Preparation method of glycosylated gelatin and application of glycosylated gelatin in microcapsules

Abstract

The invention provides a preparation method of glycosylated gelatin and application of the glycosylated gelatin in microcapsules. The method comprises the following steps: catalyzing sugar and gelatin to generate glycosylation reaction under the action of a photocatalyst 9-methyl-10-phenylacridine-10-ammonium chloride, washing and drying to obtain the glycosylation modified gelatin. According to the method, the preparation of the glycosylation modified gelatin is realized through photocatalysis, the glycosylation modified gelatin is applied to the vitamin A microcapsule, an emulsifier does not need to be additionally added, a stable O / W type emulsion can be prepared only by common stirring, a traditional emulsification process is simplified, the particle size D90 of the prepared emulsion reaches 0.3-1.0 mu m, the oil carrying rate is greater than 45%, and the embedding rate of a dried product is greater than or equal to 99%.

Description

Technical Field

[0001] The present invention belongs to the technical field of microcapsule preparation, and particularly relates to a method for preparing glycosylated gelatin and its application in microcapsules. Background Art

[0002] In a broad sense, vitamin A refers to a general term for a large class of substances with a retinol structure and its biological activity. It includes vitamin A (retinol) and vitamin A2 (3-dehydroretinol) derived from animal foods, as well as a group of substances such as retinal, retinoic acid and their esters and various isomers.

[0003] Vitamin A has excellent antioxidant properties, but it is susceptible to oxidation and degradation under the influence of light and oxygen. Under high temperature and ultraviolet irradiation conditions, its oxidation rate accelerates. When oxidized, the ester, alcohol, aldehyde, and acid groups in the molecular structure are successively oxidized and damaged.

[0004] Patent CN109452467B reported a method for preparing vitamin A microcapsule products using gelatin. In this process, the amount of gelatin used is more than 1 time that of vitamin A, and the emulsion particle size D50 is as high as 1 μm. The product stability is poor, and the loss rate is relatively high in the subsequent premix application.

[0005] Patent CN101703491A reported a method using gum arabic as a wall material, which needs to be emulsified under the action of monoglyceride and sucrose ester emulsifiers and can only form an emulsion through high-pressure homogenization by a homogenizer. Its emulsification process is complex, uses too many emulsifiers, and the downstream applicability of the product is poor.

[0006] In summary, currently, when using conventional wall materials to prepare emulsions, the particle size of the emulsion is relatively large and the emulsion stability is poor, resulting in poor product stability in downstream applications. And in industrial production, multiple homogenizers are required for emulsification production, and both equipment investment and energy consumption are relatively high. Summary of the Invention

[0007] One of the purposes of the present invention is to provide a method for preparing glycosylated modified gelatin. This method realizes the preparation of glycosylated modified gelatin through photocatalysis. When it is applied to vitamin A microcapsules, no additional emulsifier is needed, and only ordinary stirring is required to prepare a stable O / W type emulsion, which simplifies the traditional emulsification process. The prepared emulsion has a particle size D90 reaching 0.3 - 1.0 μm, an oil loading rate > 45%, and a spray-dried product embedding rate ≥ 99%.

[0008] In order to achieve the above purpose, the technical scheme adopted by the present invention is as follows:

[0009] A method for preparing glycosylated modified gelatin, the method comprising: under the action of a photocatalyst 9-methyl-10-phenylacridine-10-ammonium chloride, catalyzing the glycosylation reaction of sugar and gelatin, and washing and drying to obtain glycosylated modified gelatin. The structure of the catalyst is as follows:

[0010]

[0011] The inventors found that the above photocatalyst can be used to prepare glycosylated modified gelatin: under the irradiation of a light source within a wavelength range, the catalyst releases free radical electrons, and the high-energy free radical electrons oxidize the hydroxyl groups in the sugar to obtain oxygen-based free radicals. The oxygen-based free radicals combine with the carboxyl groups in the gelatin to form ester groups, while releasing a molecule of water and free radical electrons, thereby realizing the glycosylation reaction.

