阅读说明：本技术 一种高纯度抗坏血酸镁及其制备方法 (High-purity magnesium ascorbate and preparation method thereof ) 是由 王雷 宋亚琴 缪铭 赵中秀 邬浩杰 顾奇伟 于 2020-12-28 设计创作，主要内容包括：本发明公开了一种高纯度抗坏血酸镁的制备方法,包括以下步骤：(1)将一定量的水投入到反应器中,加热煮沸冷却至常温,然后按照比例投入抗坏血酸和镁原料,搅拌混合均匀；(2)调节溶液的pH、温度和超声功率,超声反应一段时间；(3)反应结束后,迅速降温,冷却,过滤,备用。(4)采用结晶法或喷雾干燥法对滤液进行提取处理制备抗坏血酸镁成品。本发明工艺路线短,无固体废弃物,所制备的抗坏血酸镁产品性能稳定,不仅可以达到均衡补充微量元素的目的,而且工艺简单,适合大批量产业化生产。(The invention discloses a preparation method of high-purity magnesium ascorbate, which comprises the following steps: (1) putting a certain amount of water into a reactor, heating, boiling and cooling to normal temperature, then putting ascorbic acid and magnesium raw materials in proportion, and stirring and mixing uniformly; (2) adjusting the pH, temperature and ultrasonic power of the solution, and carrying out ultrasonic reaction for a period of time; (3) after the reaction is finished, quickly cooling, cooling and filtering for later use. (4) And extracting the filtrate by adopting a crystallization method or a spray drying method to prepare a finished magnesium ascorbate product. The method has the advantages of short process route, no solid waste, stable performance of the prepared magnesium ascorbate, capability of achieving the aim of supplementing trace elements in a balanced manner, simple process and suitability for large-scale industrial production.)

1. A preparation method of high-purity magnesium ascorbate is characterized by comprising the following steps:

(1) putting a certain amount of water into a reactor, heating, boiling and cooling to normal temperature, then putting ascorbic acid and magnesium raw materials in proportion, and stirring and mixing uniformly;

(2) adjusting the pH, temperature and ultrasonic power of the solution, and carrying out ultrasonic reaction for a period of time;

(3) after the reaction is finished, quickly cooling, cooling and filtering for later use;

(4) and extracting the filtrate by adopting a crystallization method or a spray drying method to prepare a finished magnesium ascorbate product.

2. The method according to claim 1, wherein in the step (1), the magnesium raw material comprises magnesium carbonate, magnesium oxide, magnesium hydroxide, magnesium sulfate, and magnesium chloride; the mass ratio of the ascorbic acid to the magnesium raw material is 160-180: 45-50, and the mass ratio of the total reaction materials to water is 2: 3-4.

3. The method for preparing high-purity magnesium ascorbate according to claim 2, wherein the temperature in the step (2) is 30-80, the pH value at DEG C is 4.5-7.5, the ultrasonic time is 0.5-3 h, and the ultrasonic power is 150-350 w.

4. The method according to claim 3, wherein the diameter of the filter membrane used in the step (3) is 0.1-0.45 mm.

5. The method for preparing magnesium ascorbate with high purity according to claim 4, wherein the extraction treatment by spray drying in step (4) is carried out by atomizing the filtrate into particles by an atomizer, directly contacting with hot air, and carrying out heat exchange drying to obtain magnesium ascorbate solid powder.

6. The method for preparing high-purity magnesium ascorbate according to claim 4, wherein the spray drying method adopted in the step (4) has the process conditions of 150-300 ℃ at the air inlet, 50-150 ℃ at the air outlet and 40-80 kg/h at the feeding speed.

7. The method for preparing magnesium ascorbate with high purity according to claim 4, wherein the step (4) of extracting magnesium ascorbate by crystallization comprises the following steps: evaporating and concentrating the filtrate until magnesium ascorbate crystals are separated out, stopping concentrating, slowly cooling, filtering after a large amount of crystals are gradually separated out, and washing and drying the filter cake to obtain uniform magnesium ascorbate crystals.

8. The method according to claim 4, wherein the crystallization process in step (4) is performed under conditions of an evaporation concentration temperature of 40-90, a stirring speed at 10-25 r/min at DEG C, and a temperature gradient of 5-15 ℃/h.

9. A high-purity magnesium ascorbate, prepared according to any one of claims 1 to 8.

Technical Field

The invention belongs to the technical field of organic trace element chelates, and particularly relates to high-purity magnesium ascorbate and a preparation method thereof.

