Method for refining edible oil without water washing

Abstract

The application provides a kind of anhydrous washing edible oil refining method, belongs to edible oil refining technical field.The anhydrous washing edible oil refining method of the application, including crude oil is sequentially subjected to three-stage physical filtration, acid reaction treatment, base reaction treatment, desoap treatment, obtains the edible oil;The three-stage physical filtration includes that the crude oil is heated and then subjected to initial filtration treatment by filter, then is maintained temperature and is subjected to two-stage membrane coupling ultrafiltration;The two-stage membrane is stainless steel-ceramic composite nanometer membrane and stainless steel carrier silica hybrid mesoporous nanofiltration membrane.The edible oil refining method of the application breaks the traditional technology of industry " base refining is matched with water washing", neutralization section realizes anhydrous washing, no waste water discharge;Reduce alkali consumption, reduce neutral oil loss, improve refining yield;Retain vitamin E, sterol and other nutritional ingredients, improve oil quality;Simplify process, reduce energy consumption and operation and maintenance cost, provide green refining method that can be popularized on a large scale.

Description

Technical Field

[0001] This invention belongs to the field of edible oil refining technology, specifically relating to a waterless edible oil refining method. Background Technology

[0002] The traditional edible oil refining and neutralization process involves heating the crude oil to 65-85℃, adding 0.03-0.15% (by mass) of a 75-85% phosphoric acid solution, mixing via high-speed shearing, and then stirring in an acid reaction tank for 45-90 minutes. Next, an appropriate amount of liquid alkali (calculated based on the crude oil's acid value and phospholipid content) is added, and the mixture is stirred for approximately 20 minutes. The soap sac is then separated using a desoap centrifuge. Finally, 1.5-7% (by mass of crude oil) of hot water is added and mixed, followed by separation using a water washing centrifuge. The oil is then heated to 100-120℃ and dried under vacuum conditions ≤100mbar. Next, it is mixed with bleaching clay (activated clay + attapulgite clay) for approximately 45 minutes to remove pigments. Finally, it undergoes high-temperature deodorization (220-260℃) to remove odorous substances such as aldehydes, ketones, and acids, as well as some pigments, ultimately achieving a refined first-grade oil that meets national standards. This traditional edible oil refining and neutralization process has been used since the 1980s. This method is applicable to all types of oils, has moderate investment costs, and mature operating technology, but it has many technical limitations: the yield of neutral oil is relatively large, about 4.5 tons of oily wastewater are generated per day with a processing capacity of 300 tons / day, energy consumption is high, auxiliary material consumption is large, the loss of nutrients such as vitamin E is about 25%, the process is complicated, and the equipment maintenance cost is high.

[0003] Enzymatic degumming refining is also a commonly used edible oil refining process. This process has a high yield, good nutrient retention, and relatively stable degumming effect. However, the investment cost of this process is more than 30% higher than that of traditional processes, and the cost of enzyme preparations is about 120 yuan / ton of oil. It is only suitable for high value-added oils (such as corn oil) and cannot be widely promoted. Moreover, the acidity index of the processed oil is very high (>0.5mg / g), which is difficult to meet the current development requirements of product quality.

[0004] In recent years, with the development of social science and technology, all aspects of the edible oil processing industry have been significantly improved. Whether it is the upstream links such as seed development, planting, harvesting, dust removal, transportation, and transshipment, or the midstream links such as pressing or solvent extraction for oil production, all have achieved technological upgrades with the development of the times. Therefore, the innovation of refining processes has become an inevitable requirement for the development of the industry. Summary of the Invention

[0005] The purpose of this invention is to address the problems of high alkali consumption, high neutral oil loss, large amount of oily wastewater discharge, high energy consumption, and serious loss of nutrients in traditional edible oil refining processes. This invention provides a waterless edible oil refining method that breaks away from the industry's traditional "alkali refining with water washing" technology. The neutralization stage achieves waterless washing and zero wastewater discharge; it reduces alkali consumption and neutral oil loss, increasing refining yield; it retains nutrients such as vitamin E and sterols, improving oil quality; it simplifies the process, reduces energy consumption and operation and maintenance costs, and provides a green refining method that can be scaled up and promoted.

[0006] To achieve the above objectives, the technical solution adopted by the present invention is as follows: a waterless edible oil refining method, comprising subjecting crude oil to three-stage physical filtration, acid reaction treatment, alkali reaction treatment, and desoaping treatment in sequence to obtain the edible oil; the three-stage physical filtration includes heating the crude oil and then performing initial filtration through a filter, followed by maintaining the temperature and then performing ultrafiltration through a two-stage membrane coupling; the two-stage membrane is a stainless steel-ceramic composite nanomembrane and a stainless steel carrier silica hybrid mesoporous nanofiltration membrane.

