Preparation method and application of chitosan-ferrous fumarate complex

Abstract

The application discloses a preparation method and application of a chitosan-ferrous fumarate compound. Chitosan and fumaric acid are blended and dissolved, a soluble strong base weak acid salt solution and an antioxidant are added to obtain a chitosan suspension, the chitosan suspension is heated in a water bath, a ferrous sulfate solution is added dropwise, stirring reaction is carried out, and then filtration, water washing and freeze-drying are carried out to obtain the chitosan-ferrous fumarate compound. The preparation method is used for compounding chitosan and ferrous fumarate, improves the suspensibility of the chitosan-ferrous fumarate compound, and is used as an iron fortifier in a nutrient supplement food containing oil and fat, can effectively delay the oxidation of the oil and fat, does not produce a rancid smell, can improve the taste of the food and is beneficial to health, and also provides a new development direction for ferrous fumarate preparations.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of iron fortifier preparation, in particular to a preparation method and application of a chitosan-ferrous fumarate complex. BACKGROUND

[0002] Iron is an essential trace element in human body, and its content is also the most in human body. Iron is widely distributed in human body, and almost all tissues contain iron, among which the content in liver and spleen is the highest, followed by kidney, heart, bone, muscle and brain. Iron participates in oxygen transport, exchange and tissue respiration in the body; maintains normal hematopoietic function, and the content of iron in red blood cells accounts for about 2 / 3 of the total iron content in the body. In addition, iron is also related to maintaining normal immune function. Studies have found that iron deficiency can reduce lymphocytes and reduce natural killer cell activity. However, in daily life, the content of iron in food is very small; if the content of iron in the human body is insufficient, the amount of hemoglobin decreases, the oxygen transport capacity decreases, and anemia symptoms are caused; if the human body suffers from iron deficiency, not only anemia symptoms are caused, but also low birth weight babies are born during pregnancy, and children's development is delayed, abnormal movement, etc.

[0003] Homogenization plays a very important role in modern food processing industry. The suspension stability of the dispersed phase of the heterogeneous liquid food in the continuous phase is closely related to the particle size and uniformity of the dispersed phase. The smaller the particle size and the more uniform the distribution, the greater the stability. Homogenization is applied during processing to improve sensory quality and increase the nutritional absorption rate of food.

[0004] Ultrasonic treatment technology, as a new non-thermal processing method, has a series of advantages that traditional processing methods cannot achieve, and has been widely used in food processing. In addition, the ultrasonic treatment equipment can also realize high automation, saving labor cost, and has broad development prospects.

[0005] Chitosan can inhibit the growth of bacteria and mold, and is often added to pickled foods or used for preservation of marine shrimp, lychee and kiwi fruit. Chitosan is also an excellent wound dressing and can be used directly on wounds. In addition, chitosan is a basic natural polysaccharide, has anti-gastric acid and anti-ulcer effects, and is also used to treat allergic dermatitis and reduce the levels of serum cholesterol, urea and creatine in patients with kidney disease. Chitosan can also be used as a sustained-release carrier for medicines and pesticides, a gelation reagent, a biosensor, a synthetic artificial organ artificial skin, mucosa, key, tooth, bone and bone fixation rod material, and can also be used as a weight loss drug.

[0006] When used as an iron fortifier, ferrous fumarate has low activity due to easy oxidation, and poor suspension in liquid matrix and rapid sedimentation, resulting in low consumer reselection rate. Therefore, it is necessary to study how to improve the water insolubility of iron fortifier. SUMMARY

[0007] The present application aims to provide a preparation method of chitosan-ferrous fumarate complex, at least to solve the dispersion problem of ferrous fumarate in the liquid matrix in the prior art.

