Composite food-grade nano iron oxide particles for iron supplementing and coloring and preparation method of composite food-grade nano iron oxide particles

Abstract

The invention discloses a composite food-grade nano iron oxide particle for iron supplement coloring and a preparation method thereof, the nano iron oxide core with the particle size of 3-8nm is prepared by using food-grade ferric chloride and ferrous sulfate as raw materials through an alkaline coprecipitation method, and sodium citrate and gelatin are used for surface modification to obtain the composite food-grade nano iron oxide particle. And embedding with food-grade polysaccharides such as fructo-oligosaccharide to form stable composite particles. The iron content of the obtained product is greater than or equal to 65%, the absolute value of Zeta potential is greater than or equal to 25mV, the product can be stably dispersed for more than 30 days in a pH range of 3-8, the CIELAB chromaticity parameters are as follows: the L value is 28-35, the a value is 10-15 and the b value is 5-8, and the product has the coloring property required by dark food and excellent iron bioavailability; by accurately controlling the particle size and the surface characteristics, the problems that a traditional iron supplementing agent is low in absorptivity and a coloring agent is single in function are solved; the product is suitable for deep-color health-care food such as donkey-hide gelatin cakes and black sesame pills, and can achieve the dual effects of nutrient enrichment and appearance improvement.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of food and nanomaterial technology, and in particular to a composite food-grade nano-iron oxide particle for iron supplementation and coloring and a preparation method thereof. BACKGROUND

[0002] Iron, as an essential trace element for human body, plays a key role in physiological processes such as hemoglobin synthesis, oxygen transport and cell metabolism. However, iron deficiency is still a common nutritional health problem worldwide, especially in special groups such as women and children. Traditional iron supplementation preparations such as ferrous sulfate and ferrous fumarate, although low in price, have obvious technical defects: on the one hand, these inorganic iron compounds are prone to form insoluble precipitates in the gastrointestinal tract, resulting in low absorption rate (usually less than 10%) and strong irritation, often causing adverse reactions such as nausea and constipation; on the other hand, these iron supplementation agents usually do not have food coloring function, making it difficult to meet the dual requirements of nutrition and aesthetics for modern functional foods.

[0003] In the field of food coloring, the widely used ferric oxide (Fe2O3) pigment has stable coloring performance, but has obvious functional limitations: first, conventional iron oxide particles have large particle size (usually micron level), resulting in poor dispersibility in food systems and easy to produce a grainy feeling, affecting the taste of the product; second, these traditional colorants only have color modification function and do not have nutritional supplementation value at all, which cannot meet the current market demand for functional food additives. More notably, commercially available iron oxide pigments are mostly prepared from industrial-grade raw materials, which may contain harmful impurities such as heavy metals, posing a food safety risk.

[0004] In recent years, the development of nanotechnology has provided a new way to solve the above problems. Nano-iron oxide can theoretically significantly improve the bioavailability of iron due to its unique surface effect and small size characteristics. However, existing nano-iron oxide preparation techniques still have many technical bottlenecks: first, most preparation methods use organic solvents (such as ethylene glycol, N,N-dimethylformamide, etc.) as reaction media, which are difficult to completely remove and do not meet the food-grade safety standards; second, the traditional preparation process lacks sufficient control over particle size, resulting in a wide particle size distribution (usually in the range of 10-100 nm), which seriously affects its stability and sensory properties in food systems; third, unmodified nanoparticles are prone to aggregation, which not only reduces the iron supplementation efficiency, but also affects the texture and appearance of food.

[0005] Especially worth noting is that in the application scene of dark health food (such as Ejiao cake, black sesame pill, etc.), the existing technology product faces double challenges: both to meet the strict food safety requirements and to achieve good coloring effect and nutritional function. At present, there is a lack of products that can meet these needs at the same time in the market, resulting in the fact that manufacturers have to add coloring agents and nutritional fortifiers respectively, which not only increases the cost, but also may affect the product quality due to the interaction of ingredients.

[0006] Therefore, the present application provides a kind of composite food-grade nano iron oxide particles for iron supplementation and coloring and a preparation method, develops a kind of green, safe, edible, has excellent coloring effect and iron supplementation and absorption capacity of nano iron oxide composite particles, adapts to the dual needs of functional strengthening and product appearance of dark health food such as Ejiao cake, black sesame pill, etc. SUMMARY

[0007] The purpose of the present application is to provide a kind of composite food-grade nano iron oxide particles for iron supplementation and coloring and a preparation method, to adapt to the dual needs of functional strengthening and product appearance of dark health food such as Ejiao cake, black sesame pill, etc.

