Method for removing mineral oil in linseed oil

Abstract

The invention discloses a method for removing mineral oil in linseed oil. The method comprises the steps of pretreatment, molecular distillation, emulsification, standing layering, respective treatment of an oil phase and an emulsified phase, combined refining and the like. Preliminarily removing oil by adjusting the temperature and the viscosity of an oil product and combining a molecular distillation technology; and emulsifying, standing and layering to separate an oil phase and an emulsified phase, and respectively carrying out high-voltage pulse electric field treatment, plasma treatment and ultrafiltration to realize deep deoiling. Wherein the detail optimization of filtration, emulsifier selection, molecular distillation, ultrafiltration parameters and the like ensures efficient deoiling and retains the quality of the linseed oil at the same time. Finally, the treated linseed oil is combined and refined, the high-quality linseed oil with the mineral oil content obviously reduced is obtained, and the health requirement of the market for the linseed oil with the low mineral oil content is met.

Description

Technical Field

[0001] The invention belongs to the field of vegetable oil refining, and specifically discloses a method for removing mineral oil from linseed oil. Background Art

[0002] Flaxseed oil is a natural vegetable oil rich in beneficial ingredients such as α-linolenic acid. Due to its unique nutritional value and health benefits, it is widely used in food, health products and cosmetics. However, it is often difficult to completely avoid the mixing of mineral oil in the production and processing of flaxseed oil, which mainly comes from the contamination of processing equipment, storage containers and transportation. The presence of mineral oil not only reduces the purity of flaxseed oil, but also may pose a potential threat to human health, such as affecting the digestion and absorption of oil and increasing the burden on the liver.

[0003] Existing methods for removing mineral oil from linseed oil mainly rely on physical and chemical means, such as solvent extraction, adsorbent treatment and traditional distillation. However, these methods have many shortcomings: although solvent extraction can effectively remove mineral oil, it may introduce new solvent residues, affecting product quality; adsorbent treatment has the problems of low adsorption efficiency and high cost; traditional distillation may destroy the heat-sensitive components in linseed oil due to high temperature treatment, reducing the nutritional value.

[0004] Therefore, it is particularly important to develop a method that can effectively remove mineral oil from linseed oil while maintaining its original nutrients and quality. Summary of the invention

[0005] In order to solve the above problems, the present invention discloses a method for removing mineral oil from linseed oil. By combining advanced technologies such as molecular distillation, emulsification and stratification, high-voltage pulse electric field treatment and plasma treatment, the mineral oil in linseed oil is efficiently removed, while the nutritional components and flavor of the linseed oil are retained, providing strong support for the deep processing and utilization of linseed oil.

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

[0007] A method for removing mineral oil from linseed oil, characterized in that it comprises the following steps:

[0008] (1) Pretreatment: The linseed oil containing mineral oil is pretreated, including filtering to remove large particle impurities and adjusting the temperature and viscosity of the oil to an appropriate range;

[0009] (2) Molecular distillation: The pretreated linseed oil is subjected to molecular distillation using a molecular distillation device to partially remove the mineral oil component therein;

[0010] (3) Emulsification: Molecularly distilled linseed oil, water and emulsifier are mixed in a certain proportion and stirred at 40-70°C for 25-75 minutes to form an unstable emulsion;

[0011] (4) Standing and stratifying: The emulsified mixture is allowed to stand for 1 to 5 hours to allow the emulsion to stratify naturally to form an oil phase, an emulsified phase or an oil phase, an emulsified phase, and an aqueous phase. The different phases are separated respectively, and the oil phase and the emulsified phase are retained for subsequent processing;

[0012] (5) Oil phase treatment: Take the oil phase liquid, stir it at 0-4°C, and then treat it with a high-voltage pulse electric field. After the treatment, ultrafiltration is performed to obtain linseed oil I from which mineral oil is preliminarily removed;

[0013] (6) Emulsified phase treatment: taking the emulsified phase liquid, using a discharge method to perform plasma treatment, the discharge method is pulse discharge, the pulse voltage peak is 30-80 kV, the discharge frequency is 50-100 Hz, the treatment time is 5-30 min, and the treatment is repeated 2-5 times; taking the upper oil phase, and then performing ultrafiltration and molecular distillation treatment to obtain linseed oil II from which mineral oil is further removed;

[0014] (7) Combining and refining: The linseed oil I and linseed oil II obtained in step (5) and step (6) are combined and refined to finally obtain linseed oil with significantly reduced mineral oil content.