[0008] In view of this, the scheme of the present application is as follows:

[0009] A preparation method of chitosan-ferrous fumarate complex, comprising the following steps:

[0010] S1. Fumaric acid and chitosan are added to deionized water, and heated and stirred until dissolved;

[0011] S2. A soluble strong base weak acid salt is added to the solution obtained in S1, and after the chitosan is precipitated, an antioxidant is added;

[0012] S3. The temperature is raised to 95-100℃, a ferrous sulfate solution is added, and the reaction is stirred for 2-3h to obtain a yellow-brown suspension;

[0013] S4. The suspension obtained in S3 is filtered, and the filtrate is purified to obtain chitosan-ferrous fumarate complex.

[0014] Further, the molar ratio of the soluble strong base weak acid salt to ferrous sulfate is 0.8-1.1. The use of the soluble strong base weak acid salt can promote the reaction conversion rate on the one hand by reacting with fumaric acid to generate soluble salt, and on the other hand by changing the pH value of the solution to precipitate chitosan. According to the selection of personnel in the art, the soluble strong base weak acid salt can be selected from sodium carbonate, sodium bicarbonate, potassium carbonate, potassium bicarbonate, sodium acetate, etc.

[0015] Further, the concentration of the soluble strong base weak acid salt solution is 10-20wt%, and the concentration of the ferrous sulfate solution is 5-10wt%.

[0016] Further, the addition amount of the antioxidant is 0.2-0.5% of the mass of fumaric acid.

[0017] Further, the filter residue purification process in step S4 is: washing the filter residue several times; collecting the filter residue, adding deionized water, and stirring to mix uniformly; then homogenizing and ultrasonic treatment to obtain a yellow-brown turbid liquid; freeze-drying the turbid liquid to obtain chitosan-ferrous fumarate complex.

[0018] Preferably, the homogenization is performed by a high-speed dispersion homogenizer at a speed of 12000-20000 rpm for 5-10 min. The force of homogenization is mainly shear force and pressure. During the homogenization, the laminar flow effect is generated, the dispersed phase particles or droplets are sheared and stretched to be broken; the turbulent flow effect is generated, the particles or droplets are randomly deformed under pressure fluctuation; the cavitation effect is generated, the small bubbles are broken rapidly under the action of high pressure, energy is released, thereby causing local hydraulic impact and vibration. Under the combined action, the material is in a good uniform distribution state.

[0019] Preferably, the ultrasonic treatment is performed by a probe-type ultrasonic cell disruptor for 5-20 min at an ultrasonic power of 100-500 W and an ultrasonic frequency of 20-25 KHz. The ultrasonic wave can accelerate mass and heat transfer, shorten the unit operation time, and improve the operation efficiency; can also control the crystal size distribution and improve the quality of food.

[0020] Further, the soluble strong base weak acid salt is a carbonate salt; and the antioxidant is at least one of ascorbic acid, sodium ascorbate and sodium erythorbate.

[0021] Another object of the present application is to provide the chitosan-ferrous fumarate complex prepared by the above preparation method, which has an infrared spectrum of 3600-3291 cm -1 a single peak absorption of -NH2.

[0022] Another object of the present application is to provide the application of the chitosan-ferrous fumarate complex in food additives. The chitosan-ferrous fumarate complex can be added to human food and animal feed as an iron fortifier to achieve the effects of iron supplementation and anemia improvement; preferably, the chitosan-ferrous fumarate complex is compounded with functional oil nutrients or other reducing active ingredients as an additive to form functional food or feed. Since the chitosan-ferrous fumarate complex has strong antioxidant activity and oil catalytic oxidation stability, it can maintain the stability of oil and other active ingredients in the fortified food matrix, such as reducing the oxidation rate of oil, thereby improving the stability of the fortified product and prolonging the shelf life, and improving the selection rate of consumers. In one embodiment, when the chitosan-ferrous fumarate complex is added as an antioxidant preparation, the molecular weight of the chitosan used in the above preparation process is preferably 30KD-1000KD.

[0023] Compared with the prior art, the present application has the following beneficial effects, but not limited to:

[0024] 1. The preparation method of the present application, in the presence of fumaric acid in the acidic environment, the introduction of chitosan solution, the solution pH from acidic to neutral change is uniform, so that it participates in the complex reaction, obtain chitosan-ferrous fumarate complex; the complex has good suspension, as iron fortifier added, can be long time in food solution system to maintain uniform dispersion, will not produce precipitation.