[0012] In one embodiment of the present invention, the sugar is one or more of cellulose, chitosan, sucrose, mannitol, xylitol, fructose, and glucose.

[0013] In one embodiment of the present invention, the gelatin is animal-derived gelatin, preferably one or more of bovine gelatin, porcine gelatin, and fish gelatin; preferably, the mass ratio of the gelatin to the sugar is 1:0.1-2.

[0014] In one embodiment of the present invention, the mass ratio of the gelatin to the photocatalyst is 1:0.01-0.05.

[0015] In one embodiment of the present invention, water is added during the preparation process, and preferably the mass ratio of the gelatin to the water is 1:2-10.

[0016] In one embodiment of the present invention, the light is one or more of LED blue light, green light, and white light.

[0017] In one embodiment of the present invention, the temperature of the reaction is 30-80°C.

[0018] In one embodiment of the present invention, the washing is with a salt solution, and preferably the salt solution is saturated sodium chloride solution and / or saturated ammonium bicarbonate solution.

[0019] Another object of the present invention is to provide a glycosylated modified gelatin.

[0020] A glycosylated modified gelatin, which is prepared by the above method.

[0021] Another object of the present invention is to provide a use of the glycosylated modified gelatin.

[0022] Use of glycosylated modified gelatin, wherein the glycosylated modified gelatin is prepared by the above method or is the above modified gelatin, and the glycosylated modified gelatin is used for preparing vitamin microcapsules, preferably for preparing vitamin A microcapsules.

[0023] Yet another object of the present invention is to provide a method for preparing vitamin A microcapsules.

[0024] A method for preparing vitamin A microcapsules, wherein the vitamin A microcapsules are prepared with the glycosylated modified gelatin prepared by the above method or with the above glycosylated modified gelatin, and the preparation method is as follows:

[0025] S1: Dissolve the glycosylated modified gelatin to form an aqueous phase;

[0026] S2: Melt vitamin A crystals and an antioxidant to prepare an oil phase;

[0027] S3: Add the oil phase to the aqueous phase for emulsification, and then dry to obtain vitamin A microcapsules.

[0028] In one embodiment of the present invention, the temperature in S1 is 40 - 70 °C.

[0029] In one embodiment of the present invention, the mass ratio of vitamin A crystals to the antioxidant in S2 is 1:0.01 - 0.05; preferably, the antioxidant is one or more of ethoxyquinoline and / or 2,6-di-tert-butyl-4-methylphenol (BHT).

[0030] In one embodiment of the present invention, the melting temperature in S2 is 50 - 70 °C.

[0031] In one embodiment of the present invention, the mass ratio of vitamin A crystals to the modified gelatin in S3 is 1:0.1 - 1.

[0032] In one embodiment of the present invention, the drying method in S3 is spray drying; preferably, the drying temperature is 150 - 200 °C.

[0033] In one embodiment of the present invention, the emulsion particle size D90 prepared in S3 is 0.3 - 1.0 μm, the oil loading rate > 45%, and the embedding rate of the dried product ≥ 99%.

[0034] Yet another object of the present invention is to provide a vitamin A microcapsule.

[0035] A vitamin A microcapsule, which is prepared with the glycosylated modified gelatin prepared by the above method, or with the above glycosylated modified gelatin, or obtained by the above preparation method.

[0036] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0037] (1) This method uses light as an energy source and undergoes a glycosylation reaction under the action of a photocatalyst. The preparation process is simple and green, and the grafting degree of the prepared modified gelatin is as high as 40 - 60%.