[0015] Furthermore, in the above step (1), the filtration is performed using a plate and frame filter press, the filter medium is gauze, and the filtration pressure is 2-4 kg / cm 2 .

[0016] Furthermore, in the above step (1), the temperature of the oil is adjusted to 20-30°C and the viscosity is 7.10-7.50 cP.

[0017] Furthermore, in the above step (2), the evaporation pressure of the molecular distillation is controlled at 20-25 KPa, the distillation temperature is set at 115-125° C., and the feed rate is maintained at 25-40 mL / min.

[0018] Furthermore, in the above step (3), the volume ratio of linseed oil to water is 1:1-3, the emulsifier content accounts for 0.75-2.5wt% of the whole system, and the emulsifier is a nonionic surfactant with an HLB value of 12-15 or a composite emulsifier thereof.

[0019] Furthermore, in the above step (3), the emulsifier is PEG-40 stearate.

[0020] Furthermore, in the above step (5), the electric field strength is 30-80 kV / cm, the pulse width is 5-20 μs, and the total number of pulses is 50-150; the ultrafiltration parameters are: membrane pore size: 50-100 nm, operating pressure: 0.3-0.5 MPa, temperature: 25-35 ° C, flow rate: 200-400 L / h / m 2 .

[0021] Furthermore, in the above step (6), the molecular distillation conditions are: evaporation pressure 2-6KPa, distillation temperature 125-160°C, feed rate 20-40mL / min; ultrafiltration parameters are: membrane pore size: 100-200nm, operating pressure: 0.2-0.4Mpa, temperature: 25-35°C, flow rate: 300-500L / h / m 2 .

[0022] Furthermore, in the above step (7), the refining treatment includes decolorization and deodorization.

[0023] Furthermore, the present invention discloses linseed oil with low mineral oil content, which is prepared by any of the methods described above.

[0024] Compared with the prior art, the present invention has the following beneficial effects:

[0025] The present invention uses a set of comprehensive and refined process steps, including pretreatment, molecular distillation, emulsification, static stratification, high-voltage pulse electric field treatment, plasma treatment, ultrafiltration and refining, etc., to efficiently remove the mineral oil components in linseed oil; each step sets precise operating conditions to ensure the stability and repeatability of the process, thereby significantly reducing the mineral oil content while retaining the beneficial components and natural flavor of linseed oil, and improving the purity and quality of the product. This method is not only environmentally friendly and energy-saving, but also has a wide range of applicability, providing an effective means for the purification of linseed oil and other vegetable oils, and has important economic and social value. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] Figure 1 Process flow chart for removing mineral oil from linseed oil;

[0027] Figure 2 Subjective test, linseed oil color;

[0028] Figure 3 Subjective test, flaxseed oil flavor;

[0029] Figure 4 Subjective test, flaxseed oil taste;

[0030] Figure 5 Objective test, mineral oil content wt%;

[0031] Figure 6 Objective test, mineral oil removal rate %. DETAILED DESCRIPTION

[0032] The technical solutions in the embodiments of the present invention are described clearly and completely below. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of them. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0033] Example 1

[0034] like Figure 1 A method for removing mineral oil from linseed oil is shown, comprising the following steps:

[0035] (1) Pretreatment: The linseed oil containing mineral oil is pretreated, including filtering to remove large particle impurities and adjusting the temperature and viscosity of the oil to an appropriate range;

[0036] (2) Molecular distillation: The pretreated linseed oil is subjected to molecular distillation using a molecular distillation device to partially remove the mineral oil component therein;

[0037] (3) Emulsification: Molecularly distilled linseed oil, water and emulsifier are mixed in a certain proportion and stirred at 40-70°C for 25-75 minutes to form an unstable emulsion;

[0038] (4) Standing and stratifying: The emulsified mixture is allowed to stand for 1 to 5 hours to allow the emulsion to stratify naturally to form an oil phase, an emulsified phase or an oil phase, an emulsified phase, and an aqueous phase. The different phases are separated respectively, and the oil phase and the emulsified phase are retained for subsequent processing;

