Purification and color reduction oleic acid refining method

Abstract

The invention relates to the technical field of oil refining, and discloses an oleic acid refining method capable of purifying and reducing color. Mixing the crude oil with water according to a volume ratio of 1: 1-1: 2; alkali liquor is added into the degummed oleic acid for a neutralization reaction, and the pH of a reaction system is adjusted to 5-7; adding a biocatalyst into the deacidified oleic acid, and reacting for 1-2 hours at the temperature of 40-60 DEG C under the condition that the pH is 4.5-6; adding a composite nano adsorbent into the oleic acid subjected to catalytic treatment; separating the adsorbent from the oleic acid through a micro-filtration membrane with the aperture of 0.5-1 mu m; and carrying out steam deodorization on the obtained oleic acid. By introducing the composite nano adsorbent, the impurities and pigments in the oleic acid are efficiently removed. The synergistic structure of nano silicon and nano aluminum oxide in the composite adsorbent has excellent adsorption performance and surface reaction activity, pigment molecules and polar impurities can be accurately captured in the refining process, and the color and purity of oleic acid are remarkably improved.

Description

Technical Field

[0001] The invention relates to the technical field of oil refining, in particular to a method for refining oleic acid for purification and color reduction. Background Art

[0002] Currently, the refining of oleic acid primarily relies on traditional degumming, deacidification, decolorization, and deodorization processes. However, these conventional technologies often suffer from inefficiencies and difficulties in quality control when dealing with complex oil phase systems. For example, single adsorbents or high-temperature physical methods are often used to remove pigments and impurities. However, due to poor adsorption selectivity and intense heat treatment reactions, the color and purity of the refined oleic acid are difficult to meet high standards. Furthermore, for color control, commonly used chemical bleaching or high-temperature oxidation methods, while effective, can easily destroy the natural components of the oleic acid, leading to a decrease in flavor and even the introduction of potentially harmful byproducts.

[0003] Regarding the above-mentioned related technologies, activated clay or bleaching agents are still widely used in the decolorization stage, which can easily damage the flavor of oleic acid and have poor stability. The finished oleic acid is prone to color reversion during storage, affecting the final performance.

[0004] Existing deodorization technologies mostly rely on high-temperature steam conditions. This method is not capable of removing certain low-concentration but strong-smelling odor components, and high temperatures can easily cause oleic acid oxidation, reducing quality.

[0005] Regarding deacidification treatment, traditional methods often use high-concentration strong alkali for rapid neutralization, but side reactions are obvious, impurity dissolution increases, and even causes local damage to the oil structure, resulting in a deterioration in flavor and increased difficulty in controlling the refining process.

[0006] In terms of impurity removal, the lack of efficient adsorbents with composite structures is still a shortcoming. Conventional materials have limited composite adsorption capacity for various impurities such as pigments and metal ions. Oleic acid residues still remain after treatment, affecting their further processing and quality improvement. Summary of the Invention

[0007] The purpose of the present invention is to provide a method for refining oleic acid for purification and color reduction, which solves the problems of incomplete impurity removal, unstable color and obvious residual odor in the existing oleic acid refining process.

[0008] To achieve the above objectives, the present invention is implemented through the following technical solutions: A method for purifying and reducing the color of oleic acid, comprising the following steps; The crude oil is mixed with water in a volume ratio of 1:1-1:2, heated to 60°C-80°C, and a gelatinase is added to obtain degummed oleic acid; adding alkali solution to the degummed oleic acid for neutralization reaction, adjusting the pH of the reaction system to 5-7, controlling the acid value of the oleic acid to be less than 2 mgKOH / g after the reaction, separating the aqueous phase, and obtaining deacidified oleic acid; Adding a biocatalyst to the deacidified oleic acid, reacting at 40°C-60°C for 1-2 hours under pH 4.5-6 conditions; Adding a composite nano-adsorbent to the catalytically treated oleic acid in an amount of 1% to 5% by weight of the oleic acid, and reacting at 30° C. to 50° C. for 1 to 3 hours; The adsorbent was separated from the oleic acid by a microfiltration membrane with a pore size of 0.5 μm-1 μm; The obtained oleic acid is steam deodorized for 30 minutes to 1 hour. Preferably, the gelatin decomposing enzyme is phospholipase A; Furthermore, the enzyme can degrade phospholipids and colloids in crude oil, reducing the content of non-fatty acid impurities in oleic acid and alleviating the burden of subsequent processing. Specifically, the enzyme catalyzes the hydrolysis of phospholipids, breaking down the colloid particles in the crude oil and converting them into more easily separable water-soluble substances, effectively removing the colloid impurities.