Background

The development direction of the ascorbic acid (vitamin C) industry at present mainly has two aspects: firstly, the process and equipment are continuously improved, and the production scale of the ascorbic acid bulk drug is enlarged by adopting a more advanced technology; on the other hand, China is a country with the largest VC production capacity in the world, and accounts for about 65% of the worldwide yield, and the requirement of people on ascorbic acid cannot be met due to the instability of vitamin C, so that the development of downstream products, namely the magnesium ascorbate serving as a VC derivative, is necessary to meet the requirement of people on the application of vitamin C.

The magnesium ascorbate is odorless and tasteless crystal or powder, and has the advantages of high dissolution rate, easy absorption by human body, and only one magnesium salt compared with other ascorbic acid products; after being eaten by human body, the food is immediately decomposed into ascorbic acid (VC) under the action of enzyme in the human body and is directly absorbed by the human body; the magnesium ascorbate processed by the advanced process has the advantages that the magnesium ascorbate is not easily oxidized when meeting water and heat and can be stored for a long time, the main composition of the product is magnesium ascorbate (vitamin C), the vitamin C is one of essential vitamins of a human body, the magnesium is a trace element required by the human body, the product is odorless and tasteless, the quality of the food is not changed when the product is added into the food, and the activity and the nutritional value of the ascorbic acid (VC) are kept. The nutrient supplement is used for strengthening infant food, old food, functional food, military food and the like, and is necessary for improving the health level of people.

Patent CN201810042609.3 discloses a preparation method of phosphate radical-free magnesium ascorbate, deionized water is added into an enamel reaction kettle, the temperature is raised to 40 +/-1 ℃, then ascorbic acid raw materials are added, sodium hydroxide is added after stirring to adjust the pH value to be about 4, then the feed liquid is discharged and injected into a cation resin column for sodium removal treatment, magnesium hydroxide or magnesium oxide is used for magnesium connection after the sodium ion feed liquid is exchanged, when the pH value is 8-10, magnesium addition is stopped, stirring is carried out for about 10 minutes, then fine filtration and concentration are carried out, and finally magnesium ascorbate is obtained. The method for preparing the magnesium ascorbate by the ion exchange resin has low yield, low environmental protection property and large energy consumption, and is not suitable for large-scale production.

Disclosure of Invention

Against this background, the object of the present invention is to provide a high-purity magnesium ascorbate and a method for the preparation thereof. The invention relates to a method for preparing magnesium ascorbate with high efficiency, rapidness, simplicity, convenience and large scale, which has simple operation steps, can effectively overcome the characteristic that the ascorbic acid is easy to change when meeting oxygen, light, heat and the like, and realizes industrialization. The invention has short process route and no solid pollutant, and the prepared magnesium ascorbate has stable product performance and the yield can reach more than 98 percent.

The purpose of the invention is realized by the following technical scheme:

the invention provides a preparation method of high-purity magnesium ascorbate, which comprises the following steps:

(1) putting a certain amount of water into a reactor, heating, boiling and cooling to normal temperature, then putting ascorbic acid and magnesium raw materials in proportion, and stirring and mixing uniformly;

(2) adjusting the pH, temperature and ultrasonic power of the solution, and carrying out ultrasonic reaction for a period of time;

(3) after the reaction is finished, quickly cooling, cooling and filtering for later use;

(4) and extracting the filtrate by adopting a crystallization method or a spray drying method to prepare a finished magnesium ascorbate product.

Preferably, the magnesium raw material includes magnesium oxide, magnesium carbonate, magnesium sulfate, magnesium hydroxide or magnesium chloride. Preferably, the magnesium raw material is one of magnesium oxide, magnesium carbonate, magnesium sulfate, and magnesium chloride.

Preferably, the mass ratio of the ascorbic acid to the magnesium raw material in the step (1) is 160-180: 45-50, and the ratio of the total reaction materials to water is 2: 3-4. The total reaction mass refers to the total mass of ascorbic acid and magnesium raw materials.

Preferably, in the step (2), the temperature is 30-80 ℃, the pH value is 4.5-7.5, the ultrasonic time is 0.5-3 h, and the ultrasonic power is 150-350 w.

Preferably, the aperture of the filter membrane filtered in the step (3) is 0.1-0.45 mm.

Preferably, the process for preparing the magnesium ascorbate by performing extraction treatment by using a spray drying method in the step (4) is that the filtrate is atomized into mist-shaped particles by an atomizer, and the mist-shaped particles are directly contacted with hot air for heat exchange drying to obtain magnesium ascorbate solid powder.