[0039] (5) Oil phase treatment: Take the oil phase liquid, stir it at 0-4°C, and then treat it with a high-voltage pulse electric field. After the treatment, ultrafiltration is performed to obtain linseed oil I from which mineral oil is preliminarily removed;

[0040] (6) Emulsified phase treatment: taking the emulsified phase liquid, and subjecting it to plasma treatment by using a discharge method, wherein the discharge method is pulse discharge, the pulse voltage peak is 30 kV, the discharge frequency is 50 Hz, the treatment time is 30 min, and the treatment is repeated 5 times; taking the upper oil phase, and subjecting it to ultrafiltration and molecular distillation treatment to obtain linseed oil II from which mineral oil is further removed;

[0041] (7) Combining and refining: The linseed oil I and linseed oil II obtained in step (5) and step (6) are combined and refined to finally obtain linseed oil with significantly reduced mineral oil content.

[0042] In the step (1), the filtration is carried out using a plate and frame filter press, the filter medium is gauze, and the filtration pressure is 2-4 kg / cm 2 .

[0043] In the step (1), the temperature of the oil is adjusted to 20° C. and the viscosity is 7.50 cP.

[0044] In the step (2), the evaporation pressure of the molecular distillation is controlled at 20 KPa, the distillation temperature is set at 115° C., and the feed rate is maintained at 25 mL / min.

[0045] In the step (3), the volume ratio of linseed oil to water is 1:1, and the emulsifier content accounts for 0.75wt% of the entire system;

[0046] In the step (3), the emulsifier is PEG-40 stearate.

[0047] In the step (5), the electric field strength is 30 kV / cm, the pulse width is 5 to 20 μs, and the total number of pulses is 50; the ultrafiltration parameters are: membrane pore size: 50-100 nm, operating pressure: 0.3-0.5 MPa, temperature: 25-35° C., flow rate: 200-400 L / h / m 2 .

[0048] In the step (6), the molecular distillation conditions are: evaporation pressure 2KPa, distillation temperature 125°C, feed rate 20mL / min; ultrafiltration parameters are: membrane pore size: 100-200nm, operating pressure: 0.2-0.4Mpa, temperature: 25-35°C, flow rate: 300-500L / h / m 2 .

[0049] In the step (7), the refining treatment includes decolorization and deodorization.

[0050] Example 2

[0051] A method for removing mineral oil from linseed oil comprises the following steps:

[0052] (1) Pretreatment: The linseed oil containing mineral oil is pretreated, including filtering to remove large particle impurities and adjusting the temperature and viscosity of the oil to an appropriate range;

[0053] (2) Molecular distillation: The pretreated linseed oil is subjected to molecular distillation using a molecular distillation device to partially remove the mineral oil component therein;

[0054] (3) Emulsification: Molecularly distilled linseed oil, water and emulsifier are mixed in a certain proportion and stirred at 40-70°C for 25-75 minutes to form an unstable emulsion;

[0055] (4) Standing and stratifying: The emulsified mixture is allowed to stand for 1 to 5 hours to allow the emulsion to stratify naturally to form an oil phase, an emulsified phase or an oil phase, an emulsified phase, and an aqueous phase. The different phases are separated respectively, and the oil phase and the emulsified phase are retained for subsequent processing;

[0056] (5) Oil phase treatment: Take the oil phase liquid, stir it at 0-4°C, and then treat it with a high-voltage pulse electric field. After the treatment, ultrafiltration is performed to obtain linseed oil I from which mineral oil is preliminarily removed;

[0057] (6) Emulsified phase treatment: taking the emulsified phase liquid, using a discharge method to perform plasma treatment, the discharge method is pulse discharge, the pulse voltage peak is 50 KV, the discharge frequency is 75 Hz, the treatment time is 15 min, the treatment is repeated 3 times, and the treatment is repeated 2-5 times; taking the upper oil phase, and then performing ultrafiltration and molecular distillation treatment to obtain linseed oil II from which mineral oil is further removed;

[0058] (7) Combining and refining: The linseed oil I and linseed oil II obtained in step (5) and step (6) are combined and refined to finally obtain linseed oil with significantly reduced mineral oil content.

[0059] In the step (1), the filtration is carried out using a plate and frame filter press, the filter medium is gauze, and the filtration pressure is 2-4 kg / cm 2 .