[0025] 2. The preparation method of the present application uses chitosan, a natural, non-toxic polymer, raw material source is abundant, low price; at the same time, chitosan gives iron complex certain antioxidant and stability, as iron fortifier used in the high content of unsaturated fatty acid of soybean raw material as the matrix of high vitamin mineral density of nutrient supplement food, especially the special diet food of complementary food nutrition supplement category, can effectively reduce the degree and rate of oil oxidation, will not produce halitosis, improve the taste of food and is beneficial to health. BRIEF DESCRIPTION OF DRAWINGS

[0026] Figure 1 The complex prepared in examples 1-3 of the present application and ferrous fumarate apparent contrast results.

[0027] Figure 2 The complex prepared in examples 1-3 of the present application and ferrous fumarate infrared spectrum contrast results.

[0028] Figure 3 The complex prepared in examples 1-3 of the present application and ferrous fumarate apparent suspension contrast results.

[0029] Figure 4 The complex prepared in examples 1-3 of the present application and ferrous fumarate DPPH free radical scavenging ability contrast results.

[0030] Figure 5 The complex prepared in example 1 of the present application and ferrous fumarate on the influence of soybean oil peroxide value contrast results. DETAILED DESCRIPTION

[0031] In order to make the purpose, technical scheme and beneficial technical effect of the present application more clear, the following will be further described in detail. It should be understood that the specific embodiments described in the specification are only for the purpose of explaining the present application, and are not intended to limit the present application.

[0032] Example 1

[0033] A preparation method of chitosan-ferrous fumarate complex, comprising the following steps:

[0034] 1. Add 2.9g of anhydrous sodium carbonate to reaction vessel I, add 20g of deionized water, place on a magnetic stirrer at 200rpm, and stir for 1h until completely dissolved; add 7.2g of ferrous sulfate heptahydrate to reaction vessel II, add 100g of deionized water, and place on a magnetic stirrer at 800rpm, and stir for 1h until completely dissolved.

[0035] 2. Add 3g fumaric acid, 0.5g chitosan (30KD), and 80g deionized water to reaction vessel III. Stir for 1 hour at a water bath temperature of 95℃ to obtain a clear solution. While stirring, slowly add the prepared anhydrous sodium carbonate solution and 0.01g ascorbic acid dropwise to the solution, stirring vigorously to obtain a chitosan suspension. Then, raise the water bath temperature to 98℃ and add the prepared ferrous sulfate solution dropwise while stirring. After the addition is complete, maintain this temperature and stir for 2 hours to obtain a yellowish-brown suspension. No stratification was observed after standing for 30 minutes.

[0036] 3. Filter the yellowish-brown suspension and wash the filter residue 6 times with water. Add deionized water at a ratio of 70g water per 5g filter residue, then homogenize (16000rpm, 8min) and sonicate (500W, 10min, 20KHz) to obtain a yellowish-brown turbid liquid. Freeze-dry the turbid liquid to obtain the chitosan-ferrous fumarate complex with a purity of 99.1% and a yield of 64.3% based on the mass of ferrous sulfate added.

[0037] Example 2

[0038] A method for preparing a chitosan-ferrous fumarate complex includes the following steps:

[0039] 1. Add 6g of anhydrous sodium carbonate to reaction vessel I, add 40g of deionized water, place it on a magnetic stirrer at 600rpm, and stir for 1h until completely dissolved; add 15g of ferrous sulfate heptahydrate to reaction vessel II, add 200g of deionized water, and place it on a magnetic stirrer at 800rpm, and stir for 1h until completely dissolved.

[0040] 2. Add 6.5g fumaric acid, 1.2g chitosan (300KD), and 160g deionized water to reaction vessel III. Stir for 1 hour at a water bath temperature of 95℃ to obtain a clear solution. While stirring, slowly add the prepared anhydrous sodium carbonate solution dropwise to the solution, stirring vigorously. Add 0.03g reduced iron powder to obtain a chitosan suspension. Then, raise the water bath temperature to 95℃ and add the prepared ferrous sulfate solution dropwise while stirring. After the addition is complete, maintain this temperature and stir for 2 hours to obtain a yellowish-brown suspension. No stratification was observed after standing for 30 minutes.

