Method for controlling 3-chloropropanol ester and glycidyl ester in linseed oil

Abstract

The invention discloses a method for controlling 3-chloropropanol ester and glycidyl ester in linseed oil, which is characterized in that a weak acidic condition is coupled with a low-temperature freezing process in a degumming link, pollutant precursors and wax deacidification are synchronously removed in a degumming and dewaxing link, and the generation basis of the 3-chloropropanol ester and the glycidyl ester is reduced from the source. Carclazyte, silicon dioxide and perlite are adopted to prepare a composite adsorbent in the decoloration link, and the adsorption efficiency of catalytic substances such as chloride ions and heavy metals is remarkably improved by utilizing the adsorption synergistic effect of the three components; a low-temperature short-time decolorization process is matched, so that the secondary generation risk of glycidyl ester in the technological process is reduced while pigments and peculiar smell are efficiently removed. In the deodorization link, low temperature-high vacuum-sufficient steam cooperation is adopted, and the steam injection amount is optimized to be 15-20% of the oil weight, so that the deodorization effect is ensured, and the thermal induction generation of 3-chloropropanol ester and glycidyl ester is effectively inhibited by shortening the high-temperature retention time and improving the vacuum environment.

Description

Technical Field

[0001] This invention relates to the field of flaxseed oil preparation technology, and in particular to a method for controlling 3-chloropropanol esters and glycidyl esters in flaxseed oil. Background Technology

[0002] 3-Chloropropanol esters (3-MCPDEs) are esterification products of chloropropanol compounds and fatty acids, mainly including 3-chloropropanol esters (3-MCPDEs), 2-chloro-1,3-propanediol esters (2-MCPD esters), 1,3-dichloro-2-propanol esters (1,3-DCP esters), and 2,3-dichloro-2-propanol esters (2,3-DCP esters). Among them, 3-chloropropanol esters are found in relatively high amounts in food. Glycidyl esters (GEs) are esterification products of fatty acids and glycidyl esters, and their formation mechanism is similar to that of chloropropanol esters. They are usually formed along with 3-chloropropanol esters during oil refining.

[0003] 3-MCPDE and GEs are food safety risk components in edible oils and oil-containing foods that have attracted significant attention in recent years. 3-MCPDE is a component present in a very high proportion of chloropropanol esters (compounds formed by replacing the acyl group of triglycerides with one or two chlorine groups), and therefore, its content is often used as an indicator to assess the risk of chloropropanol esters. GEs are esterification products formed by the dehydration condensation of the 1 and 2 hydroxyl groups in glycerol to form an epoxy group, while the other hydroxyl group undergoes esterification with a fatty acid. They are a type of terminal epoxy ester, which can be metabolized to produce glycidyl and fatty acids, and under certain conditions, can be converted into 3-MCPDE. Therefore, 3-MCPDE and GEs are usually studied together as food safety risk components. 3-MCPDE itself is toxic, and its decomposition product, 3-MCPD, is a carcinogenic contaminant with nephrotoxicity, reproductive toxicity, and genotoxicity. GEs themselves are not carcinogenic, but glycidyl produced through lipid metabolism in the body is a genotoxic carcinogen (Group 2A carcinogen for humans).

[0004] Therefore, several countries and regions internationally have assessed the limits for 3-MCPDE and GEs in edible oils. In 2018, the European Commission (EC) issued a revised Regulation (EU) 1881 / 2006, stipulating a limit of 1 mg / kg for GEs in edible vegetable oils and 0.5 mg / kg for GEs in oils used in infant formula. On July 23, 2019, the renowned magazine OFI (Oils & Fats International) reported that the European Commission recommended setting the limit for 3-MCPDE in edible vegetable oils at 1.25 mg / kg and the limit for infant formula at 0.75 mg / kg. Currently, although my country has not yet set clear limits for the content of 3-MCPDE and GEs in edible vegetable oils, the industry is paying close attention.