[0060] In the step (1), the temperature of the oil is adjusted to 25° C. and the viscosity is 7.30 cP.

[0061] In the step (2), the evaporation pressure of the molecular distillation is controlled at 22 KPa, the distillation temperature is set at 120° C., and the feed rate is maintained at 35 mL / min.

[0062] In the step (3), the volume ratio of linseed oil to water is 1:2, and the emulsifier content accounts for 1.5wt% of the entire system.

[0063] In the step (3), the emulsifier is PEG-40 stearate.

[0064] In the step (5), the electric field strength is 50 kV / cm, the pulse width is 5 to 20 μs, and the total number of pulses is 75; the ultrafiltration parameters are: membrane pore size: 50-100 nm, operating pressure: 0.3-0.5 MPa, temperature: 25-35° C., flow rate: 200-400 L / h / m 2 .

[0065] In the step (6), the molecular distillation conditions are: evaporation pressure 4KPa, distillation temperature 140°C, feed rate 30mL / min; ultrafiltration parameters are: membrane pore size: 100-200nm, operating pressure: 0.2-0.4Mpa, temperature: 25-35°C, flow rate: 300-500L / h / m 2 .

[0066] In the step (7), the refining treatment includes decolorization and deodorization.

[0067] Example 3

[0068] A method for removing mineral oil from linseed oil comprises the following steps:

[0069] (1) Pretreatment: The linseed oil containing mineral oil is pretreated, including filtering to remove large particle impurities and adjusting the temperature and viscosity of the oil to an appropriate range;

[0070] (2) Molecular distillation: The pretreated linseed oil is subjected to molecular distillation using a molecular distillation device to partially remove the mineral oil component therein;

[0071] (3) Emulsification: Molecularly distilled linseed oil, water and emulsifier are mixed in a certain proportion and stirred at 40-70°C for 25-75 minutes to form an unstable emulsion;

[0072] (4) Standing and stratifying: The emulsified mixture is allowed to stand for 1 to 5 hours to allow the emulsion to stratify naturally to form an oil phase, an emulsified phase or an oil phase, an emulsified phase, and an aqueous phase. The different phases are separated respectively, and the oil phase and the emulsified phase are retained for subsequent processing;

[0073] (5) Oil phase treatment: Take the oil phase liquid, stir it at 0-4°C, and then treat it with a high-voltage pulse electric field. After the treatment, ultrafiltration is performed to obtain linseed oil I from which mineral oil is preliminarily removed;

[0074] (6) Emulsified phase treatment: taking the emulsified phase liquid, using a discharge method to perform plasma treatment, the discharge method is pulse discharge, the pulse voltage peak is 80 kV, the discharge frequency is 100 Hz, the treatment time is 5 min, and the treatment is repeated twice; taking the upper oil phase, and then performing ultrafiltration and molecular distillation treatment to obtain linseed oil II from which mineral oil is further removed;

[0075] (7) Combining and refining: The linseed oil I and linseed oil II obtained in step (5) and step (6) are combined and refined to finally obtain linseed oil with significantly reduced mineral oil content.

[0076] In the step (1), the filtration is carried out using a plate and frame filter press, the filter medium is gauze, and the filtration pressure is 2-4 kg / cm 2 .

[0077] In the step (1), the temperature of the oil is adjusted to 30° C. and the viscosity is 7.10 cP.

[0078] In the step (2), the evaporation pressure of the molecular distillation is controlled at 25 KPa, the distillation temperature is set at 1125° C., and the feed rate is maintained at 40 mL / min.

[0079] In the step (3), the volume ratio of linseed oil to water is 1:3, and the emulsifier content accounts for 2.5wt% of the entire system.

[0080] In the step (3), the emulsifier is PEG-40 stearate.

[0081] In the step (5), the electric field strength is 80 kV / cm, the pulse width is 5-20 μs, and the total number of pulses is 150; the ultrafiltration parameters are: membrane pore size: 50-100 nm, operating pressure: 0.3-0.5 MPa, temperature: 25-35° C., flow rate: 200-400 L / h / m 2 .

[0082] In the step (6), the molecular distillation conditions are: evaporation pressure 6 KPa, distillation temperature 160°C, feed rate 40 mL / min; ultrafiltration parameters are: membrane pore size: 100-200 nm, operating pressure: 0.2-0.4 MPa, temperature: 25-35°C, flow rate: 300-500 L / h / m 2 .