[0038] (2) Using the above - mentioned modified gelatin as the wall material to prepare vitamin A microcapsule products, the dosage of modified gelatin is low (<30% wt of the vitamin A dosage). Without the need to additionally add an emulsifier, only ordinary stirring is required to prepare a stable O / W type emulsion, which simplifies the traditional emulsification process, avoids the use of high - energy - consuming homogenizers, reduces equipment investment. The prepared emulsion has a D90 particle size reaching 0.3 - 1.0 μm, an oil - loading rate >45%, and an embedding rate of the spray - dried product ≥99%. Specific embodiments

[0039] The technical solutions of the present invention will be further described below through specific examples, but are not limited thereto.

[0040] Preparation process of the photocatalyst 9 - methyl - 10 - phenylacridine - 10 - ammonium chloride:

[0041] Weigh 10 g of diphenylamine and 20 ml of acetic acid, then add 40 g of anhydrous zinc chloride, and then heat at 150 °C for 15 h. Cool to room temperature, and remove the reaction solvent by vacuum distillation. Then add 33.8 g of chlorobenzene and 100 ml of acetonitrile, and heat under reflux for 5 h until the reaction ends. Cool the reaction solution to 10 °C, cool for 1 h, then perform suction filtration, wash the filter cake with acetonitrile, and finally dry to obtain the photocatalyst 9 - methyl - 10 - phenylacridine - 10 - ammonium chloride with a purity of 96 wt%. The involved reactions are as follows:

[0042]

[0043] The model of the nuclear magnetic resonance analysis instrument is: JEOL JNM - ECZ400S made in Japan. Through nuclear magnetic resonance testing, the nuclear magnetic resonance characterization data of the photocatalyst are: 1H NMR (300 MHz, Chloroform - d) δ8.60 (m, 2H), 8.42 (m, 2H), 8.23 (m, 2H), 7.84 (m, 2H), 7.36 (s, 1H), 7.35 (m, 2H), 2.42 (s, 1H) ppm. 13C NMR (101 MHz, Chloroform - d) δ159.1, 143.8, 142.8, 138.5, 132.9, 132.4, 130.0, 126.6, 125.4, 124.7, 118.6, 15.4 ppm.

[0044]

[0045] Testing method for grafting degree in the examples:

[0046] The grafting degree was measured by the OPA method: During the measurement, 3 ml of OPA reagent was mixed with 0.2 ml of 1 mg / ml sample solution, reacted at room temperature for 5 min, and the absorbance was measured at 340 nm. Deionized water was used as the blank control. Using the same method, a standard curve was made with lysine, and the free amino group content in the sample was calculated according to the curve equation. The calculation formula for the grafting degree is as follows: Grafting degree / % = (1 - W s / W0) Where: W0, the free amino group content of the original gelatin; W s , the free amino group content of the glycosylated gelatin.

[0047] Example 1

[0048] Preparation of glycosylated modified gelatin:

[0049] Weigh 1000 g of porcine gelatin and 1000 g of glucose, add them to the reaction kettle, then add 7000 g of water and 10 g of photocatalyst, raise the reaction temperature to 30 °C, and react under LED blue light irradiation for 2 h, and the reaction ends. Cool the reaction solution to 10 °C to obtain the crude product of modified gelatin solid, filter and wash successively with saturated sodium chloride solution and water, and vacuum dry (40 °C, -50 kPa) to obtain 1050 g of glycosylated modified gelatin. After the grafting degree test, its value is 45%.

[0050] Preparation of vitamin A microcapsule product:

[0051] Weigh 50 g of the above-mentioned modified gelatin and add it to the emulsifying kettle, add 1000 g of warm water at 60 °C and stir to dissolve to prepare the aqueous phase; weigh 500 g of vitamin A crystals and 25 g of ethoxyquinoline and heat to 50 °C to melt to prepare the oil phase; then add the oil phase to the emulsifying kettle and stir and emulsify at 800 rpm for 40 min, and the emulsification ends. After sampling and dissolving in water, observe that there is no floating oil on the surface. The measured emulsion particle size D90 is 0.6 μm. The emulsified emulsion is spray-dried, and the inlet air temperature is 180 °C to obtain the vitamin A microcapsule product. The water content is 3 wt%, the embedding rate is 99.1 wt%, and the vitamin A content of the product is 86.9 wt%.

