Vegetable oil refining method and device

Abstract

The invention discloses a vegetable oil refining method and device. The method comprises the following steps: degumming, neutralizing, deacidifying, decoloring and deodorizing; the refining method can be applied to optimization of a plasticizer removal process for refining vegetable oil and accurate control of the content of trans-fatty acid and chloropropanol ester; and on the other hand, the refining device is common laboratory equipment different from customized commodity equipment of an existing device, only a small number of low-value equipment such as connecting pieces, glassware and electric jackets need to be purchased on the basis of the existing laboratory equipment, the device can be copied by all laboratories, customization is not needed, practicability is higher, and the device is low in cost and easy to popularize. The cost can be effectively reduced and the efficiency is improved.

Description

Technical Field

[0001] The present invention relates to the technical field of vegetable oil refining, and more specifically, to a method and device for refining vegetable oil. Background Art

[0002] Edible vegetable oil is refined to remove pigments, phospholipids, metal ions, free fatty acids, moisture, pollutants, etc. in the crude oil, thereby improving the sensory properties and quality of the vegetable oil and meeting different uses.

[0003] Common vegetable oil refining processes include degumming, neutralization and deacidification, decolorization, and deodorization; industrial equipment usually has a large tank capacity and high equipment power. For situations where pre-process optimization and condition exploration are required, such as conducting research using industrial equipment, a large amount of raw oil, auxiliary materials, and power consumption are needed, and the research cost is too high and it is easy to cause resource waste, which is not conducive to conducting relevant process research in the laboratory.

[0004] General industrial production is continuous production. After passing through the crude oil → degumming → neutralization and caustic refining → decolorization → deodorization sections, the vegetable oil operates continuously and automatically in each section.

[0005] There are commercially available small-scale test devices for vegetable oil refining on the market now. Their refining principle is the same as that of industrial production equipment, but they are simplified in terms of equipment capacity, power, and corresponding supporting devices. Taking a set of commercially available small-scale test equipment on the market as an example: The device is designed intermittently, and after the treatment in different sections is completed, it is necessary to manually add the sample to be treated to the next section. The degumming and neutralization tanks are the same stainless steel tank, with capacities of 10L, 20L, etc., and are equipped with heating and stirring devices; the decolorization tank and the deodorization tank are made of stainless steel, with capacities of 10L, 20L, etc., and are equipped with heating, stirring, and vacuum devices; in addition, a steam generator is equipped, and the generated steam is directly led to the deodorization tank to deodorize the vegetable oil.

[0006] Chinese Patent Technology Application 1 (Application No.: 201911265868.3, Application Date: December 11, 2019.) discloses an edible oil refining method and an edible oil refining system. The edible oil refining method sets the deodorization treatment into two stages, including plate deodorization tower deodorization treatment and packed deodorization tower deodorization treatment. The removal of odor substances and thermal decolorization achieve two different temperature treatments, which have certain limitations for the removal of risk factors in vegetable oil; using the existing equipment in the edible oil refining workshop, the production process cost is relatively large.

[0007] Therefore, there is an urgent need to provide a vegetable oil refining method and device that can effectively remove risk factors in vegetable oil while having a simple refining process operation and can effectively save the device cost. Summary of the Invention

[0008] In view of this, on the one hand, the present invention provides a method for refining vegetable oil, comprising the steps of: degumming, neutralizing and deacidifying, decolorizing and deodorizing;

[0009] The process of degumming, neutralizing and deacidifying includes: putting 150 g - 200 g of crude oil into a flask; adding a phosphoric acid solution in a first ratio to the crude oil, the first ratio being 0.03% to 0.04%; heating and stirring at a first temperature for a first time and then centrifuging to obtain layered crude oil, the first temperature being 70°C - 80°C, and the first time being 1 h - 2 h; taking the upper-layered crude oil and adding liquid caustic soda for alkali refining to remove acid, the over-alkali ratio being 10% - 15%, the Baume degree of the liquid caustic soda being 8°Bé - 12°Bé, and the amount of added alkali being calculated according to the acid value of the crude oil, and the calculation formula is:

[0010]

[0011] Heating and stirring at a second temperature for a second time and then centrifuging to remove soap to obtain soap-removed oil, the second temperature being 80°C - 90°C; the second time being 5 min - 15 min; adding citric acid in a second ratio to the soap-removed oil for water washing, and drying at a third temperature for a third time to obtain dried neutralized oil, the second ratio being 20:1 to 10:1, the mass concentration of the citric acid aqueous solution being 75 mg / kg - 80 mg / kg; the third temperature being 80°C - 90°C; the third time being 20 min - 40 min;

[0012] The decolorizing process includes: putting 150 g - 200 g of dried neutralized oil into a flask, adding activated clay in a third ratio to the weight of the neutralized oil to obtain a mixed oil, the third ratio being 100:1 to 50:1; connecting the flask with a condenser and using a vacuum pump to evacuate; heating and stirring the mixed oil to a fourth temperature and maintaining for a fourth time; filtering to obtain decolorized oil, thus completing decolorization, the fourth temperature being 100°C - 115°C, and the fourth time being 40 min - 50 min;

[0013] The deodorizing process includes the steps of: putting 150 g - 200 g of decolorized oil into a flask; adding distilled water to the steam generating unit and connecting it to the deodorizing device; evacuating through a vacuum pump, adjusting the temperature of the steam generating unit through a temperature sensor to continuously introduce steam into the decolorized oil, heating the deodorized oil to a fifth temperature and maintaining for a fifth time to complete deodorization, the fifth temperature being 230°C - 240°C, and the fifth time being 50 min - 70 min.

[0014] Optionally, the first temperature is 72°C - 78°C; the first time is 1.2 h - 1.5 h.