[0009] Preferably, the enzyme is added in an amount of 0.05% to 0.2% of the weight of the oil, the reaction is stirred for 30 to 60 minutes, and the aqueous phase and the oil phase are separated to obtain degummed oleic acid.

[0010] Preferably, the enzyme is added in an amount of 0.05% to 0.2% of the weight of the oil, the reaction is stirred for 30 to 60 minutes, and the aqueous phase and the oil phase are separated to obtain degummed oleic acid.

[0011] Preferably, the biocatalyst is lipase or phenol oxidase, and the added amount is 0.1%-0.5% of the mass of oleic acid; Furthermore, deacidification treatment is performed via a neutralization reaction. This deacidification process uses sodium hydroxide or potassium hydroxide solution to neutralize the free fatty acids in the oleic acid and adjust the acid value of the oleic acid. The acid value of the neutralized oleic acid should be controlled within a range of less than 2 mgKOH / g to ensure better physical and chemical properties and efficient subsequent processing.

[0012] Preferably, the composite nano-adsorbent is a mixture of nano-silicon, nano-aluminum oxide and plant extracts.

[0013] Preferably, the plant extract is tea polyphenols, rosemary extract or vitamin E; Furthermore, the nano-adsorbent effectively absorbs pigments, metal ions, and other impurities in oleic acid through its large specific surface area and unique adsorption properties. During the adsorption process, the nano-silicon and nano-alumina composite fully utilizes their dual adsorption properties for both polar and non-polar substances, effectively removing pigment molecules, metal ions, and some low-solubility impurity molecules from oleic acid.

[0014] Preferably, the composite nano-adsorbent is prepared by mixing nano-silicon and nano-aluminum oxide in a mass ratio of 1:1-3:1, adding a plant extract accounting for 0.5%-2% of the total mass of the adsorbent, stirring at 25°C-40°C for 30 minutes-60 minutes to form a uniform mixture, and then drying and crushing it into a powdered adsorbent with a particle size of 10nm-100nm.

[0015] Preferably, the composite nano-adsorbent has a particle size range of 10 nm to 100 nm.

[0016] Preferably, the temperature of the steam deodorization is 100°C-150°C, and the vacuum degree is 50Pa-200Pa; After the oleic acid has been adsorbed, the nano-adsorbent is separated from the oleic acid through a microfiltration or ultrafiltration membrane, further purifying the impurities in the oleic acid and removing any residues from the adsorbent. This process relies on the physical action of membrane filtration, which selectively removes large molecular impurities, ensuring the purity of the final oleic acid.

[0017] In summary, the present invention includes at least one of the following beneficial technical effects: 1. This invention achieves efficient removal of impurities and pigments from oleic acid by introducing a composite nano-adsorbent. The synergistic structure of nano-silicon and nano-alumina in the composite adsorbent possesses excellent adsorption properties and surface reactivity, enabling it to precisely capture pigment molecules and polar impurities during the refining process, significantly improving the color and purity of oleic acid.

[0018] 2. This invention successfully achieves gentle decolorization and improved color stability of oleic acid by incorporating a biocatalytic color reduction process into the refining process. This technology leverages the specificity and catalytic activity of biological enzymes to selectively degrade the natural pigments in oleic acid, effectively avoiding the flavor loss and undesirable byproduct formation associated with traditional physical or chemical methods.

[0019] 3. This invention effectively improves the sensory flavor and deodorization of oleic acid by combining low-temperature treatment with catalytic color reduction. This method utilizes temperature control to suppress adverse reactions and utilizes a catalyst to promote the conversion of odor precursors, fundamentally reducing the content of odorous components in oleic acid.

