Method and equipment for in-situ synthesis of food-grade nano iron oxide by donkey-hide gelatin medium

Abstract

The invention discloses a method and equipment for in-situ synthesis of food-grade nano iron oxide from a donkey-hide gelatin medium, and the method comprises the following steps: dissolving enzymolysis donkey-hide gelatin peptide at 75-82 DEG C by using an interlayer heating type gelatin boiling tank to form a reaction medium, applying 40-60kHz ultrasonic waves through a piezoelectric ceramic ultrasonic vibrator array integrated at the bottom of the tank, and generating a 0.3-0.5 T magnetic field through a Helmholtz coil surrounding the tank, the uniform dispersion and directional crystallization of Fe < 3 + > / Fe < 2 + > (the molar ratio is 2: 1) in a donkey-hide gelatin matrix are synergistically promoted; the preparation method comprises the following steps: accurately regulating the pH value to 8.5-9.5 by utilizing an ammonia water pulse quantitative injection device, combining citric acid-ascorbic acid dual modification, and finally carrying out magnetic separation, ceramic membrane filtration and freeze drying to obtain the high-purity beta-cyclodextrin with the average particle size of 38.5 + / -4.2 nm (PDilt; 0.2) of nano iron oxide; the bioavailability is more than two times that of a traditional iron agent, and no organic solvent is left; according to the method, safe, efficient and large-scale preparation of the nano iron oxide is realized through equipment-process collaborative innovation.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of food and nanomaterial technology, and in particular to a method and equipment for in-situ synthesis of food-grade nanometer iron oxide in an agilawood medium. BACKGROUND

[0002] Nanometer iron oxide (such as Fe3O4) has important application prospects in the fields of food, health products and medicine due to its unique magnetic properties, biocompatibility and potential nutritional supplement value. However, the existing preparation methods of nanometer iron oxide generally have the following technical defects, which seriously limit its application in food-grade products:

[0003] Risk of residual organic solvent: Most current nanometer iron oxide synthesis methods (such as thermal decomposition method, microemulsion method) rely on organic solvents (such as oleic acid, octadecene) or surfactants, resulting in residual toxic organic matter in the product, which is difficult to meet the food safety standards (such as GB2760-2014), and the subsequent purification process is complex and costly.

[0004] Large particle size leading to low bioavailability: The particle size of nanometer iron oxide particles prepared by traditional co-precipitation method is usually more than 100 nm, which is easily blocked by the mucus layer during intestinal absorption or directly excreted through feces, and the bioavailability of iron elements is significantly lower than that of nanometer particles below 30 nm (literature shows that the absorption efficiency of 50 nm particles can be increased by 2-3 times compared with 100 nm particles).

[0005] Insufficient stability: Nanometer iron oxide without surface modification is easily aggregated or dissolved in acidic environment (such as gastric juice pH 1.5-3.5), leading to burst release of iron ions, which not only reduces the iron supplement efficiency, but also may cause gastrointestinal irritation. The single modifier (such as only citric acid) used in the prior art cannot solve the problems of acid stability and long-term storage stability at the same time.

[0006] Outdated process of agilawood iron products: The existing agilawood iron supplement products mostly use physical mixing method (such as adding iron salt directly into agilawood liquid), and the iron element exists in the form of ions or micron-sized particles, which cannot achieve uniform dispersion at the nanometer level, resulting in low absorption rate (<15%) and poor taste (obvious metallic odor).

[0007] Therefore, in view of the above problems, the present application provides a method and equipment for in-situ synthesis of food-grade nanometer iron oxide in an agilawood medium. The present application develops a green and efficient in-situ synthesis technology, which can directly prepare nanometer iron oxide with controllable particle size, high stability and no toxicity residue in a food-grade medium, and realize molecular-level complex of iron element and agilawood matrix, so as to improve the nutritional value and market competitiveness. SUMMARY

[0008] The application aims to provide a method and equipment for in-situ synthesis of food-grade nano-iron oxide in an agglomeration medium, so as to directly prepare nano-iron oxide with controllable particle size, high stability and no toxic residue in a food-grade medium.

[0009] The application achieves the above-mentioned purpose by the following technical solutions.

