A method for efficiently removing plasticizers from walnut oil

Abstract

The application belongs to the field of walnut oil production and specifically discloses a method for efficiently removing plasticizers from walnut oil. The method comprises the following steps: S1, heating the walnut oil to be treated to 35-40 DEG C, and then adding a composite lipase to perform enzymolysis under stirring; S2, performing adsorption filtration of the walnut oil after enzymolysis through a macroporous weakly basic anion resin column; S3, performing first high-temperature deodorization of the filtered walnut oil, and then lowering the temperature to normal temperature under nitrogen protection; S4, performing second high-temperature deodorization of the walnut oil after the first high-temperature deodorization, and then lowering the temperature to normal temperature under nitrogen protection; S5, performing water washing, centrifugation and cold freeze filtration of the walnut oil after the second high-temperature deodorization, and the finished walnut oil is obtained, so that the contents of plasticizers and trans fatty acids in the finished oil are both lower than the national standard, wherein DBP is less than or equal to 0.02 ppm, DEHP is less than or equal to 0.3 ppm, and the trans fatty acid increase value is less than 0.35%. The method has the characteristics of simple operation, stability and reliability, economy and practicality, industrial production and the like.

Description

Technical Field

[0001] This invention belongs to the field of walnut oil production, and specifically discloses a method for efficiently removing plasticizers from walnut oil. Background Technology

[0002] Plasticizers are widely used polymer additives in industrial production, also known as plasticizers. Any substance added to polymer materials that increases their plasticity is called a plasticizer. The use of plasticizers can improve the performance of polymer materials, reduce production costs, and increase production efficiency. They are an important class of chemical additives, widely used as auxiliaries in plastic products, concrete, mortar, cement, gypsum, cosmetics, and cleaning agents. Plasticizers mainly include aliphatic diesters, phthalates (including phthalates and terephthalates), polyphenol esters, benzoates, polyol esters, chlorinated hydrocarbons, epoxy compounds, citrates, polyesters, and many others.

[0003] Phthalate esters (PAEs), also known as phthalate esters, are a collective term for esters formed from phthalic acid. When used as plasticizers, they generally refer to esters formed from phthalic acid and alcohols with 4 to 15 carbon atoms. There are many types of phthalate esters (approximately 30 or more). Phthalate ester compounds are fat-soluble compounds. Packaging butter and animal fat foods, especially hot foods, in plastic bags can increase human intake and is detrimental to health.

[0004] The sources of phthalate plasticizers in walnut oil processing mainly include the following: Walnut oil inevitably comes into contact with plastic equipment during processing, and plasticizers from the plastic can dissolve into the walnut oil, causing contamination. Chemical auxiliaries used in the extraction and refining of walnut oil can also lead to plasticizer contamination. For example, hexane, a solvent used in oil extraction, may come into contact with plastic during production, and then be used to extract the oil, thus introducing plasticizers into the walnut oil. Additionally, bleaching clay and attapulgite used for decolorization may contain plasticizers, which dissolve into the walnut oil during the decolorization process. Given the solubility of walnut oil and plasticizers, it is difficult to remove them using ordinary oil processing techniques. Furthermore, conventional walnut oil processing also produces a significant amount of trans fatty acids, resulting in a decline in oil quality. Summary of the Invention

[0005] To address the aforementioned problems, this invention discloses a method for efficiently removing plasticizers from walnut oil.

[0006] The technical solution of the present invention is as follows:

[0007] A method for efficiently removing plasticizers from walnut oil includes the following steps:

[0008] S1. Heat the walnut oil to be processed to 35-40℃, then add the compound lipase and carry out enzymatic hydrolysis while stirring;

[0009] S2. The enzymatically hydrolyzed walnut oil is adsorbed and filtered through a macroporous weakly alkaline anion exchange resin column.

[0010] S3. The filtered walnut oil is deodorized at high temperature for the first time, and then cooled to room temperature under nitrogen protection.

