Preparation of composite magnetic beads and application of composite magnetic beads in edible oil adsorption refining

Abstract

The invention discloses preparation of composite magnetic beads and application of the composite magnetic beads in edible oil refining for the first time, FeCl3. 6H2O, polyethylene glycol 6000, sodium acetate and ethylene glycol are subjected to hydrothermal synthesis to form magnetic beads (MBs), the MBs are modified by tetraethyl orthosilicate and 3-aminopropyltriethoxysilane to obtain composite magnetic beads MBs (at) mSiO2-NH2, and the obtained composite magnetic beads are added into edible oil for adsorption refining. After adsorption is completed, the composite magnetic beads are separated from the edible oil through simple magnetic separation, and the separated composite magnetic beads can be recycled. The low temperature is controlled to be 30-40 DEG C in the whole adsorption refining process, compared with a traditional refining process, the temperature is greatly reduced, and loss of heat-sensitive substances such as vitamin E and polyphenol caused by high temperature is avoided. According to the invention, simultaneous degumming and deacidification of rapeseed oil are realized, and deacidification of cold-pressed peony seed oil can also be realized. The invention aims to provide an adsorption refining technology with triple advantages of high efficiency, green circulation and nutrition preservation, and healthy development of the grease industry is promoted.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of edible oil refining, in particular to a preparation of composite magnetic beads and its application in edible oil adsorption refining. BACKGROUND

[0002] Lipids are one of the three major nutrients (in addition to carbohydrates and proteins) for the human body, and edible oil is the main source of lipid supplements. They play an important role in providing energy for humans, providing fat-soluble micronutrients, and serving as precursors of hormones. The crude edible oil obtained directly by pressing or leaching process has complex composition, generally containing impurities such as phospholipids and free fatty acids, which not only affects the quality of oil, but also brings adverse effects on the storage of oil. Therefore, the crude oil usually needs to be refined before entering the consumer market.

[0003] Phospholipids (PLs, 2%-4%) contained in crude edible oil, including phosphatidylcholine (PC), phosphatidylethanolamine (PE), phosphatidylinositol, phosphatidic acid (PA) and lysophospholipids (LPL), are by-products of crude vegetable oil processing. Phospholipids can be further divided into hydratable and non-hydratable phospholipids (calcium and magnesium salts and phosphatidic acid), 90% of which are hydratable. In particular, PC and PI are always completely hydrated, while PA and PE are non-hydratable. Since phospholipids contain hydrophobic and hydrophilic parts in their molecular structure, they are widely used as emulsifiers. However, they have a negative impact on the oil refining process. In addition, the presence of PLs in oil can lead to quality deterioration, nutrient loss, development of off-flavors and discoloration. In addition, PLs increase viscosity because they naturally bind to oil molecules. Therefore, the removal of PLs is important for the production of high-quality edible oil. Degumming is an important step in oil refining, i.e. removing phospholipids from crude vegetable oil. In recent years, various degumming methods such as hydration degumming, acid degumming, enzymatic degumming and membrane degumming have been applied to vegetable oil degumming. Traditional degumming methods, including hydration degumming (to remove hydratable phospholipids) and acid degumming (to remove non-hydratable phospholipids), are widely used in the food industry. However, due to the adsorption of viscous gums, some beneficial substances (phenols and phytosterols) are also removed in these processes. In recent years, enzymatic degumming has been widely used to hydrolyze PLs and increase oil yield. Enzymatic degumming has many advantages compared to traditional methods. These advantages include high degumming efficiency, minimal chemical requirements and less environmental disturbance. Despite the obvious advantages of this method, its disadvantage is the high cost. The advantages of membrane degumming are that it can simplify the process, reduce energy consumption, reduce waste liquid discharge and improve oil quality, but the problems of membrane cost, membrane pollution and membrane cleaning are still the main factors restricting the application of this technology in large-scale industry.