[0007] The inventors of this application have discovered that heating the crude oil before primary filtration not only ensures good fluidity and effectively removes most mechanical impurities (with a removal rate exceeding 95%), thus extending membrane lifespan, ensuring stable membrane system operation, and guaranteeing subsequent transport and filtration processes, but also prevents the degradation of nutrients in the crude oil due to high temperatures. Furthermore, to address the technical shortcomings of traditional processes—such as the difficulty in completely removing phospholipids and the high content of free fatty acids leading to increased losses during subsequent alkali refining and unstable finished oil quality—this invention employs a two-stage membrane-coupled ultrafiltration system: primary filtration via a stainless steel-ceramic composite nanomembrane, followed by precise molecular-level sieving using a stainless steel carrier-silica hybrid mesoporous nanofiltration membrane, simultaneously achieving deep degumming and selective deacidification. The system operates at a pressure of 0.5-1.5 MPa, preferably 1.0 MPa, and combined with a high-temperature, solvent-resistant, and high-pressure-resistant composite membrane structure, achieves efficient and stable separation. The waterless edible oil refining method of the present invention achieves deep degumming and simultaneous deacidification of crude oil through three-stage physical filtration. The acid value (calculated as KOH) is ≤0.8mg / g, the phosphorus content is ≤60ppm, and the removal rate of phospholipids and impurities can reach more than 90%. It also significantly reduces the color of the oil and avoids the oxidation and discoloration of phospholipids in the subsequent high-temperature stage. This step provides key support for the subsequent low-alkali neutralization and waterless washing process, and greatly reduces the consumption of chemical reagents and the loss of neutral oil.

[0008] Preferably, the filter includes a vertical blade filter; the mesh size of the filter screen of the vertical blade filter is 180-220 mesh.

[0009] More preferably, the vertical blade filter has a filter screen mesh size of 200 mesh. The inventors of this application have discovered that this mesh size can effectively reduce the probability of filter screen clogging and decrease equipment malfunctions while efficiently removing mechanical impurities from crude oil.

[0010] In a preferred embodiment of the waterless edible oil refining method of the present invention, the pore size of the stainless steel-ceramic composite nanomembrane is 3-10 nm; and the pore size of the stainless steel carrier silica hybrid mesoporous nanofiltration membrane is 1.0 nm.

[0011] Phospholipid micelle retention combined with fatty acid permeation / triglyceride retention: Phospholipid molecules are amphiphilic (one end hydrophilic, the other lipophilic), and in nonpolar edible oils (triglycerides), they do not disperse as individual small molecules. When the concentration exceeds the critical micelle concentration (CMC), phospholipids spontaneously aggregate into reverse micelles: the hydrophilic end faces inward, and the lipophilic end faces outward, stably dispersing in the oil. These phospholipid micelles have a large particle size: typically 5-20 nm, with some composite micelles reaching around 100 nm; triglyceride molecules are approximately 1.5-2.0 nm in size; and free fatty acid molecules are approximately 0.6-0.8 nm in size. This invention utilizes a stainless steel-ceramic composite nanomembrane with a specific pore size, selected through experiments, for ultrafiltration of crude oil. This process effectively retains most phospholipid micelles and colloidal impurities. Precise control of the pore size of the stainless steel-supported silica hybrid mesoporous nanofiltration membrane further retains residual trace amounts of colloids, while allowing free fatty acids to permeate and be removed, while triglycerides are retained in the oil phase.

[0012] In a preferred embodiment of the waterless edible oil refining method of the present invention, the temperature of the initial filtration treatment is 60-90℃; and the temperature of the two-stage membrane coupled ultrafiltration is 70-95℃.

[0013] Preferably, the temperature of the initial filtration treatment is 85°C.

[0014] Preferably, when the crude oil is prepared by pressing, it needs to be diluted with n-hexane to reduce its viscosity before performing two-stage membrane coupling ultrafiltration.

[0015] The two-stage membranes used in this invention are both supported by stainless steel, which offers high mechanical strength, resistance to high temperature and pressure, and resistance to organic solvents such as n-hexane. Combined with a 200-mesh pre-filter, membrane fouling is low, and the service life can reach 12-24 months under continuous operation. The membrane module is easy to clean, employing a standard online regeneration process: 1) Hot n-hexane circulation flushing at 60-70℃ for 10-20 minutes to remove surface grease; 2) Cleaning with 0.5-1.0% dilute alkaline solution at 50-70℃ for 30-60 minutes to remove phospholipids and organic matter; 3) Rinsing with 0.5-1.0% citric acid solution for 20-30 minutes to remove inorganic residues; 4) Rinsing with deionized water until neutral. After cleaning, the membrane flux is restored, allowing for long-term stable and repeated use.

