Method for continuously catalyzing grease deacidification by using deep eutectic solvent Pickering emulsion

Abstract

The invention discloses a method for continuously catalyzing grease deacidification, which comprises the following steps: mixing a deep eutectic solvent, crude oil and immobilized lipase, homogenizing into an emulsion, continuously supplementing the crude oil, and carrying out esterification deacidification reaction, the immobilized lipase is obtained by carrying out immobilization by taking silane modified silicon dioxide as a carrier. According to the method, grease deacidification can be continuously catalyzed, the cost of enzymatic deacidification is reduced, the grease yield is increased, better economical efficiency and environmental friendliness are achieved, the industrial application potential is high, and after crude oil is deacidified through the method, the acid value is low, the deacidification rate is high, the neutral oil loss is small, and the oil product stability is good.

Description

Technical Field

[0001] This invention belongs to the field of oil refining and deacidification technology, specifically relating to a method for continuous catalytic deacidification of oils using a low eutectic solvent Pickering emulsion. Background Technology

[0002] Oils and fats require refining and deacidification, with the core purpose of improving their food safety, chemical stability, and sensory quality. The free fatty acids present in crude oils are a key factor driving this need. Free fatty acids are unstable and easily oxidize and become rancid, producing unpleasant odors such as rancidity, affecting the flavor and texture of the oils and fats. Furthermore, their oxidation products may pose a potential threat to human health. Therefore, removing free fatty acids through deacidification is an indispensable refining step to ensure that oils and fats meet national food safety standards, extend their shelf life, and guarantee their edible quality.

[0003] Currently, the main oil refining and deacidification processes are chemical alkali refining, physical refining, and bio-enzymatic methods. Chemical alkali refining is the most widely used technology due to its low cost, simple operation, and high efficiency. However, it easily generates a large amount of soapstock when processing high-acid-value crude oil, leading to significant loss of neutral oil and the loss of natural active ingredients in the oil, affecting the quality of the finished oil. Simultaneously, this process generates a large amount of industrial wastewater, causing environmental pressure. Physical refining and deacidification, as a clean process, removes free fatty acids through steam distillation under high-temperature vacuum conditions, producing no wastewater and exhibiting good environmental friendliness. However, this method has high energy consumption, the high-temperature environment may trigger thermal side reactions in the oil, it requires strict pretreatment processes, and often necessitates subsequent decolorization to improve the oil's color, increasing overall costs. Bio-enzymatic deacidification is valued for its mild reaction conditions, high specificity, and good environmental compatibility. However, traditional enzymatic processes require the introduction of highly polar alcohols as acyl acceptors, the reaction process is reversible, moisture needs to be controlled under low pressure to promote forward reaction, and continuous deacidification is difficult to achieve.

[0004] Eutectic solvents (DES), as a promising class of "environmentally friendly" solvents, are composed of small-molecule metabolites derived from living organisms, such as choline derivatives, alcohols, sugars, and natural substances like urea. They exhibit significant advantages in terms of high safety, biodegradability, and complete atom utilization, demonstrating enormous application potential and broad prospects in multiple fields. The unique properties of DES—higher polarity, greater density, and stronger interfacial tension—provide opportunities for developing advanced biocatalytic systems such as DES-Pickering emulsion systems.

[0005] Currently reported DES-Pickering emulsion systems include DES-oil-encapsulated DES-Pickering emulsions and oil-encapsulated DES-Pickering emulsions. Although these emulsion systems have high stability, they cannot achieve continuous catalysis or have very short continuous catalysis times when applied to lipid catalysis. Summary of the Invention

[0006] Therefore, the purpose of this invention is to provide a method for continuous catalytic deacidification of oils and fats.

[0007] The technical solutions for achieving the above-mentioned objectives include the following.

[0008] This invention provides a method for continuous catalytic deacidification of oils, comprising the following steps: mixing a eutectic solvent, crude oil, and immobilized lipase and homogenizing the mixture into an emulsion; continuously feeding crude oil to perform an esterification deacidification reaction; wherein the immobilized lipase is obtained by immobilization using silane-modified silica as a carrier.

[0009] The inventors of this invention have discovered that by homogenizing a eutectic solvent, lipase immobilized with silane-modified silica as a carrier, and crude oil together, an oil-in-DES type DES-Pickering emulsion system can be constructed. This emulsion system can use crude oil as a continuous phase to continuously catalyze the deacidification of oils and fats, with an operating time of up to 15 days. This reduces the cost of enzymatic deacidification, improves oil and fat yield, and has better economic and environmental benefits, making it highly promising for industrial applications.