[0020] 4. By carefully controlling the alkali concentration, the present invention achieves the dual goals of deacidification efficiency and oleic acid quality. Using an appropriate alkali concentration to treat oleic acid not only helps remove free fatty acids but also reduces impurity dissolution and oil decomposition caused by excessive alkali, thereby achieving stable deacidification control. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Figure 1 Schematic diagram of the method of the present invention. DETAILED DESCRIPTION

[0022] The following is combined with Figure 1 , the present invention is described in further detail.

[0023] The present invention provides a method for refining oleic acid for purification and color reduction. Example 1; Mix 1000 mL of crude oleic acid with 1000 mL of deionized water (1:1 volume ratio), heat at 75°C, and add phospholipase A at a concentration of 0.1% by weight of the oil. Stir and react for 45 minutes, then allow to stand and separate. Discard the lower aqueous phase to obtain degummed oleic acid.

[0024] The degummed oleic acid was added to a 10% mass concentration sodium hydroxide solution to adjust the pH to 6.0 and control the acid value to be less than 2 mgKOH / g after the reaction. After the reaction was completed, the degummed oleic acid was washed twice with water and centrifuged to obtain the deacidified oleic acid.

[0025] The pH of the deacidified oleic acid was adjusted to 5.5, lipase was added (the amount added was 0.3% of the mass of the oleic acid), and the reaction was carried out at 50° C. for 1.5 hours. After the reaction was completed, the next step was directly processed.

[0026] To the catalytically treated oleic acid, 3% of a composite nano-adsorbent, comprising a mixture of nano-silicon and nano-alumina in a mass ratio of 2:1, and 1% of tea polyphenol powder were added. After drying, a composite powder with a particle size of 50 nm was prepared. The mixture was stirred and reacted at 40°C for 2 hours.

[0027] The mixture was then filtered through a microfiltration membrane with a pore size of 0.8 μm to remove the adsorbent and obtain preliminary refined oleic acid.

[0028] Finally, steam deodorization was carried out at 120°C and vacuum degree 150Pa for 45 minutes to obtain refined decolorized oleic acid. Mix 1000 mL of crude oleic acid with 2000 mL of deionized water (1:2 volume ratio), heat at 60°C, and add phospholipase A at a concentration of 0.05% by weight of the oil. After stirring for 30 minutes, allow the mixture to stand and separate into layers. Remove the aqueous phase to obtain degummed oleic acid.

[0029] Add the degummed oleic acid to a 5% mass concentration potassium hydroxide solution, adjust the reaction pH to 5.0, and react until the acid value is controlled below 2 mgKOH / g. After washing with water, separate the oil phase for later use.

[0030] Phenol oxidase was added to the deacidified oleic acid in an amount of 0.1% of the mass of the oleic acid, the pH was adjusted to 4.5, and the mixture was reacted at 40° C. for 1 hour to perform catalytic color reduction treatment.

[0031] 1% of a composite nano-adsorbent, which is a mixture of nano-silicon and nano-alumina in a ratio of 1:1, is added to the oleic acid, and 0.5% of a rosemary extract is added to form a powder with a particle size of 10 nm. The mixture is stirred at 30°C for 1 hour.

[0032] A 0.5 μm microfiltration membrane was used for adsorbent separation to obtain refined oleic acid.

[0033] The oleic acid was deodorized at 100° C. under a vacuum degree of 50 Pa for 30 minutes to obtain a refined oleic acid product after degumming, deacidification, color reduction and deodorization.

[0034] Example 2; Mix 1000 mL of crude oleic acid with 2000 mL of deionized water (1:2 volume ratio), heat at 60°C, and add phospholipase A at a concentration of 0.05% by weight of the oil. After stirring for 30 minutes, allow the mixture to stand and separate into layers. Remove the aqueous phase to obtain degummed oleic acid.

[0035] Add the degummed oleic acid to a 5% mass concentration potassium hydroxide solution, adjust the reaction pH to 5.0, and react until the acid value is controlled below 2 mgKOH / g. After washing with water, separate the oil phase for later use.

[0036] Phenol oxidase was added to the deacidified oleic acid in an amount of 0.1% of the mass of the oleic acid, the pH was adjusted to 4.5, and the mixture was reacted at 40° C. for 1 hour to perform catalytic color reduction treatment.