[0016] As a preferred embodiment of the waterless edible oil refining method of the present invention, the acid reaction treatment includes adding a citric acid solution with a mass concentration of 30-70% to the ultrafiltration crude oil, the amount added being 0.2-1.5‰ of the mass of the crude oil, and stirring and mixing at 75-85℃ for 60-120 min at a stirring speed of 60-68 rpm to obtain degummed crude oil.

[0017] Compared to the traditional process that involves adding excessive amounts of alkali solution to react with phospholipids and adsorb impurities, the waterless edible oil refining method of this invention uses a low concentration and small proportion of citric acid and dilute alkali solution in the neutralization stage. This effectively removes residual acids, phospholipids, and impurities from the oil, ensuring that the neutralized oil meets the required standards, while also avoiding the saponification reaction between excessive alkali solution and neutral oil, thus reducing neutral oil loss.

[0018] Preferably, the citric acid solution has a mass concentration of 50%. The inventors of this application have discovered that this concentration of citric acid solution can reduce the amount of citric acid used and lower production costs while ensuring the effectiveness of the acid reaction.

[0019] Preferably, the amount of citric acid solution added is 0.6‰ of the crude oil mass. This amount can precisely adjust the pH value of the crude oil to 4.5-6.5, avoiding excessive acid value of the oil due to excessive addition of citric acid.

[0020] Preferably, the stirring and mixing time is 90 minutes. This combination of speed and time ensures that citric acid and crude oil are fully mixed and react completely, avoiding impurities caused by incomplete local reactions.

[0021] As a preferred embodiment of the waterless edible oil refining method of the present invention, the alkaline reaction treatment includes mixing and stirring the alkaline solution with degummed crude oil for 5-30 minutes to obtain deacidified crude oil.

[0022] The core function of this process is to neutralize the residual citric acid and free fatty acids in the crude oil, remove the remaining phospholipids and impurities, and complete the alkali neutralization reaction. After neutralization, the pH value of the crude oil is controlled at 7.0-8.0.

[0023] Preferably, the reaction time for mixing and stirring the alkaline solution with the degummed crude oil is 15 minutes. The inventors of this application have discovered that this reaction time ensures a complete neutralization reaction while avoiding increased equipment energy consumption due to excessively long reaction times.

[0024] Preferably, the mixing temperature is 80°C.

[0025] As a preferred embodiment of the waterless edible oil refining method of the present invention, the alkaline solution comprises 0.5-2‰ of liquid alkali with a mass fraction of 32% and 1-3% hot water, based on the mass of degummed crude oil.

[0026] This invention breaks through the traditional process of "alkali refining with water washing" in this field, eliminating the water washing step of the traditional process. Through precise filtration, acid conditioning and vacuum drying, zero wastewater discharge is achieved. This not only simplifies the process flow, but also reduces the loss of neutral oil caused by the water washing process from the source, effectively reducing processing costs and environmental treatment costs. The various processes work together and support each other, ultimately achieving quality improvement, energy saving, environmental protection and efficiency enhancement in edible oil refining.

[0027] Preferably, the alkali solution, based on the mass of the degummed crude oil, comprises 32% liquid alkali (1‰ by mass) and 2% hot water. Compared to the traditional process with a liquid alkali addition ratio of approximately 2%, this invention uses a low proportion of diluted alkali, which effectively avoids excessive alkali solution reacting with neutral oil in a saponification reaction, thus reducing neutral oil loss.

[0028] As a preferred embodiment of the waterless edible oil refining method of the present invention, the soap removal process includes centrifuging the deacidified crude oil, adding a citric acid aqueous solution with a mass fraction of 30-50% and an addition amount of 0.2-1‰ of the mass of the deacidified crude oil, mixing, heating, and vacuum drying to obtain edible oil.

[0029] Preferably, the citric acid aqueous solution has a mass fraction of 40% and is added at a rate of 0.4‰ of the mass of the deacidified crude oil.

[0030] The soap removal process of this invention involves pumping edible oil into a soap removal centrifuge for soap removal and separation, removing a small amount of soap shavings generated during the reaction (soap removal rate ≥98%). After soap removal and separation, a citric acid aqueous solution is added to the edible oil to precisely adjust its pH to 6.5-7.0 and remove residual soap. The edible oil with the added citric acid aqueous solution is then thoroughly mixed in a centrifugal mixer. This eliminates the need for additional hot water, stirring, and water washing and centrifugation, effectively overcoming the traditional process of "water washing after soap removal".