[0010] The oil-in-oil DES-Pickering emulsion system of the present invention has very high stability, high deacidification rate of crude oil, low acid value of deacidified oil, almost no loss of neutral oil, and good oil stability. Attached Figure Description

[0011] Figure 1 This is a comparison of the contact angle and microstructure of the emulsion before (left) and after (right) deacidification of crude rice bran oil in Example 1 of the present invention. Detailed Implementation

[0012] To facilitate understanding of the present invention, a more complete description will be provided below. The present invention can be implemented in many different forms and is not limited to the embodiments described herein. Rather, these embodiments are provided to provide a thorough and complete understanding of the disclosure of the present invention.

[0013] Unless otherwise defined, all technical and scientific terms used in this invention have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains. The terminology used in this specification is for the purpose of describing particular embodiments only and is not intended to limit the invention. The term "and / or" as used in this invention includes any and all combinations of one or more of the associated listed items.

[0014] Unless otherwise specified, experimental methods in the following examples are generally performed under standard conditions or as recommended by the manufacturer. All commonly used chemical reagents used in the examples are commercially available products.

[0015] In some embodiments of the present invention, a method for continuous catalytic deacidification of oils is disclosed, comprising the following steps: mixing a eutectic solvent, crude oil and immobilized lipase and homogenizing the mixture into an emulsion, and continuously feeding crude oil to carry out an esterification deacidification reaction; wherein the immobilized lipase is obtained by immobilization using silane-modified silica as a carrier.

[0016] After extensive research on the DES-Pickering emulsion system, the inventors of this invention discovered that immobilized lipases, using a eutectic solvent (such as a transparent liquid glycerol-based natural eutectic solvent formed by mixing hydrogen bond donor choline chloride or betaine with hydrogen bond acceptor glycerol) and silane-modified silica as a carrier, can be homogenized with crude oil. On the one hand, the silane-modified silica acts as an emulsifier, enabling the successful construction of an oil-in-oil DES-Pickering emulsion system. On the other hand, the hydrophobic groups of the silane-modified silica specifically recognize the specific hydrophobic residues of the lipase molecule, giving the lipase better stability and enhancing its catalytic activity. Therefore, the DES-Pickering emulsion system constructed in this invention, while possessing very high stability, can catalyze efficient deacidification of oils and fats, and can continuously catalyze deacidification of oils and fats for up to 15 days. The method of this invention for deacidifying oils results in oils with low acid values, high deacidification rates (over 90%), almost no loss of neutral oil (neutral oil yield over 90%), and good oil stability. The eutectic solvent, as a co-substrate, directionally converts free fatty acids into glycerides without side reactions, improving oil yield, simplifying downstream refining processes, and reducing production costs. Furthermore, lipase catalysis simultaneously deacidifies and separates products, accelerating the deacidification process and directly yielding edible oils that meet national standards.

[0017] In one embodiment, the silane is one or more of dimethylchlorosilane (DMCS), trimethylchlorosilane (TMCS), butyltrichlorosilane (BTCS), octyltrichlorosilane (OTCS), butyltriethoxysilane (BTES), and octyltriethoxysilane (OTES).

[0018] In one embodiment, the silane-modified silica is two of trimethylchlorosilane-modified silica, butyltriethoxysilane-modified silica, and octyltriethoxysilane-modified silica.

[0019] In one embodiment, the silane-modified silica is prepared by stirring and dispersing silica in a solvent, then adding silane to react, and after the reaction is completed, washing and drying are performed to obtain the silica.

[0020] In one embodiment, the solvent is toluene.

[0021] In one embodiment, the mass ratio of silicon dioxide to silane is 1:20~40.

[0022] In one embodiment, the reaction temperature is 40°C to 60°C, and the reaction time is 1 day to 15 days.

[0023] In one embodiment, the immobilized lipase is prepared by adding silane-modified silica to a lipase solution, fixing at room temperature for 4 to 8 hours, and then lyophilizing.

[0024] In one embodiment, the mass-to-volume ratio of the silane-modified silica to the lipase solution is 1 g: 3~8 mL.

[0025] In one embodiment, the concentration of lipase in the lipase solution is 1 mg / mL to 3 mg / mL.

[0026] In one embodiment, the lipase is lipase 5000MM, lipase FM-15, and / or lipase NE-10.

[0027] In one embodiment, the weight ratio of crude oil to immobilized lipase is 10-25:1.