[0083] In the step (7), the refining treatment includes decolorization and deodorization.

[0084] Comparative Example 1

[0085] A method for removing mineral oil from linseed oil comprises the following steps:

[0086] (1) Pretreatment: The linseed oil containing mineral oil is pretreated, including filtering to remove large particle impurities and adjusting the temperature and viscosity of the oil to an appropriate range;

[0087] (3) Emulsification: Molecularly distilled linseed oil, water and emulsifier are mixed in a certain proportion and stirred at 40-70°C for 25-75 minutes to form an unstable emulsion;

[0088] (4) Standing and stratifying: The emulsified mixture is allowed to stand for 1 to 5 hours to allow the emulsion to stratify naturally to form an oil phase, an emulsified phase or an oil phase, an emulsified phase, and an aqueous phase. The different phases are separated respectively, and the oil phase and the emulsified phase are retained for subsequent processing;

[0089] (5) Oil phase treatment: Take the oil phase liquid, stir it at 0-4°C, and then treat it with a high-voltage pulse electric field. After the treatment, ultrafiltration is performed to obtain linseed oil I from which mineral oil is preliminarily removed;

[0090] (6) Emulsified phase treatment: taking the emulsified phase liquid, using a discharge method to perform plasma treatment, the discharge method is pulse discharge, the pulse voltage peak is 50 kV, the discharge frequency is 75 Hz, the treatment time is 15 min, and the treatment is repeated 3 times; taking the upper oil phase, and then performing ultrafiltration and molecular distillation treatment to obtain linseed oil II from which mineral oil is further removed;

[0091] (7) Combining and refining: The linseed oil I and linseed oil II obtained in step (5) and step (6) are combined and refined to finally obtain linseed oil with significantly reduced mineral oil content.

[0092] In the step (1), the filtration is carried out using a plate and frame filter press, the filter medium is gauze, and the filtration pressure is 2-4 kg / cm 2 .

[0093] In the step (1), the temperature of the oil is adjusted to 25° C. and the viscosity is 7.30 cP.

[0094] In the step (3), the volume ratio of linseed oil to water is 1:2, and the emulsifier content accounts for 1.5wt% of the entire system.

[0095] In the step (3), the emulsifier is PEG-40 stearate.

[0096] In the step (5), the electric field strength is 50 kV / cm, the pulse width is 5 to 20 μs, and the total number of pulses is 75; the ultrafiltration parameters are: membrane pore size: 50-100 nm, operating pressure: 0.3-0.5 MPa, temperature: 25-35° C., flow rate: 200-400 L / h / m 2 .

[0097] In the step (6), the molecular distillation conditions are: evaporation pressure 4KPa, distillation temperature 140°C, feed rate 30mL / min; ultrafiltration parameters are: membrane pore size: 100-200nm, operating pressure: 0.2-0.4Mpa, temperature: 25-35°C, flow rate: 300-500L / h / m 2 .

[0098] In the step (7), the refining treatment includes decolorization and deodorization.

[0099] This comparative example does not contain step (2) of molecular distillation, and the rest is the same as Example 2.

[0100] Comparative Example 2

[0101] A method for removing mineral oil from linseed oil comprises the following steps:

[0102] (1) Pretreatment: The linseed oil containing mineral oil is pretreated, including filtering to remove large particle impurities and adjusting the temperature and viscosity of the oil to an appropriate range;

[0103] (2) Molecular distillation: The pretreated linseed oil is subjected to molecular distillation using a molecular distillation device to partially remove the mineral oil component therein;

[0104] (3) Emulsification: Molecularly distilled linseed oil, water and emulsifier are mixed in a certain proportion and stirred at 40-70°C for 25-75 minutes to form an unstable emulsion;

[0105] (4) Standing and stratifying: The emulsified mixture is allowed to stand for 1 to 5 hours to allow the emulsion to stratify naturally to form an oil phase, an emulsified phase or an oil phase, an emulsified phase, and an aqueous phase. The different phases are separated respectively, and the oil phase and the emulsified phase are retained for subsequent processing;