[0004] Oil deacidification mainly refers to removing free fatty acids (FFA) in oil. Under the condition of frying, the content of FFA is an important factor for evaluating the quality of edible oil, because FFA can accelerate the chemical reactions of oil in the cooking process, such as hydrolysis, oxidation, isomerization and polymerization. The carboxyl group of FFA can accelerate the decomposition rate of hydrogen peroxide, thereby accelerating the oxidation of oil. This oxidation process ultimately leads to the generation of unpleasant odor and a significant reduction in the smoke point of oil, changes the original flavor of vegetable oil, and even produces unhealthy substances. Neutralization, distillation and membrane method are usually used to remove FFA from vegetable oil. Neutralization deacidification is efficient, which realizes deacidification by adding alkali to the deacidified oil, so that the free fatty acids are precipitated as soap; then the soap is removed from the neutral oil by mechanical separation. The disadvantages of this process are that chemical substances are easily left and wastewater discharge is large. Compared with alkali refining deacidification, distillation deacidification (physical deacidification) simplifies the process, reduces the loss of neutral oil, reduces the consumption of acid and alkali and wastewater discharge, and the utilization rate of by-products is high; but the pretreatment of physical deacidification requires high temperature, and polyunsaturated fatty acids are easy to produce isomers at high temperature.

[0005] In the current edible oil degumming and deacidification method, usually rely on chemical reagents or physical separation technology, but these methods often have problems of high energy consumption, high cost, environmental pollution and the like. Therefore, it is of great significance to develop an efficient, green and environmentally friendly and economical degumming and deacidification technology. SUMMARY

[0006] The purpose of the present research is to design a recyclable adsorption refining agent for edible oil adsorption refining. The simultaneous degumming and deacidification of rapeseed oil is realized, and the refining process is simplified, and the energy consumption is reduced. For cold-pressed peony seed oil, effective deacidification is realized. At the same time, the adsorbent can be recycled by simple magnetic separation, achieving green environmental protection and reducing cost.

[0007] In order to solve the above technical problems, the present application also provides a preparation method of a composite magnetic bead for edible oil adsorption refining, and the specific steps are as follows:

[0008] 1) Synthesis of MBs: FeCl3·6H2O, polyethylene glycol 6000, sodium acetate and ethylene glycol are mixed, and magnetic stirring is carried out for 1 h. After forming a uniform mixture, hydrothermal reaction is carried out, and after the reaction is completed, it is cooled to room temperature, and the magnetic beads MBs are obtained by magnetic separation, and are washed with ethanol and deionized water alternately for several times until the solution is clear after magnetic separation. The obtained product is dried at 60℃ overnight.

[0009] 2) Synthesis of MBs@mSiO2-NH2: MBs were treated with HCl solution under ultrasonication for 10 min, then the MBs were separated by a magnet and washed with ultrapure water for three times, and then they were re-dispersed in the template solution. The template solution was homogenized for 30 min to form a uniform dispersion. Under continuous mechanical stirring, 1-6 mL of tetraethyl orthosilicate (TEOS) was added dropwise to the dispersion, followed by the addition of 1-8 mL of 3-aminopropyltriethoxysilane (APTES). After 6 h of reaction, the product was collected with a magnet and repeatedly washed with ethanol and ultrapure water for three times to obtain the product MBs@nSiO2. The collected product was removed from the template CTAB, and the final product was washed with ultrapure water and ethanol alternately for 3 times, and dried at 60°C overnight to obtain MBs@mSiO2-NH2.

[0010] Further preferably, in the step 2) of the method for preparing the composite magnetic beads for the adsorption refining of rapeseed oil, the ratio of the mass (g) of CTAB, the volume (mL) of ultrapure water, the volume (mL) of concentrated ammonia water, and the volume (mL) of ethanol is 0.3:80:2:60.

[0011] Further preferably, in the step 2) of the method for preparing the composite magnetic beads for the adsorption refining of rapeseed oil, the ratio of the mass (g) of MBs, the mass (g) of TEOS, and the mass (g) of APTES is 0.1:4:3.

[0012] Further preferably, in the step 3) of the method for preparing the composite magnetic beads for the adsorption refining of rapeseed oil, the method for removing the template CTAB is to disperse the collected product in 0.1M HCl solution (50mL) under ultrasonication for 1h, magnetically separate and replace the solution, and repeat the ultrasonication process for 3 times.