[0037] 1% of a composite nano-adsorbent, which is a mixture of nano-silicon and nano-alumina in a ratio of 1:1, is added to the oleic acid, and 0.5% of a rosemary extract is added to form a powder with a particle size of 10 nm. The mixture is stirred at 30°C for 1 hour.

[0038] A 0.5 μm microfiltration membrane was used for adsorbent separation to obtain refined oleic acid.

[0039] The oleic acid was deodorized at 100°C under a vacuum of 50 Pa for 30 minutes to obtain a refined oleic acid product after degumming, deacidification, color reduction and deodorization. Example 3; Mix 1000 mL of crude oleic acid with 1000 mL of deionized water (1:1 volume ratio), heat at 80°C, and add phospholipase A at a concentration of 0.2% by weight of the oil. Stir and react for 60 minutes, then allow to stand and separate the aqueous phase to obtain degummed oleic acid.

[0040] A 15% mass concentration sodium hydroxide solution is added to the degummed oleic acid to adjust the pH to 7.0. After the reaction is completed, the alkali solution is removed by washing with water to reduce the acid value to below 1.5 mgKOH / g, thereby obtaining deacidified oleic acid.

[0041] Phenol oxidase was added to the oleic acid (the amount added was 0.5% of the mass of the oleic acid), the pH was adjusted to 6.0, and the reaction was carried out at 60° C. for 2 hours to complete catalytic decolorization.

[0042] Add 5% of a composite nano-adsorbent, which is a mixture of nano-silicon and nano-alumina in a mass ratio of 3:1, and 2% of vitamin E. After drying, obtain an adsorbent powder with a particle size of approximately 100 nm. Stir at 50°C for 3 hours.

[0043] A microfiltration membrane with a pore size of 1.0 μm was used to separate the adsorbent and oleic acid to obtain high-purity oleic acid.

[0044] The oleic acid was subjected to steam deodorization treatment at a temperature of 150° C. and a vacuum degree of 200 Pa for 1 hour, ultimately obtaining refined oleic acid with light color, little odor and excellent quality.

[0045] Comparative Example 1: Compared with Example 1, the difference is that no composite nano-adsorbent is added, and the rest are the same.

[0046] Comparative Example 2: Compared with Example 1, the difference is that the biocatalytic color reduction treatment step is not performed, and the rest are the same.

[0047] Comparative Example 3: Compared with Example 1, the difference is that no gelatin decomposing enzyme is added in the gelatin decomposition stage, and degumming is performed only by hot water hydration. The rest are the same.

[0048] Comparative Example 4: Compared with Example 1, the difference is that 20% mass concentration sodium hydroxide solution is used for deacidification, and the rest are the same.

[0049] Experiment 1: Purpose of the experiment: By comparing the oleic acid refining effects with and without the addition of composite nano-adsorbents, the role of composite nano-adsorbents in improving color, removing impurities and improving the quality of oleic acid was evaluated.

[0050] Experimental Materials: Crude oleic acid, deionized water, composite nano-adsorbent (nano-silicon and nano-alumina mixed in a mass ratio of 2:1), and oleic acid standard.

[0051] Measuring instruments: colorimeter, odor analyzer, ion chromatograph, acid value tester.

[0052] Experimental steps: Prepare the sample: In comparative group 1 (Example 1), crude oleic acid and deionized water were mixed at a volume ratio of 1:1, heated to 75° C., and the composite nano-adsorbent was added (adsorbent addition amount 3%).

[0053] In comparative group 2 (comparative example 1), crude oleic acid and deionized water were mixed in a volume ratio of 1:1, heated to 75° C., and no composite nano-adsorbent was added.

[0054] The two groups were stirred under the same conditions, reacted for 45 minutes and then allowed to stand, and the oil phase and the water phase were separated to obtain degummed oleic acid.

[0055] Sodium hydroxide solution was added to both samples to adjust the pH to 6.0 and the mixture was reacted until the acid value was less than 2 mgKOH / g. The mixture was washed twice with water and the oil phase was separated for later use.

[0056] Adding composite adsorbent (Example 1 only): A composite nano-adsorbent was added to the sample of Example 1, and the amount of the adsorbent was 3% (by mass) of the mass of oleic acid.