[0106] (5) Oil phase treatment: The oil phase liquid was taken, stirred at 0-4°C for 30 min, and then ultrafiltered to obtain linseed oil I from which mineral oil was preliminarily removed;

[0107] (6) Emulsified phase treatment: taking the emulsified phase liquid, using a discharge method to perform plasma treatment, the discharge method is pulse discharge, the pulse voltage peak is 50 KV, the discharge frequency is 75 Hz, the treatment time is 15 min, the treatment is repeated 3 times, and the treatment is repeated 2-5 times; taking the upper oil phase, and then performing ultrafiltration and molecular distillation treatment to obtain linseed oil II from which mineral oil is further removed;

[0108] (7) Combining and refining: The linseed oil I and linseed oil II obtained in step (5) and step (6) are combined and refined to finally obtain linseed oil with significantly reduced mineral oil content.

[0109] In the step (1), the filtration is carried out using a plate and frame filter press, the filter medium is gauze, and the filtration pressure is 2-4 kg / cm 2 .

[0110] In the step (1), the temperature of the oil is adjusted to 25° C. and the viscosity is 7.30 cP.

[0111] In the step (2), the evaporation pressure of the molecular distillation is controlled at 22 KPa, the distillation temperature is set at 120° C., and the feed rate is maintained at 35 mL / min.

[0112] In the step (3), the volume ratio of linseed oil to water is 1:2, and the emulsifier content accounts for 1.5wt% of the entire system.

[0113] In the step (3), the emulsifier is PEG-40 stearate.

[0114] The ultrafiltration parameters in step (5) are: membrane pore size: 50-100 nm, operating pressure: 0.3-0.5 MPa, temperature: 25-35° C., flow rate: 200-400 L / h / m 2 .

[0115] In the step (6), the molecular distillation conditions are: evaporation pressure 4KPa, distillation temperature 140°C, feed rate 30mL / min; ultrafiltration parameters are: membrane pore size: 100-200nm, operating pressure: 0.2-0.4Mpa, temperature: 25-35°C, flow rate: 300-500L / h / m 2 .

[0116] In the step (7), the refining treatment includes decolorization and deodorization.

[0117] In this comparative example, step (5) does not include high-voltage pulse electric field treatment, and the rest is the same as Example 2.

[0118] Comparative Example 3

[0119] This comparative example does not contain the molecular distillation in step (2), and the high-voltage pulse electric field treatment is not included in step (5), and the rest is the same as in Example 2.

[0120] Test Case

[0121] This test uses linseed oil containing 1% mineral oil produced by common process for removal test. The test is carried out using the method of Examples 1-3 and Comparative Examples 1-3. The experiment is divided into subjective evaluation and mineral oil content test.

[0122] The subjective test was conducted by a panel of 100 volunteers, who conducted sensory evaluations on each group of linseed oil and averaged the scores (rounded to one decimal place). The specific scoring criteria are as follows:

[0123] Color: Translucent 7-10 points, gray 4-7 points, dark gray 1-3 points;

[0124] Flavor: mellow aroma 7-10 points, slightly light aroma 4-7 points, no aroma 1-3 points;

[0125] Taste: No bitterness, smooth taste is suitable for 7-10 points, no bitterness, average taste is 4-7 points, bitterness, poor taste is ≤1-3 points.

[0126] The results are shown in Table 1 and Figure 2-6

[0127] Table 1 Linseed oil test

[0128]

[0129] It can be seen from the above test data that the subjective evaluation performance of Examples 1-3 of the present invention is generally better than that of Comparative Examples 1-3. Specifically, the scheme of Example 2 has achieved the best results in the three dimensions of color, flavor, and taste of linseed oil. From the perspective of the removal efficiency of mineral oil, the use of molecular distillation and high-voltage pulse electric field treatment can greatly improve the removal efficiency of mineral oil, and its removal effect can be improved by more than 10 times. From the above test results, it can be seen that the present invention efficiently removes the mineral oil components in linseed oil through a set of comprehensive and refined process steps, including pretreatment, molecular distillation, emulsification, static stratification, high-voltage pulse electric field treatment, plasma treatment, ultrafiltration and refining; each step sets precise operating conditions to ensure the stability and repeatability of the process, thereby significantly reducing the mineral oil content while retaining the beneficial components and natural flavor of linseed oil, and improving the purity and quality of the product.

