Preparation method of calcium ascorbate nanoemulsion and application thereof
By preparing calcium ascorbate nanoemulsions and utilizing phospholipids, cholesterol, and chitosan to form a stable encapsulation system, the problem of poor stability of calcium ascorbate in fruit and vegetable preservation was solved, achieving a long-lasting fruit and vegetable preservation effect.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- SHANGHAI ACAD OF AGRI SCI
- Filing Date
- 2026-05-08
- Publication Date
- 2026-07-24
AI Technical Summary
Calcium ascorbate has poor stability in fruit and vegetable preservation and its preservation effect is short-lived, which limits its application in agricultural product preservation.
Using phospholipids and cholesterol as the oil phase of nanoemulsions and chitosan as the polysaccharide-based encapsulation material, calcium ascorbate nanoemulsions were prepared to form a W/O/W type encapsulation system. This system addresses the oxidative degradation of calcium ascorbate caused by environmental factors such as light, heat, and oxygen, and maintains its antioxidant activity.
It improves the stability and antioxidant activity of calcium ascorbate, prolongs the preservation of fruits and vegetables, significantly slows down oxidative degradation, and maintains the quality of fruits and vegetables.
Smart Images
Figure CN122439735A_ABST
Abstract
Description
Technical Field
[0001] This invention relates to the field of nanoemulsion technology, and in particular to a method for preparing calcium ascorbate nanoemulsion and its application. Background Technology
[0002] Fruits and vegetables experience post-harvest problems such as vigorous respiration and metabolism, water loss, and wilting, leading to post-harvest losses of 20%-30%. For some fragile fruits and vegetables (such as strawberries and leafy greens), the loss rate is even higher during harvesting, transportation, and storage, causing significant economic losses. Currently, preservation technology mainly relies on chemical preservation, but this poses safety risks such as serious chemical residues and toxicity accumulation. Coating technology is a promising green preservation technology. It simulates the natural waxy layer of fruits and endows it with enhanced functions through modern technology. With the continuous advancement of materials science (such as composite films and nanotechnology) and processing technology, coating technology is expected to play an increasingly important role in the future food industry, making a greater contribution to reducing food waste, ensuring food safety, and promoting sustainable development.
[0003] Calcium ascorbate is a calcium-based preservative formed by the combination of ascorbic acid and calcium ions. It retains the core structure of ascorbic acid and preserves strong antioxidant activity and sensitivity to environmental factors such as moisture, oxygen, heat, light, and metal ions. To preserve its functional activity, encapsulation technologies such as coating and sealing are increasingly being applied to the processing of calcium ascorbate-related formulations. In fruit and vegetable preservation, the preservation effect of calcium ascorbate alone is short-lived, limited to extending the shelf life of fresh-cut fruits and vegetables. Its high instability restricts its application in agricultural product preservation. Therefore, this invention is proposed. Summary of the Invention
[0004] To address the problems of poor stability and short-lived preservation effect of calcium ascorbate in existing technologies, this invention provides a method for preparing calcium ascorbate nanoemulsion and its application.
[0005] This invention provides a method for preparing calcium ascorbate nanoemulsion, comprising the following steps: S1. Phospholipids and cholesterol are dissolved in anhydrous ethanol, and then the anhydrous ethanol is removed by rotary evaporation to obtain a transparent film; S2. The transparent membrane is heated and hydrated with ultrapure water containing calcium ascorbate to obtain a liposome suspension; S3. The liposome suspension was ultrasonically disrupted and stored at low temperature; S4. Add the product obtained in step S3 to the chitosan solution and mix well to obtain calcium ascorbate nanoemulsion.
[0006] Furthermore, the phospholipid in step S1 is soybean phospholipid, and the ratio of soybean phospholipid to cholesterol is (4-4.5):(1-1.5); even further, the ratio of soybean phospholipid to cholesterol is 4:1.