[0041] 3. Filter the yellowish-brown suspension and wash the filter residue 8 times with water. Take the filter residue and add deionized water at a ratio of 100g water to 6g of filter residue. Then homogenize (15000rpm, 10min) and sonicate (500W, 10min, 20KHz) to obtain a yellowish-brown turbid liquid. Freeze-dry the turbid liquid to obtain chitosan-ferrous fumarate complex with a purity of 99.3% and a yield of 63.7% based on the mass of ferrous sulfate added.

[0042] Example 3

[0043] A method for preparing a chitosan-ferrous fumarate complex includes the following steps:

[0044] 1. Add 3g of anhydrous sodium carbonate to reaction vessel I, add 20g of deionized water, place it on a magnetic stirrer at 600rpm, and stir for 1h until completely dissolved; add 8g of ferrous sulfate heptahydrate to reaction vessel II, add 100g of deionized water, and place it on a magnetic stirrer at 800rpm, and stir for 1h until completely dissolved.

[0045] 2. Add 3.4g fumaric acid, 0.3g chitosan (1000KD), and 80g deionized water to reaction vessel III. Stir for 1 hour at a water bath temperature of 95℃ to obtain a clear solution. While stirring, slowly add the prepared anhydrous sodium carbonate solution dropwise to the solution. Stir vigorously and add 0.01g ascorbic acid to obtain a chitosan suspension. Then, raise the water bath temperature to 95℃ and add the prepared ferrous sulfate solution dropwise while stirring. After the addition is complete, maintain this temperature and stir for 2 hours to obtain a yellowish-brown suspension. No stratification was observed after standing for 30 minutes.

[0046] 3. Filter the yellowish-brown suspension and wash the filter residue 5 times with water. Add deionized water at a ratio of 10g water to 8g filter residue. Then homogenize (16000rpm, 10min) and sonicate (400W, 10min, 20KHz) to obtain a yellowish-brown turbid liquid. Freeze-dry the turbid liquid to obtain chitosan-ferrous fumarate complex with a purity of 98.9% and a yield of 64.8% based on the mass of ferrous sulfate added.

[0047] Comparative Example 1

[0048] 1. Add 7.2g of ferrous sulfate heptahydrate to reaction vessel I, add 100g of deionized water, and stir with a magnetic stirrer at 800rpm for 1 hour until completely dissolved.

[0049] 2. Add 3g of fumaric acid and 80g of deionized water to reaction vessel II to dissolve and obtain a clear solution; then heat the water bath to 95℃, add 0.01g of ascorbic acid, and add the prepared ferrous sulfate solution dropwise while stirring, and simultaneously add 0.5g of chitosan (30KD) slowly. After the addition is complete, maintain the temperature at 95℃ and stir for 2 hours to obtain a yellowish-brown suspension. After standing for 30 minutes, a significant layering phenomenon was observed. The upper layer was taken and analyzed to find that its composition was chitosan, indicating that the chitosan added later hardly reacted.

[0050] Comparative Example 2

[0051] 1. Add 7.2g of ferrous sulfate heptahydrate to reaction vessel II, add 100g of deionized water, and stir with a magnetic stirrer at 800rpm for 1 hour until completely dissolved.

[0052] 2. Dissolve 6.5g of fumaric acid and 80g of deionized water in reaction vessel III to obtain a clear solution. Add 0.01g of ascorbic acid and, while stirring, dropwise add the prepared ferrous sulfate solution. After the addition is complete, maintain this temperature and stir for 2 hours. Then add 0.5g of chitosan (30KD) and stir for 1 hour until completely dissolved. Control the water bath temperature at 95℃ and stir for 2 hours to obtain a yellowish-brown suspension. After standing for 30 minutes, it was found that there was a layering phenomenon. The upper layer was taken and analyzed to find that its composition was chitosan, indicating that the amount of chitosan added later participated in the reaction was relatively small.