[0011] S4. After the first high-temperature deodorization, the walnut oil is subjected to a second high-temperature deodorization, followed by nitrogen protection to cool down to room temperature.

[0012] S5. The walnut oil to be treated after the second high-temperature deodorization is washed with water, centrifuged, and frozen filtered to obtain the finished walnut oil.

[0013] The complex lipase in step S1 consists of cholinesterase, alkaline phosphatase, and phospholipase; ultimately, in the walnut oil, the concentration of cholinesterase is 100-300 U / L, the concentration of alkaline phosphatase is 500-1000 U / L, and the concentration of phospholipase is 200-400 U / L.

[0014] Furthermore, in the above-mentioned method for efficiently removing plasticizers from walnut oil, the enzymatic hydrolysis time in step S1 is 3-6 hours, and the stirring speed is 200-400 rpm.

[0015] Furthermore, in the above-mentioned method for efficiently removing plasticizers from walnut oil, during the enzymatic hydrolysis step S1, oxygen is also introduced into the walnut oil at a rate of 5-15 L / L / h.

[0016] Furthermore, in the above-mentioned method for efficiently removing plasticizers from walnut oil, the macroporous weakly basic anion exchange resin in step S2 is of type D941, the resin column packing height is 1.5-2m, the inner diameter is 20-40cm, and the flow rate is 40-60L / h.

[0017] Furthermore, in the above-mentioned method for efficiently removing plasticizers from walnut oil, the first high-temperature deodorization temperature is 180-200℃, and the time is 30-60 seconds.

[0018] Furthermore, in the above-mentioned method for efficiently removing plasticizers from walnut oil, the second high-temperature deodorization temperature is 210-230℃, and the time is 15-20s.

[0019] Furthermore, in the above-mentioned method for efficiently removing plasticizers from walnut oil, step S5 includes the following steps:

[0020] S51 Water Washing: Add 20-30% by weight of water at 80-90℃ and 5-10% by weight of separation medium to walnut oil. The separation medium is a porous ceramic particle-supported nano-zero-valent iron composite material. After cooling, the mixture is obtained.

[0021] S52 centrifugation: Centrifuge the mixture at 500-2000g for 5-10 minutes, and remove the supernatant and let it stand for 10-15 minutes;

[0022] S53 Freeze-filtration: Add 1.5-2.5% of anhydrous sodium acetate by total mass to the mixture after step S52, freeze at -4 to -6°C until fully solidified, suck out the upper walnut oil layer, and discard the lower residue layer to obtain the final product, walnut oil.

[0023] The present invention also discloses a walnut oil, which is prepared by the above method.

[0024] This invention also discloses the application of the above method in the preparation of high-purity walnut oil.

[0025] Compared with the prior art, the present invention has the following beneficial effects:

[0026] This invention uses a complex lipase instead of the original single lipase. By combining cholinesterase, alkaline phosphatase, and phospholipase, the trans fatty acid content is reduced more thoroughly. Furthermore, through macroporous weakly basic anion exchange resin and two high-temperature deodorization processes, plasticizers are removed more thoroughly and the trans fatty acid content is reduced. Finally, the walnut oil is further purified by water washing, centrifugation, and freeze separation, ultimately obtaining high-quality green walnut oil free of plasticizer residues. Attached Figure Description

[0027] Figure 1 A comparison chart of DBP content (ppm);

[0028] Figure 2 A comparison chart of DEHP content (ppm);

[0029] Figure 3 This is a comparison chart of trans fatty acid content (g / 100g). Detailed Implementation

[0030] A method for efficiently removing plasticizers from walnut oil includes the following steps:

[0031] S1. Heat the walnut oil to be processed to 35-40℃, then add the compound lipase and carry out enzymatic hydrolysis while stirring;

[0032] S2. The enzymatically hydrolyzed walnut oil is adsorbed and filtered through a macroporous weakly alkaline anion exchange resin column.

[0033] S3. The filtered walnut oil is deodorized at high temperature for the first time, and then cooled to room temperature under nitrogen protection.