Preferably, the spray drying method adopted in the step (4) has the process conditions of the air inlet temperature of 150-300 ℃, the air outlet temperature of 50-150 ℃ and the feeding speed of 40-80 kg/h. Further, the rotating speed of the spray drying method adopted in the step (4) is 560 r/min.

Preferably, the process for preparing magnesium ascorbate by adopting a crystallization method for extraction treatment in the step (4) comprises the following steps: evaporating and concentrating the filtrate until magnesium ascorbate crystals are separated out, stopping concentrating, slowly cooling, filtering after a large amount of crystals are gradually separated out, and washing and drying the filter cake to obtain uniform magnesium ascorbate crystals.

Preferably, the crystallization method adopted in the step (4) has the process conditions that the temperature of evaporation concentration is 40-90 ℃, the stirring speed is 10-25 r/min, and the temperature reduction gradient is 5-15 ℃/h.

Preferably, the magnesium ascorbate can be used as a food additive or a nutritional supplement and is widely applied to foods, beverages, cosmetics, biomedicines, health care and the like.

The basic principle of the invention is as follows: the high-purity magnesium ascorbate is researched and developed according to the characteristic of changeability of VC when meeting oxygen, light, heat and the like, and is prepared by firstly preparing an aqueous solution from ascorbic acid and magnesium raw materials according to a certain proportion, then carrying out ultrasonic reaction for a period of time at a certain temperature, filtering, and then respectively carrying out spray drying or crystallization.

Compared with the prior art, the invention has the following beneficial effects:

(1) the invention has high utilization rate of raw materials and less loss, and the prepared magnesium ascorbate meets the requirement of food grade.

(2) The magnesium ascorbate is prepared by an ultrasonic method, the process is simple and easy to operate, energy-saving and environment-friendly, the characteristic that the ascorbic acid is easy to deform when meeting oxygen, light, heat and the like is overcome to the maximum extent, and the prepared magnesium ascorbate has high purity and stable quality and is suitable for industrial production; the invention adopts an ultrasonic method to prepare the magnesium ascorbate, and the chelation rate reaches 96.8-97.5%.

(3) The method adopted by the invention for preparing the magnesium ascorbate has the advantages that the spray drying method and the crystallization method are flexibly applied, no organic solvent is used, the purposes of energy saving and environmental protection are realized compared with the traditional method of obtaining the final product by alcohol precipitation, and the final product has no residual alcohol substances and better meets the requirements of food grade.

(4) The magnesium ascorbate prepared by the invention has good chemical and biochemical stability, good solubility in vivo, easy absorption and high bioavailability, and has double functions of supplementing ascorbic acid and mineral substances.

(5) The magnesium ascorbate prepared by the invention can be used as a food additive or a nutritional supplement and is widely applied to foods, beverages, cosmetics, biomedicines, health care and the like.

Drawings

FIG. 1 shows the effect of reaction temperature on magnesium ascorbate content in experimental example 1 prepared by conventional method and ultrasonic method according to the present invention;

FIG. 2 shows the effect of reaction time on magnesium ascorbate content in the preparation of test example 1 by conventional and ultrasonic methods according to the present invention;

FIG. 3 shows the effect of pH on magnesium ascorbate content of test example 1 prepared by conventional and ultrasonic methods according to the present invention;

FIG. 4 shows the effect of ultrasonic power on magnesium ascorbate content in experimental example 1 prepared by the ultrasonic method of the present invention;

FIG. 5 shows a comparison of the chelation rates of magnesium ascorbate prepared in examples 1 to 3 of the present invention and comparative examples thereof;

FIG. 6 shows a comparison of the yields of magnesium ascorbate prepared by examples 1 to 3 of the present invention and comparative examples thereof;

FIG. 7 shows a comparison of optical rotation of magnesium ascorbate prepared in examples 1 to 3 of the present invention and comparative examples thereof;

FIG. 8 is an infrared spectrum of ascorbic acid.

FIG. 9 is an infrared spectrum of a magnesium ascorbate product prepared in example 1.

FIG. 10 is an infrared spectrum of a magnesium ascorbate product prepared in example 2.

FIG. 11 is an infrared spectrum of a magnesium ascorbate product prepared in example 3.

FIG. 12 shows the gastric solubility of magnesium ascorbate and magnesium sulfate prepared in examples 1-3 of the present invention and comparative examples.

Fig. 13 shows the solubility of magnesium ascorbate and magnesium sulfate prepared according to examples 1 to 3 of the present invention and comparative examples thereof after intestinal digestion.

FIG. 14 shows the dialysance of magnesium ascorbate and magnesium sulfate after gastric and intestinal digestion as prepared in examples 1-3 of the present invention and comparative examples.

