Preparation method of high-water-solubility L-ascorbic acid-2-phosphate calcium sodium salt and application of high-water-solubility L-ascorbic acid-2-phosphate calcium sodium salt in water sprinkling of aquatic products
By combining organic calcium sources and anti-calcium precipitation agents, the problems of slow dissolution, turbidity, and precipitation of ASP calcium sodium salt in aquaculture water application were solved, and highly water-soluble L-ascorbic acid-2-phosphate calcium sodium salt was prepared, achieving complete dissolution within seconds and long-term stable clear and transparent solution, thus improving the feeding efficiency of aquaculture.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2026-02-10
- Publication Date
- 2026-03-31
AI Technical Summary
Existing ASP calcium sodium salts have slow dissolution rates, tend to sink to the bottom, produce turbidity or precipitation, and are prone to clumping, leading to loss of effective ingredients and equipment blockage.
A highly water-soluble calcium sodium salt of L-ascorbic acid-2-phosphate was prepared by reacting an organic calcium source (such as calcium lactate or calcium gluconate) with sodium trimetaphosphate, combined with sodium citrate as an anti-calcium precipitation agent, through slow dropwise addition at low temperature and buffered pH control, combined with low-temperature spray drying and cold nitrogen protection.
It enables the complete dissolution of ASP calcium sodium salt within seconds, forming a clear and transparent solution that remains stable over a long period. This solves the problems of slow dissolution, turbidity, and precipitation in aquaculture, and improves bioavailability.
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Abstract
Description
Technical Field
[0001] This invention belongs to the field of feed additive technology, specifically relating to a method for preparing highly water-soluble L-ascorbic acid-2-phosphate calcium sodium salt and its application in aquaculture water splashing scenarios. Background Technology
[0002] L-Ascorbyl Phosphate (ASP) is a stable derivative of Vitamin C. Due to its good antioxidant stability during feed processing and storage, it is widely used as a Vitamin C supplement in aquatic and livestock feed. Currently, industrially produced feed-grade ASP mainly exists in the form of a calcium-sodium complex salt, usually prepared by reacting L-ascorbic acid with sodium trimetaphosphate to introduce a calcium source.
[0003] However, despite the good thermal stability of ASP calcium sodium salts, they still have significant drawbacks in the "sprinkling" application scenario of aquaculture. In the daily management or stress intervention of aquatic animals such as fish, shrimp, and crabs, vitamin C additives are often dissolved directly in the water and sprinkled throughout the pond to achieve rapid and uniform nutrient supplementation. However, existing ASP calcium sodium salt products generally have the following problems: (1) The dissolution rate is slow, and the particles tend to sink or suspend, making them difficult for aquatic animals to absorb effectively. (2) The aqueous solution is cloudy or produces flocculent matter, which affects the judgment of its use; (3) A white precipitate forms after prolonged storage, resulting in the loss of effective ingredients; (4) When spraying at high concentrations, it is easy to clump together, causing excessively high local concentrations or equipment blockage.
[0004] The root cause of the above problems is that in traditional synthesis processes, calcium ions are often added at once using inorganic calcium salts (such as calcium chloride), which can easily cause local supersaturation and generate slightly soluble calcium phosphate aggregates. At the same time, excessively high temperatures or insufficient cooling during spray drying result in a dense product structure and small specific surface area, which further limits the solubility.
[0005] Therefore, there is an urgent need to develop a highly water-soluble ASP calcium sodium salt specifically designed for aquatic water application, which can completely dissolve within seconds to form a clear, transparent, and long-term stable solution, truly meeting the needs of modern aquaculture for efficient and precise feeding. Summary of the Invention
[0006] The purpose of this invention is to provide a highly water-soluble calcium sodium salt of L-ascorbic acid-2-phosphate and its preparation method, thereby solving the technical problems of slow dissolution, turbidity, and precipitation of existing ASP calcium sodium salts in aquatic water splashing applications.
[0007] To achieve the above objectives, the present invention adopts the following technical solution: A highly water-soluble calcium sodium salt of L-ascorbic acid-2-phosphate, whose 1% aqueous solution does not precipitate after standing at 25°C for 24 hours, and has a transmittance of ≥95% at a wavelength of 600 nm.