[0034] S4. After the first high-temperature deodorization, the walnut oil is subjected to a second high-temperature deodorization, followed by nitrogen protection to cool down to room temperature.

[0035] S5. The walnut oil to be treated after the second high-temperature deodorization is washed with water, centrifuged, and frozen filtered to obtain the finished walnut oil.

[0036] The complex lipase in step S1 consists of cholinesterase, alkaline phosphatase, and phospholipase; ultimately, in the walnut oil, the concentration of cholinesterase is 100-300 U / L, the concentration of alkaline phosphatase is 500-1000 U / L, and the concentration of phospholipase is 200-400 U / L.

[0037] The enzymatic hydrolysis time in step S1 is 3-6 hours, and the stirring speed is 200-400 rpm.

[0038] During the enzymatic hydrolysis in step S1, oxygen is also introduced into the walnut oil at a rate of 5-15 L / L / h.

[0039] The macroporous weakly basic anion exchange resin used in step S2 is of type D941, with a resin column packing height of 1.5-2m, an inner diameter of 20-40cm, and a flow rate of 40-60L / h.

[0040] The first high-temperature deodorization temperature is 180-200℃, and the time is 30-60 seconds;

[0041] The second high-temperature deodorization process is carried out at a temperature of 210-230℃ for 15-20 seconds.

[0042] Step S5 includes the following steps:

[0043] S51 Water Washing: Add 20-30% by weight of water at 80-90℃ and 5-10% by weight of separation medium to walnut oil. The separation medium is a porous ceramic particle-supported nano-zero-valent iron composite material. After cooling, the mixture is obtained.

[0044] S52 centrifugation: Centrifuge the mixture at 500-2000g for 5-10 minutes, and remove the supernatant and let it stand for 10-15 minutes;

[0045] S53 Freeze-filtration: Add 1.5-2.5% of anhydrous sodium acetate by total mass to the mixture after step S52, freeze at -4 to -6°C until fully solidified, suck out the upper walnut oil layer, and discard the lower residue layer to obtain the final product, walnut oil.

[0046] The technical solutions in the embodiments of the present invention will be clearly and completely described below. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0047] Unless otherwise specified, all reagents or instruments used in the embodiments of this invention are commercially available conventional reagent products.

[0048] Example 1

[0049] A method for efficiently removing plasticizers from walnut oil includes the following steps:

[0050] S1. Heat the walnut oil to be processed to 35°C, then add the compound lipase and perform enzymatic hydrolysis while stirring.

[0051] S2. The enzymatically hydrolyzed walnut oil is adsorbed and filtered through a macroporous weakly alkaline anion exchange resin column.

[0052] S3. The filtered walnut oil is deodorized at high temperature for the first time, and then cooled to room temperature under nitrogen protection.

[0053] S4. After the first high-temperature deodorization, the walnut oil is subjected to a second high-temperature deodorization, followed by nitrogen protection to cool down to room temperature.

[0054] S5. The walnut oil to be treated after the second high-temperature deodorization is washed with water, centrifuged, and frozen filtered to obtain the finished walnut oil.

[0055] The complex lipase in step S1 consists of cholinesterase, alkaline phosphatase, and phospholipase; ultimately, in the walnut oil, the concentration of cholinesterase is 100 U / L, the concentration of alkaline phosphatase is 500 U / L, and the concentration of phospholipase is 200 U / L.

[0056] The enzymatic hydrolysis time in step S1 is 3 hours, and the stirring speed is 200 rpm.

[0057] During the enzymatic hydrolysis in step S1, oxygen is also introduced into the walnut oil at a rate of 5 L / L / h.

[0058] The macroporous weakly basic anion exchange resin used in step S2 is of type D941, with a resin column packing height of 1.5m, an inner diameter of 20cm, and a flow rate of 40L / h.

[0059] The first high-temperature deodorization temperature is 180℃, and the time is 60s;

[0060] The second high-temperature deodorization process is at a temperature of 210℃ for 20 seconds.