Detailed Description

For a better understanding of the present invention, reference is made to the following examples. It is to be understood that these examples are for further illustration of the invention and are not intended to limit the scope of the invention. In addition, it should be understood that the invention is not limited to the above-described embodiments, but is capable of various modifications and changes within the scope of the invention.

Example 1

35kg of water was weighed into a reaction kettle, heated to boil, cooled to room temperature, and 17.7kg of ascorbic acid was added with stirring. Adding 4.94kg of magnesium carbonate after the ascorbic acid is fully dissolved, controlling the temperature of feed liquid at 50 ℃, controlling the pH value at 6, adjusting the ultrasonic power to 200w, carrying out ultrasonic reaction for 50min, filtering by adopting a 0.4mm membrane, and then carrying out spray drying to obtain the magnesium ascorbate dry powder, wherein the set spray drying parameters are that the feeding speed is 40kg/h, the rotating speed is 560r/min, the air inlet temperature is 200 ℃, and the air outlet temperature is 90 ℃.

The chelating ratio of the magnesium ascorbate dry powder prepared in example 1 was determined to be 97.5%, the yield was 98.1% and the optical rotation was +106 °.

Example 2

35kg of water was weighed into a reaction kettle, heated to boil, cooled to room temperature, and 17.7kg of ascorbic acid was added with stirring. Adding 6kg of magnesium sulfate after ascorbic acid is fully dissolved, controlling the temperature of feed liquid at 55 ℃, controlling the pH value at 6, adjusting the ultrasonic power at 150w, carrying out ultrasonic reaction for 0.5h, carrying out evaporation concentration after filtering by adopting a 0.4mm membrane, adjusting the temperature to 60 ℃, stirring at 25r/min, reducing the temperature gradient at 10 ℃/h, stopping concentration until crystals are separated out, slowly reducing the temperature at 10 ℃/h, filtering after a large amount of crystals are gradually separated out, washing and drying a filter cake, and obtaining the magnesium ascorbate crystals with uniform particles.

The crystal of magnesium ascorbate prepared in example 2 was measured to have a chelating ratio of 97.1%, a yield of 97.5% and an optical rotation of +105.5 °.

Example 3

35kg of water was weighed into a thermal reaction kettle, heated to boil, cooled to room temperature, and 17.7kg of ascorbic acid was added with stirring. Adding 4.7kg of magnesium chloride after the ascorbic acid is fully dissolved, controlling the temperature of feed liquid at 50 ℃, controlling the pH value at 6.5, adjusting the ultrasonic power at 150w, carrying out ultrasonic reaction for 0.5h, filtering by adopting a 0.4mm membrane, and then carrying out spray drying to obtain the magnesium ascorbate dry powder, wherein the set spray drying parameters are that the feeding speed is 40kg/h, the rotating speed is 560r/min, the air inlet temperature is 200 ℃, and the air outlet temperature is 90 ℃.

The chelating ratio of the magnesium ascorbate dry powder prepared in example 3 was determined to be 96.8%, the yield was 96.8% and the optical rotation was +104 °.

Comparative example 1 preparation of magnesium ascorbate by conventional method

Comparative example 1 was operated substantially the same as example 1 except that no sonication was used.

35kg of water was weighed into a reaction kettle, heated to boil, cooled to room temperature, and 17.7kg of ascorbic acid was added with stirring. Adding 4.94kg of magnesium carbonate after the ascorbic acid is fully dissolved, controlling the temperature of feed liquid at 50 ℃, controlling the pH value at 6, keeping the reaction for 50min, filtering by adopting a 0.4mm membrane, and then performing spray drying to obtain the magnesium ascorbate dry powder, wherein the spray drying parameters are that the feeding speed is 40kg/h, the rotating speed is 560r/min, the air inlet temperature is 200 ℃, and the air outlet temperature is 90 ℃.

Comparative example 2 preparation of magnesium ascorbate by conventional method

Comparative example 2 was operated substantially the same as example 2 except that no sonication was used.

35kg of water was weighed into a reaction kettle, heated to boil, cooled to room temperature, and 17.7kg of ascorbic acid was added with stirring. Adding 6kg of magnesium sulfate after ascorbic acid is fully dissolved, controlling the temperature of feed liquid at 55 ℃, controlling the pH value at 6, keeping the reaction for 0.5h, filtering by adopting a 0.4mm membrane, then carrying out evaporation concentration, adjusting the temperature to 60 ℃, stirring at a speed of 25r/min, reducing the temperature gradient to 10 ℃/h, concentrating until crystals are separated out, stopping concentrating, slowly cooling at 10 ℃/h, filtering after a large amount of crystals are gradually separated out, washing and drying a filter cake, and obtaining the magnesium ascorbate crystals with uniform particles.