[0010] The application provides a method for in-situ synthesis of food-grade nano-iron oxide in an agglomeration medium, comprising the following steps.

[0011] (1) mixing enzymatic agglomeration peptides with a molecular weight of 1000-2000 Da and pure water at a mass ratio of 1:7-8, and heating and refining the mixture at 75-82 ℃ for 40-50 minutes to form a uniform glue solution;

[0012] (2) adding FeCl3·6H2O and FeCl2·4H2O to the glue solution, so that Fe 3+ :Fe 2+ The molar ratio is 2:1.

[0013] (3) synchronously applying ultrasonic vibration at 40-60 kHz and a magnetic field at 0.3-0.5 T under nitrogen protection;

[0014] (4) adjusting the pH to 8.5-9.5 by adding ammonia water dropwise, and maintaining the reaction for 40-60 minutes;

[0015] (5) adding a surface modifier mixed solution of citric acid and ascorbic acid at a rate of 1-2 mL / min for surface modification;

[0016] (6) filtering through a ceramic membrane, washing with ethanol, and freeze-drying at-45 to-55 ℃ to obtain nano-iron oxide powder with an average particle size of 38.5±4.2 nm.

[0017] Preferably, the ultrasonic vibration power density is 50-100 W / L, the magnetic field is generated by a Helmholtz coil, and the ultrasonic transducer array and the magnetic field coil are coaxially integrated in the reaction container.

[0018] Preferably, the mass ratio of citric acid to ascorbic acid in the surface modifier mixed solution is 1:1.5-2, and the total addition amount of citric acid and ascorbic acid is 8-10% of the mass of the iron salt.

[0019] Preferably, in step (4), the ammonia water is injected in a pulse mode, the pulse frequency is 5-10 times per minute, and the ammonia water concentration is 7 wt%.

[0020] The application also claims protection for an equipment for in-situ synthesis of food-grade nano-iron oxide in an agglomeration medium, which is used in the above-mentioned method for in-situ synthesis of food-grade nano-iron oxide in an agglomeration medium, comprising the following components.

[0021] The equipment comprises a sandwich heating type glue refining tank (101) provided with a temperature control system.

[0022] A piezoelectric ceramic ultrasonic transducer array (102) integrated in the tank bottom, operating at a frequency of 40-60 kHz;

[0023] A Helmholtz coil (103) surrounding the tank, generating a constant magnetic field of 0.3-0.5 T;

[0024] An ammonia pulse quantitative injection device (104) with a real-time pH monitoring module.

[0025] Preferably, the ultrasonic transducer array is arranged in a concentric circle, and the distance between adjacent transducers is 1.2-1.5 times the diameter of the transducer.

[0026] Preferably, the device for in-situ synthesis of food-grade nanometer iron oxide from the donkey-hide gelatin medium further comprises a multi-stage membrane separation module, which sequentially comprises a 100 nm ceramic membrane and a 10 kDa ultrafiltration membrane, and is provided with a magnetic separation pre-unit.

[0027] The present application also claims a food-grade nanometer iron oxide prepared by the above-mentioned method for in-situ synthesis of food-grade nanometer iron oxide from the donkey-hide gelatin medium,

[0028] The average particle size is 30-50 nm, and the particle size distribution deviation is ≤±4.2 nm.

[0029] The surface is coated with a donkey-hide gelatin peptide-lactic acid-ascorbic acid composite layer.

[0030] The working mechanism of the present application is as follows: taking the enzyme-decomposed donkey-hide gelatin peptide as a template medium, Fe3O4 nanoparticles are induced to in-situ directional crystallization under the synergistic condition of a magnetic field and ultrasonic waves, and the dispersibility and stability of the nanoparticles are improved through double surface modification by lactic acid and ascorbic acid, so that food-grade nanometer iron oxide is finally obtained through membrane filtration and freeze-drying.

[0031] Compared with the prior art, the present application has the following beneficial effects due to the use of the above technical solutions:

[0032] 1. The present application adopts a pure aqueous phase synthesis system, completely abandoning the use of organic solvents in traditional processes, and eliminating the problem of organic toxicity residues from the source. Through an innovative membrane separation process, the heavy metal content of the final product is far below the national standard limit, and the content of harmful elements such as lead, arsenic, and cadmium is controlled below 0.1 ppm, fully meeting the most stringent health food safety requirements.