[0057] The mixture was stirred at 40°C for 2 hours, and the adsorbent was removed by filtration to obtain refined oleic acid.

[0058] Testing refined oleic acid: The color, impurity content and flavor of the two groups of refined oleic acid were tested.

[0059] Color was measured using a colorimeter.

[0060] Impurities (such as metal ions) are determined by ion chromatography.

[0061] The experimental data are shown in Table 1: Table 1 Comparative data of color, impurities and flavor during oleic acid refining Summarize; Based on the comparative experimental results of Example 1 and Comparative Example 1, the role of the composite nano-adsorbent in oleic acid refining can be deeply analyzed from a mechanistic perspective. Composite nano-adsorbents, especially the combination of nano-silicon and nano-aluminum oxide, can significantly improve the refining effect of oleic acid through their special physical and chemical properties. Nano-scale adsorbents have a large specific surface area and a high degree of surface activity, which can effectively adsorb pigments, heavy metal ions and other impurities in oleic acid, thereby improving the color and quality of oleic acid. Compared with the control group without added adsorbent, the composite nano-adsorbent added in Example 1 showed obvious advantages in reducing impurity content and improving the color of oleic acid, indicating that the adsorbent can interact with impurities at the molecular level, thereby achieving the effect of refining and purification.

[0062] Furthermore, the composite nano-adsorbent can synergize with certain polar components in oleic acid during the refining process, further enhancing decolorization and impurity removal. Nano-silicon and nano-alumina possess strong hydrophilic and lipophilic properties, respectively. Their surface activity enables them to act as a bridge between the oil and water phases, adsorbing and transferring polar impurities in the aqueous phase, preventing these impurities from forming stable emulsions or colloids with the oleic acid in the oil phase. In this way, the composite nano-adsorbent not only improves the cleanliness of oleic acid but also optimizes its sensory qualities, further enhancing its color and flavor.

[0063] Finally, regarding the improvement of oleic acid flavor, the composite nano-adsorbent reduces odor components in oleic acid by removing impurities and pigments during the oleic acid refining process. This enhanced effect is closely related to the microporous structure of the adsorbent surface, which effectively captures volatile substances in oleic acid, including chemical components that may cause unpleasant flavors.

[0064] Experiment 2: Comparative test experiment of Example 1 and Comparative Example 2 Purpose of the experiment: The aim of this study was to evaluate the effect of biocatalytic color reduction during oleic acid refining on the color and storage stability of oleic acid, and to verify its role in improving appearance quality and inhibiting color reversion.

[0065] Experimental Materials: Refined oleic acid samples (Example 1 and Comparative Example 2) Biocatalysts (including peroxidase and polyphenol oxidase, etc.) Buffer solution (for pH adjustment), constant temperature shaking water bath Colorimeter, photostability test chamber, UV-visible spectrophotometer Experimental steps: Take two groups of oleic acid samples, 50 mL each, number them respectively and place them in a constant temperature container and preheat to 40°C.

[0066] In Example 1, preactivated biocatalyst (enzyme concentration: 0.05 g / mL) was added, pH 5.5 was maintained in a buffer solution, and the reaction was carried out at 40° C. for 60 minutes with mild stirring.

[0067] Comparative Example 2 group was not added with any enzyme and was used as a control group, and was simply left to stand under the same conditions.

[0068] The sample treated in Example 1 was heated at 70° C. for 10 minutes to terminate the enzyme activity.

[0069] Color test: Use a colorimeter to measure the initial color difference (ΔE) between the two groups of samples, and record the color parameters L*, a*, and b*.

[0070] Simulated storage test; The two groups of samples were placed in a light stability test box (room temperature, 3000lx white light) and irradiated continuously for 72 hours to simulate the effects of light during the shelf life.

[0071] Color difference change determination: After the illumination is completed, ΔE is measured again to evaluate the color stability of the sample and whether there is any "color return" phenomenon.