[0007] Further, in step S2, ultrapure water containing calcium ascorbate is heated with the transparent film at 30-50°C for 1-2 hours to obtain a liposome suspension; even further, it is heated at 30°C for 2 hours.
[0008] Furthermore, the storage temperature in step S3 is 4-20℃; even further, the storage temperature is 4℃.
[0009] Further, in step S4, the chitosan solution is obtained by dissolving chitosan in an aqueous solution with a concentration of 1-2% acetic acid, wherein the concentration of the chitosan solution is 1% w / v-1.5% w / v; even further, the chitosan solution is dissolved in an aqueous solution with a concentration of 1% acetic acid, wherein the concentration of the chitosan solution is 1% w / v.
[0010] Furthermore, the concentration of calcium ascorbate in the calcium ascorbate nanoemulsion obtained in step S4 is 1% w / v-2% w / v. Even further, the concentration is 2% w / v.
[0011] This invention provides an application of calcium ascorbate nanoemulsion obtained by the above preparation method in the field of agricultural product preservation, wherein the agricultural products include fruits, vegetables, and rice.
[0012] Furthermore, the calcium ascorbate nanoemulsion is used for post-harvest preservation of agricultural products; the agricultural product is tomato.
[0013] Furthermore, the calcium ascorbate nanoemulsion is applied directly to the surface of agricultural products during use.
[0014] Furthermore, the calcium ascorbate nanoemulsion is made into a plastic wrap. The preparation steps of the plastic wrap are as follows: the calcium ascorbate nanoemulsion is poured into a flat container and placed in an oven. After drying at 35-45°C, it is equilibrated at room temperature for 20-28 hours. Even further, it is obtained by drying at 40°C and then equilibrating at room temperature for 24 hours.
[0015] In summary, compared with the prior art, the present invention has the following advantages: The preparation method provided by this invention uses calcium ascorbate as the functional substance, phospholipids and cholesterol as the oil phase of the nanoemulsion, and chitosan as the polysaccharide-based encapsulation material to prepare a nano-sustained-release system. This addresses the oxidative degradation of calcium ascorbate caused by environmental factors such as light, heat, and oxygen, maintaining its antioxidant activity and providing theoretical guidance for the development of calcium ascorbate preservation technology. The calcium ascorbate nanoemulsion obtained by this invention is a W / O / W type encapsulation, exhibiting good dispersibility, being green and safe, and having a simple preparation process, showing broad application prospects in the field of fruit and vegetable preservation. Attached Figure Description
[0016] To more clearly illustrate the specific embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the specific embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of the present invention. For those skilled in the art, other drawings can be obtained from these drawings without creative effort.
[0017] Figure 1 This is a schematic diagram of the preparation process of calcium ascorbate nanoemulsion in Example 1 of the present invention; Figure 2 This is an appearance diagram of the calcium ascorbate nanoemulsion prepared in Example 1 of the present invention; Figure 3 This is a transmission electron microscope image of the calcium ascorbate nanoemulsion prepared in Example 1 of this invention; Figure 4 This is a Zeta potential and particle size distribution diagram of the calcium ascorbate nanoemulsion prepared in Example 1 of this invention; Figure 5 This is a full-wavelength scan of the calcium ascorbate nanoemulsion prepared in Example 1 of this invention; Figure 6 This is a photograph of the calcium ascorbate preservation film prepared in Example 2 of the present invention; Figure 7 This is a photograph of the calcium ascorbate preservation film prepared in comparison to the present invention. Figure 8 This is a line graph showing the change in vitamin C content of tomatoes stored at 4°C over storage time in the test examples of this invention. Figure 9 This is a bar chart showing the changes in various indicators of tomatoes treated with different concentrations of calcium ascorbate during 4°C refrigeration in this invention. Figure 10 This is a comparison of physical samples of liposome suspensions prepared at different hydration temperatures in this invention. Detailed Implementation
[0018] It should be noted that the following detailed descriptions are illustrative and intended to provide further explanation of this application. Unless otherwise specified, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application pertains.