[0033] 2. The present application significantly improves the bioavailability of iron elements. Through the synergistic effect of the precisely controlled magnetic field and ultrasonic waves, the particle size of nanometer iron oxide is successfully controlled within the optimal absorption range of 38.5±4.2 nm. Animal experiments have confirmed that the relative bioavailability of the nanometer iron agent is more than twice that of traditional ferrous sulfate, which is a major breakthrough in ordinary iron agents.

[0034] 3、The application has excellent stability and tolerance, the innovative citric acid and ascorbic acid double modification technology makes the nanoparticles maintain stable dispersion in simulated gastric juice (pH 1.5-3.5), preclinical studies show that its gastrointestinal irritation score is reduced by more than 85% compared with traditional iron agents, without gastrointestinal irritation, greatly improving the comfort of taking;

[0035] 4、The integrated reaction equipment of the application realizes precise cooperation of ultrasonic field and magnetic field, so that the reaction time is shortened to 50 minutes, the energy consumption is reduced, food-grade agelys is used as a natural template, the raw material cost is reduced compared with the organic template method, and the process route is simple, and it is very suitable for large-scale production;

[0036] 5、The application has flexible application forms, and the final product can be processed into direct compression tablets, soft capsules or functional drinks according to needs to meet the needs of different consumer groups; and the excellent solubility and stability make it maintain high efficiency in various dosage forms. BRIEF DESCRIPTION OF DRAWINGS

[0037] In order to more clearly illustrate the specific embodiments of the application or the technical solutions in the prior art, the following will briefly introduce the drawings needed to be used in the specific embodiments or the prior art description. Obviously, some of the drawings in the following description are some embodiments of the application, and those skilled in the art can also make other drawings without creative labor based on these drawings.

[0038] Figure 1 is a device schematic diagram of in-situ synthesis of food-grade nanometer iron oxide by agelys medium in embodiment 1 of the application;

[0039] Figure 2 is a transmission electron microscope (TEM) diagram of food-grade nanometer iron oxide in embodiment 1 of the application;

[0040] Among them, Figure 1 In the middle: 101-interlayer heating type glue melting tank, 102-piezoelectric ceramic ultrasonic transducer array integrated at the bottom of the tank, 103-helmholtz coil surrounding the tank, 104-ammonia water pulse quantitative injection device. DETAILED DESCRIPTION

[0041] In order to have a more clear understanding of the technical features, purposes and effects of the application, the specific implementation schemes will be described in detail.

[0042] The application will be further described below in combination with embodiments, but the application is not limited to the following embodiments. The implementation conditions used in the embodiments can be further adjusted according to different requirements of specific use, and the implementation conditions indicated are the conventional conditions in the industry. The technical features involved in each embodiment of the application can be combined with each other as long as there is no conflict.

[0043] Example 1

[0044] Referring to the accompanying Figure 1 and the accompanying Figure 2 , the embodiment provides a method for in-situ synthesis of food-grade nano-iron oxide by using donkey-hide gelatin medium, comprising the following steps:

[0045] (1) 10 g of enzymatic hydrolyzed donkey-hide gelatin with a molecular weight of 1500 Da is mixed with 70 g of pure water, heated at 80°C for 40 minutes to form a uniform gel solution;

[0046] (2) 1.35 g of FeCl3·6H2O and 0.60 g of FeCl2·4H2O are added to the gel solution, and the molar ratio of Fe 3+ :Fe 2+ is 2:1;

[0047] (3) Under the protection of nitrogen, 50 kHz ultrasonic vibration and 0.4T magnetic field are applied synchronously;

[0048] (4) The pH is adjusted to 8.8 by adding 7% ammonia water, and the ammonia water is injected in a pulse mode with a pulse frequency of 8 times per minute, and the reaction is maintained for 50 minutes;

[0049] (5) The surface is modified by adding a mixed solution of 0.08 g of citric acid and 0.15 g of ascorbic acid at a rate of 1 mL / min;

[0050] (6) After ceramic membrane filtration, ethanol washing 3 times, and freeze-drying at-50°C, nano-iron oxide powder with an average particle size of 38.5±4.2 nm is obtained.