[0061] Step S5 includes the following steps:

[0062] S51 Water Washing: Add 20% by weight of water at 80°C and 5% by weight of separation medium to walnut oil. The separation medium is a porous ceramic particle-supported nano-zero-valent iron composite material. After cooling, a mixture is obtained.

[0063] S52 centrifugation: Centrifuge 500g of the mixture for 10min, and take out the supernatant and let it stand for 15min;

[0064] S53 Freeze-filtration: Add 1.5% of anhydrous sodium acetate by total mass to the mixture after step S52, freeze at -4 to -6°C until fully solidified, suck out the upper walnut oil layer, and discard the lower residue layer to obtain the final product, walnut oil.

[0065] Example 2

[0066] A method for efficiently removing plasticizers from walnut oil includes the following steps:

[0067] S1. Heat the walnut oil to be processed to 37°C, then add the compound lipase and perform enzymatic hydrolysis while stirring.

[0068] S2. The enzymatically hydrolyzed walnut oil is adsorbed and filtered through a macroporous weakly alkaline anion exchange resin column.

[0069] S3. The filtered walnut oil is deodorized at high temperature for the first time, and then cooled to room temperature under nitrogen protection.

[0070] S4. After the first high-temperature deodorization, the walnut oil is subjected to a second high-temperature deodorization, followed by nitrogen protection to cool down to room temperature.

[0071] S5. The walnut oil to be treated after the second high-temperature deodorization is washed with water, centrifuged, and frozen filtered to obtain the finished walnut oil.

[0072] The complex lipase in step S1 consists of cholinesterase, alkaline phosphatase, and phospholipase; ultimately, in the walnut oil, the concentration of cholinesterase is 200 U / L, the concentration of alkaline phosphatase is 750 U / L, and the concentration of phospholipase is 300 U / L.

[0073] The enzymatic hydrolysis time in step S1 is 4.5 hours, and the stirring speed is 300 rpm.

[0074] During the enzymatic hydrolysis in step S1, oxygen is also introduced into the walnut oil at a rate of 10 L / L / h.

[0075] The macroporous weakly basic anion exchange resin used in step S2 is of type D941, with a resin column packing height of 1.8m, an inner diameter of 30cm, and a flow rate of 50L / h.

[0076] The first high-temperature deodorization temperature is 180℃, and the time is 45 seconds.

[0077] The second high-temperature deodorization process is at a temperature of 220°C for 20 seconds.

[0078] Step S5 includes the following steps:

[0079] S51 Water Washing: Add 25% by weight of water at 85°C and 8% by weight of separation medium to walnut oil. The separation medium is a porous ceramic particle-supported nano-zero-valent iron composite material. After cooling, a mixture is obtained.

[0080] S52 centrifugation: Centrifuge 1000g of the mixture for 8 minutes, and take out the supernatant and let it stand for 12 minutes;

[0081] S53 Freeze-filtration: Add 2.0% of anhydrous sodium acetate by total mass to the mixture after step S52, freeze at -4 to -6°C until fully solidified, remove the upper walnut oil layer, and discard the lower residue layer to obtain the final product, walnut oil.

[0082] Example 3

[0083] A method for efficiently removing plasticizers from walnut oil includes the following steps:

[0084] S1. Heat the walnut oil to be processed to 40°C, then add the compound lipase and carry out enzymatic hydrolysis while stirring.

[0085] S2. The enzymatically hydrolyzed walnut oil is adsorbed and filtered through a macroporous weakly alkaline anion exchange resin column.

[0086] S3. The filtered walnut oil is deodorized at high temperature for the first time, and then cooled to room temperature under nitrogen protection.

[0087] S4. After the first high-temperature deodorization, the walnut oil is subjected to a second high-temperature deodorization, followed by nitrogen protection to cool down to room temperature.

[0088] S5. The walnut oil to be treated after the second high-temperature deodorization is washed with water, centrifuged, and frozen filtered to obtain the finished walnut oil.