[0008] The purpose of the present application is realized by the following technical solutions:

[0009] A kind of composite food-grade nano iron oxide particles for iron supplementation and coloring, the particle size of the composite food-grade nano iron oxide particles for iron supplementation and coloring is 3-8nm, Zeta potential absolute value is greater than or equal to 25mV, iron content is greater than or equal to 65%;It can be stably dispersed for more than 30 days in the pH range of 3-8 without precipitation or aggregation; CIELAB color parameters are: L value is 28-35, a value is 10-15, b value is 5-8.

[0010] Preferably, the surface of the composite food-grade nano iron oxide particles for iron supplementation and coloring is coated with sodium citrate, gelatin and oligofructose.

[0011] The present application also claims a kind of preparation method of the above-mentioned composite food-grade nano iron oxide particles for iron supplementation and coloring, comprising the following steps:

[0012] (1) FeCl3·6H2O and FeSO4·7H2O are added to water according to the iron molar ratio of 2:1 and dissolved;

[0013] (2) control temperature and adjust pH value by adding NaOH dropwise under constant temperature condition while stirring, for a total of 30-35 minutes;

[0014] (3) add sodium citrate and gelatin, continue to stir for 30-40 minutes for surface modification;

[0015] (4) using magnetic separation technology to collect the particles, and washing 3-5 times with deionized water, adding a polysaccharide embedding agent to adsorb and coat for 2-3 hours at 60-65 DEG C;

[0016] (5) spray drying or directly dispersing in a food-grade solvent to obtain a final product.

[0017] Preferably, in step (2), the control temperature is 50-70 DEG C, and the pH value is adjusted to 9-11 by adding NaOH under constant temperature conditions with stirring at a stirring speed of 200-400 rpm.

[0018] Preferably, in step (3), the sodium citrate accounts for 1-3%, and the gelatin accounts for 0.5-2%; the stirring speed of the continued stirring is 200-400 rpm.

[0019] Preferably, in step (4), the polysaccharide embedding agent is fructooligosaccharide, gum arabic or sodium alginate, and accounts for 0.5-2%.

[0020] Preferably, in step (5), the final product is in the form of black powder or a stable dispersion liquid.

[0021] The application also claims to protect the use of the above-mentioned composite food-grade nano iron oxide particles for iron supplementation and coloring in dark health-care food.

[0022] Due to the use of the above technical solution, the application has the following beneficial effects compared with the prior art:

[0023] 1. In terms of safety, the application realizes food-grade production through strict raw material control and process design; unlike traditional industrial-grade nano material preparation processes, the application uses food-grade ferric chloride and ferrous sulfate as the iron source throughout the process, and uses natural food additives such as sodium citrate and gelatin as surface modifiers, completely avoiding the use of organic solvents, and fundamentally eliminating the risk of heavy metal residues and toxic solvent pollution. This green production process makes the final product fully comply with the safety standards of food additives, and can be directly used in various food systems.

[0024] 2. In terms of product functionality, the application realizes the dual functions of nutritional supplementation and food coloring by precisely controlling the size (3-8 nm) and surface properties (Zeta potential ≥ ± 25 mV) of the nanoparticles, making the product have excellent iron bioavailability and ideal coloring performance; compared with traditional iron supplements, the iron absorption rate of the product can be increased by 2-3 times; compared with conventional iron oxide pigments, the coloring effect is more uniform and stable, and is particularly suitable for the aesthetic needs of dark health-care food. This "one product with dual functions" significantly improves the practical value and economy of the product.

[0025] 3、The application effectively solves the application problem of nanoparticles in food system through the innovative "co-precipitation-double coating" process in technical performance; the synergistic modification of sodium citrate and gelatin not only improves the dispersion stability of the particles (which can be stably dispersed for more than 30 days under pH 3-8), but also improves the taste characteristics; and the embedding of food-grade polysaccharides such as oligofructose further enhances the intestinal permeability of the product; this multi-layer structure design enables the nano-iron particles to well adapt to the processing requirements of different food matrices, and can be applied to cream, pills, soft candy, liquid preparations and the like;

[0026] 4、The magnetic separation technology and spray drying process adopted in the industrial application of the application have significant scale advantages; the entire production process does not require special equipment, the reaction conditions are mild (50-70 DEG C), and the yield is as high as 90% or more, without the generation of toxic by-products, which greatly reduces the production cost and is conducive to rapid industrialization transformation; at the same time, the final product can be made into powder or liquid two dosage forms, which is convenient for food enterprises to flexibly apply in different products. BRIEF DESCRIPTION OF DRAWINGS

[0027] In order to more clearly illustrate the specific embodiments of the present 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 prior art description. Obviously, some of the drawings described below are some embodiments of the present application, and those skilled in the art can also obtain other drawings according to these drawings without creative labor.