[0053] 3. The yellowish-brown suspension was filtered, the filter residue was washed with water, homogenized, and ultrasonically treated in the same manner as in Example 1. The turbid liquid was freeze-dried to obtain product 1. The content of chitosan-ferrous fumarate complex in the product was analyzed, and the result was 31.2%.

[0054] Comparative Example 3

[0055] 1. Add 7.2g of ferrous sulfate heptahydrate to reaction vessel II, add 100g of deionized water, and stir with a magnetic stirrer at 800rpm for 1 hour until completely dissolved.

[0056] 2. A clear solution was obtained by stirring 3g of fumaric acid, 0.5g of chitosan (30KD), and 80g of deionized water at a water bath temperature of 95℃ for 1 hour. 0.01g of ascorbic acid was added, and a prepared ferrous sulfate solution was added dropwise while stirring. After the addition was complete, the reaction was maintained at this temperature and stirred for 2 hours. An anhydrous sodium carbonate solution was then slowly added dropwise while stirring, and the mixture was stirred at a water bath temperature of 95℃ for 2 hours to obtain a yellowish-brown suspension. After standing for 30 minutes, significant layering was observed. Analysis of the upper layer revealed that it was composed of chitosan, indicating that the added chitosan was unlikely to react in the absence of sodium carbonate.

[0057] Comparative Example 4

[0058] 1. Add 2.9g of anhydrous sodium carbonate to reaction vessel I, add 20g of deionized water, place on a magnetic stirrer at 200rpm, and stir for 1h until completely dissolved; add 7.2g of ferrous sulfate heptahydrate to reaction vessel II, add 100g of deionized water, and place on a magnetic stirrer at 800rpm, and stir for 1h until completely dissolved.

[0059] 2. A clear solution was obtained by stirring 6.5g of fumaric acid, 0.5g of chitosan (30KD), and 80g of deionized water at a water bath temperature of 95℃ for 1 hour. 0.01g of ascorbic acid was added, and a prepared ferrous sulfate solution was added dropwise while stirring. After the addition was complete, the reaction was maintained at this temperature and stirred for 2 hours. An anhydrous sodium carbonate solution was then slowly added dropwise while stirring, and the mixture was stirred at a water bath temperature of 95℃ for 2 hours to obtain a yellowish-brown suspension. After standing for 30 minutes, stratification was observed. Analysis of the upper layer revealed that it was composed of chitosan, indicating that the amount of chitosan added later participated in the reaction in a relatively small amount.

[0060] 3. The yellowish-brown suspension was filtered, the filter residue was washed with water, homogenized, and ultrasonically treated in the same manner as in Example 1; the turbid liquid was freeze-dried to obtain product 2, and the content of chitosan-ferrous fumarate complex in the product was analyzed, and the result was 46.5%.

[0061] Compared with Examples 1-3, Comparative Examples 1-4 all showed difficulty in obtaining or were unable to obtain chitosan-ferrous fumarate complexes. This is because adding chitosan under fumaric acid conditions allows for its dissolution, while adding sodium carbonate forms disodium fumarate with fumaric acid. This not only improves the subsequent formation efficiency of ferrous fumarate but also raises the pH value, ensuring that chitosan is uniformly distributed in the solution as microparticles. Under stirring and heating conditions, disodium fumarate combines with ferrous ions through displacement to obtain ferrous fumarate, which then coordinates with chitosan microparticles to yield the product.

[0062] Experimental Example

[0063] 1. Appearance of chitosan-ferrous fumarate complex

[0064] Commercially available ferrous fumarate and the iron complexes obtained from Examples 1-3 after filtration, drying, and pulverization were compared in appearance. Figure 1 As shown, (a), (b), (c), and (d) are the appearance images of commercially available ferrous fumarate, and the chitosan-ferrous fumarate complexes prepared in Examples 1, 2, and 3, respectively, after filtration, drying, and pulverization. It can be seen that the chitosan-ferrous fumarate complexes prepared in Examples 1-3, after vacuum freeze-drying and pulverization, are orange-red or reddish-brown powders with a slippery feel, do not easily absorb moisture and clump, and have a noticeable iron odor. The iron complex is darker in color than commercially available ferrous fumarate. Furthermore, the effect is more pronounced with increasing relative molecular mass of the introduced chitosan.

