Method for preparing novel dateplum persimmon polysaccharide-iron compound through composite induction of magnetic field and electric field

Abstract

The invention relates to a method for preparing a novel dateplum persimmon polysaccharide-iron compound through composite induction of a magnetic field and an electric field, and belongs to the technical field of food processing. The method is realized by the following steps: firstly, carrying out stirring reaction on black date polysaccharide and a ferric chloride solution; placing the reaction system in an electric field device, applying an electric field, simultaneously applying an external magnetic field under the action of the electric field, after the reaction is finished, centrifuging to remove precipitate, collecting supernate, concentrating, dialyzing redundant iron ions, and freeze-drying the dialyzed sample solution to obtain black date polysaccharide-iron compound powder. According to the preparation method provided by the invention, the potential distribution in the solution is regulated and controlled, so that the migration of ions can be accelerated, and the reaction rate is increased; directional movement of iron ions can be enhanced under the action of a magnetic field, and the combining efficiency of the iron ions and polysaccharide molecules is improved under the synergistic effect by adding a proper amount of tea polyphenol; the combined action of the electric field and the magnetic field not only can accelerate the reaction, but also can improve the dispersity and stability of the compound. The application of the technology can overcome the defects of a traditional chemical method, and meanwhile, green, efficient and stable preparation of the polysaccharide-iron compound is achieved.

Description

Technical Field

[0001] The invention relates to a method for preparing a novel black date polysaccharide-iron complex through magnetic field and electric field composite induction, belonging to the technical field of food processing. Background Art

[0002] Iron is an essential trace element for the human body and plays a key role in hemoglobin synthesis, oxygen transport and enzymatic reactions. However, iron deficiency anemia is still a common health problem worldwide, especially among pregnant women, children and the elderly. Although there are many iron supplements on the market (such as ferrous sulfate, ferrous lactate, etc.), they face the following problems in use: traditional iron preparations have limited absorption efficiency and are easily affected by the pH environment of the gastrointestinal tract; high-dose iron preparations often cause stomach discomfort, nausea and constipation; free iron may induce oxidative stress in the body and cause cell damage. In order to solve the problems of traditional iron preparations, polysaccharide-iron complexes have become a research hotspot due to their unique advantages: functional groups such as hydroxyl and carboxyl groups in polysaccharides can chelate with iron ions to form a more absorbable complex; the natural source of polysaccharides makes the complex milder and has no obvious side effects; the complex can not only supplement iron, but also retain the functional properties of polysaccharides, such as antioxidant and immunomodulatory.

[0003] There have been some studies on the complex of plant polysaccharides (such as seaweed polysaccharides, chitosan, etc.) with iron, but their preparation methods are still mainly based on traditional chemical reactions, which have the following problems: traditional methods have strict requirements on chelation conditions and require a long time to complete the reaction; the iron ions in the complex are easily affected by external conditions and precipitate or dissociate; some preparation methods use organic solvents or strong acids and alkalis, which may introduce toxic residues.

[0004] The raw materials for extracting black jujube polysaccharides are mainly cracked jujubes, fallen jujubes, etc., most of which are discarded or piled up and incinerated, causing resource waste and environmental pollution. If the waste utilization of red jujube resources can be achieved, it will have a positive effect and far-reaching impact on the resource utilization of the jujube economy and the realization of "carbon peak" and "carbon neutrality". In the prior art, there is no record of using magnetic field and electric field to prepare a new black jujube polysaccharide-iron complex. Summary of the invention

[0005] In view of the problems existing in the prior art, the present invention provides a method for preparing a novel black date polysaccharide-iron complex by magnetic field and electric field composite induction. The method is simple and easy to operate, and does not introduce residual toxic substances.

[0006] The technical solution adopted by the present invention to achieve the above-mentioned purpose is: The present invention provides a method for preparing a novel black date polysaccharide-iron complex by magnetic field and electric field composite induction, comprising the following steps: (1) Add black jujube polysaccharide to deionized water, add ferric chloride solution to the mixed solution, and use sodium bicarbonate solution to maintain the pH value of the solution. When a reddish brown insoluble precipitate is produced in the reactant, stop adding ferric chloride and continue stirring the reaction; (2) placing the reaction system in an electric field device and applying an electric field. Under the action of the electric field, an external magnetic field is simultaneously applied. After the reaction is completed, the precipitate is removed by centrifugation, the supernatant is collected and concentrated, and then the excess iron ions are dialyzed. The dialyzed sample solution is freeze-dried to obtain a black date polysaccharide-iron complex powder.