Comparative example 3 preparation of magnesium ascorbate by conventional method

Comparative example 3 operates substantially the same as example 3 except that no ultrasound is used.

35kg of water was weighed into a thermal reaction kettle, heated to boil, cooled to room temperature, and 17.7kg of ascorbic acid was added with stirring. Adding 4.7kg of magnesium chloride after the ascorbic acid is fully dissolved, controlling the temperature of feed liquid at 50 ℃, controlling the pH value at 6.5, keeping the reaction for 0.5h, filtering by adopting a 0.4mm membrane, and then performing spray drying to obtain the magnesium ascorbate dry powder, wherein the spray drying parameters are that the feeding speed is 40kg/h, the rotating speed is 560r/min, the air inlet temperature is 200 ℃, and the air outlet temperature is 90 ℃.

Test examples

Test example 1

Taking example 1 as an example, this test example illustrates the effect of sonication on magnesium ascorbate by comparing the content of magnesium ascorbate prepared by conventional methods with that of sonication.

The conventional method comprises the following steps: 35kg of water was weighed into a reaction kettle, heated to boil, cooled to room temperature, and 17.7kg of ascorbic acid was added with stirring. Adding 4.94kg of magnesium carbonate after the ascorbic acid is fully dissolved, adjusting the temperature and the pH value of the feed liquid, reacting for a period of time, filtering by adopting a 0.4mm membrane, and then performing spray drying to obtain the magnesium ascorbate dry powder. The influence of each factor is respectively researched by taking the content of magnesium ascorbate as an index: firstly, adjusting the reaction temperature to 50 ℃, reacting for 50min under different pH values, and analyzing the influence of the pH value. Adjusting the pH value of the solution to 6, reacting for 50min at different temperatures, and analyzing the influence of the temperatures. Regulating the pH value of the solution to be 6, reacting at 50 ℃ for different times, and analyzing the influence of the reaction time.

An ultrasonic method: 35kg of water was weighed into a reaction kettle, heated to boil, cooled to room temperature, and 17.7kg of ascorbic acid was added with stirring. Adding 4.94kg of magnesium carbonate after the ascorbic acid is fully dissolved, adjusting the temperature and the pH value of the feed liquid, carrying out ultrasonic reaction for a period of time, filtering by adopting a 0.4mm membrane, and then carrying out spray drying to obtain the magnesium ascorbate dry powder. The influence of each factor is respectively researched by taking the content of magnesium ascorbate as an index: firstly, adjusting the reaction temperature to 50 ℃, controlling the ultrasonic power to be 150w, reacting for 50min under the conditions of different pH values, and analyzing the influence of the pH values. Regulating the pH value of the solution to be 6, controlling the ultrasonic power to be 150w, reacting for 50min at different temperatures, and analyzing the influence of the temperatures. Thirdly, adjusting the pH value of the solution to be 6, adjusting the ultrasonic power to be 150w, reacting for different times at 50 ℃, and analyzing the influence of the reaction time. Adjusting the pH value of the solution to be 6, reacting at the temperature of 50 ℃ for 50min under different ultrasonic frequencies, and analyzing the influence of the ultrasonic frequencies.

The content determination method comprises the following steps:

about 0.3g (accurate to 0.0001g) of a sample dried for 24h by taking phosphorus pentoxide is weighed, the sample is placed in a 250ml conical flask, 50ml of water is added for dissolving, and the solution is immediately titrated by 0.1mol/l iodine standard solution until the solution is light yellow and does not fade within 30s, and the titration end point is obtained. Magnesium ascorbate content (in C)₁₂H₁₄MgO₁₂Dry basis) is calculated according to the following formula:

in the formula: v is the volume of iodine standard titration consumed by the sample in milliliters (ml);

c is the concentration of the iodine standard titration solution in units of moles per liter (mol/l);

m is the molar mass of magnesium ascorbate, in grams per mole (g/mol),

1000 is a conversion factor;

m is the mass of the weighed sample in grams.

(1) The results of the single factor experiment are as follows:

as shown in FIG. 1, the reaction speed of both methods is slow at lower temperature, but the reaction speed of the magnesium ascorbate prepared by the ultrasonic method is obviously higher than that of the conventional method. With increasing temperature, the reaction rates of both methods are increased, while the reaction rate of the ultrasonic method is always higher than that of the conventional method. When the temperature reaches 50 ℃, the content of the magnesium ascorbate prepared by the ultrasonic method reaches the maximum value, and is 95.1 percent; whereas the conventional method has a maximum magnesium ascorbate content of 78% at a temperature of 60 ℃.