[0028] In one embodiment, the weight ratio of crude oil to immobilized lipase is 10-20:1.

[0029] In one embodiment, the weight ratio of crude oil to eutectic solvent is 1 to 5:1.

[0030] In one embodiment, the weight ratio of crude oil to eutectic solvent is 1 to 3:1.

[0031] In one embodiment, the weight ratio of crude oil to eutectic solvent is 1 to 1.5:1.

[0032] In one embodiment, the eutectic solvent is prepared from choline chloride or betaine and glycerol in a molar ratio of 1:4 to 6.

[0033] In one embodiment, the homogenization rotation speed is 10,000 rpm to 15,000 rpm, and the time is 1 to 3 minutes.

[0034] In one embodiment, the reaction temperature is 40°C to 60°C.

[0035] In one embodiment, the reaction time is 1 to 15 days.

[0036] In one embodiment, the crude oil is rice bran crude oil, rapeseed crude oil, and / or soybean crude oil.

[0037] In one embodiment, the crude oil is rice bran crude oil.

[0038] In the following embodiments of the present invention, the crude rice bran oil (initial acid value 36.45 mg KOH / g), crude soybean oil (initial acid value 2.89 mg KOH / g), and crude rapeseed oil (initial acid value 2.57 mg KOH / g) used were all commercially available; glycerol, choline chloride, betaine, and silicon dioxide (30-50 nm) were purchased from Shanghai Aladdin Biochemical Technology Co., Ltd.; lipase 5000MM, lipase FM-15, and lipase NE-10 were purchased from Qingdao Weilan Biotechnology Co., Ltd.; dimethylchlorosilane (DMCS) was purchased from Shanghai Aladdin Biochemical Technology Co., Ltd.; butyltrichlorosilane (BTCS) was purchased from Shanghai Yien Chemical Technology Co., Ltd.; and trimethylchlorosilane (TMCS), octyltrichlorosilane (OTCS), butyltriethoxysilane (BTES), and octyltriethoxysilane (OTES) were purchased from Shanghai Maclean Biochemical Technology Co., Ltd.

[0039] In the following embodiments of the present invention, the preparation method of silane-modified silica is as follows: 1g of silica is placed in an Erlenmeyer flask, toluene is added and stirred to disperse, then 20g of silane is added, and the mixture is reacted at 50°C for 6 hours. After the reaction is completed, the silica is washed alternately with anhydrous ethanol and dried to obtain solid particles, which are then obtained.

[0040] In the following embodiments of the present invention, the immobilized lipase was prepared by adding 1 g of silane-modified silica to 5 mL of lipase solution (protein concentration 2 mg / mL), fixing at room temperature for 6 h, lyophilizing, and storing for later use.

[0041] The present invention will be described in detail below with reference to the accompanying drawings and specific embodiments.

[0042] Example 1

[0043] This embodiment provides a method for continuous catalytic deacidification of oils and fats, including the following steps:

[0044] 1. Take 50g of eutectic solvent (choline chloride to glycerol molar ratio 1:5), 5g of immobilized lipase 5000MM (using SiO2-DMCS as carrier), and place them in different reaction vessels with 50g of crude rice bran oil, crude soybean oil, and crude rapeseed oil respectively.

[0045] 2. Homogenize at 15000 rpm for 1 min to form an emulsion, thus obtaining an oil-in-oil DES-Pickering emulsion;

[0046] 3. Place the emulsion from step 2 in a reactor at 50°C and continuously feed crude oil to react. The effluent is the oil with free fatty acids removed. Detect the acid value of the effluent. Stop the reaction when the acid value is less than 0.2 mg KOH / g.

[0047] Evaluate the stability of the emulsion system before and after deacidification. Figure 1 This image shows a comparison of the contact angle and emulsion microstructure of crude rice bran oil before and after deacidification. Figure 1 It can be seen that the emulsion structure is maintained both before and after deacidification, indicating that the emulsion system is stable and not prone to demulsification during the catalytic process.

[0048] Example 2

[0049] This embodiment provides a method for continuous catalytic deacidification of oils and fats, including the following steps:

[0050] 1. Take 33.3g of eutectic solvent (choline chloride to glycerol molar ratio 1:4), 5g of immobilized lipase FM-15 (using SiO2-TMCS as carrier), and place them in different reaction vessels with 50g of crude rice bran oil, crude soybean oil, and crude rapeseed oil respectively.