[0015] Optionally, the second temperature is 83°C - 87°C; the second time is 8 min - 12 min.

[0016] Optionally, the third temperature is 82°C - 88°C; the third time is 25 min - 35 min.

[0017] Optionally, the fourth temperature is 105°C - 110°C; the fourth time is 45 min - 48 min.

[0018] On the other hand, the present invention also provides a vegetable oil refining device for the vegetable oil refining method of any one of the above, comprising: at least two magnetic stirring electric heating mantles, at least two flasks, a thermometer, a condenser, a receiving flask, a vacuum pump and a gas guide tube.

[0019] During the degumming and neutralization and deacidification processes, the flask is placed on the heating surface of the magnetic stirring electric heating mantle, the stirrer of the magnetic stirring electric heating mantle and the glass thermometer are placed inside the flask, and the condenser, the receiving flask, the vacuum pump and the gas guide tube are not connected to the flask and the magnetic stirring electric heating mantle;

[0020] During the decolorization process, the flask is placed on the heating surface of the magnetic stirring electric heating mantle, the stirrer of the magnetic stirring electric heating mantle and the glass thermometer are placed inside the flask, one end of the flask is also connected to one end of the condenser, the other end of the condenser is connected to one end of the receiving tube, the other end of the receiving tube is connected to the receiving flask, and the vacuum pump is connected to the receiving tube;

[0021] During the deodorization process, the steam generating unit comprises: a flask for adding water is arranged on the heating surface of a magnetic stirring electric heating mantle, the flask for adding water is connected to one end of the gas guide tube, the other end of the gas guide tube is connected to a flask containing decolorized oil, the flask containing decolorized oil is arranged on another magnetic stirring electric heating mantle, the condenser is connected to the flask containing decolorized oil through the gas guide tube, the receiving tube is connected to the end of the condenser far away from the flask containing decolorized oil, the other end of the receiving tube is connected to the receiving flask, and the vacuum pump is connected to the receiving tube.

[0022] Compared with the prior art, the vegetable oil refining method and device provided by the present invention at least achieve the following beneficial effects:

[0023] The present invention provides a method and apparatus for refining vegetable oil. The method includes the steps of degumming, neutralizing and deacidifying, decolorizing, and deodorizing. The degumming, neutralizing and deacidifying process includes: putting 150 g - 200 g of crude oil into a flask; adding a phosphoric acid solution in a first ratio to the crude oil; heating and stirring at a first temperature for a first time and then centrifuging to obtain stratified crude oil, taking the upper-layer stratified crude oil and adding liquid caustic soda for caustic refining to remove acid, with an excess caustic of 10% - 15%; heating and stirring at a second temperature for a second time and then centrifuging to remove soap to obtain soap-free oil; adding a citric acid aqueous solution in a second ratio to the soap-free oil for water washing, and drying at a third temperature for a third time to obtain dried neutralized oil. The decolorizing process includes: putting 150 g - 200 g of the dried neutralized oil into a flask, adding activated clay in a third ratio to the weight of the neutralized oil to obtain a mixed oil; connecting the flask to a condenser and using a vacuum pump to evacuate; heating and stirring the mixed oil to a fourth temperature and maintaining for a fourth time; filtering to obtain decolorized oil, thus completing decolorization. The deodorizing process includes the steps of: putting 150 g - 200 g of the decolorized oil into a flask; adding distilled water to a steam generating unit and connecting it to the deodorizing device; evacuating through a vacuum pump, adjusting the temperature of the steam generating unit through a temperature sensor to continuously introduce steam into the decolorized oil, heating the deodorized oil to a fifth temperature and maintaining for a fifth time to complete deodorization. The refining method of the present application can be applied to the process research of removing plasticizers from refined vegetable oil and accurately controlling trans fatty acids and chloropropanol esters. On the other hand, the refining apparatus of the present application is different from the customized commercial equipment of existing devices in that it is composed of common laboratory equipment. Based on the existing laboratory equipment, only a small amount of low-value equipment such as connectors, glassware, and electric heating jackets needs to be purchased. Each laboratory can replicate this device without customization, with stronger practicability, and the cost of this device is relatively low, which can effectively reduce costs and increase efficiency.

[0024] Of course, it is not necessary for any product implementing the present invention to simultaneously achieve all the above-described technical effects.

[0025] Other features and advantages of the present invention will become clear from the following detailed description of the exemplary embodiments of the present invention with reference to the accompanying drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] The drawings incorporated in and constituting a part of this specification illustrate embodiments of the present invention and, together with the description, serve to explain the principles of the present invention.

[0027] Figure 1 is a flowchart of a method for refining vegetable oil according to the present invention;

[0028] Figure 2 is a vegetable oil refining apparatus provided by the present invention;

[0029] Figure 3 is another vegetable oil refining apparatus provided by the present invention;

[0030] Figure 4 is another kind of vegetable oil refining device provided by the present invention;

[0031] Figure 5 is a graph showing the change rule of trans fatty acid content at different deodorization times;

[0032] Figure 6 is a graph showing the change rule of trans fatty acid content at different deodorization temperatures;

[0033] Figure 7 is a graph showing the change rule of the growth rate of trans fatty acids at different deodorization temperatures;

[0034] 1-magnetic stirring electric heating mantle, 11-stirring bar, 12-heating surface, 2-thermometer, 31-two-necked flask, 32-three-necked flask, 33-receiving flask, 4-distillation head, 5-condenser, 51-rubber tube, 6-receiving tube, 7-vacuum pump, 8-steam generating unit, 81-air duct. Specific Embodiments

[0035] Now, various exemplary embodiments of the present invention will be described in detail with reference to the accompanying drawings. It should be noted that: unless otherwise specifically stated, the relative arrangements of components and steps, numerical expressions, and numerical values set forth in these embodiments do not limit the scope of the present invention.