[0019] It should be noted that the terminology used herein is for the purpose of describing particular implementations only and is not intended to limit the exemplary implementations according to this application. As used herein, the singular form includes the plural form unless the context clearly indicates otherwise. Furthermore, it should be understood that when the terms "comprising" and / or "including" are used in this description, they indicate the presence of features, steps, operations, devices, components, and / or combinations thereof.
[0020] The technical solution of the present invention will be clearly and completely described below with reference to the embodiments. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.
[0021] Example 1 A method for preparing calcium ascorbate nanoemulsion, such as... Figure 1 As shown, the specific process is as follows: S1. Add 200 mg of soybean lecithin and 50 mg of cholesterol to 20 mL of anhydrous ethanol and dissolve them by sonication; then pour the solution into a round-bottom flask and remove the anhydrous ethanol using a rotary evaporator at 32°C and 50 r / min under pressure until a uniform and transparent film forms on the inner wall of the flask. Continue rotary evaporation for 20 minutes to ensure complete removal of the anhydrous ethanol. The soybean lecithin and cholesterol used in this invention are commercially available products commonly used in the art and are readily available for purchase.
[0022] S2. Add 10 mL of ultrapure water containing 1 g of calcium ascorbate to the round-bottom flask in step S1, and hydrate the membrane at 30°C for 2 h to obtain a liposome suspension.
[0023] S3. The liposome suspension obtained in step S2 is sonicated at 300 W for 20 min using an ultrasonic cell disruptor and stored at 4℃ for later use.
[0024] S4. Using magnetic stirring, slowly add the product obtained in step S3 to 90 mL of a 1% w / v chitosan solution and mix thoroughly to obtain calcium ascorbate nanoemulsion. The 1% w / v chitosan solution is obtained by adding 1 g of chitosan to 100 mL of a 1% acetic acid aqueous solution.
[0025] The concentration of calcium ascorbate in the calcium ascorbate nanoemulsion prepared in this embodiment is 1% w / v. The concentration of calcium ascorbate is calculated as follows: calcium ascorbate concentration = mass of calcium ascorbate / volume of total solution. The volume of total solution = volume of ultrapure water in step S2 plus volume of chitosan solution in step S4.
[0026] Figure 2 and Figure 3 The images show the appearance and transmission electron microscopy results of the calcium ascorbate nanoemulsion. It can be seen that the calcium ascorbate nanoemulsion is uniformly dispersed, indicating that the prepared emulsion has good dispersibility.
[0027] Figure 4 The image shows the Zeta potential and particle size distribution of calcium ascorbate nanoemulsion. It can be seen that the Zeta potential is 29.8 mV, the particle size is 538 nm, and the Pdi value is 0.033, indicating that the emulsion has good stability.
[0028] Figure 5 The image shows a full-wavelength scan of calcium ascorbate nanoemulsion in the ultraviolet and visible light regions. It can be seen that the system has strong absorption in the ultraviolet region, indicating that it has good ultraviolet blocking performance.
[0029] Example 2 A food preservation film prepared from calcium ascorbate nanoemulsion is prepared by the following method: 15 mL of calcium ascorbate nanoemulsion was poured into a disposable petri dish and placed in an oven to dry at 40°C. The dried film was then allowed to equilibrate at room temperature for 24 hours to obtain the plastic wrap. The obtained plastic wrap is shown below. Figure 6 As shown, making calcium ascorbate nanoemulsion into a preservation film can improve the stability and preservation function of calcium ascorbate on the one hand, and delay the oxidative water loss of tomatoes on the other hand.
[0030] Comparative Example A method for preparing calcium ascorbate preservative film includes the following steps: S1. Add 1 g of chitosan to 100 mL of 1% acetic acid and stir to dissolve at 200 r / min.