[0051] 2. Homogenize at 10,000 rpm for 2 min to form an emulsion, thus obtaining an oil-in-oil DES-Pickering emulsion;

[0052] 3. Place the emulsion from step 2 in a reactor at 40°C and continuously feed crude oil to react. The effluent is the oil with free fatty acids removed. Detect the acid value of the effluent. Stop the reaction when the acid value is less than 0.2 mg KOH / g.

[0053] Example 3

[0054] This embodiment provides a method for continuous catalytic deacidification of oils and fats, including the following steps:

[0055] 1. Take 50g of eutectic solvent (betaine to glycerol molar ratio 1:6), 2g of immobilized lipase NE-10 (using SiO2-BTCS as carrier), and place them in different reaction vessels with 50g of crude rice bran oil, crude soybean oil, and crude rapeseed oil respectively.

[0056] 2. Homogenize at 15000 rpm for 3 min to form an emulsion, thus obtaining an oil-in-oil DES-Pickering emulsion;

[0057] 3. Place the emulsion from step 2 in a reactor at 60°C and continuously feed crude oil to react. The effluent is the oil with free fatty acids removed. Detect the acid value of the effluent. Stop the reaction when the acid value is less than 0.2 mg KOH / g.

[0058] Example 4

[0059] This embodiment provides a method for continuous catalytic deacidification of oils and fats, including the following steps:

[0060] 1. Take 10g of eutectic solvent (choline chloride to glycerol molar ratio 1:4), 2g of immobilized lipase NE-10 (using SiO2-OTCS as carrier), and place them in different reaction vessels with 50g of crude rice bran oil, crude soybean oil, and crude rapeseed oil respectively.

[0061] 2. Homogenize at 10,000 rpm for 1 min to form an emulsion, thus obtaining an oil-in-oil DES-Pickering emulsion;

[0062] 3. Place the emulsion from step 2 in a reactor at 40°C and continuously feed crude oil to react. The effluent is the oil with free fatty acids removed. Detect the acid value of the effluent. Stop the reaction when the acid value is less than 0.2 mg KOH / g.

[0063] Example 5

[0064] This embodiment provides a method for continuous catalytic deacidification of oils and fats, including the following steps:

[0065] 1. Take 30g of eutectic solvent (betaine to glycerol molar ratio 1:5), 5g of immobilized lipase FM-15 (using SiO2-BTES as a carrier), and place them in different reaction vessels with 50g of crude rice bran oil, crude soybean oil, and crude rapeseed oil respectively.

[0066] 2. Homogenize at 15000 rpm for 1 min to form an emulsion, thus obtaining an oil-in-oil DES-Pickering emulsion;

[0067] 3. Place the emulsion from step 2 in a reactor at 50°C and continuously feed crude oil to react. The effluent is the oil with free fatty acids removed. Detect the acid value of the effluent. Stop the reaction when the acid value is less than 0.2 mg KOH / g.

[0068] Example 6

[0069] This embodiment provides a method for continuous catalytic deacidification of oils and fats, including the following steps:

[0070] 1. Take 50g of eutectic solvent (choline chloride to glycerol molar ratio 1:6), 2.5g of immobilized lipase NE-10 (using SiO2-OTES as a carrier), and place them in different reaction vessels with 50g of crude rice bran oil, crude soybean oil, and crude rapeseed oil respectively.

[0071] 2. Homogenize at 10,000 rpm for 2 min to form an emulsion, thus obtaining an oil-in-oil DES-Pickering emulsion;

[0072] 3. Place the emulsion from step 2 in a reactor at 60°C and continuously feed crude oil to react. The effluent is the oil with free fatty acids removed. Detect the acid value of the effluent. Stop the reaction when the acid value is less than 0.2 mg KOH / g and evaluate the stability of the emulsion system.

[0073] Example 7

[0074] This embodiment provides a method for continuous catalytic deacidification of oils, including the following steps:

[0075] 1. Take 50g of eutectic solvent (choline chloride to glycerol molar ratio 1:5), 2.5g of immobilized lipase FM-15 (using SiO2-TMCS as a carrier), and 2.5g of immobilized lipase FM-15 (using SiO2-BTES as a carrier), and place them in different reaction vessels with 50g of crude rice bran oil, crude soybean oil, and crude rapeseed oil respectively.