[0036] The following description of at least one exemplary embodiment is merely illustrative in nature and is in no way a limitation on the present invention or its application or use.

[0037] Techniques, methods, and devices known to those of ordinary skill in the relevant art may not be discussed in detail, but where appropriate, such techniques, methods, and devices should be considered as part of the specification.

[0038] In all examples shown and discussed herein, any specific values should be construed as merely exemplary and not as limitations. Thus, other examples of the exemplary embodiments may have different values.

[0039] It should be noted that: like reference numerals and letters denote like items in the following drawings, and thus, once an item is defined in one drawing, it need not be further discussed in subsequent drawings.

[0040] Referring to Figure 1 , the present invention provides a method for refining vegetable oil, including the steps of: S1 degumming and neutralizing deacidification, S2 decolorization, and S3 deodorization;

[0041] S1: The degumming and neutralizing deacidification process includes: S11: Take 150 g - 200 g of crude oil and put it into a flask; S12: Add a phosphoric acid solution in a first ratio to the crude oil, and the first ratio is 0.03% to 0.04%; S13: Heat and stir at a first temperature for a first time and then centrifuge to obtain layered crude oil, the first temperature is 70°C - 80°C, and the first time is 1 h - 2 h; S14: Take the upper-layered crude oil and add liquid caustic soda for caustic refining deacidification, the over-alkali ratio is 10% - 15%, the Baume degree of the liquid caustic soda is 8°Bé - 12°Bé, and the amount of added alkali is calculated according to the acid value of the crude oil. The calculation formula is:

[0042]

[0043] S15: Heat and stir at a second temperature for a second time and then centrifuge to remove soap to obtain soap-free oil, the second temperature is 80°C - 90°C; the second time is 5 min - 15 min; S16: Add citric acid in a second ratio to the soap-free oil for water washing, and dry at a third temperature for a third time to obtain dried neutralized oil, the second ratio is 20:1 to 10:1, the mass concentration of the citric acid aqueous solution is 75 mg / kg - 80 mg / kg; the third temperature is 80°C - 90°C; the third time is 20 min - 40 min;

[0044] S2: The decolorization process includes: S21: Take 150 g - 200 g of dried neutralized oil and put it into a flask, add activated clay in a third ratio to the weight of the neutralized oil to obtain a mixed oil, and the third ratio is 100:1 to 50:1; S22: Connect the flask to a condenser 5 and use a vacuum pump 7 to evacuate; S23: Heat and stir the mixed oil to a fourth temperature and keep it for a fourth time; S24: Filter to obtain decolorized oil and complete decolorization, the fourth temperature is 100°C - 115°C, and the fourth time is 40 min - 50 min;

[0045] S3: The deodorization process includes the steps: S31: Take 150 g - 200 g of decolorized oil and put it into a flask; S32: Add distilled water to a steam generation unit 8 and connect it to a deodorization device; S33: Evacuate through a vacuum pump 7, adjust the temperature of the steam generation unit 8 through a temperature sensor, so that steam continuously passes into the decolorized oil, heat the deodorized oil to a fifth temperature and keep it for a fifth time to complete deodorization, the fifth temperature is 230°C - 240°C, and the fifth time is 50 min - 70 min.

[0046] Specifically, referring to Figure 1 , the present invention provides a method for refining vegetable oil, including the steps: S1 degumming and neutralizing deacidification, S2 decolorization, and S3 deodorization;

[0047] S1: The degumming and neutralization deacidification process includes: S11: Take 150 g - 200 g of crude oil and put it into a flask; S12: Add a phosphoric acid solution in a first ratio to the crude oil, and the first ratio is 0.03% to 0.04%; S13: Heat and stir at a first temperature for a first time and then centrifuge to obtain layered crude oil, the first temperature is 70°C - 80°C, and the first time is 1 h - 2 h; S14: Take the upper-layered crude oil and add liquid caustic soda for caustic refining deacidification, the over-alkali ratio is 10% - 15%, the Baume degree of the liquid caustic soda is 8°Bé - 12°Bé, and the amount of added alkali is calculated according to the acid value of the crude oil. The calculation formula is:

[0048]

[0049] S15: Heat and stir at a second temperature for a second time and then centrifuge to remove soapstock to obtain soapstock-removed oil, the second temperature is 80°C - 90°C; the second time is 5 min - 15 min; S16: Add citric acid in a second ratio to the soapstock-removed oil for water washing, and dry at a third temperature for a third time to obtain dried neutralized oil, the second ratio is 20:1 to 10:1, the mass concentration of the citric acid aqueous solution is 75 mg / kg - 80 mg / kg; the third temperature is 80°C - 90°C; the third time is 20 min - 40 min;

[0050] It should be noted that degumming refers to the process of removing gum impurities such as phospholipids, proteins, and sugars in vegetable oil by physical or chemical methods. This can prevent the catalyst poisoning, equipment blockage, or product quality decline of vegetable oil during subsequent processing (such as decolorization and deodorization); the role of degumming is to remove phospholipids. Phospholipids are the main gum components in vegetable oil and are prone to oxidation and produce odors at high temperatures, affecting the quality of vegetable oil; it can also reduce impurities. Degumming removes impurities such as proteins and sugars to avoid adverse reactions in subsequent processes; in this embodiment, acid refining degumming is used. Phosphoric acid is added to the crude vegetable oil to convert non-hydratable phospholipids into hydratable phospholipids, and then hydratable degumming is used to remove them.