[0007] Preferably, in step (1), the concentration of the black date polysaccharide in deionized water is 5 mg / mL; and the concentration of the ferric chloride solution is 2 mol / L.

[0008] Preferably, the ferric chloride solution contains 0.1% tea polyphenols.

[0009] Preferably, in step (1), the pH value of the mixed solution is maintained at 7-8; and the stirring reaction time is 20 minutes.

[0010] Preferably, in step (2), the electric field condition is: a DC voltage of 10 V or an alternating voltage frequency of 50 Hz; and the magnetic field condition is: a magnetic induction intensity of 0.3-0.5 T.

[0011] Preferably, in step (2), the dialysis time is 72 hours.

[0012] The black jujube polysaccharide used in the present invention is blackened golden thread jujube polysaccharide, which is specifically prepared by the following method: 1) Extraction of blackened golden thread jujube polysaccharide The golden thread jujube was washed and blackened at 50-70℃ and 30-40% humidity for 144-216h. Then, hot water was extracted at 60-80℃ for 1-4h at a material-liquid ratio of 1:5-1:10, and the extraction was repeated twice. After that, 95% ethanol was added at a ratio of 1:4, and the blackened golden thread jujube crude polysaccharide was obtained by precipitation and freeze-drying.

[0013] 2) Isolation and purification of blackened golden thread jujube polysaccharide Take the crude polysaccharide, dissolve it in water, and then use macroporous resin AB-8 to perform decolorization by dynamic adsorption; extract it 7-10 times according to the solution: petroleum ether = 1:1 for defatting; then use the sevage method (chloroform: n-butanol = 4:1) to remove protein from the extract 7-10 times.

[0014] The defatted and deproteinized polysaccharide solution is filtered through a 0.45 μm filter membrane for later use. The above solution is added to an anion chromatography column (such as DEAE-52 or DEAE-FF) at 3%-5% of the column volume, and eluted with distilled water, 0.1, 0.2, 0.3, 0.4, and 0.5 mol / L NaCl in sequence at a pressure of less than 0.3 MPa, with a flow rate of 5-15 ml / min.

[0015] The polysaccharide solution was placed in a pretreated dialysis bag, leaving one-third of the space, and dialyzed in deionized water; the deionized water was replaced every 6 hours, and the dialysis was continued for 48 hours.

[0016] The dialyzed polysaccharide solution is purified using a gel column (such as Chromdex 75 PG or Sephadex G-100) and eluted with distilled water at a pressure of less than 0.3 MPa at a flow rate of 0.5-2 ml / min.

[0017] The beneficial effects of the present invention are: (1) The present invention utilizes the application of electric field and magnetic field to increase the yield of black date polysaccharide-iron complex and improve the product quality; (2) The preparation method provided by the present invention can accelerate the migration of ions and improve the reaction rate by regulating the potential distribution in the solution; the effect of the magnetic field can enhance the directional movement of iron ions, and by adding an appropriate amount of tea polyphenols, the binding efficiency of iron ions and polysaccharide molecules can be improved under synergistic effect; the combined effect of the electric field and the magnetic field can not only accelerate the reaction, but also improve the dispersibility and stability of the complex. The application of this technology can overcome the drawbacks of traditional chemical methods and realize the preparation of polysaccharide iron complexes in a green, efficient and stable manner. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] Figure 1 This is the sample diagram for circular dichroism measurement; In Figure 2, a, b, and c are scanning electron microscope energy spectra of carbon, oxygen, and iron of black jujube polysaccharide, and d, e, and f are scanning electron microscope energy spectra of carbon, oxygen, and iron of black jujube polysaccharide-iron complex, respectively; Figure 3 The middle left picture shows the element content of polysaccharides, and the right picture shows the element content of polysaccharide-iron complexes; Figure 4 The figure is a comparison chart of the antioxidant capacity of black date polysaccharide and black date polysaccharide-iron complex (Example 1). DETAILED DESCRIPTION

[0019] The technical solution of the present invention is further explained and illustrated by means of specific embodiments below.