[0076] 2. Homogenize at 15000 rpm for 1 min to form an emulsion, thus obtaining an oil-in-oil DES-Pickering emulsion;

[0077] 3. Place the emulsion from step 2 in a reactor at 40°C and continuously feed crude oil to react. The effluent is the oil with free fatty acids removed. Detect the acid value of the effluent. Stop the reaction when the acid value is less than 0.2 mg KOH / g.

[0078] Example 8

[0079] This embodiment provides a method for continuous catalytic deacidification of oils and fats, including the following steps:

[0080] 1. Take 16.7g of eutectic solvent (betaine to glycerol molar ratio 1:4), 2.5g of immobilized lipase NE-10 (using SiO2-TMCS as a carrier), and 2.5g of immobilized lipase NE-10 (using SiO2-OTES as a carrier), and place them in different reaction vessels with 50g of crude rice bran oil, crude soybean oil, and crude rapeseed oil, respectively.

[0081] 2. Homogenize at 15000 rpm for 3 min to form an emulsion, thus obtaining an oil-in-oil DES-Pickering emulsion;

[0082] 3. Place the emulsion from step 2 in a reactor at 50°C and continuously feed crude oil to react. The effluent is the oil with free fatty acids removed. Detect the acid value of the effluent. Stop the reaction when the acid value is less than 0.2 mg KOH / g.

[0083] Example 9

[0084] This embodiment provides a method for continuous catalytic deacidification of oils and fats, including the following steps:

[0085] 1. Take 33.3g of eutectic solvent (choline chloride to glycerol molar ratio 1:6), 2.5g of immobilized lipase NE-10 (using SiO2-OTES as a carrier), and 2.5g of immobilized lipase NE-10 (using SiO2-BTES as a carrier), and place them in different reaction vessels with 50g of crude rice bran oil, crude soybean oil, and crude rapeseed oil, respectively.

[0086] 2. Homogenize at 15000 rpm for 1 min to form an emulsion, thus obtaining an oil-in-oil DES-Pickering emulsion;

[0087] 3. Place the emulsion from step 2 in a reactor at 60°C and continuously feed crude oil to react. The effluent is the oil with free fatty acids removed. Detect the acid value of the effluent. Stop the reaction when the acid value is less than 0.2 mg KOH / g.

[0088] Example 10

[0089] This embodiment provides a method for continuous catalytic deacidification of oils and fats, including the following steps:

[0090] 1. Take 16.7g of eutectic solvent (choline chloride to glycerol molar ratio 1:5), 5g of immobilized lipase FM-15 (using SiO2-DMCS as carrier), and place them in different reaction vessels with 50g of crude rice bran oil, crude soybean oil, and crude rapeseed oil respectively.

[0091] 2. Homogenize at 10,000 rpm for 2 min to form an emulsion, thus obtaining an oil-in-oil DES-Pickering emulsion;

[0092] 3. Place the emulsion from step 2 in a reactor at 60°C and continuously feed crude oil to react. The effluent is the oil with free fatty acids removed. Detect the acid value of the effluent. Stop the reaction when the acid value is less than 0.2 mg KOH / g.

[0093] Comparative Example 1

[0094] This comparative example provides a method for deacidifying oils, including the following steps:

[0095] 1. Mix 30g of crude rice bran oil, crude soybean oil, and crude rapeseed oil with 70g of glycerol in different reaction vessels; add 3g of lipase 5000MM to obtain a mixture (non-emulsion system).

[0096] 2. Stir the mixture in a 40°C water bath for 12 hours, then centrifuge to obtain the supernatant, which is the deacidified oil.

[0097] Comparative Example 2

[0098] This comparative example provides a method for deacidifying oils, including the following steps:

[0099] 1. Mix 30g of crude rice bran oil, crude soybean oil, and crude rapeseed oil with 70g of eutectic solvent (choline chloride:glycerol molar ratio 1:4) in different reaction vessels; add 3g of lipase FM-15 to obtain a mixture (non-emulsion system).

[0100] 2. Stir the mixture in a 50°C water bath for 12 hours, then centrifuge to obtain the supernatant, which is the deacidified oil.

[0101] Comparative Example 3

[0102] This comparative example provides a method for deacidifying oils, including the following steps:

[0103] 1. Take 70g of eutectic solvent (choline chloride: glycerol molar ratio 1:5), 3g of Novozym 435, and 2g of soy whey protein. Mix 30g of rice bran oil, soybean oil, and rapeseed oil in different reaction vessels.

[0104] 2. Homogenize at 12000 rpm for 2 min to form an emulsion, thus obtaining a DES-Pickering emulsion with oil in it;

[0105] 3. Stir the emulsion from step 2 in a 50°C water bath for 12 hours, centrifuge to obtain the supernatant, which is the deacidified oil.