[0065] 2. Infrared analysis

[0066] Dry ferrous fumarate, 30KD chitosan, and the iron complex powder prepared in Examples 1-3 were mixed with potassium bromide dried to constant weight at a mass ratio of 1:200. After thorough grinding, the mixture was prepared into tablets, and Fourier transform infrared spectroscopy was used to analyze the powders at 4000–4000 cm⁻¹. -1 The infrared spectrum was measured within the wavenumber range, and the obtained spectra were compared and analyzed. Figure 2 As shown. By Figure 2 It can be seen that the main component of the complex is ferrous fumarate, so the spectra of the two are basically similar; among them, 1077 cm⁻¹ -1 and 1157cm -1 This is a superposition peak of chitosan and ferrous fumarate. The iron complex is located at 3600–3291 cm⁻¹. -1 The region shows a single-peak absorption of -NH2, and this peak shifts to a lower frequency direction compared to chitosan, indicating that the amino groups in the chitosan molecule underwent a coordination reaction, possibly forming a chitosan-iron complex. This suggests that the iron complex is not a simple mixture of chitosan and ferrous fumarate, but a novel complex.

[0067] 3. Apparent suspension

[0068] The suspension properties of the chitosan-ferrous fumarate complexes prepared in Examples 1, 2, and 3 were evaluated. The chitosan-ferrous fumarate complexes were lyophilized, pulverized, and dispersed in deionized water, compared with those without chitosan-ferrous fumarate (concentration: 1 mg Fe / mL). The experimental results after 120 min of dispersion are shown below. Figure 3 As shown, ferrous fumarate (a) clearly formed a precipitate, while the chitosan-ferrous fumarate complex rehydrated suspensions prepared in Examples 1 (b), 2 (c), and 3 (d) exhibited a stable and homogeneous suspension state. Figure 3 It can be seen that the introduction of chitosan significantly improves the suspension properties of ferrous fumarate, and the effect is more pronounced with the increase of chitosan molecular weight.

[0069] 4. Evaluation of antioxidant activity

[0070] Ferrous fumarate at concentrations of 0, 2, 4, 6, 8, and 10 mg / mL, iron complexes prepared in Examples 1, 2, and 3 (based on total iron content), and 0.4 mL of ascorbic acid solution were mixed with 2.0 mL of 50 mg / L DPPH ethanol solution and placed in 5 mL centrifuge tubes. The mixtures were incubated in the dark for 30 min, and the absorbance at 517 nm was measured using a spectrophotometer to evaluate the DPPH free radical scavenging ability of the iron complexes. Results are as follows: Figure 4 As shown, by Figure 4It was found that ferrous fumarate had almost no DPPH radical scavenging ability in the range of 2-10 mg / mL. The addition of chitosan endowed the iron complex with certain antioxidant activity; the larger the molecular weight of chitosan, the stronger the antioxidant capacity. Furthermore, the DPPH radical scavenging ability of the iron complex showed a certain concentration dependence.

[0071] 5. Iron absorption detection

[0072] Animal experiments were conducted using the chitosan-ferrous fumarate complex prepared in Example 3. Rats weighing 150±10g were acclimatized for one week and then fed a low-iron diet for four weeks. They were then weighed and randomly divided into two groups: one receiving ferrous fumarate and the other receiving the chitosan-ferrous fumarate complex (n=20 per group). While continuing to be fed the low-iron diet, both groups were administered ferrous fumarate or chitosan-ferrous fumarate by gavage at a ferrous content of 0.65 mg / kg·d for four consecutive weeks. Serum iron and hemoglobin levels were then measured. The experimental results are shown in Table 1.