[0020] Example 1 (1) Take 0.5 ml of black jujube polysaccharide and add it to 100 mL of deionized water. Add 2 mol / L ferric chloride solution (containing 0.1% tea polyphenols) to the mixed solution, and use sodium bicarbonate solution to keep the pH of the solution at 7. When a reddish-brown insoluble precipitate is produced in the reactant, stop adding ferric chloride and continue stirring the reaction for 20 minutes. (2) Place the reaction system in an electric field device and apply an electric field (DC voltage 10 V or AC voltage frequency 50 Hz). Under the action of the electric field, an external magnetic field (magnetic induction intensity 0.3-0.5 T) is applied at the same time. During the process of polysaccharide and iron complexation, the electric field and magnetic field are continuously applied for 20 minutes after the precipitation is produced. After the reaction is completed, the precipitate is removed by centrifugation, the supernatant is collected and concentrated, and then dialyzed for 72 hours to remove excess iron ions in the polysaccharide iron solution. The dialyzed sample solution is freeze-dried to obtain black jujube polysaccharide iron complex powder.

[0021] Figure 1 The circular dichroism spectrum of the sample was determined, and it was found that the black date polysaccharide had a positive peak at 200 nm with a strong peak signal. The peak disappeared after chelating with iron, which was due to the reorganization of the polysaccharide chain and the interaction between the polysaccharide and iron; indicating that the black date polysaccharide-iron complex was successfully prepared by the present invention.

[0022] In Figure 2, a, b, and c are the scanning electron microscope energy spectra of carbon, oxygen, and iron of black jujube polysaccharide, respectively, and d, e, and f are the scanning electron microscope energy spectra of carbon, oxygen, and iron of black jujube polysaccharide-iron complex, respectively. It can be seen that there are no clustered element points in the iron energy spectrum of black jujube polysaccharide, proving that the iron content is extremely low, while there are a large number of clustered areas in the iron energy spectrum of black jujube polysaccharide-iron complex, indicating that the polysaccharide iron conformity effect is better.

[0023] Figure 3 The left picture shows the element content of polysaccharides, and the right picture shows the element content of polysaccharide-iron complex. The difference in content is obvious, indicating that the complex effect of polysaccharides and iron is better.

[0024] Comparative Example 1 (1) Take 0.5 ml of black jujube polysaccharide and dilute it to 100 mL of deionized water. Add 2 mol / L ferric chloride solution to the mixed solution and use sodium bicarbonate solution to maintain the pH of the solution at 7. When a reddish-brown insoluble precipitate is produced in the reactants, stop adding ferric chloride and continue stirring the reaction for 20 min.

[0025] (2) The reaction system was placed in an electric field device and an electric field (direct current voltage of 10 V or alternating voltage frequency of 50 Hz) was applied. Under the action of the electric field, an external magnetic field (magnetic induction intensity of 0.3-0.5 T) was applied at the same time. During the complexation process of polysaccharide and iron, after precipitation was generated, the electric field and magnetic field were continuously applied for 20 min. After the reaction was completed, the precipitate was removed by centrifugation, the supernatant was collected and concentrated, and then dialyzed for 72 h to remove excess iron ions in the polysaccharide iron solution. The dialyzed sample solution was freeze-dried to obtain black date polysaccharide iron complex powder.

[0026] Potassium ferrocyanide was used to test the aqueous solution of the black date polysaccharide-iron complex. In Comparative Example 1, a red solution was generated; while in Example 1, no red solution was generated. Its binding ability and stability were better than those of Comparative Example 1.

[0027] Effect Example 1. DPPH free radical scavenging ability test Determination of the DPPH free radical scavenging ability of polysaccharide iron: Accurately weigh 0.0118 g of DPPH, dissolve it in anhydrous ethanol, and dilute it to a 200 mL volumetric flask to obtain a 150 μmoL / L DPPH alcohol solution. Use 50 mM acetate buffer to prepare the samples into solutions of 2.5 mg / mL, 2.0 mg / mL, 1.5 mg / mL, 1.0 mg / mL, and 0.5 mg / mL, respectively. Mix 3 mL of DPPH alcohol solution with an equal volume of sample solution, shake well, place in the dark for 60 min, and measure the absorbance at 517 nm. Using ascorbic acid as the positive control, calculate the scavenging rate of DPPH according to the following formula: Where: A1 is the absorbance value of the sample after the reaction, A2 is the absorbance value of the sample solution itself, and A0 is the absorbance value of the blank control.