[0013] The present application also provides a method for adsorption degumming and deacidification of rapeseed oil using composite magnetic beads, and the specific refining steps are as follows:

[0014] 1) Weigh the crude rapeseed oil and add MBs@mSiO2-NH2 at a weight of 0.5%-2.5% of the weight of the crude rapeseed oil, and maintain the water bath temperature at 20-60°C; 2) ultrasonically disperse the rapeseed oil with added MBs@mSiO2-NH2 for 3 min, and then perform electric stirring; 3) the adsorption time is 40-80 min, and the stirring speed is controlled at 100-500 r / min; 4) separate the magnetic beads by an external magnetic field, and collect the adsorbed rapeseed oil; 5) recycle and use the separated magnetic beads for 1-10 times.

[0015] Further preferably, in the specific refining step 1) above, the weight of MBs@mSiO2-NH2 added is 1.5% of the weight of the crude rapeseed oil, and the water bath temperature is 30-40°C.

[0016] The application also provides a method for adsorbing and deacidifying cold-pressed peony seed oil by using the composite magnetic beads.

[0017] 1) Weigh the cold-pressed peony seed oil, and add MBs@mSiO2-NH2 at a weight of 0.5%-2.5% of the cold-pressed peony seed oil; keep the water bath temperature at 20-60℃; 2) ultrasonically disperse the rapeseed oil to which MBs@mSiO2-NH2 has been added for 3 min, and then perform electric stirring; 3) the adsorption time is 25-150 min, and the stirring speed is controlled at 100-500 r / min.

[0018] Further preferably, the adsorption time in the specific refining step 3) above is 30-90 min, and the stirring speed is controlled at 100-300 r / min. BRIEF DESCRIPTION OF DRAWINGS

[0019] The specific embodiments of the application will be further described in detail below with reference to the accompanying drawings, in which:

[0020] Figure 1 HRTEM and Mapping element diagram of MBs@mSiO2-NH2

[0021] Figure 2 XRD and FT-IR diagrams of MBs and MBs@mSiO2-NH2

[0022] Figure 3 Optimization of TEOS volume and optimization of APTES volume

[0023] Figure 4 Effect of adsorption time on the acid value change value and phospholipid removal rate of rapeseed oil

[0024] Figure 5 Effect of adsorption temperature on the acid value change value and phospholipid removal rate of rapeseed oil

[0025] Figure 6 Effect of stirring rate on the acid value reduction rate of cold-pressed peony seed oil

[0026] Figure 7 Effect of addition amount on the acid value reduction rate of cold-pressed peony seed oil

[0027] Figure 8 Schematic diagram of recycling process

[0028] Figure 9 Effect of recycling times on the acid value change value and phospholipid removal rate DETAILED DESCRIPTION

[0029] The following examples, in conjunction with the accompanying drawings, further describe the implementation process and beneficial effects of the method of the present invention. The examples are for illustrative purposes only and do not limit the scope of the present invention. At the same time, obvious modifications made by ordinary technicians in this field based on the present invention are also included in the scope of the present invention.

[0030] Example 1:

[0031] In this study, composite magnetic beads were prepared for rapeseed oil adsorption refining. The specific preparation steps are as follows: 1) Synthesis of MBs: FeCl₃·6H₂O, polyethylene glycol 6000, sodium acetate, and ethylene glycol were mixed and vigorously stirred magnetically for 1 hour. After forming a homogeneous mixture, a hydrothermal reaction was performed. After the reaction, the mixture was cooled to room temperature and magnetically separated to obtain magnetic beads (MBs). The MBs were then washed alternately with ethanol and deionized water multiple times until the solution was clear after magnetic separation. The resulting product was dried at 60°C overnight. 2) Synthesis of MBs@mSiO₂-NH₃: MBs were sonicated with HCl solution for 10 minutes, magnetically separated, washed three times with ultrapure water, and then redispersed in a template solution. The template solution was homogenized for 30 minutes to form a uniform dispersion. Under continuous mechanical stirring, 1-6 mL of tetraethyl orthosilicate (TEOS) was added dropwise to the dispersion, followed by 1-8 mL of 3-aminopropyltriethoxysilane (APTES). After 6 hours of reaction, the product was collected with a magnet and washed three times with ethanol and ultrapure water to obtain MBs@nSiO2. The template CTAB was removed from the collected product, and the resulting product was washed three times with ultrapure water and ethanol alternately and dried at 60°C overnight to obtain MBs@mSiO2-NH2.