[0031] Preferably, the heating and vacuum drying after mixing specifically involves heating to 90-120℃ and drying the moisture under a vacuum of 50-100 mbar. Experiments have shown that this combination of temperature and vacuum can quickly remove moisture from edible oils, with a drying time of ≤30 minutes, while simultaneously preventing the loss of nutrients in the oil. After drying, the various indicators of the dried oil are controlled as follows: acid value (calculated as KOH) ≤0.3 mg / g, phosphorus content ≤15 ppm, moisture content ≤0.05%, and soap content ≤80 ppm, fully meeting the feed requirements for subsequent decolorization and deodorization processes.

[0032] More preferably, the heating temperature is 110°C and the vacuum degree is 70 mbar.

[0033] As a preferred embodiment of the waterless edible oil refining method of the present invention, the waterless edible oil refining method further includes decolorization treatment and deodorization treatment.

[0034] After decolorization and deodorization, a finished first-grade edible oil that meets national quality standards can be obtained.

[0035] Preferably, in the decolorization process, the addition ratio of attapulgite clay is 0.1-1% of the mass of the dried oil, and the preferred addition ratio is 0.2%. Experiments have shown that this addition ratio of attapulgite clay can effectively remove the color of the oil, with a removal rate of ≥80%, while avoiding the loss caused by excessive clay addition leading to the adsorption of a large amount of neutral oil.

[0036] Preferably, the deodorization treatment temperature is 220-260℃, the vacuum degree is ≤2.0mbar, and the direct stripping rate is 50-80kg / h. Based on a refining process of 300 tons / day, this parameter combination can effectively remove odorous substances from oils with a removal rate ≥95%, while maximizing the preservation of the original nutrients in the oils.

[0037] The present invention also provides the application of the waterless edible oil refining method described above in edible oil production.

[0038] Compared with existing traditional alkali refining processes, the waterless edible oil refining method of this invention achieves significant technical advantages in terms of nutrient retention, energy saving and consumption reduction, economic benefits, and ease of operation. All these advantages have been verified through large-scale production (calculated based on a processing capacity of 300 tons / day and 300 production days per year), as detailed below: (1) Significant nutrient retention effect, improving the quality of finished edible oil: The waterless edible oil refining method of the present invention can effectively retain most of the nutrients such as VE in edible oil. Compared with the traditional alkali refining process, it can reduce the loss of nutrients caused by neutralizing excessive alkali by about 15%, making the finished oil more nutritious and healthy, meeting the needs of modern consumers for healthy edible oil, and enhancing the market competitiveness of finished oil.

[0039] (2) Significantly reduce electricity consumption and achieve energy-saving goals: The waterless edible oil refining method of this invention eliminates the water washing process in the neutralization stage, eliminating the need for the centrifuge used for water washing separation in traditional processes, thus saving the electricity consumption of the water washing centrifuge. The centrifuge has a power of 37kw, and the matching water washing tank has a stirring motor of 1.5kw and a pump of 1.5kw, for a total power of 40kw, which can be eliminated. With a power factor of 0.7, 28 kWh of electricity can be saved per hour, that is: energy consumption can achieve energy saving of 28 kWh / 12.5 tons / h ≈ 2 kWh / ton of oil. Based on a processing volume of 300 tons / day, 300 days of production per year, and an electricity unit price of 0.9 yuan / kWh, the annual energy saving cost is: 300 tons / day × 300 days × 0.9 yuan / kWh × 2 kWh / ton = 162,000 yuan. The energy saving effect is significant, greatly reducing the energy cost of enterprises.

[0040] (3) Improve refining yield and increase enterprise economic benefits: The waterless edible oil refining method of the present invention can increase the edible oil refining yield by about 0.4% by reducing the loss of neutral oil caused by excessive alkali and eliminating the operating loss caused by centrifuge separation. Based on a refining volume of 300 tons / day, a price of 9,000 yuan per ton of soybean oil, and 300 production days per year, the annual increase in receivables (based on soybean oil) is: 300 tons / day × 0.4% × 300 days × 9,000 yuan / ton = 3.24 million yuan, which directly improves the enterprise's profitability.

[0041] (4) Simplify the operation process and reduce labor and equipment maintenance costs: The waterless edible oil refining method of this invention optimizes and simplifies the refining operation process, eliminates the water washing process and the operation of the supporting centrifuge. On the one hand, it effectively reduces the operating intensity of employees and reduces the manual operation links, eliminating the need for additional water washing and centrifugation separation related operations; on the other hand, it reduces the daily operation of one centrifuge, which can significantly reduce equipment maintenance costs. According to industry standard calculations, the annual maintenance cost of each centrifuge is about RMB 100,000 (including intermediate repair package, major repair package, machine oil, maintenance labor, etc.), which can directly save this part of the maintenance cost every year.