[0031] S2. Add 1 g of calcium ascorbate to the product obtained in step S1 and stir for 20 min until completely dissolved.
[0032] S3. Take 15 mL of the solution obtained in step S2, pour it into a disposable petri dish, and place it in an oven to dry at 40°C.
[0033] Figure 7 This is a photograph of a comparative example of calcium ascorbate plastic wrap. Figure 6 and Figure 7In comparison, it can be seen that the surface of the plastic wrap prepared in the comparative example is obviously yellow, indicating that the calcium ascorbate oxidation reaction is accelerated during the drying process, and the antioxidant capacity is weakened.
[0034] The plastic wrap prepared in Example 2 has a uniform, transparent, light yellow surface with a smooth and flat surface, and is compatible with... Figure 7 Compared to the comparative cling film shown, the cling film of Example 2 of the present invention showed that the oxidation reaction of calcium ascorbate was significantly inhibited during the drying process, indicating that the nanoemulsion system has a good encapsulation and protection effect on the active ingredients, significantly slows down the oxidative degradation of calcium ascorbate, effectively preserves its antioxidant capacity, and enables the cling film to maintain a stable appearance and performance during preparation and subsequent storage.
[0035] Test case The calcium ascorbate nanoemulsion prepared in Example 1 was uniformly coated onto tomatoes as the experimental group (Ca-Vccoating), and deionized water was uniformly coated onto tomatoes as the control group (CK). Tomatoes from both the experimental and control groups were stored at 4°C. During storage, samples were periodically taken to determine the vitamin C content of the tomatoes. The results are as follows: Figure 8 As shown. It can be observed that: The vitamin C content of both groups of samples decreased with prolonged storage time. This is because vitamin C is easily oxidized and decomposed, and is continuously lost during storage. In the control group, the vitamin C content had dropped to approximately 30 mg / 100g by day 15, a significant decrease. In the experimental group, the vitamin C content remained at approximately 35 mg / 100g by day 15, much higher than the control group, and the rate of decline was significantly slower.
[0036] As can be seen, the calcium ascorbate nanoemulsion provided in Example 1 of the present invention can effectively delay the occurrence of chilling injury during the storage of tomatoes at 4℃, maintain a high vitamin C content, and extend the refrigeration period to more than 15 days.
[0037] To determine the optimal concentration of ascorbic acid in the calcium ascorbate nanoemulsion of the present invention, a screening experiment on the concentration of calcium ascorbate at low temperature was conducted, and the steps are as follows: First, tomato fruits were coated with calcium ascorbate nanoemulsions at concentrations of 0.5% w / v, 1% w / v, 2% w / v, and 3% w / v, respectively, as experimental groups. The preparation method of the calcium ascorbate nanoemulsions in the experimental groups was the same as in Example 1, except that the mass of calcium ascorbate added in step S2 was different. Tomatoes treated with deionized water were selected as the control group. Then, the tomatoes in the experimental and control groups were stored at 4°C.
[0038] Color difference test: The colorimeter was used to measure the color difference of the tomatoes, and the results were recorded. (Brightness) value (Redness) value, (Yellowness) value.
[0039] Hardness test: The hardness of the tomatoes was measured using a texture analyzer.
[0040] Test data such as Figure 9 As shown, it can be observed that in the experimental group, as the concentration of calcium ascorbate increases, the firmness of tomatoes during storage and shelf life gradually increases, and the concentration of calcium ascorbate can be slightly increased. value, The control group of tomatoes showed signs of chilling injury during the shelf life, such as rotting and indentation of the stem area. The experimental group of tomatoes with a concentration of 3% w / v also showed signs of rotting, indicating that high concentrations of calcium ascorbate can have a negative effect on preservation. The most suitable concentration range for calcium ascorbate treatment to control chilling injury is 1-2% w / v, and the recommended concentration is 2% w / v.