[0072] The experimental data are shown in Table 2: Table 2: Color difference and color return evaluation data before and after oleic acid biocatalytic color reduction treatment Summarize; Based on the results of Experiment 2, the effect of biocatalytic color reduction treatment in oleic acid refining is obvious. The biocatalyst reduces the color components in oleic acid by degrading the pigment substances in oleic acid, especially the oxidation products of flavonoids and some unsaturated fatty acids. This process is to destroy the structure of these pigment molecules through enzyme-catalyzed reactions, so that they no longer have strong light absorption ability, thereby reducing the color depth of oleic acid. The biocatalytic treatment used in Example 1 significantly improves the color quality of oleic acid, proving that biocatalytic color reduction can not only remove pigments, but also avoid the side effects of traditional chemical methods on oleic acid, achieving a more gentle and efficient color improvement effect.

[0073] At the same time, the biocatalyst not only removes the pigment from the oleic acid, but also effectively prevents color reversion. Color reversion is typically caused by the reprecipitation of pigments under the influence of external light and heat. Biocatalytic color reduction treatment, through the properties of the enzyme, stabilizes the pigment structure in the oleic acid, reducing secondary oxidation and polymerization reactions under light and heat treatment. In the experiment, after 72 hours of light exposure, the oleic acid sample from Example 1 showed the least color change, demonstrating the unique advantage of biocatalytic color reduction treatment in improving the storage stability of oleic acid, reducing the tendency for color reversion, and extending the shelf life of oleic acid.

[0074] Another important mechanism of biocatalytic color reduction is the enzyme-mediated destruction of impurity molecules in oleic acid, improving its purity and flavor. Enzymatic color reduction not only removes pigments that affect oleic acid's color but also decomposes substances that may cause off-flavors, such as oxidized fatty acids and organic acids, further enhancing the sensory quality of oleic acid.

[0075] Experiment 3: Testing the Improved Effects of Oleic Acid Color Reduction and Deodorization Experiments Purpose of the experiment: To verify the effect of low temperature treatment combined with catalytic color reduction technology on color reduction, deodorization and flavor improvement of oleic acid, and to evaluate its comprehensive impact on the quality of oleic acid, especially for the removal of odorous substances in oleic acid.

[0076] Experimental Materials: Oleic acid sample (oleic acid after preliminary refinement) Low temperature cooling device (-5℃ to 5℃ range) Specific catalysts (catalysts containing metal components such as copper and molybdenum) Odor analyzer, colorimeter, acid value tester Nitrogen or other inert gas Experimental steps: 50 mL of oleic acid samples were taken, numbered and divided into two groups: Example 1 (addition of catalyst and low-temperature treatment) and Comparative Example 3 (only low-temperature treatment, no catalyst).

[0077] Example 1: The oleic acid sample was placed in a cooling device at a temperature between -5°C and 5°C, and cooled and maintained for 48 hours.

[0078] Comparative Example 3: The oleic acid sample was placed in the same cooling device, but without adding a catalyst, and cooled for 48 hours.

[0079] Catalyst addition (Example 1 only): A specific catalyst (0.1% by mass) was added to the oleic acid after low-temperature treatment, and the mixture was stirred and reacted at room temperature for 2 hours to ensure that the catalyst was fully in contact with the oleic acid.

[0080] Odor removal treatment: The two groups of oleic acid were deodorized using an inert gas (such as nitrogen) for 3 hours while maintaining slight stirring to remove volatile odorous substances in the oleic acid.

[0081] Color difference and flavor test: Use a colorimeter to measure the color change before and after treatment, and record the ΔE value and L*, a*, and b* values.

[0082] The flavor of the two groups of oleic acid was analyzed using an odor analyzer, and the deodorization effect and the degree of odor removal were recorded.

[0083] Acid value and sensory evaluation: The acid value was measured to evaluate the changes in oleic acid. Professionals evaluated the sensory flavor of the two groups of oleic acid, including the presence of residual odor and freshness of the taste.

[0084] The experimental data are shown in Table 3: Table 3 Color difference and color return evaluation data before and after oleic acid biocatalytic color reduction treatment Summarize; Based on the results of Experiment 3, the combination of low-temperature treatment and catalytic color reduction technology demonstrated unique advantages in reducing the color and deodorizing oleic acid. Low-temperature treatment inhibited the polymerization of pigment molecules in the oleic acid, reducing the color degradation that can occur under high-temperature conditions. Combined with the use of a catalyst, it further promoted the decomposition and conversion of the pigment, avoiding the quality loss that can occur with traditional high-temperature treatment. This process effectively reduced the color depth of the oleic acid while preserving its natural hue, demonstrating the synergistic effect of low temperature and catalytic color reduction, effectively improving the color of the oleic acid.