[0073] Table 1. Blood parameters in rats

[0074]

[0075]

[0076] As can be seen from Table 1, the chitosan-ferrous fumarate complex of the present invention has an absorption effect comparable to that of traditional commercially available iron supplements, while also having good processing performance.

[0077] 6. Oil Oxidation Stability Testing

[0078] Pure soybean flour was mixed separately with ferrous fumarate and the iron complex prepared in Example 1, and sealed in PE plastic bags, 120g of soybean flour per bag, with the iron content controlled at 100mg / bag (based on total iron content). A blank control group was also set up. Each group had 3 replicates. Accelerated storage conditions were achieved by storing at a constant temperature of 37℃ for 35 days, with samples taken every 5 days to extract soybean flour oil and monitor the change in peroxide value of the sample oil during storage. The results are as follows: Figure 5 As shown. By Figure 5 It can be seen that the peroxide value of the oils in both the ferrous fumarate group and the iron complex group showed an increasing trend during the 35-day storage period. The iron complex, due to the introduction of chitosan, possessed a certain antioxidant capacity, and its increase was less than that of the ferrous fumarate group. Therefore, it can be concluded that the introduction of chitosan endowed the complex with good antioxidant activity, effectively slowing down the rate of oil oxidation.

[0079] This invention is not limited to the description in the specification and embodiments, and thus other advantages and modifications can be readily realized by those skilled in the art. Therefore, without departing from the spirit and scope of the general concept defined by the claims and their equivalents, this invention is not limited to the specific details, representative solutions and examples described herein.

Claims

1. A method for preparing a chitosan-ferrous fumarate complex, characterized in that, Includes the following steps: S1. Add fumaric acid and chitosan to deionized water, heat and stir until dissolved; S2. Add a soluble strong base weak acid salt to the solution obtained in S1, stir until chitosan precipitates, and then add an antioxidant; S3. Heat to 95-100℃, add ferrous sulfate solution, keep warm and stir for 2-3 hours to obtain a yellowish-brown suspension; S4. Filter the suspension obtained in S3, and purify the filter residue to obtain the chitosan-ferrous fumarate complex.

2. The preparation method according to claim 1, characterized in that, The molar ratio of the soluble strong base weak acid salt to ferrous sulfate is 0.8–1.1, the molar ratio of the soluble strong base weak acid salt to fumaric acid is 0.8–1.1, the mass ratio of fumaric acid to deionized water is 1:20–1:50, and the mass ratio of fumaric acid to chitosan is 1:5–1:

10.

3. The preparation method according to claim 1, characterized in that, The concentration of the soluble strong base weak acid salt solution is 10-20 wt%, and the concentration of the ferrous sulfate solution is 5-10 wt%.

4. The preparation method according to claim 1, characterized in that, The amount of antioxidant added is 0.2 to 0.5% of the mass of fumaric acid.

5. The preparation method according to claim 1, characterized in that, The filter residue purification process described in step S4 is as follows: wash the filter residue with water several times; collect the filter residue, add deionized water, and stir to mix evenly; then homogenize and sonicate to obtain a yellowish-brown turbid liquid; freeze-dry the turbid liquid to obtain the chitosan-ferrous fumarate complex.

6. The preparation method according to claim 1, characterized in that, The soluble strong base weak acid salt is a carbonate; the antioxidant is at least one of ascorbic acid, sodium ascorbate, and sodium isoascorbate.

7. The preparation method according to claim 1, characterized in that, The chitosan has a molecular weight of 30KD to 1000KD.

8. The chitosan-ferrous fumarate complex obtained by the preparation method according to any one of claims 1 to 7, characterized in that, Its infrared spectrum is between 3600 and 3291 cm⁻¹. -1 The region exhibits a single-peak absorption of -NH2.

9. The application of the chitosan-ferrous fumarate complex according to claim 8 in iron fortifying agents.

10. The application according to claim 9, characterized in that, The chitosan-ferrous fumarate complex is added to oil-containing foods.

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