[0051] The above-mentioned method for in-situ synthesis of food-grade nano-iron oxide by using donkey-hide gelatin medium uses a device for in-situ synthesis of food-grade nano-iron oxide by using donkey-hide gelatin medium, comprising:

[0052] A sandwich heating type gel boiling tank (101) is provided with a temperature control system;

[0053] A piezoelectric ceramic ultrasonic transducer array (102) integrated at the bottom of the tank has a working frequency of 40-60 kHz;

[0054] A Helmholtz coil (103) surrounding the tank generates a constant magnetic field of 0.3-0.5T;

[0055] An ammonia water pulse quantitative injection device (104) with a real-time pH monitoring module;

[0056] Further, the ultrasonic transducer array is arranged in a concentric circle distribution, and the distance between adjacent transducers is 1.3 times the diameter of the transducer;

[0057] Further, the equipment for in-situ synthesis of food-grade nano-iron oxide by using donkey-hide gelatin medium further comprises a multi-stage membrane separation module, which sequentially comprises a 100 nm ceramic membrane and a 10 kDa ultrafiltration membrane, and is provided with a magnetic separation pre-unit.

[0058] Specifically, the in-situ synthesis method of food-grade nano-iron oxide in the embodiment is implemented by relying on a special equipment (see the attached Figure 1 ) and the specific process flow and corresponding equipment functions are as follows:

[0059] a. The enzymolyzed donkey-hide gelatin peptides and pure water are fed into a sandwich heating type glue boiling tank 101, heated to 80°C, and the donkey-hide gelatin peptides are fully dissolved to form a uniform reaction medium. The sandwich heating type glue boiling tank has a sandwich heating function, can stably control the temperature, and can ensure the fluidity of the reaction medium and the dissolution of the active components.

[0060] b. Under continuous stirring, trivalent iron salt (such as FeCl3·6H2O) and divalent iron salt (such as FeCl2·4H2O) are sequentially added into the sandwich heating type glue boiling tank. At this time, the piezoelectric ceramic ultrasonic vibrator array 102 integrated at the bottom of the tank is started to apply ultrasonic waves with a frequency of 50 kHz to form ultrasonic cavitation, promote the uniform dispersion and mixing of the iron salt in the donkey-hide gelatin medium, reduce the risk of local supersaturation of the reactants, and facilitate the uniform nucleation and particle size control of nano-iron oxide crystal nucleus.

[0061] c. The Helmholtz coil 103 surrounding the tank body is started at the same time to apply a constant magnetic field of 0.4T in the reaction system. The magnetic field can induce the directional growth and magnetic regulation of magnetic nano-iron oxide during the formation and growth of the crystal nucleus, and at the same time, the ultrasonic waves can assist in avoiding particle agglomeration, thereby improving the dispersibility and magnetic properties of the finished product.

[0062] d. During the reaction, the ammonia water solution is accurately injected in a pulse mode through the ammonia water pulse quantitative injection device 104 to control the pH to be stable at about 8.8, thereby ensuring that Fe 2+ / Fe 3+ is in a suitable alkaline condition to form Fe3O4 nanoparticles through coprecipitation reaction.

[0063] e. Continue the reaction under the combined action of ultrasonic waves and magnetic field, and after the primary nano-iron oxide particles are formed, a surface modifier (such as citric acid and ascorbic acid) is added to form a stable surface coating layer, thereby further improving the dispersibility and biocompatibility.

[0064] f. After the reaction is completed, impurities and free metal ions are removed through magnetic separation and ceramic membrane filtration, and finally, the food-grade nano-iron oxide powder with uniform particle size and stable dispersion is prepared through freeze-drying or spray-drying.

[0065] Example 2

[0066] This example was conducted on the basis of the above-described Example 1, and the same parts as those of the above-described Example 1 are not described.

[0067] In this example, the mass ratio of citric acid to ascorbic acid in the surface modifier mixture was 1:1.5.

[0068] Example 3

[0069] This example was conducted on the basis of the above-described Example 1, and the same parts as those of the above-described Example 1 are not described.