[0052] Example 2

[0053] Preparation of glycosylated modified gelatin:

[0054] Weigh 1000 g of porcine gelatin and 100 g of sucrose, add them to the reaction kettle, then add 2000 g of water and 50 g of photocatalyst, raise the reaction temperature to 80 °C, and react for 12 h under the irradiation of LED green light. After the reaction, cool the reaction solution to 25 °C to obtain the crude modified gelatin solid. Filter it and wash it successively with saturated sodium chloride solution and water, and then conduct vacuum drying (30 °C, -20 kPa) to obtain 1450 g of glycosylated modified gelatin. After grafting degree test, its value is 56%.

[0055] Preparation of vitamin A microcapsule product:

[0056] Weigh 500 g of the above-mentioned modified gelatin and add it to the emulsification kettle. Add 1500 g of warm water at 60 °C and stir to dissolve to prepare the aqueous phase; weigh 500 g of vitamin A crystals and 5 g of BHT, heat them to 70 °C to melt and prepare the oil phase; then pour the oil phase into the emulsification kettle and stir and emulsify at 600 rpm for 35 min. After the emulsification, take a sample and observe that there is no floating oil on the surface after dissolving in water. Test the emulsion particle size D90 to be 0.5 μm. Spray-dry the emulsified emulsion, with the inlet air temperature being 150 °C, to obtain the vitamin A microcapsule product, with a water content of 4.5 wt%, an embedding rate of 99 wt%, and the vitamin A content of the product being 49.7 wt%.

[0057] Example 3

[0058] Preparation of glycosylated modified gelatin:

[0059] Weigh 1000 g of fish gelatin and 2000 g of chitosan, add them to the reaction kettle, then add 10000 g of water and 40 g of photocatalyst, raise the reaction temperature to 40 °C, and react for 10 h under the irradiation of LED white light. After the reaction, cool the reaction solution to 15 °C to obtain the crude modified gelatin solid. Filter it and wash it successively with saturated sodium bicarbonate solution and water, and then conduct vacuum drying (35 °C, -45 kPa) to obtain 1355 g of glycosylated modified gelatin. After grafting degree test, its value is 50%.

[0060] Preparation of vitamin A microcapsule product:

[0061] Weigh 200 g of the above-mentioned modified gelatin and add it to the emulsification kettle. Add 1500 g of warm water at 50 °C and stir to dissolve to prepare the aqueous phase; weigh 500 g of vitamin A crystals and 18 g of ethoxyquinoline, heat them to 55 °C to melt and prepare the oil phase; then add the oil phase to the emulsification kettle and stir and emulsify at 700 rpm for 45 min. After the emulsification, take a sample and observe that there is no floating oil on the surface after dissolving in water. Test the emulsion particle size D90 to be 0.8 μm. Spray-dry the emulsified emulsion, with the inlet air temperature being 200 °C, to obtain the vitamin A microcapsule product, with a water content of 3.8 wt%, an embedding rate of 99.2 wt%, and the vitamin A content of the product being 69.64 wt%.

[0062] Example 4

[0063] Preparation of glycosylated modified gelatin:

[0064] Weigh 1000 g of porcine gelatin and 500 g of cellulose, add them to a reaction kettle, then add 6000 g of water and 30 g of photocatalyst, raise the reaction temperature to 60 °C, and react under LED blue light irradiation for 8 h to end the reaction. Cool the reaction solution to 20 °C to obtain a crude product of modified gelatin solid, filter and wash successively with saturated sodium bicarbonate solution and water, and vacuum dry (38 °C, -35 kPa) to obtain 1550 g of glycosylated modified gelatin. After grafting degree test, its value is 60%.

