages in all key indicators. Regarding basic physicochemical indicators, the acid values ​​of Examples 1-3 were 0.100 mg KOH / g, 0.123 mg KOH / g, and 0.085 mg KOH / g, respectively; the peroxide values ​​were 0.026 g / 100g, 0.013 g / 100g, and 0.012 g / 100g, respectively; and the insoluble impurity contents were 0.02%, 0.03%, and 0.01%, respectively. These values ​​are all significantly lower than those of the comparative examples using only a single template agent (Comparative Examples 1-2), without a template agent (Comparative Example 3), or using a single ultrasonic power (Comparative Examples 4-6). Furthermore, all of these values ​​are superior to or meet the national standards for Grade 1 soybean oil and Grade 1 rapeseed oil. In particular, compared with unrefined neutralized soybean oil and neutralized rapeseed oil, the refining effect is extremely significant, effectively reducing the acid value, peroxide value, and impurity content of the oils, thereby improving the quality and stability of the oils.

[0077] Regarding the retention of functional components, Examples 1-3 also demonstrated excellent performance. Example 1 showed a tocopherol retention rate of 98.8% and a sterol retention rate of 98.9%; Example 3 showed a tocopherol retention rate of 99.2% and a sterol retention rate of 99.3%; Example 2, as a rapeseed oil sample, showed a tocopherol retention rate of 99.5%, a polyphenol retention rate of 72.8%, and a sterol retention rate of 97.9%. These figures are significantly higher than the comparative ratios, especially far exceeding those of commercially available Grade 1 soybean oil (tocopherol retention rate 79.0%, sterol retention rate 92.2%) and Grade 1 rapeseed oil (tocopherol retention rate 94.3%, polyphenol retention rate 23.4%, sterol retention rate 93.6%). This indicates that the method of the present invention, while deeply refining oils, can maximize the retention of beneficial natural active ingredients such as tocopherols, polyphenols, and phytosterols, achieving "moderate refining" of oils and overcoming the drawbacks of significant loss of functional components in traditional refining processes.

[0078] Oxidative stability is an important indicator for evaluating the shelf life and quality of oils. The oxidation induction times of Examples 1-3 were 6.81 h, 7.84 h, and 7.20 h, respectively, all of which were better than or close to the 7.21 h of Grade 1 rapeseed oil, and significantly higher than the 6.20 h of the comparative products and Grade 1 soybean oil. This further confirms that using a functional adsorbent with a gradient porous structure constructed by a dual-template agent, combined with negative pressure-cavitation coupling and gradient ultrasonic technology, can effectively improve the oxidative stability of refined oils and extend their shelf life.

[0079] In summary, by comparing the experimental data of the examples and comparative examples, it can be clearly demonstrated that the functional adsorbent prepared using polyethylene glycol and polylactic acid as dual templates can form a uniform and highly ordered gradient porous structure, significantly enhancing its selective adsorption capacity for impurities; due to its unique gradient porous structure, Figure 1-3 As can be seen, the porous material in the examples exhibits uniform surface pores and a clear gradient pore size distribution, while the pore distribution in Comparative Examples 1-3 is disordered, with some pore structures showing closure or collapse, leading to a significant decrease in adsorption efficiency. The porous material in Example 1 has superior adsorption capacity and mass transfer efficiency, and can more effectively remove undesirable components from the neutralized oil. Furthermore, the gradient ultrasonic process under negative pressure-cavitation coupling, through optimized power settings at different stages, ensures adsorption efficiency while minimizing damage to the natural nutrients in the oil. The synergistic effect of these two processes results in refined oil prepared by the method of this invention achieving ideal results in sensory indicators such as color, transparency, odor, and taste; physicochemical indicators such as acid value and peroxide value; and retention rates and oxidative stability of functional components such as tocopherols, polyphenols, and phytosterols. This fully demonstrates the advanced nature and practicality of this method for moderately refining neutralized oil.

[0080] It should be noted that the above embodiments are merely some preferred embodiments of the present invention, and not all embodiments. Obviously, based on the above embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort should fall within the scope of protection of the present invention.