[0106] Comparative Example 4

[0107] This comparative example provides a method for deacidifying oils, including the following steps:

[0108] 1. Take 70g of eutectic solvent (choline chloride: glycerol molar ratio 1:5), 5g of immobilized lipase FM-15 (using unmodified silica as a carrier), and mix 30g of crude rice bran oil, crude soybean oil, and crude rapeseed oil in different reaction vessels.

[0109] 2. Homogenize at 12000 rpm for 2 min to form an emulsion, thus obtaining a DES-Pickering emulsion with oil in it;

[0110] 3. Stir the emulsion from step 2 in a 50°C water bath for 12 hours, centrifuge to obtain the supernatant, which is the deacidified oil.

[0111] Comparative Example 5

[0112] This comparative example provides a method for deacidifying oils, including the following steps:

[0113] 1. Take 70g of eutectic solvent (choline chloride: glycerol molar ratio 1:5), 5g of immobilized lipase 5000 MM (using unmodified silica as a carrier), and mix 30g of rice bran oil, soybean oil, and rapeseed oil in different reaction vessels respectively.

[0114] 2. Homogenize at 12000 rpm for 2 min to form an emulsion, thus obtaining a DES-Pickering emulsion with oil in it;

[0115] 3. Stir the emulsion from step 2 in a 50°C water bath for 12 hours, centrifuge to obtain the supernatant, which is the deacidified oil.

[0116] Comparative Example 6

[0117] This comparative example provides a method for deacidifying oils, including the following steps:

[0118] 1. Take 70g of eutectic solvent (choline chloride: glycerol molar ratio 1:5), 5g of immobilized lipase NE-10 (using unmodified silica as a carrier), and mix 30g of crude rice bran oil, crude soybean oil, and crude rapeseed oil in different reaction vessels.

[0119] 2. Homogenize at 12000 rpm for 2 min to form an emulsion, thus obtaining a DES-Pickering emulsion with oil in it;

[0120] 3. Stir the emulsion from step 2 in a 50°C water bath for 12 hours, centrifuge to obtain the supernatant, which is the deacidified oil.

[0121] Comparative Example 7

[0122] This comparative example provides a method for deacidifying oils, including the following steps:

[0123] 1. Take 50g of eutectic solvent (choline chloride: glycerol molar ratio 1:5), 3g of lipase 5000 MM, and 5g of polyglycerol fatty acid ester, and mix 50g of rice bran oil, soybean oil, and rapeseed oil in different reaction vessels respectively.

[0124] 2. Homogenize at 12000 rpm for 2 min to form an emulsion, thus obtaining an oil-in-oil DES-Pickering emulsion;

[0125] 3. React the emulsion from step 2 in a 50°C water bath, centrifuge to obtain the supernatant, which is the deacidified oil.

[0126] Comparative Example 8

[0127] This comparative example provides a method for deacidifying oils, including the following steps:

[0128] 1. Take 50g of eutectic solvent (choline chloride: glycerol molar ratio 1:5), 3g of lipase NE-10, and 5g of polyglycerol fatty acid ester, and mix 50g of rice bran oil, soybean oil, and rapeseed oil in different reaction vessels respectively.

[0129] 2. Homogenize at 12000 rpm for 2 min to form an emulsion, thus obtaining an oil-in-oil DES-Pickering emulsion;

[0130] 3. React the emulsion from step 2 in a 50°C water bath, centrifuge to obtain the supernatant, which is the deacidified oil.

[0131] Comparative Example 9

[0132] This comparative example provides a method for deacidifying oils, including the following steps:

[0133] 1. Take 50g of eutectic solvent (choline chloride: glycerol molar ratio 1:5), 3g of lipase FM-15, and 5g of polyglycerol fatty acid ester, and mix 50g of rice bran oil, soybean oil, and rapeseed oil in different reaction vessels respectively.

[0134] 2. Homogenize at 12000 rpm for 2 min to form an emulsion, thus obtaining an oil-in-oil DES-Pickering emulsion;

[0135] 3. React the emulsion from step 2 in a 50°C water bath, centrifuge to obtain the supernatant, which is the deacidified oil.

[0136] Experimental Example 1: Stability of the Reaction System

[0137] The stability of the emulsion systems of Examples 1-10, the reaction systems of Comparative Examples 1-2, and the emulsion systems of Comparative Examples 3-9 was evaluated (after being left at room temperature for a period of time, and observing whether the emulsion broke or separated). The results are shown in Table 1.