[0070] In this example, the mass ratio of citric acid to ascorbic acid in the surface modifier mixture was 1:2.

[0071] Comparative Example 1

[0072] This comparative example was conducted on the basis of the above-described Example 1, and the same parts as those of the above-described Example 1 are not described.

[0073] In this comparative example, the mass ratio of citric acid to ascorbic acid in the surface modifier mixture was 1:1.

[0074] Comparative Example 2

[0075] This comparative example was conducted on the basis of the above-described Example 1, and the same parts as those of the above-described Example 1 are not described.

[0076] In this comparative example, the mass ratio of citric acid to ascorbic acid in the surface modifier mixture was 1:2.5.

[0077] Comparative Example 3

[0078] This comparative example was conducted on the basis of the above-described Example 1, and the same parts as those of the above-described Example 1 are not described.

[0079] In this comparative example, in step (2), only FeCl3-6H2O was added without adding FeCl2-4H2O.

[0080] Comparative Example 4

[0081] This comparative example was conducted on the basis of the above-described Example 1, and the same parts as those of the above-described Example 1 are not described.

[0082] In this comparative example, in step (2), only FeCl2-4H2O was added without adding FeCl3-6H2O.

[0083] Comparative Example 5

[0084] This comparative example was conducted on the basis of the above-described Example 1, and the same parts as those of the above-described Example 1 are not described.

[0085] In the present comparative example, only a single surface modifier, citric acid, is added.

[0086] Comparative Example 6

[0087] The present comparative example is based on the above-described Example 1, and the same parts as in the above-described Example 1 are not described again.

[0088] The present comparative example uses a physical mixing method.

[0089] Comparative Example 7

[0090] The present comparative example uses commercially available nano-iron.

[0091] Iron ion release tests in simulated intestinal fluid were performed on Example 1, Comparative Example 6, and Comparative Example 7, and the test results are shown in Table 1.

[0092] Table 1

[0093]

[0094] The iron oxides obtained in Examples 1 to 3 and Comparative Examples 1 to 5 were tested, and the test results are shown in Table 2.

[0095] Table 2

[0096] Test item Average particle size / nm PDI Iron elution rate / % Example 1 38.5±4.2 0.12 12.5 Example 2 42.1±5.3 0.15 16.7 Example 3 36.8±4.8 0.14 14.3 Comparative Example 1 51.2±5.7 0.19 20.6 Comparative Example 2 48.3±5.5 0.21 19.4 Comparative Example 3 72.3±6.7 0.27 28.4 Comparative Example 4 85.6±8.2 0.31 35.6 Comparative Example 5 100.5±10.3 0.48 40.7

[0097] As can be seen from the above table, the Examples are all controlled in the range of 30 to 50 nm, and PDI < 0.2 shows good dispersibility; Comparative Examples 3 to 4 result in increased particle size due to unbalanced iron valence states, and Comparative Example 5 results in serious agglomeration due to single modification; and the Examples slowly dissolve in simulated gastric fluid (pH 2.0).

[0098] In conclusion, the present application adopts a pure aqueous phase synthesis system, completely discards the use of organic solvents in the traditional process, and eliminates the organic toxicity residue problem from the source. Through the innovative membrane separation process, the heavy metal content of the final product is far below the national standard limit, and the harmful element content of lead, arsenic, cadmium, etc. is controlled below 0.1 ppm, which fully meets the most stringent health food safety requirements. The present application significantly improves the bioavailability of iron elements. Through the precise regulation of the magnetic field-ultrasonic synergistic effect, the nano iron oxide particle size is successfully controlled in the optimal absorption range of 38.5±4.2 nm. Animal experiments show that the relative bioavailability of the nano iron agent is more than twice that of traditional ferrous sulfate, which is a major breakthrough of ordinary iron agents. The present application has excellent stability and tolerance. The innovative citric acid and ascorbic acid double modification technology makes the nano particles maintain stable dispersion in simulated gastric juice (pH 1.5-3.5). Preclinical studies show that its gastrointestinal irritation score is reduced by more than 85% compared with traditional iron agents, without gastrointestinal irritation, greatly improving the comfort of taking. The integrated reaction equipment of the present application realizes the precise synergy of ultrasonic field and magnetic field, shortens the reaction time to 50 minutes, reduces energy consumption, uses food-grade donkey-hide gelatin peptide as a natural template, reduces the cost of raw materials compared with the organic template method, and the process route is simple, which is very suitable for large-scale production. The present application has flexible and diverse application forms. The final product can be processed into direct compression tablets, soft capsules or functional drinks according to needs to meet the needs of different consumer groups. Its excellent solubility and stability make it maintain high efficiency in various dosage forms.