As shown in FIG. 2, the conventional method requires 80min for the preparation of magnesium ascorbate to reach its maximum content, which is about 77%; and the ultrasonic method is only required for preparing the magnesium ascorbate within 50min, the content reaches 91 percent, and then the magnesium ascorbate is decomposed and the content is reduced, so that the ultrasonic method can greatly shorten the reaction time and increase the content.

The pH value is an important factor influencing the quality of magnesium ascorbate, ascorbic acid is relatively stable and is not easy to be oxidized under the condition of low pH value, and the content of reactants is reduced because the ascorbic acid is easy to be damaged under the influence of alkaline conditions under the condition of high pH value. As can be seen from FIG. 3, the magnesium ascorbate content in both methods increased with increasing pH at lower pH and tended to decrease after pH reached 6.

As shown in FIG. 4, the content of magnesium ascorbate is maximized at an ultrasonic power of 200w, and decreases as the ultrasonic power is increased, so that it is more suitable to select an ultrasonic power of 200 w.

(2) The results of the orthogonal optimization experiments are as follows:

in the conventional method, on the basis of a single-factor test, 3 factors of temperature, reaction time and pH value are selected as independent variables, the content (Y) of the magnesium ascorbate is taken as a response value, a three-factor three-level orthogonal experiment is carried out, and the analysis result is shown in table 1.

In the ultrasonic method, on the basis of a single-factor test, 4 factors of temperature, pH value, reaction time and ultrasonic power are selected as independent variables, the content (Y) of the magnesium ascorbate is taken as a response value, a four-factor three-level orthogonal experiment is carried out, and the analysis result is shown in table 2.

TABLE 1 results of conventional orthogonal experiments

TABLE 2 results of the ultrasonic orthogonal experiments

As can be seen from R in Table 1, the conventional method has the following factors affecting the magnesium ascorbate content: reaction temperature > pH > reaction time. According to the content of the magnesium ascorbate at different levels, the optimal combination is A2B2C3, and further experiments with the combination A2B2C3 verify that the content of the magnesium ascorbate is 82.9%.

Meanwhile, as can be seen from R in table 2, the sequence of factors affecting the content of magnesium ascorbate in the ultrasonic method is: the reaction temperature is more than the pH value is more than the reaction time is more than the ultrasonic power. According to the content of the magnesium ascorbate of different levels, the optimal combination is A2B2C2D2, namely the reaction temperature is 50 ℃, the pH value is 6, the reaction time is 50min, the ultrasonic power is 200w, and the content of the magnesium ascorbate obtained by further experimental verification of the A2B2C2D2 combination is 98.3%. Namely, the content of the magnesium ascorbate prepared by adopting an ultrasonic method under the optimal process condition is higher than that of the magnesium ascorbate prepared by adopting a conventional method.

Test example 2

The test examples show the physical and chemical indexes of examples 1 to 3 and comparative examples thereof.

(1) The chelation rate was determined as follows:

the chelating rate of magnesium ions is determined by EDTA complexation titration.

The method for processing the sample when the total magnesium content is measured comprises the following steps: accurately weighing ascorbic acid-magnesium raw material mixture in a 250ml conical flask, adding 25ml water for dissolving, and dripping a few drops of hydrochloric acid if the ascorbic acid-magnesium raw material mixture is not dissolved, and shaking until the ascorbic acid-magnesium raw material mixture is completely dissolved for later use.

The sample treatment method for the determination of the content of magnesium ascorbate comprises the following steps: and accurately weighing magnesium ascorbate dried to constant weight at 105 ℃ in a 250ml conical flask, and adding 25ml of water for dissolving for later use.

EDTA complexometric titration: and (3) adding 10mL of ammonia-ammonium chloride buffer solution and a small amount of chrome black T indicator into the dissolved solution for later use, and titrating by using 0.05mol/L of disodium ethylene diamine tetraacetate standard titration solution until the solution is changed from purple to pure blue. Meanwhile, a blank test is also carried out, and the type and the amount of the reagent added (except for the standard titration solution) of the blank sample solution are the same as those of the sample solution except that the sample is not added. The experiment was performed in parallel with 2 portions being prepared and the results averaged. The absolute difference between the results of the two replicates is no greater than 0.3%.