[0032] The present invention characterizes MBs and MBs@mSiO2-NH2 to determine the coating effect of amino-modified silica shell on MBs. The characterization results of MBs@mSiO2-NH2 are shown in Figures 1-2 At the same time, single factors were designed for TEOS volume dosage and APTES volume dosage, and the phospholipid content and acid value of rapeseed oil before and after adsorption refining were determined. The difference in degumming rate and acid value change was calculated. The optimization results of MBs@mSiO2-NH2 are shown in Figure 3 .

[0033] As a preferred solution, the preparation parameters of the MBs@mSiO2-NH2 of the present application are as follows: 1) synthesis of MBs: FeCl3·6H2O, polyethylene glycol 6000, sodium acetate and ethylene glycol are mixed and stirred vigorously by magnetic force for 1 h. After a homogeneous mixture is formed, a hydrothermal reaction is carried out, and after the reaction is completed, the mixture is cooled to room temperature. The magnetic beads (MBs) are obtained by magnetic separation and washed with ethanol and deionized water alternately for multiple times until the solution is clear after magnetic separation. The obtained product is dried at 60℃ overnight. 2) synthesis of MBs@mSiO2-NH2: the MBs are treated with an HCl solution under ultrasonic for 10 min, and then the MBs are separated by a magnet and washed with ultrapure water for three times, and then they are re-dispersed in a template liquid. The template liquid is homogenized for 30 min to form a uniform dispersion liquid. Under continuous mechanical stirring, 4 mL of tetraethyl orthosilicate (TEOS) is added dropwise to the dispersion liquid, followed by the addition of 3 mL of 3-aminopropyltriethoxysilane (APTES). After 6 h of reaction, the product is collected by a magnet and washed repeatedly with ethanol and ultrapure water for three times to obtain the product MBs@nSiO2. The collected product is removed from the template CTAB, and finally the obtained product is washed with ultrapure water and ethanol alternately for three times and dried at 60℃ overnight to obtain the MBs@mSiO2-NH2.

[0034] Example 2

[0035] The rapeseed crude oil is weighed, and the MBs@mSiO2-NH2 added weighs 1% of the weight of the rapeseed crude oil; the adsorption temperature is maintained at 30℃; the rapeseed oil to which the MBs@mSiO2-NH2 has been added is ultrasonically dispersed for 3 min, and then electric stirring is performed; the adsorption time is 60 min, and the stirring speed is controlled at 200 r / min.

[0036] Example 3

[0037] The rapeseed crude oil is weighed, and the MBs@mSiO2-NH2 added weighs 1.5% of the weight of the rapeseed crude oil; the adsorption temperature is maintained at 20℃; the rapeseed oil to which the MBs@mSiO2-NH2 has been added is ultrasonically dispersed for 3 min, and then electric stirring is performed; the adsorption time is 40 min, and the stirring speed is controlled at 200 r / min.

[0038] Example 4

[0039] According to the normalization method of GB 5009.168—2016 National Food Safety Standard Determination of Fatty Acids in Foods, the fatty acid composition of the rapeseed oil before and after adsorption is detected, and the results are shown in Table 1. The fatty acid composition of the rapeseed oil before and after adsorption does not change significantly.

[0040] Table 1 Fatty acid composition before and after adsorption refining (%)

[0041]

[0042] Table 1 (continued)

[0043]

[0044] Example 5:

[0045] Take 1.0 g (accurate to 0.0001 g) of rapeseed oil sample in a 25 mL brown volumetric flask, add 0.1 g of BHT, and flow phase n-hexane and 1,4-dioxane (95:5) to the mark. Take 1-2 mL of sample into a 2 mL sample bottle, and measure. The high performance liquid chromatography conditions are: 1) chromatographic column: Si60 silica gel column (column length 250 mm, inner diameter 4.6 mm, particle size 5 μm); 2) column temperature: 25°C; 3) mobile phase: n-hexane and 1,4-dioxane are prepared by volume ratio (95+5); 4) ultraviolet detection wavelength: 292 nm; 5) sample size: 10 μL. Through the above steps, the tocopherol content of the rapeseed oil sample before and after adsorption refining is detected.