[0008] Preferably, the calcium sodium salt is prepared by reacting L-ascorbic acid with sodium trimetaphosphate and then introducing an organic calcium source; the organic calcium source is selected from at least one of calcium lactate and calcium gluconate.
[0009] Furthermore, the product contains 0.1–0.5 wt% sodium citrate or disodium EDTA as an anti-calcium precipitation protectant, effectively preventing the migration and precipitation of calcium ions during drying and storage.
[0010] The present invention also provides a method for preparing the above-mentioned calcium sodium salt, comprising the following steps: (1) Dissolve L-ascorbic acid in deionized water, add sodium trimetaphosphate, and react at pH 8.8–9.2 and temperature 45–50℃ for 2–3 hours to obtain ASP sodium salt solution; (2) Cool the reaction solution to 10–15°C and adjust the pH to 7.5–8.0 with food-grade alkali; (3) Slowly add the organic calcium source aqueous solution, controlling the addition time to ≥30 minutes, and maintain the pH at 7.5–8.0; (4) Add 0.1–0.5 wt% sodium citrate and stir until homogeneous; (5) Concentrate the liquid to a solid content of 15–25 wt%, and spray dry it with an inlet air temperature of 150–170℃ and an outlet air temperature of 65–75℃. (6) Immediately cool the dried product with dry nitrogen gas to ≤25℃, and then seal it in packaging.
[0011] Another object of the present invention is to provide a new use of the L-ascorbic acid-2-phosphate calcium sodium salt in aquaculture: it is directly dissolved in pond water and applied by spraying. At a concentration of 10 g / L, it completely dissolves within 30 seconds, and the solution is clear and transparent without flocculent matter or precipitate.
[0012] The beneficial effects of this invention are as follows: (1) An organic calcium source (calcium lactate / calcium gluconate) is used to avoid the introduction of chloride ions, and the organic anions synergistically solubilize and effectively inhibit the formation of calcium phosphate precipitate; (2) By slowly adding water at low temperature and buffering pH, local supersaturation is prevented and calcium is ensured to complex evenly; (3) Add trace amounts of food-grade anti-precipitant (sodium citrate) to improve the long-term stability of the product; (4) Low-temperature spray drying + cold nitrogen protection to obtain a loose powder with high specific surface area, achieving dissolution in seconds; (5) The product is designed for water splashing, which completely solves the pain points of ASP in aquaculture and improves the efficiency of biological utilization. Attached image description: Figure 1 The photos show the comparison of the state of the 1% aqueous solution of the product of Example 1 and Comparative Example 1 after standing for 24 hours (left: this invention, clear; right: comparative example 1, turbid with precipitate). Figure 2 The images show a comparison of the states of a 0.1% aqueous solution of the product from Example 1 and Comparative Example 1 (left: this invention, clear and transparent; right: comparative example 1, turbid). Detailed Implementation
[0013] The present invention will be further described below with reference to the embodiments, but the present invention is not limited to the embodiments.
[0014] Example 1 Synthesis of sodium ASP: Weigh 176 g (1.0 mol) of L-ascorbic acid and dissolve it in 800 mL of deionized water. Add 102 g (0.5 mol) of sodium trimetaphosphate and adjust the pH to 9.0 with 10% NaOH solution. Keep the reaction at 50℃ for 2.5 hours.
[0015] Calcification reaction: Cool the reaction solution to 12°C and adjust the pH to 7.8 with NaOH solution; prepare an aqueous solution containing calcium lactate (providing 0.25 mol Ca²⁺) and slowly add it dropwise to the reaction solution over 30 minutes, maintaining the pH at 7.5–8.0.
[0016] Stabilization treatment: Add 0.8 g of sodium citrate (approximately 0.3 wt% of the final product) and stir for 30 minutes.
[0017] Spray drying: The liquid material is concentrated under reduced pressure to a solid content of 20 wt%, and then dried using a centrifugal spray drying tower with an inlet air temperature of 160℃ and an outlet air temperature of 70℃. The collected powder is immediately cooled to 22℃ by passing it through drying nitrogen gas and then sealed in an aluminum foil composite bag for storage.
[0018] Product testing results: Dissolution time: Complete dissolution visible to the naked eye in 25 seconds (1.0 g sample + 100 mL deionized water, 25℃, 300 rpm stirring). Transmittance: 96.3% (0.1% aqueous solution, 600 nm wavelength) 24-hour stability: A 1% solution remains clear and transparent, without any precipitation or turbidity.