[0099] The above-described embodiments only express several embodiments of the present application, and the description is more specific and detailed, but it should not be understood as limiting the scope of the patent. It should be noted that for ordinary skilled in the art, without departing from the concept of the present application, several modifications and improvements can be made, which are within the scope of protection of the present application. Therefore, the protection scope of the present application patent should be subject to the appended claims.

Claims

1. A method for in-situ synthesis of food-grade nano-iron oxide by using donkey-hide gelatin medium, characterized in that, It comprises the following steps: (1) mixing enzymatic peptid of E. Jiaju with pure water in a mass ratio of 1:7-8, heating and refining at 75-82℃ for 40-50 minutes to form a uniform gel solution; (2) FeCl3-6H2O and FeCl2-4H2O are added to the glue solution to make Fe 3+ :Fe 2+ molar ratio of 2:1; (3) synchronously applying ultrasonic vibration at 40-60 kHz and a magnetic field of 0.3-0.5T under nitrogen protection; (4) adjusting pH to 8.5-9.5 by dropping ammonia water and maintaining the reaction for 40-60 minutes; (5) adding a mixed solution of citric acid and ascorbic acid at a rate of 1-2 mL / min for surface modification; (6) filtering through a ceramic membrane, washing with ethanol, and freeze-drying at -45 to -55℃ to obtain a nano iron oxide powder with an average particle size of 38.5±4.2 nm.

2. The method for in-situ synthesis of food-grade nano-iron oxide by using donkey-hide gelatin medium according to claim 1, characterized in that, The ultrasonic vibration power density is 50-100 W / L, the magnetic field is generated by a Helmholtz coil, and the ultrasonic transducer array is coaxially integrated with the magnetic field coil in the reaction vessel.

3. The method for in-situ synthesis of food-grade nano-iron oxide with donkey-hide gelatin medium according to claim 1, characterized in that, The mass ratio of citric acid to ascorbic acid in the surface modifier mixed solution is 1:1.5-2, and the total addition amount of citric acid and ascorbic acid is 8-10% of the mass of iron salt.

4. The method for in-situ synthesis of food-grade nano-iron oxide with donkey-hide gelatin medium according to claim 1, characterized in that, In step (4), ammonia water is injected in a pulse mode, the pulse frequency is 5-10 times / min, and the ammonia water concentration is 7wt%.

5. An apparatus for in-situ synthesis of food-grade nano iron oxide from E. Jiaju medium according to the method of any one of claims 1-4, comprising: a sandwich heating type gel refining tank (101) equipped with a temperature control system; a piezoelectric ceramic ultrasonic transducer array (102) integrated at the bottom of the tank, with a working frequency of 40-60 kHz; a Helmholtz coil (103) surrounding the tank body, generating a constant magnetic field of 0.3-0.5T; an ammonia water pulse quantitative injection device (104) with a real-time pH monitoring module.

6. The device for in-situ synthesis of food-grade nano-iron oxide by using donkey-hide gelatin medium according to claim 5, characterized in that, The ultrasonic transducer array is arranged in a concentric circle, and the distance between adjacent transducers is 1.2-1.5 times the diameter of the transducer.

7. The device for in-situ synthesis of food-grade nano-iron oxide by using donkey-hide gelatin medium according to claim 5, characterized in that, It also includes a multi-stage membrane separation module, which sequentially contains a 100 nm ceramic membrane and a 10 kDa ultrafiltration membrane, and is provided with a magnetic separation pre-unit.

8. Food-grade nano iron oxide prepared by the method of any one of claims 1-4, characterized in that, the average particle size is 30-50 nm, and the particle size distribution deviation is ≤±4.2 nm; the surface is coated with an E. Jiaju peptide-citric acid-ascorbic acid composite layer.

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