[0005] Therefore, it is urgent to study the effects of different decolorization and deodorization processes on the formation of 3-chloropropanol esters and glycidyl esters in flaxseed oil during crude oil extraction and refining, so as to develop a processing technology to control the content of 3-chloropropanol esters and glycidyl esters in flaxseed oil and thus improve the health standards of the finished oil. Summary of the Invention

[0006] The purpose of this application is to provide a method for controlling 3-chloropropanol esters and glycidyl esters in flaxseed oil, so as to effectively reduce the content of 3-chloropropanol esters and glycidyl esters in flaxseed oil, ensure that the final flaxseed oil has a 3-MCPDE content ≤0.1mg / kg and a GEs content ≤0.8mg / kg, and does not affect the retention rate of nutrients such as α-linolenic acid in the oil.

[0007] To address the aforementioned technical problems, this application provides a method for controlling 3-chloropropanol esters and glycidyl esters in flaxseed oil, comprising: Degumming: After obtaining crude oil, degumming is carried out under weakly acidic conditions of pH 4.0-5.0 and a temperature of -5 to -8℃ to remove contaminant precursors; Dewaxing: Crystallization filtration to remove wax; Deacidification: The process of removing free fatty acids from oils using an alkali refining method; Decolorization: A composite adsorption system is prepared using bleaching clay, silica, and perlite. The system is decolorized at 100-110℃ for 20-25 minutes to adsorb pigments, residual soap, metal ions, and chloride ions from the oil. The ratio of bleaching clay, silica, and perlite is 85:10:5. Deodorization: Deodorization is carried out through a deodorization tower, and steam is introduced into the oil layer to remove free fatty acids and volatile odor substances. The deodorization temperature is ≤220℃, a three-stage Roots vacuum pump is used to raise the vacuum to 0.2-0.6kPa, the deodorization time is 25-40min, and the steam injection volume is 15%-20% of the oil weight.

[0008] As a preferred embodiment, a method for controlling 3-chloropropanol esters and glycidyl esters in flaxseed oil is provided, wherein the pollutant precursors include phospholipids, waxes and chloride ions.

[0009] The solution requires detailed explanation of a method for controlling 3-chloropropanol esters and glycidyl esters in flaxseed oil, wherein the removal of free fatty acids from the oil using an alkali refining method includes: Prepare NaOH solutions of appropriate concentrations based on the quality and acid value of the crude oil; After heating the crude oil to 50-70°C and stirring, the NaOH solution is evenly sprayed into the oil, the temperature is slowly raised to 75-85°C, and stirring is stopped. Alkali-refined oil is obtained by separating soap residue from oil using a disc centrifuge at 80-85℃. Heat the alkali-refined oil to 85-90°C, add 10%-15% of the oil weight of soft water or hot water at the same temperature, stir gently, and then let it stand or centrifuge again to separate the washing wastewater. The washed oil is dried and deacidified by passing it through a dryer at 100-110℃ to remove residual moisture.

[0010] Compared with the prior art, the present invention provides a method for controlling 3-chloropropanol esters and glycidyl esters in flaxseed oil, comprising degumming: after obtaining crude oil, under weakly acidic conditions with a pH of 4.0-5.0 and -5- Degumming is performed at -8℃ to remove precursor contaminants; dewaxing: crystallization filtration to remove wax; deacidification: alkali refining is used to remove free fatty acids from the oil; decolorization: a composite adsorption system is prepared using bleaching clay, silica, and perlite, and decolorization is performed at 100-110℃ for 20-25 minutes to adsorb pigments, residual soap, metal ions, and chloride ions from the oil; wherein the ratio of bleaching clay, silica, and perlite is 85:10:5; and deodorization: deodorization is performed through a deodorization tower, and steam is introduced into the oil layer to remove free fatty acids and volatile odor substances; wherein the deodorization temperature is ≤220℃, a three-stage Roots vacuum pump is used to raise the vacuum to 0.2-0.6 kPa, the deodorization time is 25-40 minutes, and the steam injection volume is 15%-20% of the oil weight.