[0089] The complex lipase in step S1 consists of cholinesterase, alkaline phosphatase, and phospholipase; ultimately, in the walnut oil, the concentration of cholinesterase is 300 U / L, the concentration of alkaline phosphatase is 1000 U / L, and the concentration of phospholipase is 400 U / L.

[0090] The enzymatic hydrolysis time in step S1 is 6 hours, and the stirring speed is 400 rpm.

[0091] During the enzymatic hydrolysis in step S1, oxygen is also introduced into the walnut oil at a rate of 15 L / L / h.

[0092] The macroporous weakly basic anion exchange resin used in step S2 is of type D941, with a resin column packing height of 2m, an inner diameter of 40cm, and a flow rate of 60L / h.

[0093] The first high-temperature deodorization temperature is 1200℃, and the time is 30 seconds;

[0094] The second high-temperature deodorization process is at a temperature of 230°C for 15 seconds.

[0095] Step S5 includes the following steps:

[0096] S51 Water Washing: Add 30% by weight of water at 90°C and 10% by weight of separation medium to walnut oil. The separation medium is a porous ceramic particle-supported nano-zero-valent iron composite material. After cooling, a mixture is obtained.

[0097] S52 centrifugation: Centrifuge the mixture at 2000g for 5 minutes, and remove the supernatant and let it stand for 10 minutes;

[0098] S53 Freeze-filtration: Add 2.5% anhydrous sodium acetate by total mass to the mixture after step S52, freeze at -4 to -6°C until fully solidified, suck out the upper walnut oil layer, and discard the lower residue layer to obtain the final product, walnut oil.

[0099] Comparative Example 1

[0100] The difference between Comparative Example 1 and Example 2 is that the complex lipase only includes cholinesterase 1250 U / L.

[0101] A method for efficiently removing plasticizers from walnut oil includes the following steps:

[0102] S1. Heat the walnut oil to be processed to 37°C, then add the compound lipase and perform enzymatic hydrolysis while stirring.

[0103] S2. The enzymatically hydrolyzed walnut oil is adsorbed and filtered through a macroporous weakly alkaline anion exchange resin column.

[0104] S3. The filtered walnut oil is deodorized at high temperature for the first time, and then cooled to room temperature under nitrogen protection.

[0105] S4. After the first high-temperature deodorization, the walnut oil is subjected to a second high-temperature deodorization, followed by nitrogen protection to cool down to room temperature.

[0106] S5. The walnut oil to be treated after the second high-temperature deodorization is washed with water, centrifuged, and frozen filtered to obtain the finished walnut oil.

[0107] The complex lipase in step S1 is cholinesterase with a concentration of 1250 U / L.

[0108] The enzymatic hydrolysis time in step S1 is 4.5 hours, and the stirring speed is 300 rpm.

[0109] During the enzymatic hydrolysis in step S1, oxygen is also introduced into the walnut oil at a rate of 10 L / L / h.

[0110] The macroporous weakly basic anion exchange resin used in step S2 is of type D941, with a resin column packing height of 1.8m, an inner diameter of 30cm, and a flow rate of 50L / h.

[0111] The first high-temperature deodorization temperature is 180℃, and the time is 45 seconds.

[0112] The second high-temperature deodorization process is at a temperature of 220°C for 20 seconds.

[0113] Step S5 includes the following steps:

[0114] S51 Water Washing: Add 25% by weight of water at 85°C and 8% by weight of separation medium to walnut oil. The separation medium is a porous ceramic particle-supported nano-zero-valent iron composite material. After cooling, a mixture is obtained.

[0115] S52 centrifugation: Centrifuge 1000g of the mixture for 8 minutes, and take out the supernatant and let it stand for 12 minutes;

[0116] S53 Freeze-filtration: Add 2.0% of anhydrous sodium acetate by total mass to the mixture after step S52, freeze at -4 to -6°C until fully solidified, remove the upper walnut oil layer, and discard the lower residue layer to obtain the final product, walnut oil.