Claims

1. A method for moderately refining neutralized oil based on negative pressure-cavitation coupling, characterized in that, Includes the following steps: (1) Mix the functional adsorbent with the neutralizing oil in a certain proportion; (2) Refine the homogeneous system in a negative pressure-cavitation environment; (3) Separate the functional adsorbent and refined oil to obtain a moderately refined finished oil; (4) Conduct quality testing and evaluation of the finished oil products, and then fill and store them.

2. The method for moderate refining of neutralized oil based on negative pressure-cavitation coupling assistance according to claim 1, characterized in that, The neutralizing oil is one or more of the following: rapeseed oil, soybean oil, tea seed oil, camellia seed oil, olive oil, corn oil, and sunflower seed oil, which have undergone degumming and deacidification.

3. The method for moderate refining of neutralized oil based on negative pressure-cavitation coupling assistance according to claim 2, characterized in that, The neutralizing oil is rapeseed oil or soybean oil that has undergone degumming and deacidification.

4. The method for moderate refining of neutralized oil based on negative pressure-cavitation coupling assistance according to claim 1, characterized in that, The functional adsorbent is a spherical porous composite adsorbent, and its preparation method is as follows: (a) The porous material, the first template agent, the second template agent and deionized water are mixed in a mass ratio of (6-8):(0.5-2):(0.3-1.5):(3-5) and ball-milled to form a uniform slurry; (b) The slurry is spray-dried to form spherical precursor particles; (c) The spherical precursor particles are subjected to programmed temperature-controlled calcination, and successively undergo the first template agent decomposition and pore-forming stage, the second template agent decomposition and pore-forming stage, and the high-temperature stabilization stage to obtain the spherical porous functional adsorbent; before use, the spherical porous functional adsorbent is impregnated with a 0.5-5 wt% citric acid solution and dried at 100-120℃.

5. The method for moderate refining of neutralized oil based on negative pressure-cavitation coupling assistance according to claim 4, characterized in that, The porous material is one or more of the following: activated clay, activated carbon, diatomaceous earth, attapulgite, zeolite, and sepiolite.

6. The method for moderate refining of neutralized oil based on negative pressure-cavitation coupling assistance according to claim 4, characterized in that, The first template agent is polylactic acid, and the second template agent is polyethylene glycol. The programmed temperature-controlled calcination is specifically as follows: under an inert atmosphere, the temperature is first raised to 200-240℃ and held for 1-2 hours to decompose the polyethylene glycol; then the temperature is raised to 300-350℃ and held for 1.5-2.5 hours to pyrolyze and carbonize the polylactic acid; finally, in an air atmosphere, it is calcined at 450-550℃ for 2-3 hours to remove residual carbon.

7. The method for moderate refining of neutralized oil based on negative pressure-cavitation coupling assistance according to claim 1, characterized in that, The amount of adsorbent added is 1.0 - 3.0 wt% of the neutralized oil mass.

8. The method for moderate refining of neutralized oil based on negative pressure-cavitation coupling assistance according to claim 1, characterized in that, A negative pressure-cavitation environment refers to placing a mixture of functional adsorbent and neutralizing oil in a container and evacuating it to a specified vacuum level, maintaining the vacuum level, keeping the system temperature constant, and applying ultrasonic waves to induce cavitation; wherein, the vacuum level is ≤-0.1 MPa and the temperature is 40-90℃.

9. The method for moderate refining of neutralized oil based on negative pressure-cavitation coupling assistance according to claim 8, characterized in that, The ultrasound employs a gradient ultrasound process, specifically: the first stage has a power of 700-750W and an ultrasound time of 1-3 minutes; the second stage has a power of 550-600W and a time of 10-15 minutes; and the third stage has a power of 450-500W and a time of 20-30 minutes.

10. The method for moderate refining of neutralized oil based on negative pressure-cavitation coupling assistance according to claim 1, characterized in that, Step (3) separation method is as follows: after the reaction is completed, the reaction system is cooled to room temperature, the vacuum is slowly broken, the mixture is transferred to a centrifuge for centrifugation, the supernatant is collected, filtered through a filter membrane, and then placed in a refrigerator at 4°C for testing.

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