[0051] It should be noted that neutralization deacidification is to add an alkali solution, which can be sodium hydroxide or potassium hydroxide, to the layered crude oil after degumming, and it reacts with the free fatty acids (FFAs) in the vegetable oil to form soapstock, that is, fatty acid salts and water; neutralization deacidification can reduce the acid value of vegetable oil and improve the stability of vegetable oil; remove the odor and impurities in vegetable oil, improve the flavor and quality of vegetable oil, and provide good raw materials for subsequent steps such as decolorization and deodorization; among them, FFA is one of the main reasons for the rancidity of vegetable oil. Neutralization deacidification can significantly reduce the acid value of vegetable oil, and the removal of FFA can reduce the catalyst for the oxidation reaction of vegetable oil and improve the oxidation stability of vegetable oil; the soapstock generated during the neutralization deacidification process can adsorb impurities such as pigments, proteins, and phospholipids in the vegetable oil, playing a synergistic purification role.

[0052] It should be noted that the excess alkali of 10%-15% means that in the actual alkali addition operation, the amount of alkali added exceeds the theoretically calculated required amount of alkali by 10%-15%.

[0053] Optionally, the specific excess alkali can be 10%, 11%, 12%, 13.5%, 14.2%, 14.5% and 15%. When the excess alkali is greater than 15%, the excess alkali is too much, and the excess alkali solution will saponify with neutral oil, increasing the refining loss and reducing the yield of refined oil; too much alkali will cause an increase in the amount of soapstock, and the number of water washing times needs to be increased, resulting in an increase in oil loss and an increase in process cost; when the excess alkali is less than 10%, the amount of alkali is too little, which will lead to incomplete neutralization of free fatty acids and affect the deacidification effect; the amount of soapstock generated decreases, the adsorption capacity for impurities such as proteins and mucilages decreases, and the degumming effect is reduced; when the excess alkali is 10%-15%, it can ensure that free fatty acids are fully neutralized, and the generated soapstock can adsorb impurities in the oil, improving the deacidification and degumming effects.

[0054] It can be understood that the degumming and neutralization deacidification processes are carried out simultaneously. After the degumming removes gum impurities, the formation of soapstock is more uniform and the separation is more complete during the neutralization deacidification process; the soapstock generated during the neutralization deacidification process can further adsorb residual gum, improving the purification effect; the removal of gum and FFA reduces the possibility of oxidation and rancidity of vegetable oil, and can effectively extend the shelf life of vegetable oil.

[0055] S2: The decolorization process includes: S21: Take 150 g - 200 g of dry neutralized oil and put it into a flask, add activated clay in a third ratio to the weight of the neutralized oil to obtain a mixed oil, and the third ratio is 100:1 to 50:1; S22: Connect the flask with a condenser 5 and use a vacuum pump 7 to evacuate; S23: Heat and stir the mixed oil to a fourth temperature and maintain it for a fourth time; S24: Filter to obtain decolorized oil, completing the decolorization. The fourth temperature is 100°C - 115°C, and the fourth time is 40 min - 50 min;

[0056] It should be noted that step S2 mainly uses adsorbents such as activated clay or activated carbon. In this embodiment, activated clay is used to remove impurities such as pigments (such as chlorophyll and carotenoids), phospholipid residues, soap particles, and trace metals in vegetable oil. Completing the decolorization process can improve the appearance of vegetable oil, making it present a clear and transparent light yellow or colorless. After removing impurities, the oxidation stability of vegetable oil is improved, and the shelf life can be effectively extended.

[0057] S3: The deodorization process includes the steps of: S31: Put 150 g - 200 g of decolorized oil into a flask; S32: Add distilled water to the steam generation unit 8 and connect it to the deodorization device; S33: Evacuate the air through the vacuum pump 7, adjust the temperature of the steam generation unit 8 through the temperature sensor, continuously introduce steam into the decolorized oil, heat the deodorized oil to the fifth temperature and maintain it for the fifth time to complete deodorization. The fifth temperature is 230°C - 240°C, and the fifth time is 50 min - 70 min.

[0058] It should be noted that in step S3: Deodorization is mainly carried out under high temperature and high vacuum conditions to remove odor substances in vegetable oil, such as free fatty acids, aldehydes, ketones, and alcohols, etc.; it can remove the odor and bad flavor in vegetable oil, improve the quality of vegetable oil; further reduce the acid value of vegetable oil and improve its stability; it can remove harmful substances such as residual pesticides and solvents to ensure food safety.

[0059] In some optional embodiments, the first ratio is 0.03% to 0.04%; the first temperature is 70°C - 80°C; the first time is 1 h - 2 h.

[0060] Optionally, the first ratio can specifically be 0.03% to 0.04%. When the addition amount of phosphoric acid is too high, it will reduce the pH value of the vegetable oil system, decompose the formed flocculent gel, and the phospholipid micelles that were originally aggregated together may re-disperse, making it difficult for phospholipids to be separated by centrifugation, thereby reducing the degumming rate; when the added phosphoric acid solution is too little, not enough non-hydrophilic phospholipids can be converted into hydrophilic phospholipids, resulting in insufficient hydration and aggregation of phospholipids, reducing the degumming rate; so when the first ratio is 0.03% to 0.04%, the addition amount of the phosphoric acid solution is appropriate, which can maintain a high degumming efficiency and fully complete degumming.

[0061] Optionally, the first temperature can specifically be 70°C, 71.3°C, 72°C, 73.4°C, 74.3°C, 75.6°C, 76°C, 77.5°C, 78°C, 79°C, and 80°C. When the first temperature is greater than 80°C, the temperature is too high, and the aggregated phospholipid molecules will be disassembled from the large micelles, resulting in a decrease in the degumming rate and possibly causing oil oxidation or thermal denaturation, affecting the quality of the oil; when the first temperature is less than 70°C, the temperature is too low, the movement of phospholipid molecules slows down, and the hydration efficiency decreases, resulting in incomplete removal of phospholipids; so when the first temperature is 70°C - 80°C, the temperature is appropriate, and while the reaction is sufficient, the degumming effect is ensured.