[0042] (5) Reduce wastewater discharge and achieve green and environmentally friendly production: The waterless edible oil refining method of this invention eliminates the water washing section and has no water washing wastewater discharge. Compared with the traditional process (about 4.5 tons / day of oily wastewater), it can reduce the discharge of oily wastewater by about 1,350 tons per year. It reduces the generation of oily wastewater from the source, which not only reduces the wastewater treatment cost of enterprises (calculated at 80 yuan / ton of oily wastewater treatment cost, it can save 108,000 yuan of wastewater treatment cost per year), but also reduces the pollution of water resources. It is in line with the industrial development trend of green production, environmental protection and energy conservation, and can help enterprises meet environmental emission requirements, enhance the social image of enterprises, and avoid the risk of environmental penalties caused by non-compliance with wastewater discharge standards.

[0043] The beneficial effects of the present invention are as follows: The present invention provides a waterless edible oil refining method, which has the following advantages compared with the existing traditional refining process and enzymatic degumming refining process: (1) Eliminate the water washing section and realize waterless production: Break the inherent process of "alkali refining must be matched with water washing process" in the field of technology, remove the water washing and centrifugal dehydration operation in the traditional process, and obtain qualified neutral oil (acid value ≤0.3mg / g, phosphorus content ≤15ppm) and finished first grade oil that meets national standards through precise filtration, acid adjustment and vacuum drying. Solve the problems of wastewater pollution and neutral oil loss caused by the water washing process from the source, realize waterless production throughout the process, and have no oily wastewater discharge. (2) Optimize the pretreatment process and construct a three-stage physical filtration system: The innovative three-stage physical filtration pretreatment method of "primary filtration + nano-membrane coupling treatment" is adopted to replace the traditional crude oil pretreatment process. It can deeply remove more than 90% of phospholipids and impurities in crude oil (the phosphorus content in the oil after ultrafiltration is ≤60ppm), which greatly reduces the processing load of the subsequent neutralization stage and provides the necessary prerequisite for the realization of the low-alkali neutralization process. At the same time, high-quality phospholipid raw materials are obtained to provide high-quality raw materials for the subsequent deep processing of phospholipids. (3) Innovate the neutralization process to achieve low consumption and high efficiency: The neutralization reaction is carried out with low concentration and small proportion of citric acid solution and dilute alkali solution, replacing the high concentration of phosphoric acid (85%) and excessive alkali refining method in the traditional process. This avoids the saponification reaction between excessive alkali solution and neutral oil, reduces the loss of neutral oil (0.4% lower than the traditional process), and effectively retains nutrients such as VE in crude oil (VE loss can be reduced by more than 15%), taking into account both yield and quality. (4) Strong economic efficiency and suitable for large-scale production: Compared with the enzymatic degumming process, the investment cost of this invention is not much different from that of the traditional process (±5%). There is no need to invest in high equipment and enzyme preparation costs (which can save about RMB 120 / ton of oil in enzyme preparation costs). At the same time, it has the advantages of energy saving, emission reduction and good yield. It is suitable for the refining production of various types of edible oils, has stronger practicality, and is easier to achieve large-scale promotion. There is no need to carry out large-scale transformation of the existing production line. Attached Figure Description

[0044] Figure 1 This is a flowchart of the waterless edible oil refining method of the present invention. Detailed Implementation

[0045] The following detailed embodiments further illustrate the above-described content of the present invention. However, this should not be construed as limiting the scope of the present invention to the following embodiments. Unless otherwise specified, the reagents involved in the embodiments of the present invention are all commercially available products and can be purchased through commercial channels.

[0046] In the embodiments and comparative examples of this invention: Primary crude oil: Selected soybean crude oil from the same batch with consistent initial indicators: acid value (KOH) 2.2mg / g, phosphorus content 280ppm, vitamin E content 1250ppm, and moisture 0.12%.

[0047] Example 1 This embodiment provides a waterless edible oil refining method, such as... Figure 1 As shown, it includes the following steps: S1 Pre-filtration treatment: The crude oil produced in the initial stage is heated to 85°C, and the heated crude oil is pumped into a vertical blade filter by a centrifugal pump to obtain pre-filtered crude oil. The filter screen of the vertical blade filter has a mesh size of 200 mesh. S2 Two-stage membrane coupled ultrafiltration: The crude oil that was initially filtered was heated to 90°C and coupled with a stainless steel-ceramic composite nanomembrane and a stainless steel-supported silica hybrid mesoporous nanofiltration membrane under a pressure of 1.0 MPa to obtain the ultrafiltered crude oil; the pore size of the stainless steel-ceramic composite nanomembrane is 5 nm and the pore size of the stainless steel-supported silica hybrid mesoporous nanofiltration membrane is 1 nm.