[0011] A weakly acidic, coupled low-temperature freezing process is employed to simultaneously remove precursor pollutants and deacidify waxes during the degumming and dewaxing stages, reducing the basis for the formation of 3-chloropropanol esters and glycidyl esters at the source. This gentle process also avoids oxidative rancidity of the oils. In the decolorization stage, a composite adsorbent composed of bleaching clay, silica, and perlite is used. Utilizing the synergistic adsorption effect of these three materials, the adsorption efficiency for catalytic substances such as chloride ions and heavy metals is significantly improved. Combined with a low-temperature, short-time decolorization process, this efficiently removes pigments and odors while reducing the risk of secondary glycidyl ester formation during the process. In the deodorization process, a synergistic approach of "low temperature-high vacuum-sufficient steam" is adopted, with strict control over deodorization temperature and time. A three-stage Roots vacuum pump is used to raise the system vacuum to 0.2-0.6 kPa, and the steam injection volume is optimized to 15%-20% of the oil weight. This ensures deodorization effect while effectively inhibiting the thermally induced formation of 3-chloropropanol esters and glycidol esters by shortening the high-temperature residence time and improving the vacuum environment. This achieves precise control of target pollutants, ensuring that the final flaxseed oil contains ≤0.1 mg / kg of 3-chloropropanol esters and ≤0.8 mg / kg of glycidol esters, without affecting the retention rate of nutrients such as α-linolenic acid in the oil. Attached Figure Description

[0012] To more clearly illustrate the technical solution of this application, the drawings used in the embodiments will be briefly introduced below. Obviously, for those skilled in the art, other drawings can be obtained based on these drawings without any creative effort.

[0013] Figure 1 A flowchart of a method for controlling 3-chloropropanol esters and glycidyl esters in flaxseed oil provided in an embodiment of this application; Figure 2 This is a schematic diagram of key process parameters for deodorization effect and safety provided in an embodiment of this application. Detailed Implementation

[0014] To enable those skilled in the art to better understand the technical solutions in this application, the technical solutions in the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings.

[0015] The core of this application is to provide a method for controlling 3-chloropropanol esters and glycidyl esters in flaxseed oil, so as to effectively reduce the content of 3-chloropropanol esters and glycidyl esters in flaxseed oil, ensure that the final flaxseed oil has a 3-MCPDE content ≤0.1mg / kg and a GEs content ≤0.8mg / kg, and does not affect the retention rate of nutrients such as α-linolenic acid in the oil.

[0016] Figure 1 This is a flowchart illustrating a method for controlling 3-chloropropanol esters and glycidyl esters in flaxseed oil, as provided in an embodiment of this application. Figure 2 This is a schematic diagram illustrating key process parameters for deodorization effect and safety provided in an embodiment of this application. (See attached diagram.) Figures 1 to 2 As shown.

[0017] A method for controlling 3-chloropropanol esters and glycidyl esters in flaxseed oil includes the following steps: S1 Degumming: After obtaining crude oil, degumming is carried out under weakly acidic conditions of pH 4.0-5.0 and a temperature of -5 to -8℃ to remove pollutant precursors.

[0018] Acidic conditions facilitate the conversion and removal of non-hydrated phospholipids into hydrated phospholipids, while also promoting the dissolution and removal of chloride ions; low-temperature freezing promotes the crystallization and precipitation of waxes. This process reduces the two key precursors (chlorine source and glycerol ester skeleton) for the formation of 3-MCPDEs and GEs at the source, and the conditions are mild, avoiding oil oxidation caused by high temperatures.

[0019] S2 Dewaxing: Crystallization filtration to remove wax; low-temperature crystallization filtration can be performed to remove high-melting-point wax and improve the low-temperature clarity of oil products.