[0062] Optionally, the first time can be specifically 1h, 1.2h, 1.4h, 1.6h, 1.8h and 2h. When the first time is greater than 2h, the stirring time is too long, which will destroy the oil-water interface balance, form a stable emulsion, and increase the difficulty of oil foot separation; it may also promote the reaction between neutral oil and alkali solution, resulting in increased refining loss; when the first time is less than 1h, the stirring time is too short, the contact time between phosphoric acid and phospholipids is insufficient, and the conversion of non-hydratable phospholipids is incomplete, affecting the degumming effect and reducing the centrifugal separation efficiency. Therefore, when the first time is 1h-2h, the stirring time is appropriate and sufficient stirring will not affect the degumming effect.

[0063] In some optional embodiments, the second temperature is 80° C.-90° C.; and the second time is 5 min-15 min.

[0064] Optionally, the second time can be specifically 5min, 6min, 7min, 8min, 9min, 10min, 11min, 12min, 13min, 14min and 15min. When the second time is greater than 15min, the stirring time is too long, the mixing intensity is too high, and a stable emulsion is easily formed, which increases the difficulty of oil-soap separation and causes the phenomenon of oil droplets hanging on the wall. When the second time is less than 5min, the stirring time is too short, the contact between the alkali solution and the free fatty acids is insufficient, the neutralization reaction is incomplete, the amount of soap stock generated is small and it is difficult to flocculate, affecting the deacidification effect; when the second time is 5min-15min, the stirring time is appropriate, can fully react, and accelerate the deacidification efficiency.

[0065] Optionally, the second temperature can be specifically 80℃, 81℃, 82.3℃, 83.5℃, 84.6℃, 85℃, 86.5℃, 87.6℃, 88℃, 89.9℃ and 90℃; the second temperature is greater than 90℃, the stirring temperature is too high, high temperature accelerates the saponification reaction of neutral oil, reduces the yield of refined oil, and high temperature is also easy to cause oil oxidation, affecting product quality; the second temperature is less than 70℃, the temperature is too low, low temperature slows down the neutralization reaction rate, and will prolong the alkali refining time; low temperature will cause the viscosity of oil to increase, the sedimentation rate of soap stock slows down, and affects the separation efficiency; so when the second temperature is 80℃-90℃, the temperature is appropriate, the soap stock generation rate is consistent, and the alkali neutralization efficiency is improved.

[0066] In some optional embodiments, the second ratio is 20:1 to 10:1; the mass concentration of citric acid is 75 mg / kg-80 mg / kg; the third temperature is 80° C.-90° C.; and the third time is 20 min-40 min.

[0067] Optionally, the second ratio is from 20:1 to 10:1. When the second ratio is greater than 10:1, excessive citric acid will corrode the reaction equipment and shorten its service life. At the same time, the excessive acidic environment may cause partial hydrolysis of the oil, increasing the refining loss. When the second ratio is less than 20:1, insufficient citric acid cannot effectively demulsify, affecting the oil-water separation efficiency, and will also result in incomplete removal of soap particles, leaving impurities in the refined oil and affecting the quality.

[0068] Optionally, the third temperature can specifically be 80°C, 81°C, 82.3°C, 83.5°C, 84.6°C, 85°C, 86.5°C, 87.6°C, 88°C, 89.9°C, and 90°C. When the third temperature is greater than 90°C, the drying temperature is too high, and the high temperature will accelerate the oxidation of the oil, producing odor substances and reducing the product quality. The oil undergoes thermal denaturation, affecting the flavor and stability. When the third temperature is less than 80°C, the temperature is too low, which will prolong the drying time and reduce the production efficiency. If the drying is incomplete and moisture remains, it will increase the risk of oil rancidity.

[0069] In some alternative embodiments, the third ratio is from 100:1 to 50:1; the fourth temperature is 100°C - 115°C; the fourth time is 40 min - 50 min.

[0070] Optionally, the third ratio is from 100:1 to 50:1. When the third ratio is less than 50:1, excessive addition of activated clay will adsorb a large amount of neutral oil, resulting in a reduction in the yield of refined oil. Moreover, too much usage will form a high-viscosity filter cake, clogging the filter medium and prolonging the filtration time. When the third ratio is greater than 100:1, too little activated clay is added, and the insufficient dosage cannot completely adsorb impurities such as pigments and phospholipids, resulting in incomplete decolorization. When the third ratio is from 100:1 to 50:1, the proportion of activated clay added is appropriate, which can completely adsorb impurities such as pigments and phospholipids without affecting the filtration efficiency.

[0071] Optionally, the fourth temperature can specifically be 100°C, 102°C, 103°C, 104°C, 105°C, 106°C, 107°C, 108°C, 109°C, 110°C, 111°C, 112°C, 113°C, 114°C, and 115°C. When the fourth temperature is less than 100°C, the adsorption rate of clay slows down, and the pigment diffusion is insufficient, resulting in incomplete decolorization, and the stirring time needs to be extended or the amount of clay increased. When the fourth temperature is greater than 120°C, the high temperature will promote the reaction of oil with oxygen, generating peroxides and hydroperoxides, increasing the acid value and peroxide value of the refined oil and decreasing the oxidation stability. It may also cause damage to the pore structure of the clay and a decrease in the adsorption capacity. When the fourth temperature is 100°C - 115°C, the temperature is appropriate, and the activated clay has a strong adsorption capacity and will not react excessively.

[0072] In some alternative embodiments, the fifth temperature is 230°C - 240°C, and the fifth time is 50 min - 70 min.