In the formula: v₁: values for the volume of EDTA standard titration solution consumed by magnesium ascorbate in milliliters (mL);

V₀: blank test consumes a value in milliliters (mL) of EDTA standard titration solution volume;

v: consumption of ascorbic acid-magnesium raw Material by volume of EDTA Standard titration solution in milliliters (mL)

c: the concentration of EDTA standard solution, in units of moles per liter (mol/L);

m: the number of molar masses of magnesium, in grams per mole (g/mol) [ M (magnesium) ═ 24 ];

the results are shown in fig. 5, and it is apparent from fig. 5 that the ultrasonication has a certain effect on the chelation rate of magnesium ascorbate. Compared with the magnesium ascorbate synthesized by the conventional method, the chelating rate of the magnesium ascorbate synthesized by the ultrasonic method is further improved. The chelation rates of the magnesium ascorbate prepared in the embodiments 1 to 3 by the ultrasonic method are 97.5%, 97.1% and 96.8% respectively; the chelation rates of the magnesium ascorbate prepared in the comparative examples 1 to 3 by the conventional method are respectively 88.2%, 85.3% and 86.1%.

(2) The yield was determined as follows: accurately weighing the mass of the ascorbic acid and magnesium raw materials to be added, calculating the theoretical mass of a product obtained by reaction according to a chemical method and a reaction principle, and finally comparing the theoretical mass with the mass of the practically collected magnesium ascorbate. The calculation formula is shown in the following chart:

in the test, the actual yield is the mass of the magnesium ascorbate which is actually obtained, and the unit is g; the theoretical yield is the theoretical mass of the magnesium ascorbate obtained by the reaction calculated according to a chemical method and a reaction principle, and the unit is g.

The yield of magnesium ascorbate synthesized by sonication and conventional conditions as determined by the test is shown in figure 6. It is obvious from the figure that the ultrasound has the promotion effect on the improvement of the yield of the magnesium ascorbate, and the yields of the magnesium ascorbate in the preparation examples 1 to 3 of the ultrasound methods are respectively 98.1%, 97.5% and 96.1%; the yields of magnesium ascorbate prepared by the conventional method in comparative examples 1 to 3 were 89.2%, 82.3% and 85.1%, respectively.

(3) The specific optical rotation is measured as follows:

weighing 4g (accurate to 0.0001g) of magnesium ascorbate, placing in a 100ml volumetric flask, adding distilled water for dissolving, diluting, fixing the volume to the scale, and shaking up. The solution was poured into a2 dm polarimeter while the temperature was adjusted to 20 ℃ and the specific rotation was measured by using the D-line of the sodium spectrum. Additionally, distilled water was used for blank correction. The polarimeter readings were repeated three times and averaged.

Specific rotation degree alpha_mThe value of (20 ℃ C., D) is in (. degree.). dm²·kg^-1Expressed, calculated as:

in the formula: d: d-line of the sodium spectrum;

α: measured angle of rotation in degrees (°);

l: the length of the optical rotation tube is decimeter (dm);

ρ_α: the mass concentration of magnesium ascorbate in the solution is given in grams per milliliter (g/mL).

The optical rotation can not only reflect the structure of the substance, but also reflect the content of the substance, and the optical rotation of the magnesium ascorbate synthesized by ultrasound and conventional conditions measured by the test is shown in fig. 7. It is apparent from the figure that the optical rotation of the magnesium ascorbate is significantly affected by the ultrasound, the optical rotations of the magnesium ascorbate in the preparation examples 1 to 3 by the ultrasound are respectively +106 °, +105.5 ° and +104 °, and the optical rotations of the magnesium ascorbate in the preparation comparative examples 1 to 3 by the conventional method are respectively +98.2 °, +95.6 ° and +97 °.

Test example 3

This test example illustrates the structural characterization of magnesium ascorbate.

Scanning and analyzing the ascorbic acid and the magnesium chelate thereof respectively by adopting a Nexus470 intelligent Fourier transform infrared spectrometer to obtain infrared spectra of figures 8-11. From the figure, 3530-2920 cm of the ascorbic acid in the figure 8 can be seen^-1The multiple peak in (1) disappears in the magnesium ascorbate in FIGS. 9 to 11, and is replaced with 3410cm^-1A broad peak as a center, which is a stretching vibration peak of water molecule-OH, indicates that crystal water exists in the product; meanwhile, compared with ascorbic acid, carbonyl and double carbon bonds in magnesium ascorbate are respectively red-shifted to 1730cm^-1And 1610cm^-1This is a change in the infrared spectrum due to the binding of magnesium ions to ascorbic acid, which confirms the formation of the chelate.