[0028] Figure 1 is the preparation flowchart of the composite food-grade nano-iron oxide particles for iron supplementation and coloring of example 1 of the present application;

[0029] Figure 2 is the TEM particle size diagram of the composite food-grade nano-iron oxide particles for iron supplementation and coloring of example 1 of the present application;

[0030] Figure 3 is the dispersion stability diagram of the composite food-grade nano-iron oxide particles for iron supplementation and coloring of example 1 of the present application at different pH values;

[0031] Figure 4 is the coloring force comparison diagram of example 1, comparative example 1 and comparative example 2 of the present application. DETAILED DESCRIPTION

[0032] In order to have a more clear understanding of the technical features, purposes and effects of the present application, the specific implementation schemes will be described in detail.

[0033] The application will be further described in connection with the following examples without being limited to the following examples. The implementation conditions used in the examples can be further adjusted according to different requirements of specific uses, and the implementation conditions indicated are conventional conditions in the industry. The technical features involved in each embodiment of the application can be combined with each other as long as they do not constitute a conflict.

[0034] Example 1

[0035] Referring to the accompanying drawings Figure 1 - the accompanying Figure 4 The embodiment provides a preparation method of a composite food-grade nano iron oxide particle for iron supplementation and coloring, comprising the following steps:

[0036] (1) FeCl3·6H2O and FeSO4·7H2O are added to water according to a molar ratio of iron 2:1 for dissolution;

[0037] (2) The temperature is controlled at 60°C, and NaOH is added dropwise under constant temperature and stirring at a stirring speed of 350 rpm to adjust the pH value to 10, and the co-precipitation is performed for 30 minutes;

[0038] (3) 2% sodium citrate and 1% gelatin are added, and the stirring is continued at a stirring speed of 300 rpm for 30 minutes for surface modification;

[0039] (4) The particles are collected by magnetic separation technology, and washed with deionized water for 3-5 times, 1% oligofructose is added, and adsorption coating is performed at 60°C for 2 hours;

[0040] (5) The composite food-grade nano iron oxide particle black powder for iron supplementation and coloring is obtained by spray drying.

[0041] It is detected that the TEM particle size distribution of the composite food-grade nano iron oxide particle for iron supplementation and coloring in the embodiment is 4.8 nm;

[0042] The Zeta potential is -28.2 mV;

[0043] The Fe content is 68.2%;

[0044] The dispersion stability is no precipitation after storage at 25°C for 30 days.

[0045] Comparative Example 1

[0046] The comparative example is a traditional iron oxide red.

[0047] Comparative Example 2

[0048] The comparative example is a traditional iron oxide black.

[0049] By Figure 4It can be seen that the L, a, b parameters of the nano iron oxide of the present application and traditional iron oxide red and iron oxide black in CIELAB color difference space, and the results show that:

[0050] The L value of the product of the present application is 32.5, which is significantly lower than that of traditional iron oxide red (45.2) and slightly higher than that of iron oxide black (28.4), indicating that it has good visual dark color tone of black and red, and strong hiding power;

[0051] The a value (redness) is 12.8, which shows moderate red color tone, is better than that of iron oxide black, is close to that of iron oxide red, and is suitable for black sesame pill, donkey-hide gelatin cake and other dark food;

[0052] The b value (yellowness) is 6.2, which shows that the product has a certain warm color tone, making the coloring effect more natural and soft; it can be seen that the product of the present application has more balanced color tone and luster while maintaining good coloring power, and is suitable for appearance improvement and function strengthening of nutrient type dark health food.