[0020] S3 deacidification: This method uses alkali refining to remove free fatty acids from oils. An alkali (usually a sodium hydroxide solution) reacts with the free fatty acids in the oil to produce water-soluble soapstock (sodium fatty acid salts), which is then removed from the oil by centrifugation. Simultaneously, the alkali neutralizes some phosphoric acid and adsorbs and removes some pigments (such as chlorophyll and carotenoids), colloids, and proteins.

[0021] S4 Decolorization: A composite adsorption system is prepared using bleaching clay, silica, and perlite. Decolorization is performed at 100-110℃ for 20-25 minutes to adsorb pigments, residual soaps, metal ions, and chloride ions from the oils. The ratio of bleaching clay, silica, and perlite is 85:10:5. Bleaching clay primarily adsorbs pigments and polar substances; silica efficiently adsorbs phospholipids, soaps, and metal ions; and perlite assists in filtration and adsorption. The three components work synergistically to enhance the adsorption and removal of residual chloride ions, heavy metal ions, and other catalysts, as well as pigments and residual soaps. Furthermore, the low-temperature, short-time decolorization significantly reduces the risk of GEs (glucose ions) generation due to thermocatalysis during the decolorization process.

[0022] S5 Deodorization: Deodorization is performed using a deodorization tower, and steam is introduced into the oil layer to remove free fatty acids and volatile odor substances. The deodorization temperature is ≤220℃, and a three-stage Roots vacuum pump is used to raise the vacuum level to 0.2-0.6 kPa. The deodorization time is 25-40 minutes, and the steam injection rate is 15%-20% of the oil weight. A three-in-one synergistic deodorization technology of "low temperature-high vacuum-sufficient steam" is employed. The three-stage Roots vacuum pump raises the vacuum level to 0.2-0.6 kPa, and the high-temperature residence time is shortened to improve the vacuum environment. The steam injection rate is increased to 15%-20% of the oil weight, enhancing stripping and mass transfer efficiency. While ensuring deodorization effect and removing FFA and odors, the generation of 3-MCPDE and GEs is suppressed to the maximum extent in the final high-temperature stage. A comparison of the deodorization method in this embodiment with the traditional method is shown in Figure 2.

[0023] Based on Example 1, a method for controlling 3-chloropropanol esters and glycidyl esters in flaxseed oil is provided, wherein the pollutant precursors include phospholipids, waxes and chloride ions.

[0024] Based on Example 1, a method for controlling 3-chloropropanol esters and glycidyl esters in flaxseed oil, wherein the removal of free fatty acids from the oil using an alkali refining method includes: Prepare NaOH solutions of appropriate concentrations according to the quality and acid value of the crude oil; oils with low acid value and light color can use a more dilute alkali solution, while oils with high acid value and dark color require a more concentrated alkali solution.

[0025] After heating the crude oil to 50-70℃ and stirring, the NaOH solution is evenly sprayed into the oil to ensure full contact. At this point, small soap granules begin to form. The temperature is slowly increased to 75-85℃, and stirring is stopped. At this temperature, the soap granules act as crystal nuclei, adsorbing impurities such as pigments and phospholipids, and colliding and aggregating to form larger soap residue flocculent matter. This process takes about 20-40 minutes.

[0026] Alkali-refined oil is obtained by separating soapstock from oil using a disc centrifuge at 80-85℃. The separated heavy phase is soapstock, which can be further processed for the production of fatty acids or feed, while the light phase is alkali-refined oil.

[0027] Heat the alkali-refined oil to 85-90°C, add 10%-15% by weight of soft or hot water at the same temperature, stir gently, and let stand or centrifuge again to separate the washing wastewater; this process may be repeated 1-2 times.

[0028] The washed oil is dried at 100-110℃ to remove residual moisture, resulting in dried deacidified oil. Washing and dehydration remove trace amounts of soap and alkali remaining in the alkali-refined oil.