[0085] The combination of low temperatures and catalytic color reduction technology also plays a key role in deodorization. Low-temperature treatment allows some volatile odorous compounds in oleic acid to be retained, while the catalyst promotes chemical reactions that help break down and transform these odorous components. The catalyst not only removes some residual impurities in the oleic acid but also triggers reactions within the oleic acid, effectively removing odorous compounds that could affect the flavor. Experimental results show that the odor removal rate of the treated oleic acid is significantly improved, resulting in a fresher flavor, fully demonstrating the effectiveness of this technology in improving the flavor of oleic acid.

[0086] Furthermore, low temperature combined with catalytic color reduction technology has also shown a positive effect on controlling the acid value of oleic acid. Low temperatures effectively inhibit the formation of acidic components, while the introduction of catalysts further reduces the acid value of oleic acid, maintaining its stability and excellent edible quality.

[0087] Experiment 4: Effect of sodium hydroxide concentration on deacidification effect Purpose of the experiment: The deacidification effects of sodium hydroxide solutions of different concentrations on oleic acid value, free fatty acid content, color and impurity content were tested to verify the influence of concentration changes on oleic acid quality.

[0088] Experimental design: Example 1: A sodium hydroxide solution with a mass concentration of 10% was used.

[0089] Comparative Example 4: A sodium hydroxide solution with a mass concentration of 20% was used.

[0090] Experimental steps: 100 mL of refined oleic acid sample was taken and divided into two groups: Example 1 group and Comparative Example 4 group.

[0091] Prepare sodium hydroxide solutions with a mass concentration of 10% and 20% respectively as required to ensure that the solutions are uniform and fully dissolved.

[0092] The oleic acid sample of Example 1 was mixed with a 10% sodium hydroxide solution at a volume ratio of 1:1, gently stirred, and reacted at 40° C. for 30 minutes.

[0093] The oleic acid sample of Comparative Example 4 was mixed with 20% sodium hydroxide solution at a volume ratio of 1:1, gently stirred, and reacted at the same temperature for 30 minutes.

[0094] After the reaction, the aqueous phase and impurities are removed by centrifugation, and the upper oleic acid portion is retained.

[0095] Use a pH meter to measure the acid value (mgKOH / g) of the two groups of oleic acid samples and record the data.

[0096] The free fatty acid content in oleic acid was determined by gas chromatography (GC) and the deacidification effect was calculated.

[0097] The color change before and after deacidification was measured using a colorimeter (ΔE, L*, a*, b*), and the color difference was recorded and analyzed.

[0098] The standard filter paper filtration method was used to determine the impurity content in the oleic acid sample and evaluate the removal effect of impurities during the deacidification process.

[0099] The acid value, free fatty acid content, color change and impurity content after treatment with different concentrations of sodium hydroxide solution were compared, and the influence of concentration change on the deacidification effect was analyzed.

[0100] The experimental data are shown in Table 4: Table 4 Data table of the effect of sodium hydroxide concentration on oleic acid deacidification effect Summarize; Based on the results of Experiment 4, changes in sodium hydroxide concentration significantly affected the deacidification and overall quality of oleic acid. Low-concentration sodium hydroxide solutions neutralized the free fatty acids in oleic acid during the deacidification process, reducing the acid value and free fatty acid content. However, this effect was relatively mild and did not significantly affect color and impurity removal. At low concentrations, sodium hydroxide reacted mildly with the fatty acid molecules in oleic acid, avoiding the formation of excessive chemical reaction byproducts. Consequently, the color and flavor of the oleic acid were well preserved. This result demonstrates that low-concentration sodium hydroxide solutions can effectively remove acidic substances during the deacidification process while maintaining high oleic acid quality.