[0053] In summary, the application realizes food-grade production in the aspect of safety through strict raw material control and process design; different from traditional industrial-grade nanometer material preparation process, the application uses food-grade ferric chloride and ferrous sulfate as iron source, and uses natural food additives such as sodium citrate and gelatin as surface modifier, completely avoids the use of organic solvent, and fundamentally eliminates the risk of heavy metal residue and toxic solvent pollution, so that the green production process makes the final product completely meet the safety standard of food additives, and the product can be directly used in various food systems; the application realizes the dual effects of nutrition supplement and food coloring in the aspect of product functionality, through accurate control of the size (3-8 nm) and surface properties (Zeta potential ≥ ± 25 mV) of the nanoparticles, the product has excellent iron bioavailability and ideal coloring performance; compared with traditional iron supplements, the iron absorption rate of the product can be increased by 2-3 times; compared with conventional iron oxide pigments, the coloring effect is more uniform and stable, and it is particularly suitable for the aesthetic needs of dark health food, the "one product with dual effects" feature significantly improves the practical value and economy of the product; through the innovative "co-precipitation-double coating" process, the application effectively solves the application problem of nanoparticles in food systems; the synergistic modification of sodium citrate and gelatin not only improves the dispersion stability of the particles (stable dispersion for more than 30 days under pH 3-8 conditions), but also improves the taste characteristics; and the embedding of food-grade polysaccharides such as fructooligosaccharides further enhances the intestinal permeability of the product; the multi-layer structure design makes the nanometer iron particles well adapt to the processing requirements of different food matrices, and the product can be applied to cream, pills, soft candy, liquid preparations and the like; the magnetic separation technology and spray drying process used in the application have significant scale advantages; the whole production process does not require special equipment, the reaction conditions are mild (50-70℃), and the yield is as high as more than 90%, without the generation of toxic by-products, so that the simple and efficient preparation method greatly reduces the production cost and is conducive to rapid industrialization transformation; at the same time, the final product can be made into powder or liquid two dosage forms, which is convenient for food enterprises to flexibly apply in different products.

[0054] The above-described embodiment only expresses one embodiment of the application, which is described in detail, but cannot be understood as a limitation on the scope of the patent. It should be noted that for ordinary skilled persons in the art, without departing from the concept of the application, a number of modifications and improvements can be made, which are within the scope of the application. Therefore, the protection scope of the patent of the application should be subject to the appended claims.

Claims

1. A composite food-grade nano-iron oxide particle for iron supplementation and coloring, characterized by, The compound food-grade nano-iron oxide particles for iron supplementing and coloring have a particle size of 3-8 nm, an absolute value of Zeta potential of ≥25 mV, and an iron content of ≥65%; the particles can be stably dispersed for more than 30 days without precipitation or aggregation in a pH range of 3-8; and the CIELAB chromaticity parameters are as follows: L value, 28-35; a value, 10-15; and b value, 5-8.

2. The complex food-grade nano-iron oxide particles for iron-fortified coloring according to claim 1, characterized by, The compound food-grade nano-iron oxide particles for iron supplementing and coloring are coated with sodium citrate, gelatin and fructooligosaccharide on the surface.

3. A method for preparing the complex food-grade nano-iron oxide particles for iron fortification and coloring according to any one of claims 1 to 2, characterized in that, The method comprises the following steps: (1) dissolving FeCl3·6H2O and FeSO4·7H2O in water according to a molar ratio of iron of 2:1; (2) controlling the temperature and adjusting the pH value by adding NaOH dropwise under constant temperature and stirring for 30-35 minutes; (3) adding sodium citrate and gelatin, and continuing to stir for 30-40 minutes for surface modification; (4) collecting the particles by magnetic separation, washing 3-5 times with deionized water, adding a polysaccharide embedding agent, and adsorbing and coating at 60-65℃ for 2-3 hours; (5) spray drying or directly dispersing in a food-grade solvent to obtain the final product.

4. The preparation method of the complex food-grade nano-iron oxide particles for iron fortification and coloring according to claim 3, characterized in that, In step (2), the temperature is controlled at 50-70℃, and the pH value is adjusted to 9-11 by adding NaOH dropwise under constant temperature and stirring at a speed of 200-400 rpm.

5. The preparation method of the complex food-grade nano-iron oxide particles for iron supplementation and coloring according to claim 3, characterized in that, In step (3), the sodium citrate accounts for 1-3%, and the gelatin accounts for 0.5-2%; and the stirring speed during the continuous stirring is 200-400 rpm.

6. The preparation method of the complex food-grade nano-iron oxide particles for iron fortification and coloring according to claim 3, characterized in that, In step (4), the polysaccharide embedding agent is fructooligosaccharide, gum arabic or sodium alginate, and accounts for 0.5-2%.

7. The preparation method of the complex food-grade nano-iron oxide particles for iron fortification and coloring according to claim 3, characterized in that, In step (5), the final product is in the form of black powder or stable dispersion liquid.

8. Application of the compound food-grade nano-iron oxide particles for iron supplementing and coloring prepared by the method of any one of claims 1-2 or 3-7 in iron supplementing and coloring in dark health-care food.

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