[0073] Optionally, the fifth temperature can specifically be 230 °C, 231 °C, 232 °C, 233 °C, 234 °C, 235 °C, 236 °C, 237 °C, 238 °C, 239 °C, and 240 °C. When the fifth temperature is greater than 240 °C, the excessively high temperature will accelerate the thermal decomposition of the oil, generating harmful substances such as trans fatty acids and polymers; at high temperatures, neutral oil volatilizes or decomposes, resulting in a decrease in the yield of refined oil; when the fifth temperature is less than 230 °C, the temperature is too low. At low temperatures, the vapor pressure of volatile odor substances (such as aldehydes and ketones) is insufficient, making it difficult to completely remove them, and the produced vegetable oil has a residual odor and poor flavor; at low temperatures, free fatty acids do not volatilize completely, resulting in a relatively high acid value of the deodorized oil; when the fifth temperature is 230 °C - 240 °C, the temperature during the deodorization process is reasonable, neither producing excessive trans fatty acids nor leaving a residual odor.

[0074] Optionally, the fifth time can specifically be 50 min, 51 min, 52 min, 53 min, 54 min, 55 min, 57 min, 58 min, 60 min, 62 min, 64 min, 66 min, 68 min, and 70 min; when the fifth time is greater than 70 min, long-term high-temperature exposure will accelerate the reaction of the oil with oxygen, generating peroxides and hydroperoxides; when the fifth time is less than 50 min, the insufficient time will cause volatile substances not to be fully distilled and remain in the oil, and may also result in a large temperature gradient inside the oil, with incomplete deodorization in some areas; when the fifth time is 50 min - 70 min, the time is appropriate, with sufficient reaction and no excessive reaction.

[0075] On the other hand, referring to Figures 2 - 4 , the present invention also provides a vegetable oil refining device for the vegetable oil refining method of any one of the foregoing, including: at least two magnetic stirring electric heating mantles 1, at least two flasks, a thermometer 2, a condenser 5, a receiving flask 33, a vacuum pump 7, and a gas guide tube 81.

[0076] It should be noted that the flask, thermometer 2, condenser 5, receiving flask 33, vacuum pump 7, and gas guide tube 81 are all commonly used laboratory equipment at present. Based on the existing laboratory equipment, only a small number of low-value equipment such as connectors, glassware, and electric heating mantles need to be purchased. Each laboratory can replicate this device without customization, with stronger practicability, and the cost of this device is relatively low, which can effectively reduce costs and increase efficiency.

[0077] Referring to Figures 2 - 4 , in step S1: during the degumming and neutralization and deacidification process, the flask is placed on the heating surface 12 of the magnetic stirring electric heating mantle 1, the stirring bar 11 of the magnetic stirring electric heating mantle 1 and the glass thermometer 2 are placed inside the flask, and the condenser 5, receiving flask 33, vacuum pump 7, and gas guide tube 81 are not connected to the flask and the magnetic stirring electric heating mantle 1;

[0078] In step S2: During the decolorization process, the flask is placed on the heating surface 12 of the magnetic stirring electrothermal mantle 1. The stirring bar 11 of the magnetic stirring electrothermal mantle 1 and the glass thermometer 2 are placed inside the flask. One end of the flask is also connected to the condenser 5, the other end of the condenser 5 is connected to one end of the receiving tube 6, the other end of the receiving tube 6 is connected to the receiving flask 33, and the vacuum pump 7 is connected to the receiving tube 6.

[0079] In step S3: During the deodorization process, the steam generating unit 8 includes the magnetic stirring electrothermal mantle 1, a flask filled with water. The flask filled with water is connected to one end of the gas guide tube 81, and the other end of the gas guide tube 81 is connected to the flask containing the decolorized oil in the decolorization device. The flask containing the decolorized oil is placed on the magnetic stirring electrothermal mantle 1. The condenser 5 is connected to the flask containing the decolorized oil. The receiving tube 6 is connected to the end of the condenser 5 far from the flask containing the decolorized oil. The other end of the receiving tube 6 is connected to the receiving flask 33, and the vacuum pump 7 is connected to the receiving tube 6.

[0080] It should be noted that in step S1, referring to Figure 2 , a two-necked flask 31 is selected and placed on the heating surface 12 of the magnetic stirring electrothermal mantle 1. The stirring bar 11 of the magnetic stirring electrothermal mantle 1 and the glass thermometer 2 are placed inside the flask. The oil is heated and stirred by the magnetic stirring electrothermal mantle 1 to uniformly increase its temperature and be evenly mixed with the acid and base. The heating end of the electrothermal mantle is controlled by the temperature sensor, and the oil temperature is measured by the glass thermometer 2 to control the actual reaction temperature.

[0081] In step S2, referring to Figure 3 , one end of the flask is also connected to the condenser 5. The other end of the condenser 5 is connected to the receiving flask 33 through the receiving tube 6. The vacuum pump 7 is connected to the condenser 5. The oil is uniformly mixed with the decolorizing agent and heated for decolorization by the magnetic stirring electrothermal mantle 1. The heating end of the electrothermal mantle is controlled by the temperature sensor, and the actual oil temperature is measured by the glass thermometer 2. The condenser 5 condenses the volatile steam during the heating of the oil, the receiving flask 33 receives it, and the vacuum pump 7 provides vacuum for the above device.

[0082] In step S3, referring to Figure 4 , the magnetic stirring electrothermal mantle 1 heats the water in the two-necked flask 31 to generate steam. The steam is introduced into the oil heated in the three-necked flask 33 through the gas guide tube 81. The oil is heated and stirred by the magnetic electrothermal mantle 1. The thermometer 2 controls the oil temperature. The deodorized distillate is condensed by the condenser 5, the receiving flask 33 receives the distillate, and the vacuum pump 7 provides vacuum for the deodorization device.