[0101] In contrast, although high-concentration sodium hydroxide solution can quickly and effectively neutralize more free fatty acids and significantly reduce the acid value during the deacidification process, it also leads to a larger range of color changes and an increase in impurity content. The strong alkalinity of high-concentration sodium hydroxide solution means that it not only removes free fatty acids from oleic acid during the deacidification process, but may also cause some non-polar impurities to dissolve or react with oleic acid to generate new by-products, which will affect the color and flavor stability of oleic acid. In the experimental results, the impurity content and color difference values of the high-concentration sodium hydroxide group were higher, indicating that excessively high sodium hydroxide concentration may cause unnecessary side reactions during the deacidification process, leading to a decline in the quality of oleic acid.

[0102] Comparative analysis of experimental data reveals that optimizing sodium hydroxide concentration significantly impacts oleic acid deacidification. Lower sodium hydroxide concentrations achieve more effective deacidification while maintaining the color and flavor of the oleic acid. While higher sodium hydroxide concentrations offer advantages in deacidification efficiency, they also negatively impact the quality of the oleic acid.

[0103] While embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that various changes, modifications, substitutions, and variations may be made to these embodiments without departing from the principles and spirit of the invention, and that the scope of the invention is defined by the appended claims and their equivalents.

Claims

1. A method for refining oleic acid for purification and color reduction, characterized in that: The following steps are included: The crude oil is mixed with water in a volume ratio of 1:1-1:2, heated to 60°C-80°C, and a gelatinase is added to obtain degummed oleic acid; adding alkali solution to the degummed oleic acid for neutralization reaction, adjusting the pH of the reaction system to 5-7, controlling the acid value of the oleic acid to be less than 2 mgKOH / g after the reaction, separating the aqueous phase, and obtaining deacidified oleic acid; Adding a biocatalyst to the deacidified oleic acid, reacting at 40°C-60°C for 1-2 hours under pH 4.5-6 conditions; Add the composite nano-adsorbent to the catalytically treated oleic acid in an amount of 1%-5% of the mass of the oleic acid, and react at 30°C-50°C for 1-3 hours; The adsorbent was separated from the oleic acid by a microfiltration membrane with a pore size of 0.5 μm-1 μm; The obtained oleic acid is subjected to steam deodorization, and the treatment time is 30 minutes to 1 hour.

2. The method for refining oleic acid for purification and color reduction according to claim 1, wherein: The gelatin decomposing enzyme is phospholipase A.

3. The method for refining oleic acid for purification and color reduction according to claim 1, wherein: The enzyme is added in an amount of 0.05% to 0.2% of the weight of the oil, stirred for reaction for 30 to 60 minutes, and the aqueous phase and the oil phase are separated to obtain degummed oleic acid.

4. The method for refining oleic acid for purification and color reduction according to claim 1, wherein: The alkali solution is sodium hydroxide or potassium hydroxide solution with a mass concentration of 5%-15%.

5. The method for refining oleic acid for purification and color reduction according to claim 1, wherein: The biocatalyst is lipase or phenol oxidase, and the added amount is 0.1%-0.5% of the mass of oleic acid.

6. The method for refining oleic acid for purification and color reduction according to claim 1, wherein: The composite nano-adsorbent is a mixture of nano-silicon, nano-aluminum oxide and plant extracts.

7. The method for refining oleic acid for purification and color reduction according to claim 1, wherein: The plant extract is tea polyphenols, rosemary extract or vitamin E.

8. The method for refining oleic acid for purification and color reduction according to claim 7, wherein: The composite nano-adsorbent is prepared by mixing nano-silicon and nano-aluminum oxide in a mass ratio of 1:1-3:1, adding a plant extract accounting for 0.5%-2% of the total mass of the adsorbent, stirring at 25°C-40°C for 30 minutes-60 minutes to form a uniform mixture, and then drying and crushing it into a powdered adsorbent with a particle size of 10nm-100nm.

9. The method for refining oleic acid for purification and color reduction according to claim 1, wherein: The particle size of the composite nano-adsorbent is in the range of 10 nm to 100 nm.

10. The method for refining oleic acid for purification and color reduction according to claim 1, wherein: The temperature of the steam deodorization is 100° C.-150° C., and the vacuum degree is 50 Pa-200 Pa.

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