[0117] Comparative Example 2

[0118] The difference between Comparative Example 2 and Example 2 is that the complex lipase only includes alkaline phosphatase 1250 U / L.

[0119] A method for efficiently removing plasticizers from walnut oil includes the following steps:

[0120] S1. Heat the walnut oil to be processed to 37°C, then add the compound lipase and perform enzymatic hydrolysis while stirring.

[0121] S2. The enzymatically hydrolyzed walnut oil is adsorbed and filtered through a macroporous weakly alkaline anion exchange resin column.

[0122] S3. The filtered walnut oil is deodorized at high temperature for the first time, and then cooled to room temperature under nitrogen protection.

[0123] S4. After the first high-temperature deodorization, the walnut oil is subjected to a second high-temperature deodorization, followed by nitrogen protection to cool down to room temperature.

[0124] S5. The walnut oil to be treated after the second high-temperature deodorization is washed with water, centrifuged, and frozen filtered to obtain the finished walnut oil.

[0125] The complex lipase in step S1 is alkaline phosphatase with a concentration of 1250 U / L.

[0126] The enzymatic hydrolysis time in step S1 is 4.5 hours, and the stirring speed is 300 rpm.

[0127] During the enzymatic hydrolysis in step S1, oxygen is also introduced into the walnut oil at a rate of 10 L / L / h.

[0128] The macroporous weakly basic anion exchange resin used in step S2 is of type D941, with a resin column packing height of 1.8m, an inner diameter of 30cm, and a flow rate of 50L / h.

[0129] The first high-temperature deodorization temperature is 180℃, and the time is 45 seconds.

[0130] The second high-temperature deodorization process is at a temperature of 220°C for 20 seconds.

[0131] Step S5 includes the following steps:

[0132] S51 Water Washing: Add 25% by weight of water at 85°C and 8% by weight of separation medium to walnut oil. The separation medium is a porous ceramic particle-supported nano-zero-valent iron composite material. After cooling, a mixture is obtained.

[0133] S52 centrifugation: Centrifuge 1000g of the mixture for 8 minutes, and take out the supernatant and let it stand for 12 minutes;

[0134] S53 Freeze-filtration: Add 2.0% of anhydrous sodium acetate by total mass to the mixture after step S52, freeze at -4 to -6°C until fully solidified, remove the upper walnut oil layer, and discard the lower residue layer to obtain the final product, walnut oil.

[0135] Comparative Example 3

[0136] The difference between Comparative Example 3 and Example 2 is that the complex lipase only includes phospholipase 1250 U / L.

[0137] A method for efficiently removing plasticizers from walnut oil includes the following steps:

[0138] S1. Heat the walnut oil to be processed to 37°C, then add the compound lipase and perform enzymatic hydrolysis while stirring.

[0139] S2. The enzymatically hydrolyzed walnut oil is adsorbed and filtered through a macroporous weakly alkaline anion exchange resin column.

[0140] S3. The filtered walnut oil is deodorized at high temperature for the first time, and then cooled to room temperature under nitrogen protection.

[0141] S4. After the first high-temperature deodorization, the walnut oil is subjected to a second high-temperature deodorization, followed by nitrogen protection to cool down to room temperature.

[0142] S5. The walnut oil to be treated after the second high-temperature deodorization is washed with water, centrifuged, and frozen filtered to obtain the finished walnut oil.

[0143] The complex lipase in step S1 is a phospholipase with a concentration of 1250 U / L.

[0144] The enzymatic hydrolysis time in step S1 is 4.5 hours, and the stirring speed is 300 rpm.

[0145] During the enzymatic hydrolysis in step S1, oxygen is also introduced into the walnut oil at a rate of 10 L / L / h.

[0146] The macroporous weakly basic anion exchange resin used in step S2 is of type D941, with a resin column packing height of 1.8m, an inner diameter of 30cm, and a flow rate of 50L / h.

[0147] The first high-temperature deodorization temperature is 180℃, and the time is 45 seconds.

[0148] The second high-temperature deodorization process is at a temperature of 220°C for 20 seconds.