[0046] The results are shown in Table 2. The retention rate of total tocopherol after adsorption by composite magnetic beads is 84.54%, which shows that the composite magnetic beads have high retention capacity for tocopherol in rapeseed oil.

[0047] Table 2 Change of tocopherol in rapeseed oil before and after adsorption

[0048]

[0049] Example 6:

[0050] Take cold-pressed peony seed crude oil, and the weight of MBs@mSiO2-NH2 added is 2.5% of the weight of the cold-pressed peony seed crude oil; keep the water bath temperature at 40°C; ultrasonically disperse the cold-pressed peony seed crude oil to which MBs@mSiO2-NH2 has been added for 3 min, and then perform electric stirring; the adsorption time is 30 min, and the stirring speed is controlled at 200 r / min.

[0051] Example 7:

[0052] Take cold-pressed peony seed crude oil, and the weight of MBs@mSiO2-NH2 added is 2% of the weight of the cold-pressed peony seed crude oil; keep the water bath temperature at 30°C; ultrasonically disperse the cold-pressed peony seed crude oil to which MBs@mSiO2-NH2 has been added for 3 min, and then perform electric stirring; the adsorption time is 60 min, and the stirring speed is controlled at 200 r / min.

[0053] Example 8:

[0054] The cold-pressed peony seed crude oil was weighed, and the acid values of the cold-pressed peony seed crude oil before and after adsorption deacidification were detected according to the second method of GB 5009.229-2025 National Food Safety Standard Determination of Acid Value in Food, the results were that the acid value before adsorption was 7.0 mg / g, and the acid value after adsorption was 2.5 mg / g, according to the provisions of GB / T 40622-2021 Peony Seed Oil, the acid value of the peony seed oil after adsorption deacidification meets the standard of first-class oil.

[0055] Example 9:

[0056] The rapeseed crude oil was weighed, and the MBs@mSiO2-NH2 added was 2% of the weight of the rapeseed crude oil; the adsorption temperature was kept at 30 DEG C; the rapeseed oil with added MBs@mSiO2-NH2 was ultrasonically dispersed for 3 min, and then electrically stirred; the adsorption time was 60 min, and the stirring speed was controlled at 300 r / min; the magnetic beads were separated by an external magnetic field, and the adsorbed rapeseed oil was collected; the separated magnetic beads were recycled and regenerated for 1-10 times.

[0057] The separated magnetic beads were recycled and regenerated for 10 times, the phospholipid content and acid value of the rapeseed oil before and after adsorption refining were determined, the degumming rate and acid value change difference were calculated, the recycling process schematic diagram was shown in Figure 8 , and the recycling effect data was shown in Figure 9 .

[0058] As a preferred scheme, the MBs@mSiO2-NH2 is used in the rapeseed oil adsorption degumming and deacidification method, and the separated magnetic beads can be recycled and regenerated for 1-4 times.

[0059] The above-mentioned examples are only preferred examples for fully illustrating the present application, and the protection scope of the present application is not limited thereto. The equivalent substitution or transformation made by the person skilled in the art on the basis of the present application is within the protection scope of the present application. The protection scope of the present application is subject to the claims.

Claims

1. Preparation of a composite magnetic bead and its application in edible oil adsorption refining, characterized in that: The composite magnetic beads are MBs@mSiO2-NH2.