[0138] Table 1

[0139]

[0140]

[0141]

[0142]

[0143] As can be seen from Table 1:

[0144] Compared to the systems in Comparative Examples 1-9, the systems in Examples 1-10 showed significantly higher stability. Overall, the lipase was immobilized using two types of silane-modified silica as carriers. Compared to immobilization using a single silane-modified silica as a carrier, the resulting oil-in-oil DES-Pickering emulsion system exhibited higher stability (Examples 7-9), and a higher immobilized lipase content further enhanced emulsion stability.

[0145] Comparative Examples 1 and 2 are non-emulsion systems, and the catalytic system shows significant stratification, indicating instability.

[0146] Comparative Examples 3-6 used organic soy whey protein or inorganic unmodified silica as emulsifiers, which could form DES-Pickering emulsion systems, but the resulting system was an oil-encapsulated DES emulsion system, which was unstable and demulsified after 1 day. Comparative Examples 7-9 used polyglycerol fatty acid esters as emulsifiers, which formed an oil-encapsulated DES-Pickering emulsion system, but the system was still unstable and demulsified after 1 day.

[0147] Experimental Example 2: Analysis of Deacidification Efficiency, Acid Value, and Oil Yield of Oils

[0148] The deacidification efficiency, acid value, and oil yield of the oils in Examples 1-10 and Comparative Examples 1-9 were analyzed, and the continuous catalytic time was statistically analyzed. The results are shown in Tables 2-4.

[0149] Table 2

[0150]

[0151] Note: ╳ in the table indicates that the system cannot be continuously catalyzed.

[0152] Table 3

[0153]

[0154] Note: ╳ in the table indicates that the system cannot be continuously catalyzed.

[0155] Table 4

[0156]

[0157] Note: ╳ in the table indicates that the system cannot be continuously catalyzed.

[0158] The results in Tables 2-4 show that:

[0159] The catalytic systems constructed in Examples 1-10 and Comparative Examples 1-9 can all achieve enzymatic deacidification of different crude vegetable oils. However, there are significant differences in the continuous catalytic time, deacidification efficiency, acid value, and oil yield among the different catalytic systems.

[0160] Regarding high-acid-value crude vegetable oil (rice bran crude oil), the DES-Pickering emulsion systems in oil-in-oil emulsion constructed in Examples 1-10 all achieved continuous catalysis. However, in the comparative examples, only the DES-Pickering emulsion systems in oil-in-oil emulsion constructed in Examples 7-9 achieved continuous catalysis, but the continuous catalysis time was significantly shorter than that of the catalytic systems in the examples (only 1 day). This is because the enzymes used in Comparative Examples 7-9 were free enzymes, which were confined within the eutectic solvent DES in the dispersed phase. The lipases failed to uniformly disperse at the emulsion interface to form an interfacial layer and exert their catalytic properties, which also affected their interfacial stability. In the oil-in-oil DES-Pickering emulsion systems constructed in Examples 1-10 of this invention, the emulsion systems using two types of silane-modified silica as carriers to immobilize the enzyme (Examples 7-9) exhibited longer continuous catalysis times compared to the emulsion systems using a single silane-modified silica as a carrier. This may be because the chemical structure of the mixed silane-modified silica as an emulsifier is more conducive to emulsion interface stability, providing conditions for continuous catalysis. The deacidification efficiency of the catalytic systems in Comparative Examples 1-9 was lower than that of the catalytic systems in Examples 1-10. We speculate that this may be because when using silane-modified silica as a carrier for immobilized enzymes, the hydrophobic groups of the silane-modified silica specifically recognize the specific hydrophobic residues of the enzyme molecule, giving the lipase better stability and enhancing its catalytic activity. The neutral oil yields in Examples 1-10 were good, and there was no direct correlation between the neutral oil yield and the glycerol content, indicating that glycerol is gradually consumed as a co-substrate during the continuous catalysis process, making it less likely to produce glycerolysis side reactions and not affecting the neutral oil yield. In contrast, in Comparative Examples 1-9, glycerol was not gradually consumed, resulting in a high concentration that led to a glycerol reaction and ultimately reduced neutral oil yield.