[0149] Step S5 includes the following steps:

[0150] S51 Water Washing: Add 25% by weight of water at 85°C and 8% by weight of separation medium to walnut oil. The separation medium is a porous ceramic particle-supported nano-zero-valent iron composite material. After cooling, a mixture is obtained.

[0151] S52 centrifugation: Centrifuge 1000g of the mixture for 8 minutes, and take out the supernatant and let it stand for 12 minutes;

[0152] S53 Freeze-filtration: Add 2.0% of anhydrous sodium acetate by total mass to the mixture after step S52, freeze at -4 to -6°C until fully solidified, remove the upper walnut oil layer, and discard the lower residue layer to obtain the final product, walnut oil.

[0153] Comparative Example 4

[0154] The difference between Comparative Example 4 and Example 2 is that S2 adsorption uses an activated carbon adsorption column.

[0155] A method for efficiently removing plasticizers from walnut oil includes the following steps:

[0156] S1. Heat the walnut oil to be processed to 37°C, then add the compound lipase and perform enzymatic hydrolysis while stirring.

[0157] S2. The enzymatically hydrolyzed walnut oil is filtered through an activated carbon adsorption column.

[0158] S3. The filtered walnut oil is deodorized at high temperature for the first time, and then cooled to room temperature under nitrogen protection.

[0159] S4. After the first high-temperature deodorization, the walnut oil is subjected to a second high-temperature deodorization, followed by nitrogen protection to cool down to room temperature.

[0160] S5. The walnut oil to be treated after the second high-temperature deodorization is washed with water, centrifuged, and frozen filtered to obtain the finished walnut oil.

[0161] The complex lipase in step S1 consists of cholinesterase, alkaline phosphatase, and phospholipase; ultimately, in the walnut oil, the concentration of cholinesterase is 200 U / L, the concentration of alkaline phosphatase is 750 U / L, and the concentration of phospholipase is 300 U / L.

[0162] The enzymatic hydrolysis time in step S1 is 4.5 hours, and the stirring speed is 300 rpm.

[0163] During the enzymatic hydrolysis in step S1, oxygen is also introduced into the walnut oil at a rate of 10 L / L / h.

[0164] The activated carbon adsorption column packing in step S2 has a height of 1.8m, an inner diameter of 30cm, and a flow rate of 50L / h.

[0165] The first high-temperature deodorization temperature is 180℃, and the time is 45 seconds.

[0166] The second high-temperature deodorization process is at a temperature of 220°C for 20 seconds.

[0167] Step S5 includes the following steps:

[0168] S51 Water Washing: Add 25% by weight of water at 85°C and 8% by weight of separation medium to walnut oil. The separation medium is a porous ceramic particle-supported nano-zero-valent iron composite material. After cooling, a mixture is obtained.

[0169] S52 centrifugation: Centrifuge 1000g of the mixture for 8 minutes, and take out the supernatant and let it stand for 12 minutes;

[0170] S53 Freeze-filtration: Add 2.0% of anhydrous sodium acetate by total mass to the mixture after step S52, freeze at -4 to -6°C until fully solidified, remove the upper walnut oil layer, and discard the lower residue layer to obtain the final product, walnut oil.

[0171] Test case

[0172] The walnut oils from Examples 1-3 and Comparative Examples 1-4 were subjected to quality tests, and the results are shown in Table 1 and 2. Figure 1-3 As shown.

[0173] Table 1 Rooting Status

[0174]

[0175] From Table 1 and Figure 1-3 The data shows that using a complex lipase instead of the original single lipase, by combining cholinesterase, alkaline phosphatase, and phospholipase, can reduce the trans fatty acid content to less than half of the original, below 0.3g / 100g, thus achieving the standard of zero trans fatty acids in walnut oil. Furthermore, a comparison between Examples 1-3 and Comparative Example 4 shows that using macroporous weakly basic anion exchange resin, compared to activated carbon adsorption, reduces the content of DBP and DEHP to less than 30% of the original, significantly reducing the plasticizer content.