2. The preparation of a composite magnetic bead according to claim 1 and its application in edible oil adsorption refining, characterized in that: The preparation steps of the composite magnetic beads MBs@mSiO2-NH2 are as follows: 1) Synthesis of MBs: 2.7 g of FeCl₃·6H₂O, 1 g of polyethylene glycol (PEG) 6000, 8 g of sodium acetate, and 80 mL of ethylene glycol were mixed and vigorously stirred magnetically for 1 hour. After the mixture formed a homogeneous mixture, a hydrothermal reaction was performed at 200°C for 12 hours. After the reaction was completed, the mixture was cooled to room temperature and magnetic separation was performed to obtain magnetic MBs. The MBs were then washed alternately with ethanol and deionized water several times until the solution was clear after magnetic separation. The resulting product was dried at 60°C overnight. 2) Synthesis of MBs@mSiO2-NH2: MBs were sonicated with HCl solution for 10 minutes. The MBs were then magnetically separated and washed three times with ultrapure water before being redispersed in the template solution. The template solution was homogenized for 30 minutes to form a uniform dispersion. Under continuous mechanical stirring, 1-6 mL of tetraethyl orthosilicate (TEOS) was added dropwise to the dispersion, followed by 1-8 mL of 3-aminopropyltriethoxysilane (APTES). After 6 hours of reaction, the product was collected using a magnet and washed three times with ethanol and ultrapure water to obtain MBs@nSiO2. The template CTAB was removed from the collected product, and the resulting product was washed three times with ultrapure water and ethanol alternately and dried at 60°C overnight to obtain MBs@mSiO2-NH2.

3. The preparation of a composite magnetic bead and its application in edible oil adsorption refining according to claim 2, characterized in that : In the step 2), the template liquid is hexadecyltrimethylammonium bromide (CTAB) mass (g), ultrapure water volume (mL), concentrated ammonia volume (mL) and ethanol volume (mL) in a ratio of 0.3:80:2:

60.

4. The preparation of a composite magnetic bead according to claim 2 and its application in edible oil adsorption refining, characterized in that : In the step 2), the ratio of MBs mass (g), tetraethyl orthosilicate (TEOS) and 3-aminopropyltriethoxysilane (APTES) is 0.1:4:

3.

5. The preparation of a composite magnetic bead according to claim 2 and its application in edible oil adsorption refining, characterized in that In the step 2), the template CTAB was removed by dispersing the collected product in a 0.1 M HCl solution (50 mL) and ultrasonically treating it for 1 h. The solution was replaced by magnetic separation, and the ultrasonic treatment process was repeated 3 times.

6. The preparation of a composite magnetic bead according to claim 1 and its application in edible oil adsorption refining, characterized in that The steps of adsorption degumming and deacidification in rapeseed oil are as follows: 1) weighing crude rapeseed oil, adding MBs@mSiO2-NH2 with a weight of 0.5%-2.5% of the weight of the crude rapeseed oil; maintaining the water bath temperature at 20°C-60°C; 2) ultrasonically dispersing the rapeseed oil to which MBs@mSiO2-NH2 has been added for 3 minutes, and then stirring it electrically; 3) the adsorption time is 40min-80min, and the stirring speed is controlled at 100r / min-500r / min; 4) separating the magnetic beads through an external magnetic field and collecting the adsorbed rapeseed oil; 5) recycling the separated magnetic beads for 1-4 times.

7. The preparation of a composite magnetic bead according to claim 6 and its application in edible oil adsorption refining, characterized in that In the step 1) of adsorption degumming and deacidification in rapeseed oil, the weight of MBs@mSiO2-NH2 added is 1.5% of the weight of the crude rapeseed oil, and the water bath temperature is 30-40°C.

8. The preparation of a composite magnetic bead and its application in edible oil adsorption refining according to claim 1, characterized in that The steps of adsorption deacidification in cold-pressed peony seed oil are as follows: 1) weighing cold-pressed peony seed crude oil, adding MBs@mSiO2-NH2 with a weight of 0.5%-2.5% of the weight of the cold-pressed peony seed crude oil; maintaining the water bath temperature at 20℃-60℃; 2) ultrasonically dispersing the rapeseed oil to which MBs@mSiO2-NH2 has been added for 3 minutes, and then stirring it electrically; 3) the adsorption time is 25min-150min, and the stirring speed is controlled at 100r / min-500r / min.

9. The preparation of a composite magnetic bead according to claim 8 and its application in edible oil adsorption refining, characterized in that In step 3) of adsorption deacidification in cold-pressed peony seed oil, the adsorption time is 30-90 min, and the stirring speed is controlled at 100 r / min-300 r / min.

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