[0048] S3 Acid Reaction Treatment: Add 50% citric acid to the ultrafiltered crude oil, the amount of which is 0.6‰ of the ultrafiltered crude oil, and stir and mix at 80℃ for 90 min at a stirring speed of 65 rpm to obtain degummed crude oil.

[0049] S4 Alkali reaction treatment: 32% liquid alkali is mixed with hot water to obtain an alkali solution, which is then added to degummed crude oil and mixed thoroughly. The mixture is then pumped into an alkali reaction tank through a mixing pump and stirred for 15 minutes to obtain deacidified crude oil. The amount of liquid alkali added is 1‰ based on the mass of the degummed crude oil, and the concentration of the alkali solution is 1%.

[0050] S5 Desoaping Process: The deacidified crude oil is pumped into a desoaping centrifuge for desoaping separation. After desoaping separation, a 40% citric acid aqueous solution is added at a rate of 0.4‰ of the mass of the deacidified crude oil. The mixture is then thoroughly mixed in a centrifugal mixer, heated to 110°C, and dried under a vacuum of 70 mbar to obtain edible oil.

[0051] S6 Decolorization and Deodorization Treatment: 0.6% attapulgite clay is added to the edible oil for decolorization, and deodorization is carried out under the conditions of 245℃, vacuum degree 2.0mbar, and direct stripping rate 65kg / h to obtain the finished oil.

[0052] Example 2 This embodiment provides a waterless edible oil refining method, including the following steps: S1 Pre-filtration treatment: The crude oil produced in the initial stage is heated to 88°C, and the heated crude oil is pumped into a vertical blade filter by a centrifugal pump to obtain pre-filtered crude oil. The filter screen of the vertical blade filter has a mesh size of 200 mesh. S2 Two-stage membrane coupled filtration: The crude oil from the initial filtration is heated to 85°C and subjected to coupled ultrafiltration at 1.1 MPa through a stainless steel-ceramic composite nanomembrane and a stainless steel-supported silica hybrid mesoporous nanofiltration membrane to obtain ultrafiltered crude oil; the pore size of the stainless steel-ceramic composite nanomembrane is 5 nm, and the pore size of the stainless steel-supported silica hybrid mesoporous nanofiltration membrane is 1 nm.

[0053] S3 Acid Reaction Treatment: Add 50% citric acid to the ultrafiltered crude oil, at a dosage of 0.4‰ of the ultrafiltered crude oil, and stir and mix at 75℃ for 90 minutes at a stirring speed of 65 rpm to obtain degummed crude oil. S4 Alkali reaction treatment: 32% liquid alkali is mixed with hot water to obtain an alkali solution, which is then added to degummed crude oil and mixed thoroughly. The mixture is then pumped into an alkali reaction tank through a mixing pump and stirred for 15 minutes to obtain deacidified crude oil. The amount of liquid alkali added is 0.8‰ based on the mass of the degummed crude oil, and the concentration of the alkali solution is 1%.

[0054] S5 Desoaping Process: The deacidified crude oil is pumped into a desoaping centrifuge for desoaping separation. After desoaping separation, a 40% citric acid aqueous solution is added at a rate of 0.4‰ of the mass of the deacidified crude oil. The mixture is then thoroughly mixed in a centrifugal mixer, heated to 110°C, and dried under a vacuum of 70 mbar to obtain edible oil.

[0055] S6 Decolorization and Deodorization Treatment: 0.4% attapulgite clay is added to the edible oil for decolorization, and deodorization is carried out under the conditions of 240℃, vacuum degree 2.0mbar, and direct stripping rate of 50kg / h to obtain the finished oil.

[0056] Examples 3-7 provide a waterless edible oil refining method, the steps of which are the same as those in Example 1, the only difference being the parameters shown in Table 1.

[0057] Table 1 Examples 8-10 provide a waterless edible oil refining method, the steps of which are the same as those in Example 1, the only difference being the parameters shown in Table 2.

[0058] Table 2 Comparative Example 1 This comparative example provides a method for refining edible oil, including the following steps: S1 crude oil temperature rise: to 75℃; S2 acid reaction: Add 85% phosphoric acid to crude oil, the amount of which is 1‰ of the crude oil, stir and react for 60 minutes to obtain degummed crude oil. S3 Alkali Reaction: A 32% (w / w) liquid alkali is mixed with hot water to obtain an alkali solution. This solution is then added to degummed crude oil and thoroughly mixed. The mixture is then pumped into an alkali reaction tank using a mixing pump and stirred for 20 minutes to obtain deacidified crude oil. The amount of liquid alkali added is 1% based on the mass of the degummed crude oil; the concentration of the alkali solution is 12%. S4 Desoaping: Deacidified crude oil is pumped into a desoaping centrifuge for desoaping and separation. S5 Washing: After the soap removal and separation are completed, add 1.5% hot water + 0.5‰ citric acid, wash for 15 minutes, and then separate the oily wastewater (about 4.5 tons / day) using a washing centrifuge. S6 Drying: After washing with water, heat to 110°C and dry under vacuum conditions of 70 mbar to obtain edible oil; S7 Decolorization and Deodorization: Add 0.6% attapulgite clay to the edible oil for decolorization, deodorize at 243℃ and 2.0mbar, and directly strip at a rate of 75kg / h to obtain the finished oil.