[0029] This embodiment provides a method for controlling 3-chloropropanol esters and glycidyl esters in flaxseed oil. In the degumming stage, a weakly acidic condition coupled with a low-temperature freezing process is employed. During degumming and dewaxing, precursor pollutants and waxes are simultaneously removed, reducing the basis for the formation of 3-chloropropanol esters and glycidyl esters at the source. Furthermore, this process is gentle and avoids oxidative rancidity of the oil. In the decolorization stage, a composite adsorbent composed of kaolin, silica, and perlite is used. Utilizing the synergistic adsorption effect of these three substances, the adsorption efficiency for catalytic substances such as chloride ions and heavy metals is significantly improved. Combined with a low-temperature, short-time decolorization process, pigments and odors are efficiently removed while reducing the risk of secondary glycidyl ester formation during the process. In the deodorization process, a synergistic approach of "low temperature-high vacuum-sufficient steam" is adopted, with strict control over deodorization temperature and time. A three-stage Roots vacuum pump is used to raise the system vacuum to 0.2-0.6 kPa, and the steam injection volume is optimized to 15%-20% of the oil weight. This ensures deodorization effect while effectively inhibiting the thermally induced formation of 3-chloropropanol esters and glycidol esters by shortening the high-temperature residence time and improving the vacuum environment. This achieves precise control of target pollutants, ensuring that the final flaxseed oil contains ≤0.1 mg / kg of 3-chloropropanol esters and ≤0.8 mg / kg of glycidol esters, without affecting the retention rate of nutrients such as α-linolenic acid in the oil.

[0030] Other embodiments of this application will readily occur to those skilled in the art upon consideration of the specification and practice of the application disclosed herein. This application is intended to cover any variations, uses, or adaptations of this application that follow the general principles of this application and incorporate common knowledge or customary techniques in the art disclosed herein. The specification and examples are to be considered exemplary only, and the true scope of this application is indicated by the claims.

[0031] It should be understood that this application is not limited to the precise structure described above and shown in the accompanying drawings, and various modifications and changes can be made without departing from its scope. The embodiments of this application described above do not constitute a limitation on the scope of protection of this application.

Claims

1. A method for controlling 3-chloropropanol esters and glycidyl esters in flaxseed oil, characterized in that, include: Degumming: After obtaining crude oil, degumming is carried out under weakly acidic conditions of pH 4.0-5.0 and a temperature of -5 to -8℃ to remove contaminant precursors; Dewaxing: Crystallization filtration to remove wax; Deacidification: The process of removing free fatty acids from oils using an alkali refining method; Decolorization: A composite adsorption system is prepared using bleaching clay, silica, and perlite. The system is decolorized at 100-110℃ for 20-25 minutes to adsorb pigments, residual soap, metal ions, and chloride ions from the oil. The ratio of bleaching clay, silica, and perlite is 85:10:

5. Deodorization: Deodorization is carried out through a deodorization tower, and steam is introduced into the oil layer to remove free fatty acids and volatile odor substances. The deodorization temperature is ≤220℃, a three-stage Roots vacuum pump is used to raise the vacuum to 0.2-0.6kPa, the deodorization time is 25-40min, and the steam injection volume is 15%-20% of the oil weight.

2. The method for controlling 3-chloropropanol esters and glycidyl esters in flaxseed oil according to claim 1, characterized in that, The pollutant precursors include phospholipids, waxes, and chloride ions.

3. The method for controlling 3-chloropropanol esters and glycidyl esters in flaxseed oil according to claim 1, characterized in that, The method of removing free fatty acids from oils using alkali refining includes: Prepare NaOH solutions of appropriate concentrations based on the quality and acid value of the crude oil; After heating the crude oil to 50-70°C and stirring, the NaOH solution is evenly sprayed into the oil, the temperature is slowly raised to 75-85°C, and stirring is stopped. Alkali-refined oil is obtained by separating soap residue from oil using a disc centrifuge at 80-85℃. Heat the alkali-refined oil to 85-90°C, add 10%-15% of the oil weight of soft water or hot water at the same temperature, stir gently, and then let it stand or centrifuge again to separate the washing wastewater. The washed oil is dried and deacidified by passing it through a dryer at 100-110℃ to remove residual moisture.

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