[0041] To determine the optimal hydration temperature for preparing the liposome suspension in step S2 of this invention, hydration experiments were conducted at different temperatures. Three parallel experimental groups were set up, with each group having the same operating steps except for the hydration temperature. The specific steps are as follows: First, 200 mg of soybean lecithin and 50 mg of cholesterol were added to 20 mL of anhydrous ethanol and dissolved by sonication. Then, the mixture was poured into a round-bottom flask and the anhydrous ethanol was removed by rotary evaporation at 32°C and 50 r / min under pressure until a uniform and transparent film was formed on the inner wall of the round-bottom flask. Rotary evaporation was continued for 20 min to ensure that the anhydrous ethanol was completely removed. Then, 10 mL of ultrapure water containing 3 g of calcium ascorbate was added to the round-bottom flask in step S1, and the three films were hydrated at 30°C, 40°C, and 50°C for 2 h, respectively, to obtain liposome suspensions.
[0042] Appearance test: Directly observe the color of the prepared liposome suspension to determine its degree of oxidation.
[0043] Experimental results are as follows Figure 10 As shown (temperatures from left to right: 30℃, 40℃, 50℃), it can be observed that the color of the liposome suspension gradually deepens with increasing hydration temperature, indicating a higher content of oxidized calcium ascorbate. This suggests that a lower hydration temperature is more conducive to maintaining the antioxidant properties of calcium ascorbate, resulting in better encapsulation. The optimal hydration temperature for preparing the liposome suspension is 30℃.
[0044] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and not to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some or all of the technical features; and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.
Claims
1. A method for preparing calcium ascorbate nanoemulsion, characterized in that, Includes the following steps: S1. Phospholipids and cholesterol are dissolved in anhydrous ethanol, and then the anhydrous ethanol is removed by rotary evaporation to obtain a transparent film; S2. The transparent membrane is heated and hydrated with ultrapure water containing calcium ascorbate to obtain a liposome suspension; S3. The liposome suspension was ultrasonically disrupted and stored at low temperature; S4. Add the product obtained in step S3 to the chitosan solution and mix well to obtain calcium ascorbate nanoemulsion.
2. The preparation method according to claim 1, characterized in that, The phospholipids in step S1 are soybean phospholipids, and the ratio of soybean phospholipids to cholesterol is (4-4.5):(1-1.5).
3. The preparation method according to claim 1, characterized in that, In step S2, ultrapure water containing calcium ascorbate and the transparent membrane are heated at 30-50°C for 1-2 hours to obtain a liposome suspension.
4. The preparation method according to claim 1, characterized in that, The storage temperature in step S3 is 4-20℃.
5. The preparation method according to claim 1, characterized in that, In step S4, the chitosan solution is obtained by dissolving chitosan in an aqueous solution of 1-2% acetic acid, wherein the concentration of the chitosan solution is 1% w / v-1.5% w / v.
6. The preparation method according to claim 1, characterized in that, The concentration of calcium ascorbate in the calcium ascorbate nanoemulsion obtained in step S4 is 1%w / v-2%w / v.
7. The application of calcium ascorbate nanoemulsion obtained by any one of claims 1-6 in the field of agricultural product preservation, characterized in that, The agricultural products mentioned include fruits, vegetables, and rice.
8. The application according to claim 7, characterized in that, The calcium ascorbate nanoemulsion is used for post-harvest preservation of agricultural products; the agricultural product is tomato.
9. The application according to claim 7, characterized in that, The calcium ascorbate nanoemulsion is applied directly to the surface of agricultural products during use.
10. The application according to claim 7, characterized in that, The calcium ascorbate nanoemulsion is made into a plastic wrap. The preparation steps of the plastic wrap are as follows: the calcium ascorbate nanoemulsion is poured into a flat container and placed in an oven. After drying at 35-45℃, it is placed at room temperature for equilibration for 20-28 hours to obtain the plastic wrap.