[0130] The above are limited to several preferred embodiments of the present invention, and the description thereof is relatively specific and detailed, but it cannot be understood as limiting the scope of the present invention. It should be pointed out that for ordinary technicians in this field, several variations and improvements can be made without departing from the concept of the present invention, which all belong to the protection scope of the present invention.

Claims

1. A method for removing mineral oil from linseed oil, characterized in that: The following steps are involved: (1) Pretreatment: The linseed oil containing mineral oil is pretreated, including filtering to remove large particle impurities and adjusting the temperature and viscosity of the oil to an appropriate range; (2) Molecular distillation: The pretreated linseed oil is subjected to molecular distillation using a molecular distillation device to partially remove the mineral oil component therein; (3) Emulsification: Molecularly distilled linseed oil, water and emulsifier are mixed in a certain proportion and stirred at 40-70°C for 25-75 minutes to form an unstable emulsion; (4) Standing and stratifying: The emulsified mixture is allowed to stand for 1 to 5 hours to allow the emulsion to stratify naturally to form an oil phase, an emulsified phase or an oil phase, an emulsified phase, and an aqueous phase. The different phases are separated respectively, and the oil phase and the emulsified phase are retained for subsequent processing; (5) Oil phase treatment: Take the oil phase liquid, stir it at 0-4°C, and then treat it with a high-voltage pulse electric field. After the treatment, ultrafiltration is performed to obtain linseed oil I from which mineral oil is preliminarily removed; (6) Emulsified phase treatment: taking the emulsified phase liquid, using a discharge method to perform plasma treatment, the discharge method is pulse discharge, the pulse voltage peak is 30-80 kV, the discharge frequency is 50-100 Hz, the treatment time is 5-30 min, and the treatment is repeated 2-5 times; taking the upper oil phase, and then performing ultrafiltration and molecular distillation treatment to obtain linseed oil II from which mineral oil is further removed; (7) Combining and refining: The linseed oil I and linseed oil II obtained in step (5) and step (6) are combined and refined to finally obtain linseed oil with significantly reduced mineral oil content.

2. The method for removing mineral oil from linseed oil according to claim 1, characterized in that: In the step (1), the filtration is carried out using a plate and frame filter press, the filter medium is gauze, and the filtration pressure is 2-4 kg / cm 2 .

3. The method for removing mineral oil from linseed oil according to claim 1, characterized in that: In the step (1), the temperature of the oil is adjusted to 20-30° C. and the viscosity is 7.10-7.50 cP.

4. The method for removing mineral oil from linseed oil according to claim 1, characterized in that: In the step (2), the evaporation pressure of the molecular distillation is controlled at 20-25 KPa, the distillation temperature is set at 115-125° C., and the feed rate is maintained at 25-40 mL / min.

5. The method for removing mineral oil from linseed oil according to claim 1, characterized in that: In the step (3), the volume ratio of linseed oil to water is 1:1-3, the emulsifier content accounts for 0.75-2.5wt% of the whole system, and the emulsifier is a nonionic surfactant with an HLB value of 12-15 or a composite emulsifier thereof.

6. The method for removing mineral oil from linseed oil according to claim 5, characterized in that: In the step (3), the emulsifier is PEG-40 stearate.

7. The method for removing mineral oil from linseed oil according to claim 1, characterized in that: In the step (5), the electric field strength is 30-80 kV / cm, the pulse width is 5-20 μs, and the total number of pulses is 50-150; the ultrafiltration parameters are: membrane pore size: 50-100 nm, operating pressure: 0.3-0.5 MPa, temperature: 25-35° C., flow rate: 200-400 L / h / m 2 .

8. The method for removing mineral oil from linseed oil according to claim 1, characterized in that: In the step (6), the molecular distillation conditions are: evaporation pressure 2-6 KPa, distillation temperature 125-160°C, feed rate 20-40 mL / min; ultrafiltration parameters are: membrane pore size: 100-200 nm, operating pressure: 0.2-0.4 MPa, temperature: 25-35°C, flow rate: 300-500 L / h / m 2 .

9. The method for removing mineral oil from linseed oil according to claim 1, characterized in that: In the step (7), the refining treatment includes decolorization and deodorization.

10. A linseed oil with a low mineral oil content, characterized in that: The method is prepared by any one of claims 1 to 9.

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