[0028] 2. ABTS + Free radical scavenging ability test Scavenging ability of ABTS free radicals: Weigh 0.3841 g ABTS and 0.0662 g potassium persulfate and dissolve them in deionized water respectively. Combine the two solutions and make up to 100 mL volumetric flask. Place in dark for 12-16 h to obtain ABTS + Free radical solution, dilute the solution with PBS buffer at pH 7.4 to an absorbance of 0.7 ± 0.02. Add 0.1 mL of sample solution of different concentrations (2.5 mg / mL, 2.0 mg / mL, 1.5 mg / mL, 1.0 mg / mL, 0.5 mg / mL), 1 mL of deionized water and 2 mL of diluted ABTS to each test tube. ＋The solution was mixed evenly and kept in dark for 6 min. The absorbance of each sample was measured at 734 nm. Ascorbic acid was used as a positive control and the scavenging rate of ABTS free radicals was calculated according to the following formula: Where: A1 is the absorbance value of the sample after the reaction, A2 is the absorbance value of the sample solution itself, and A0 is the absorbance value of the blank control.

[0029] 3. Lipid peroxidation inhibition ability test Anti-lipid peroxidation ability: Accurately weigh 56 mg of soybean lecithin and dissolve it in PBS buffer to prepare a 4 mg / mL lecithin solution for use. Add 0.2 mL of lecithin solution to each test tube, then add 1 mL of sample solution of different concentrations (2.5 mg / mL, 2.0 mg / mL, 1.5 mg / mL, 1.0 mg / mL, 0.5 mg / mL), 0.1 mL of 25 mmol / L FeSO4 solution and 1.7 mL of PBS buffer, mix well and react in a water bath at 37°C for 40 min. After the reaction, add 1 mL of 10% trichloroacetic acid solution and 1 mL of 0.8% thiobarbituric acid solution, mix well, heat in a water bath at 100°C for 15 min, cool to room temperature, centrifuge at 5000 r / min for 10 min, take the supernatant and measure the absorbance of each sample at a wavelength of 532 nm. Take ascorbic acid as the positive control and calculate the lipid peroxidation inhibition rate according to the following formula: Where: A1 is the absorbance value of the sample after the reaction, A2 is the absorbance value of the sample solution itself, and A0 is the absorbance value of the blank control.

[0030] Specific results such as Figure 4 The DPPH free radical scavenging ability and BTS of the black date polysaccharide-iron complex prepared in Example 1 + The free radical scavenging ability and anti-lipid peroxidation ability are better than those of black date polysaccharide.

Claims

1. A method for preparing a novel black date polysaccharide-iron complex by magnetic field and electric field composite induction, characterized in that: The following steps are involved: (1) Add black jujube polysaccharide to deionized water, add ferric chloride solution to the mixed solution, and use sodium bicarbonate solution to maintain the pH value of the solution. When a reddish brown insoluble precipitate is produced in the reactant, stop adding ferric chloride and continue stirring the reaction; (2) placing the reaction system in an electric field device and applying an electric field. Under the action of the electric field, an external magnetic field is simultaneously applied. After the reaction is completed, the precipitate is removed by centrifugation, the supernatant is collected and concentrated, and then the excess iron ions are dialyzed. The dialyzed sample solution is freeze-dried to obtain a black date polysaccharide-iron complex powder.

2. The method according to claim 1, characterized in that In step (1), the concentration of the black date polysaccharide in deionized water is 5 mg / mL; the concentration of the ferric chloride solution is 2 mol / L.

3. The method according to claim 2, characterized in that The ferric chloride solution contains 0.1% tea polyphenols.

4. The method according to any one of claims 1 to 3, characterized in that: In step (1), the pH value of the mixed solution is maintained at 7-8; and the stirring reaction time is 20 minutes.

5. The method according to claim 1, characterized in that In step (2), the electric field condition is: a DC voltage of 10 V or an alternating voltage frequency of 50 Hz; the magnetic field condition is: a magnetic induction intensity of 0.3-0.5 T.

6. The method according to claim 1 or 5, characterized in that: In step (2), the dialysis time is 72 hours.

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