[0161] Overall, the continuous catalytic time of the low-acid-value soybean oil and rapeseed oil catalytic systems is shorter than that of the rice bran oil catalytic system (except for Examples 7-9). This is because rice bran oil has a higher content of diglycerides and monoglycerides, both of which have good emulsifying properties, providing favorable conditions for maintaining interfacial stability. The viscosity of soybean oil and rapeseed oil is comparable to that of rice bran oil, and their continuous catalytic flow is indistinguishable. The catalytic systems used in the examples and comparative examples all achieved better deacidification efficiency because both have low acid values ​​and low free fatty acid content, allowing them to rapidly undergo esterification with the substrate glycerol under lipase catalysis. Therefore, there is almost no significant difference in deacidification efficiency. Soybean oil and rapeseed oil have low acid values ​​and low free fatty acid content, allowing the substrate glycerol to rapidly esterify into glycerol ester products under lipase catalysis. In the continuous catalytic system, as free fatty acids are continuously added, the concentration of the glycerol substrate is gradually consumed, effectively reducing glycerolysis side reactions and thus increasing the yield of neutral oils. The catalytic systems in Comparative Examples 1-6 could not achieve continuous catalysis. After esterification, a large amount of glycerol remained in the catalytic system. Lipase catalyzed the reaction of glycerol with triglycerides to produce diglycerides and monoglycerides, resulting in a low yield of neutral oils. Although the catalytic systems in Comparative Examples 7-9 could achieve continuous catalysis, the continuous catalysis time was only 24 hours. Glycerolysis side reactions also occurred, so the yield of neutral oils was also very low.

[0162] The technical features of the above embodiments can be combined in any way. For the sake of brevity, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0163] The embodiments described above are merely illustrative of several implementations of the present invention, and while the descriptions are relatively specific and detailed, they should not be construed as limiting the scope of the invention patent. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of the present invention, and these all fall within the protection scope of the present invention. Therefore, the protection scope of this invention patent should be determined by the appended claims.

Claims

1. A method for continuous catalytic deacidification of oil, characterized by, The method comprises the following steps: The homogeneous emulsion is prepared by mixing the eutectic solvent, crude oil and immobilized lipase, and the esterification deacidification reaction is carried out by continuously feeding the crude oil.

2. The method of claim 1, wherein the deacidification of the continuous catalytic oil is performed by a method comprising: The silane is one or more of dimethylchlorosilane, trimethylchlorosilane, butyltrichlorosilane, octyltrichlorosilane, butyltriethoxysilane and octyltriethoxysilane. Preferably, the silane-modified silicon dioxide is two of trimethylchlorosilane-modified silicon dioxide, butyltriethoxysilane-modified silicon dioxide and octyltriethoxysilane-modified silicon dioxide.

3. The method of claim 1, wherein the deacidification is performed continuously. The silane-modified silicon dioxide is prepared by the following method: the silicon dioxide is dispersed by stirring in a solvent, and then the silane is added for reaction.

4. The method of claim 3, wherein the deacidification is performed continuously. The solvent is toluene. The mass ratio of the silicon dioxide to the silane is 1:20-40. The reaction temperature is 40-70℃, and the reaction time is 1-15 days.

5. The method of claim 1, wherein the deacidification is performed continuously. The immobilized lipase is prepared by the following method: the silane-modified silicon dioxide is added to a lipase solution, and then the solution is fixed at room temperature for 4-8 hours and freeze-dried. Preferably, the mass-volume ratio of the silane-modified silicon dioxide to the lipase solution is 1 g:3-8 mL, and the concentration of the lipase in the lipase solution is 1-3 mg / mL.

6. The method of claim 5, wherein the deacidification is performed continuously. The lipase is lipase 5000 MM, lipase FM-15 and / or lipase NE-10.

7. The method of claim 1, wherein the deacidification is performed continuously. The weight ratio of the crude oil to the immobilized lipase is 10-25:1, preferably 10-20:

1. The weight ratio of the crude oil to the eutectic solvent is 1-5:1, preferably 1-3:1, and more preferably 1-1.5:

1.

8. The method of claim 1, wherein the deacidification is performed continuously. The eutectic solvent is prepared by using choline chloride or betaine and glycerol as raw materials in a molar ratio of 1:4-6.

9. The method of claim 1, wherein the deacidification is performed continuously. The rotation speed of the homogenization is 10,000-15,000 rpm, and the time is 1-3 minutes. The reaction temperature is 40-60℃, and the reaction time is 1-15 days.

10. The method of claim 1 to 9, wherein the method is continuous. The crude oil is rice bran crude oil, rapeseed crude oil and / or soybean crude oil, preferably rice bran crude oil.

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