[0083] Example 1

[0084] Step S1: Degumming and neutralization deacidification: weigh 150-200 g of soybean crude oil into a two-necked flask 31, add 0.035% phosphoric acid accounting for the oil weight, heat and stir at 75° C. for 1.5 hours, centrifuge, take the upper layer of soybean crude oil and add liquid caustic soda for alkali refining and deacidification, the excess alkali is 10%, the liquid alkali has a Baume degree of 10, and the amount of alkali added is calculated according to the acid value of the crude oil, heat and stir at 85° C. for 10 minutes, and centrifuge to remove soap; add hot water accounting for 5% of the oil weight and containing 80 mg / kg of citric acid to wash the desoaped oil, and dry under reduced pressure at 85° C. for 30 minutes to obtain dry neutralized oil.

[0085] Step S2: Decolorization: Weigh 150-200 g of dry neutralized oil into a two-necked flask 31, add 1% of the weight of the oil in activated clay, assemble the decolorization device, heat and stir to 115° C. and maintain for 45 minutes, evacuate the entire process, and filter while hot to obtain the decolorized oil after decolorization.

[0086] Step S3: Deodorization: 150-200 g of the oil to be deodorized is weighed into a three-necked flask 32, an appropriate amount of distilled water is added to the steam generating unit 8, the deodorization device is assembled, vacuum is applied throughout the process, the temperature of the steam generating unit 8 is adjusted so that steam is continuously introduced into the oil to be deodorized, and the deodorized oil is heated to 240° C. and maintained for 60 minutes.

[0087] Comparative analysis:

[0088] Study on the migration of arsenic, lead and plasticizers in refining auxiliary materials into vegetable oil during the refining process

[0089] Arsenic, lead, and plasticizer were added to the auxiliary materials liquid alkali and activated clay used in the neutralization and decolorization process, and the refining was carried out according to the refining method in Example 1. The neutralized oil, bleached oil, and deodorized oil obtained were respectively tested for arsenic, lead, and plasticizer content, and the mobility was calculated by comparing with the theoretical addition amount.

[0090] Table 1 Results of migration test of plasticizer spiked in liquid caustic soda

[0091]

[0092] The results showed that when plasticizers were spiked at high concentrations in the alkali solution, the DBP in the oil was below the limit of quantification after alkali refining, while DEHP and DINP had almost no migration, indicating that soapstock can carry the plasticizers in the oil.

[0093] Table 2 Results of migration test of plasticizer spiked in bleached soil

[0094]

[0095] The experimental results show that during the decolorization process, all three plasticizers in the soil migrated into the oil. The migration rates of DBP and DEHP were close to 80%, and the migration rate of high-concentration DINP was about 50%. It may be due to the high concentration and the need for a longer migration equilibrium time.

[0096] Table 3 Results of the spike recovery experiment of arsenic and lead in liquid caustic soda

[0097]

[0098] The experimental results show that lead and arsenic were basically not detected in the alkali-refined oil, while high contents of arsenic and lead were detected in the soapstock, indicating that heavy metals can be effectively removed by entraining with the soapstock.

[0099] Table 4 Results of the spike recovery experiment of arsenic and lead in decolorizing earth

[0100]

[0101] The results show that when high-concentration spike-added activated clay was used, lead and arsenic were basically not detected in the decolorized oil, indicating that arsenic and lead in the activated clay will not migrate into the oil.

[0102] Effect of the deodorization process on the formation of trans fatty acids and chloropropanol esters

[0103] Regarding the risk that high-temperature deodorization may cause an increase in trans fatty acids and chloropropanol esters, the results are shown in Figure 6 , Figure 5 It shows that when the deodorization temperature is 240 °C, with the extension of the deodorization time, the content of trans fatty acids gradually increases and is basically linearly correlated. Figure 5 The different colored lines in it represent the changes in the content of different types of trans fatty acids with the extension of the deodorization time. Figure 6 The different colored lines in it represent the changes in the content of different types of trans fatty acids with the increase of the deodorization temperature. Among them, the blue line represents C18:2T, which refers to trans fatty acids containing 18 carbon atoms and 2 double bonds; the red line represents C18:3T, indicating trans fatty acids containing 18 carbon atoms and 3 double bonds; the green line represents the total TFAC, that is, the total trans fatty acid content (Total TransFatty Acid Content), which is the sum of the contents of all trans fatty acids; refer to Figures 6 - 7 , and the results show that when the deodorization time is 1 h, the generation rate of trans fatty acids increases with the increase of temperature. The temperature peak during the deodorization process in this application is 240 °C, and the generation amount of trans fatty acids is less.

[0104] As can be seen from the above embodiments, a vegetable oil refining method and device provided by the present invention have at least achieved the following beneficial effects:

[0105] A method and device for refining vegetable oil provided by the present invention, the method comprising the steps of: degumming, neutralizing and deacidifying, decolorizing and deodorizing; the degumming, neutralizing and deacidifying process comprising: putting 150 g - 200 g of crude oil into a flask; adding a phosphoric acid solution in a first ratio to the crude oil; heating and stirring at a first temperature for a first time and then centrifuging to obtain stratified crude oil, taking the upper-layer stratified crude oil and adding liquid alkali for alkali refining to remove acid, with an excess alkali of 10% - 15%; heating and stirring at a second temperature for a second time and then centrifuging to remove soap to obtain soap-free oil; adding citric acid in a second ratio to the soap-free oil for water washing, and drying at a third temperature for a third time to obtain dried neutralized oil; the decolorizing process comprising: putting 150 g - 200 g of the dried neutralized oil into a flask, adding activated clay in a third ratio to the weight of the neutralized oil to obtain a mixed oil; connecting the flask to a condenser and using a vacuum pump to evacuate; heating and stirring the mixed oil to a fourth temperature and maintaining for a fourth time; filtering to obtain decolorized oil, thus completing decolorization; the deodorizing process comprising the steps of: putting 150 g - 200 g of the decolorized oil into a flask; adding distilled water into a steam generating unit and connecting it to a deodorizing device; evacuating through a vacuum pump, adjusting the temperature of the steam generating unit through a temperature sensor to continuously introduce steam into the decolorized oil, heating the deodorized oil to a fifth temperature and maintaining for a fifth time to complete deodorization. The refining method of the present application can be applied to the optimization of the plasticizer removal process for refined vegetable oil and the precise control of the contents of trans fatty acids and chloropropanol esters; on the other hand, the refining device of the present application is different from the customized commercial devices of existing devices in that it is composed of common laboratory equipment. On the basis of existing laboratory equipment, only a small number of low-value equipment such as connecting parts, glassware, and heating mantles need to be purchased. Each laboratory can replicate this device without customization, with stronger practicability, and the cost of this device is relatively low, which can effectively reduce costs and increase efficiency.

[0106] Although some specific embodiments of the present invention have been described in detail by way of examples, those skilled in the art should understand that the above examples are for illustrative purposes only and not for limiting the scope of the present invention. Those skilled in the art should understand that the above embodiments can be modified without departing from the scope and spirit of the present invention. The scope of the present invention is defined by the appended claims.

Claims

1. A method for refining vegetable oil, characterized in that, Including the steps: degumming, neutralizing and deacidifying, decolorizing and deodorizing; The degumming, neutralizing and deacidifying process includes: putting 150 g - 200 g of crude oil into a flask; adding a phosphoric acid solution with a mass fraction in a first ratio to the crude oil, the first ratio being 0.03% to 0.04%; heating and stirring at a first temperature for a first time and then centrifuging to obtain stratified crude oil, the first temperature being 70°C - 80°C, the first time being 1 h - 2 h; taking the upper-layer stratified crude oil and adding liquid caustic soda for caustic refining to remove acid, the over-alkali ratio being 10% - 15%, the Baume degree of the liquid caustic soda being 8°Bé - 12°Bé, and the amount of added caustic soda being calculated according to the acid value of the crude oil, and the calculation formula is: Heating and stirring at a second temperature for a second time and then centrifuging to remove soap to obtain soap-removed oil, the second temperature being 80°C - 90°C; the second time being 5 min - 15 min; adding a citric acid aqueous solution in a second ratio to the soap-removed oil for water washing, and drying at a third temperature for a third time to obtain dried neutralized oil, the second ratio being 20:1 to 10:1, the mass concentration of the citric acid aqueous solution being 75 mg / kg - 80 mg / kg; the third temperature being 80°C - 90°C; the third time being 20 min - 40 min; The decolorizing process includes: putting 150 g - 200 g of dried neutralized oil into a flask, adding activated clay in a third ratio to the weight of the neutralized oil to obtain a mixed oil, the third ratio being 100:1 to 50:1; connecting the flask to a condenser and using a vacuum pump to evacuate; heating and stirring the mixed oil to a fourth temperature and maintaining for a fourth time; filtering to obtain decolorized oil and completing decolorization, the fourth temperature being 100°C - 115°C, the fourth time being 40 min - 50 min; The deodorizing process includes the steps: putting 150 g - 200 g of decolorized oil into a flask; adding distilled water to a steam generating unit and connecting it to a deodorizing device; evacuating through a vacuum pump, adjusting the temperature of the steam generating unit through a temperature sensor to continuously introduce steam into the decolorized oil, heating the deodorized oil to a fifth temperature and maintaining for a fifth time to complete deodorization, the fifth temperature being 230°C - 240°C, the fifth time being 50 min - 70 min.

2. The vegetable oil refining method according to claim 1, wherein The first temperature is 72°C - 78°C; the first time is 1.2 h - 1.5 h.

3. The vegetable oil refining method according to claim 1, wherein The second temperature is 83°C - 87°C; the second time is 8 min - 12 min.

4. The vegetable oil refining method according to claim 1, wherein ​ 5. The vegetable oil refining method according to claim 1, characterized in that, ​ 6. A vegetable oil refining device for the vegetable oil refining method according to any one of claims 1 to 5, characterized in that ​ ​ During degumming and neutralizing deacidification, the flask is placed on the heating surface of the magnetic stirring electrothermal mantle, the stirrer of the magnetic stirring electrothermal mantle and the glass thermometer are placed inside the flask, and the condenser, the receiving flask, the vacuum pump and the gas guide tube are not connected to the flask and the magnetic stirring electrothermal mantle; During decolorization, the flask is placed on the heating surface of the magnetic stirring electrothermal mantle, the stirrer of the magnetic stirring electrothermal mantle and the glass thermometer are placed inside the flask, one end of the condenser is connected to the flask, the other end of the condenser is connected to one end of the receiving tube, the other end of the receiving tube is connected to the receiving flask, and the vacuum pump is connected to the receiving tube; During deodorization, the steam generating unit includes: a flask for adding water is arranged on the heating surface of one of the magnetic stirring electrothermal mantles, the flask for adding water is connected to one end of the gas guide tube, the other end of the gas guide tube is connected to a flask containing decolorized oil, the flask containing decolorized oil is arranged on another magnetic stirring electrothermal mantle, the condenser is connected to the flask containing decolorized oil through a gas guide tube, one end of the receiving tube away from the flask containing decolorized oil is connected to the condenser, the other end of the receiving tube is connected to the receiving flask, and the vacuum pump is connected to the receiving tube.

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