[0059] Comparative Example 2 This comparative example provides a method for refining edible oil, including the following steps: S1 crude oil heating: 80℃; S2 acid reaction: Add 85% phosphoric acid to crude oil, the amount of which is 0.6‰ of the crude oil, stir and react for 90 min to obtain degummed crude oil; S3 Alkali Reaction: A 32% (w / w) liquid alkali is mixed with hot water to obtain an alkali solution. This solution is then added to degummed crude oil and thoroughly mixed. The mixture is then pumped into an alkali reaction tank using a mixing pump and stirred for 20 minutes to obtain deacidified crude oil. The amount of liquid alkali added is 1.5% based on the mass of the degummed crude oil; the concentration of the alkali solution is 10%. S4 Desoaping: Deacidified crude oil is pumped into a desoaping centrifuge for desoaping and separation. S5 Washing: After soap removal and separation, add 2% hot water + 0.5‰ citric acid, wash for 15 minutes, and then separate the oily wastewater (approximately 6 tons / day) using a washing centrifuge. S6 Drying: After washing with water, heat to 110°C and dry under vacuum conditions of 70 mbar to obtain edible oil; S7 Decolorization and Deodorization: Add 0.5% attapulgite clay to the edible oil for decolorization, deodorize at 241℃ and 2.0mbar, and directly strip at a rate of 75kg / h to obtain the finished oil.

[0060] Comparative Example 3 This comparative example provides a method for refining edible oil, including the following steps: S1 crude oil heating: 85℃; S2 acid reaction: Add 85% phosphoric acid to crude oil, the amount of which is 0.5‰ of the crude oil, stir and react for 100 min to obtain degummed crude oil; S3 Alkali Reaction: A 32% (w / w) liquid alkali is mixed with hot water to obtain an alkali solution. This solution is then added to degummed crude oil and thoroughly mixed. The mixture is then pumped into an alkali reaction tank using a mixing pump and stirred for 25 minutes to obtain deacidified crude oil. The amount of liquid alkali added is 1.3% by weight of the degummed crude oil; the concentration of the alkali solution is 8%. S4 Desoaping: Deacidified crude oil is pumped into a desoaping centrifuge for desoaping and separation. S5 Water Wash: After soap removal and separation, add 3% hot water + 0.5‰ citric acid, water wash reaction for 20 minutes, and water washing centrifuge to separate oily wastewater (about 9 tons / day). S6 Drying: After washing with water, heat to 110°C and dry under vacuum conditions of 70 mbar to obtain edible oil; S7 Decolorization and Deodorization: Add 0.7% attapulgite clay to the edible oil for decolorization, deodorize at 240℃ and 2.0mbar, and directly strip at a rate of 70kg / h to obtain the finished oil.

[0061] Example of effect The relevant indicators of the edible oils prepared in the examples and comparative examples were tested, and the testing methods are as follows: 1. Testing Standards: Product indicators (acid value, phosphorus content, etc.) are tested in accordance with national and industry standards, and the testing methods are uniform. Among them, the acid value is determined according to GB 5009.229-2025; the phosphorus content is determined according to GB 5009.87-2016; and the color is determined according to GB / T 5009.37-2003 "Analytical Methods for Hygienic Standards of Edible Vegetable Oils".

[0062] The results are shown in Table 3-4.

[0063] As shown in Table 3, the proportion of citric acid added is generally controlled between 0.2-1.5‰, preferably 0.6‰. Furthermore, by adding 0.8% dilute alkali (preferably 1.0‰), the acid value of the desoaped oil is controlled between 0.1-0.3 mg / g. For the same crude soybean oil quality, the acid value is 2.2 mg / g and the phosphorus content is 280 ppm. Different filtration methods have a significant impact on the use of subsequent auxiliary materials and the control of semi-finished product process indicators. The three-stage filtration method of this invention, which reduces the acid value and phospholipids, is a prerequisite for the operation of this invention. Based on the quality characteristics of the crude oil after ultrafiltration, selecting low-acid and dilute-alkali process parameters can effectively remove acid value, phospholipids, gums, and impurities from the oil without further water washing to remove impurities. This yields qualified neutralized semi-finished oil, which can then be used for subsequent decolorization and deodorization refining processes, resulting in finished first-grade oil that meets national and industry standards.