[0176] As can be seen from the above embodiments, the present invention discloses a method for efficiently removing plasticizers from walnut oil. The present invention uses a complex lipase to replace the original single lipase. By combining cholinesterase, alkaline phosphatase and phospholipase, the trans fatty acid content is reduced more thoroughly. Furthermore, the plasticizer is removed and the trans fatty acid content is reduced more thoroughly by using macroporous weakly basic anion exchange resin and two high-temperature deodorization processes. Finally, the walnut oil is further purified by water washing, centrifugation and freeze separation, ultimately obtaining high-quality green walnut oil without plasticizer residue.

[0177] The few preferred embodiments of the invention are described in detail, but they should not be construed as limiting the scope of the invention. It should be noted that those skilled in the art can make various modifications and improvements without departing from the inventive concept, and these all fall within the scope of protection of this invention.

Claims

1. A method for efficiently removing plasticizers from walnut oil, characterized in that, Includes the following steps: S1. Heat the walnut oil to be processed to 35-40℃, then add the compound lipase and carry out enzymatic hydrolysis while stirring; S2. The enzymatically hydrolyzed walnut oil is adsorbed and filtered through a macroporous weakly alkaline anion exchange resin column. S3. The filtered walnut oil is deodorized at high temperature for the first time, and then cooled to room temperature under nitrogen protection. S4. After the first high-temperature deodorization, the walnut oil is subjected to a second high-temperature deodorization, followed by nitrogen protection to cool down to room temperature. S5. The walnut oil to be treated after the second high-temperature deodorization is washed with water, centrifuged, and frozen filtered to obtain the finished walnut oil. The complex lipase in step S1 consists of cholinesterase, alkaline phosphatase, and phospholipase; ultimately, in the walnut oil, the concentration of cholinesterase is 100-300 U / L, the concentration of alkaline phosphatase is 500-1000 U / L, and the concentration of phospholipase is 200-400 U / L.

2. The method for efficiently removing plasticizers from walnut oil according to claim 1, characterized in that, The enzymatic hydrolysis time in step S1 is 3-6 hours, and the stirring speed is 200-400 rpm.

3. The method for efficiently removing plasticizers from walnut oil according to claim 1, characterized in that, During the enzymatic hydrolysis in step S1, oxygen is also introduced into the walnut oil at a rate of 5-15 L / L / h.

4. The method for efficiently removing plasticizers from walnut oil according to claim 1, characterized in that, The macroporous weakly basic anion exchange resin used in step S2 is of type D941, with a resin column packing height of 1.5-2m, an inner diameter of 20-40cm, and a flow rate of 40-60L / h.

5. The method for efficiently removing plasticizers from walnut oil according to claim 1, characterized in that, The first high-temperature deodorization process takes place at 180-200℃ for 30-60 seconds.

6. The method for efficiently removing plasticizers from walnut oil according to claim 1, characterized in that, The second high-temperature deodorization process takes place at a temperature of 210-230℃ for 15-20 seconds.

7. The method for efficiently removing plasticizers from walnut oil according to claim 1, characterized in that, Step S5 includes the following steps: S51 Water Washing: Add 20-30% by weight of water at 80-90℃ and 5-10% by weight of separation medium to walnut oil. The separation medium is a porous ceramic particle-supported nano-zero-valent iron composite material. After cooling, the mixture is obtained. S52 centrifugation: Centrifuge the mixture at 500-2000g for 5-10 minutes, and remove the supernatant and let it stand for 10-15 minutes; S53 Freeze-filtration: Add 1.5-2.5% of anhydrous sodium acetate by total mass to the mixture after step S52, freeze at -4 to -6°C until fully solidified, suck out the upper walnut oil layer, and discard the lower residue layer to obtain the final product, walnut oil.

8. A walnut oil, characterized in that, The walnut oil is prepared by the method according to any one of claims 1-7.

9. The application of the method according to any one of claims 1-7 in the preparation of high-purity walnut oil.

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