[0019] Example 2 The steps were the same as in Example 1, except that calcium lactate was replaced with an equimolar amount of calcium gluconate. Results: Dissolution time: Complete dissolution visible to the naked eye in 25 seconds (1.0 g sample + 100 mL deionized water, 25℃, 300 rpm stirring). Transmittance: 95.8% (0.1% aqueous solution, 600 nm wavelength), no precipitation after 24 hours.
[0020] Comparative Example 1 (using conventional inorganic calcium processing) L-ascorbic acid 176 g + sodium trimetaphosphate 102 g, pH 9.0, reaction at 50℃ for 2.5 h; CaCl2·2H2O (providing 0.25 mol of Ca²⁺) was added directly without temperature control or slow dropwise addition; After the liquid is concentrated, it is spray-dried (inlet air 190℃, outlet air 85℃). Naturally cooled packaging.
[0021] Results: The transmittance of the 0.1% solution was only 72%; the dissolution time of the 1% aqueous solution was >120 seconds, and obvious precipitate appeared at the bottom after standing for 24 hours.
[0022] Comparative Example 2 (without anti-precipitant) The steps are the same as in Example 1, except that sodium citrate is omitted.
[0023] Results: The initial transmittance was 95.5%, but after the product was stored at 40℃ / 75%RH for 7 days, slight clumping occurred, and the transmittance of the 0.1% solution dropped to 88%.
[0024] Test method description: Transmittance: Prepare a 0.1 wt% aqueous solution, let it stand for 5 minutes, and then measure the absorbance A at 600 nm using a UV-Vis spectrophotometer. Transmittance T (%) = 10⁻ᴬ × 100%; Dissolution time: Visual inspection method, record the time to complete dissolution; Stability: After standing at room temperature for 24 hours, observe with the naked eye whether there is turbidity or precipitation in a 1% aqueous solution.
Claims
1. A highly water-soluble L-ascorbic acid-2-phosphate calcium sodium salt, characterized by: Its 1% aqueous solution at 25℃ is placed for 24 hours without precipitation, and the transmittance at 600 nm is ≥95%.
2. The L-ascorbyl-2-phosphate calcium sodium salt of claim 1, wherein, The salt is prepared by reacting L-ascorbic acid with sodium trimetaphosphate, and then introducing an organic calcium source.
3. The L-ascorbyl-2-phosphate calcium sodium salt of claim 2, wherein, The organic calcium source is selected from at least one of calcium lactate and calcium gluconate.
4. The sodium calcium L-ascorbyl-2-phosphate salt according to any one of claims 1 to 3, characterized in that, 0.1-0.5 wt% of sodium citrate or disodium EDTA is contained as an anti-calcium precipitation protective agent.
5. A process for the preparation of the sodium calcium salt of L-ascorbic acid-2- phosphate according to any one of claims 1 to 4, characterized in that, The method comprises the following steps: (1) Dissolve L-ascorbic acid in deionized water, add sodium trimetaphosphate, and react at pH 8.8-9.2 and temperature 45-50℃ for 2-3 hours to obtain an AMP sodium salt solution; (2) Cool the reaction solution to 10-15℃, and adjust the pH to 7.5-8.0 with a food-grade base; (3) Slowly add an aqueous solution of the organic calcium source, control the dropwise adding time to be ≥30 minutes, and maintain the pH at 7.5-8.0; (4) Add 0.1-0.5 wt% of sodium citrate and stir uniformly; (5) Concentrate the solution to a solid content of 15-25 wt%, and spray dry at an inlet temperature of 150-170℃ and an outlet temperature of 65-75℃; (6) Immediately cool the dried product to ≤25℃ under dry nitrogen, and seal and package.
6. The production method according to claim 5, wherein The organic calcium source in step (3) is calcium lactate.
7. The production method according to claim 5, wherein The obtained product has a moisture content of ≤2.5 wt% and a specific surface area of ≥8 m² / g.
8. Use of L-ascorbyl-2-phosphate calcium sodium salt according to any one of claims 1 to 4 for the preparation of a water-soluble vitamin C additive for aquaculture, characterized in that: The calcium sodium salt is directly dissolved in pond water for spraying application, and is completely dissolved within 30 seconds at a concentration of 10 g / L, and the solution is clear and transparent without flocculation or precipitation.