Test example 3

This test example illustrates the simulated digestion of magnesium ascorbate in vitro

Dissolving the three magnesium ascorbate and magnesium sulfate prepared in the examples 1-3 and the comparative examples in deionized water, adjusting the pH value of the solution to 2.0 by using 1mol/L HCl, adding pepsin in a certain proportion, uniformly mixing, and performing shaking water bath at 37 ℃ for 2 hours; after the reaction is finished, adding pancreatin and bile extract in a certain proportion into the mixed system, adjusting the pH value of the system to 7.2, transferring the mixture into a dialysis bag (6000Da), and shaking the water bath at 37 ℃ for 2 h.

(1) Determination of magnesium ion dissolution Rate

In the simulated digestion process, after pepsin is digested for 2 hours and pepsin-pancreatin is digested for 4 hours, supernatant is taken, and the content of magnesium ions in the supernatant is determined by an EDTA (ethylene diamine tetraacetic acid) complexation titration method so as to represent the dissolution rate of the magnesium ions in different digestion stages.

V1: titrating the volume of EDTA solution required by magnesium ions in the supernatant, namely mL;

v2: titrating the volume of EDTA solution required by magnesium ions in the equal volume of the solution, wherein the volume is mL;

c: concentration of EDTA solution, mol/L.

(2) Determination of the dialysis Rate of magnesium ions

After the digestion by pancreatin, taking the water solution outside the dialysis bag, and measuring the content of magnesium ions in the water solution by EDTA complexometric titration to show the content of the magnesium ions penetrating through the simulated intestinal tract.

V1: titrating the volume of EDTA solution required by magnesium ions in the supernatant, namely mL;

v2: titrating the volume of EDTA solution required by magnesium ions in the equal volume of the solution, wherein the volume is mL;

c: concentration of EDTA solution, mol/L.

The factors influencing the utilization rate of magnesium in diet are many, the absorption rate of magnesium in diet is low by human body, the main reason is that magnesium and phytic acid can form insoluble complex in small intestine, the insoluble magnesium-phytic acid complex can not be absorbed and utilized by human body due to lack of corresponding phytase in human intestine, the bioavailability of magnesium is greatly reduced, the bioavailability of mineral elements can be evaluated by using in vitro simulated gastrointestinal tract digestion-dialysis method, the dialysis rate and solubility of magnesium ascorbate and magnesium sulfate are determined according to the experimental method described by Wolfgor, and the dissolution rate and dialysis rate of two substances after gastrointestinal tract digestion are shown in figures 12-14.

From the experimental results, the dissolution rates of magnesium ions in the magnesium ascorbate of examples 1 to 3 after stomach digestion are 97.91%, 97.87% and 97.82% respectively, and the dissolution rates after intestinal digestion are 54.38%, 54.56% and 54.33% respectively; comparative examples 1 to 3 the dissolution rates of magnesium ions in magnesium ascorbate after gastric digestion were 97.44%, 97.36% and 97.29%, respectively, and the dissolution rates after intestinal digestion were 51.99%, 52.29% and 52.13%, respectively; the dissolution rates of magnesium ions in the magnesium sulfate after being digested by stomach and intestinal tracts are respectively 97.8% and 33.15%. Examples 1 to 3 had respective dialyzates of 42.68%, 41.59% and 41.71% for magnesium ions in magnesium ascorbate, and comparative examples 1 to 3 had respective dialyzates of 36.37%, 35.98% and 35.12% for magnesium ions in magnesium ascorbate, while the diafiltration of 22.93% for magnesium ions in magnesium sulfate. It can be seen that the dialysis rate of magnesium ions in magnesium ascorbate is significantly higher than that of magnesium sulfate, and although magnesium sulfate exists in a stomach environment in a dissolved state, the solubility of magnesium sulfate is significantly reduced after the magnesium sulfate enters an intestinal environment, so that the magnesium ions in magnesium ascorbate can easily enter the intestinal environment, which indicates that the bioavailability of magnesium ascorbate is higher than that of magnesium sulfate, and the bioavailability of magnesium ascorbate prepared by an ultrasonic method is higher than that of a conventional method, which may be related to the content of magnesium ascorbate.

The above embodiments are only used for illustrating the technical solution of the present invention, and not for limiting the same; although the invention has been described in detail with reference to the foregoing embodiments, it will be apparent to those skilled in the art that various changes may be made and equivalents may be substituted for elements thereof; but it is also intended to cover such modifications or alterations insofar as they come within the scope of the appended claims.