[0064] As shown in Figure 4, by using a three-stage physical filtration method to reduce the acid value and phospholipids of crude oil, a higher quality crude oil can be obtained. Then, by selecting low acid and light alkali process parameters, the acid value, phospholipids, gums and impurities in the oil can be effectively removed without further water washing to remove impurities. This yields a qualified semi-finished neutralized oil to meet the requirements of subsequent decolorization and deodorization refining processes, thus obtaining a finished first-grade oil that meets national and industry standards. Furthermore, the overall evaluation of the finished oil in the example is better than that of the comparative example.

[0065] Table 3

[0066] Table 4 2. (Shelf life) quality testing: (1) Test method: The shelf life of oils is estimated according to the Van't Hoff equation, which describes the relationship between reaction temperature and reaction rate, as shown in the following formula: k(T+10) / k(T)=2~4. Where: k is the reaction rate constant; T is the temperature.

[0067] Based on the Van't Hoff equation, the empirical relationship between temperature and shelf life coefficient is obtained, as shown in Table 5.

[0068] Table 5 For example, an accelerated test at 40℃ for 30 days is equivalent to extending the test from room temperature (20℃) to 120 days, and an accelerated test at 50℃ for 45 days is equivalent to extending the test from room temperature (20℃) to 360 days, etc.

[0069] (2) Testing process: Select the process products of the example and comparative example as control samples, put them into 750ml packaging bottles, set different sampling time points to take out the samples of each independent package to determine the acid value and peroxide value in order to predict the changes in the quality of the oil.

[0070] (3) Determination methods: Peroxide value: determined according to the first method "titration method" of GB5009.227; Acid value: determined according to the first method "cold solvent indicator titration method" of GB5009.229.

[0071] The results are shown in Table 6.

[0072] Table 6 Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit the scope of protection of the present invention. Although the present invention has been described in detail with reference to preferred embodiments, those skilled in the art should understand that modifications or equivalent substitutions can be made to the technical solutions of the present invention without departing from the essence and scope of the technical solutions of the present invention.

Claims

1. A waterless edible oil refining method, characterized in that, The process includes sequentially subjecting crude oil to three-stage physical filtration, acid reaction treatment, alkali reaction treatment, and desoaping treatment to obtain the edible oil. The three-stage physical filtration includes heating the crude oil and then performing initial filtration through a filter, followed by maintaining the temperature and then performing ultrafiltration through a two-stage membrane coupling. The two-stage membranes are a stainless steel-ceramic composite nanomembrane and a stainless steel carrier silica hybrid mesoporous nanofiltration membrane.

2. The waterless edible oil refining method according to claim 1, characterized in that, The stainless steel-ceramic composite nanomembrane has a pore size of 3-10 nm; the stainless steel-supported silica hybrid mesoporous nanofiltration membrane has a pore size of 1.0 nm.

3. The waterless edible oil refining method according to claim 1, characterized in that, The temperature of the initial filtration treatment is 60-90℃; the temperature of the two-stage membrane coupled ultrafiltration is 70-95℃.

4. The waterless edible oil refining method according to claim 1, characterized in that, The acid reaction treatment includes adding a citric acid solution with a mass concentration of 30-70% to the ultrafiltration crude oil, with the amount added being 0.2-1.5‰ of the crude oil mass, and stirring and mixing at 75-85℃ for 60-120 minutes at a stirring speed of 60-68 rpm to obtain degummed crude oil.

5. The waterless edible oil refining method according to claim 1 or 2, characterized in that, The alkaline reaction treatment includes mixing and stirring the alkaline solution with the degummed crude oil for 5-30 minutes to obtain deacidified crude oil.

6. The waterless edible oil refining method according to claim 5, characterized in that, Based on the mass of degummed crude oil, the alkaline solution comprises 0.5-2‰ of liquid alkali with a mass fraction of 32% and 1-3% hot water.

7. The waterless edible oil refining method according to any one of claims 1-3, characterized in that, The soap removal process includes centrifuging the deacidified crude oil, adding a citric acid aqueous solution with a mass fraction of 30-50% at a mass of 0.2-1‰ of the deacidified crude oil, mixing, heating, and vacuum drying to obtain edible oil.

8. The waterless edible oil refining method according to claim 1, characterized in that, The waterless edible oil refining method also includes decolorization and deodorization treatments.

9. The application of the waterless edible oil refining method according to any one of claims 1 to 8 in edible oil production.

Images