[0065] Preparation of vitamin A microcapsule product:

[0066] Weigh 400 g of the above-mentioned modified gelatin and add it to an emulsifying kettle, add 1005 g of warm water at 57 °C and stir to dissolve to prepare an aqueous phase; weigh 500 g of vitamin A crystals and 10 g of ethoxyquinoline, heat to 60 °C and melt to prepare an oil phase; then add the oil phase to the emulsifying kettle, stir and emulsify at 550 rpm for 60 min to end the emulsification. After sampling and dissolving in water, observe that there is no floating oil on the surface. Test the emulsion particle size D90 to be 0.55 μm. Spray dry the emulsified emulsion, and the inlet air temperature is 160 °C to obtain a vitamin A microcapsule product, with a water content of 3.6 wt%, an encapsulation rate of 99.1 wt%, and a vitamin A content of 54.9 wt% in the product.

[0067] Comparative Example 1

[0068] Compared with Example 1, the difference is that titanium dioxide photocatalyst is used instead.

[0069] Preparation of glycosylated modified gelatin:

[0070] Weigh 1000 g of porcine gelatin and 1000 g of glucose, add them to a reaction kettle, then add 7000 g of water and 10 g of photocatalyst, raise the reaction temperature to 30 °C, and react under LED blue light irradiation for 2 h to end the reaction. Cool the reaction solution to 10 °C to obtain a crude product of modified gelatin solid, filter and wash successively with saturated sodium chloride solution and water, and vacuum dry (40 °C, -50 kPa) to obtain 1050 g of glycosylated modified gelatin. After grafting degree test, its value is 0%.

[0071] Preparation of vitamin A microcapsule product:

[0072] Weigh 50 g of the above-mentioned modified gelatin and add it to the emulsification kettle. Then add 1000 g of warm water at 60 °C and stir to dissolve to prepare the aqueous phase. Weigh 500 g of vitamin A crystals and 25 g of ethoxyquinoline, heat them to 50 °C and melt to prepare the oil phase. Then add the oil phase to the emulsification kettle, stir and emulsify at 800 rpm for 40 min to end the emulsification. After sampling and dissolving in water, observe that there is no floating oil on the surface. Test that the emulsion particle size D90 is 0.6 μm. Spray-dry the emulsified emulsion with an inlet air temperature of 180 °C to obtain a vitamin A microcapsule product with a water content of 3 wt%, an encapsulation rate of 40 wt%, and a vitamin A content of 20 wt% in the product.

[0073] It is found by comparison that the titanium dioxide photocatalyst cannot achieve the photocatalytic effect of the present invention.

Claims

1. A method for preparing glycosylated modified gelatin, characterized in that, The method is as follows: Under the action of the photocatalyst 9-methyl-10-phenylacridine-10-ammonium chloride, a glycosylation reaction occurs between the sugar and gelatin, and after washing and drying, glycosylated modified gelatin is obtained.

2. The method according to claim 1, wherein The sugar is one or more of cellulose, chitosan, sucrose, mannitol, xylitol, fructose, and glucose; And / or, the gelatin is animal-derived gelatin, preferably one or more of bovine gelatin, porcine gelatin, and fish gelatin; Preferably, the mass ratio of the gelatin to the sugar is 1:0.1 - 2; And / or, the mass ratio of the gelatin to the photocatalyst is 1:0.01 - 0.05; And / or, water is added during the preparation process, preferably the mass ratio of the gelatin to water is 1:2 - 10.

3. The method according to claim 1 or 2, characterized in that, The light is one or more of LED blue light, green light, and white light; And / or, the temperature of the reaction is 30 - 80 °C; And / or, the washing is with a salt solution, preferably the salt solution is saturated sodium chloride solution and / or saturated ammonium bicarbonate solution.

4. A glycosylated modified gelatin, wherein the glycosylated modified gelatin is prepared by the method described in any one of claims 1 - 3.

5. Use of a glycosylated modified gelatin, wherein the glycosylated modified gelatin is prepared by the method described in any one of claims 1 - 3, or is the modified gelatin described in claim 4, and the glycosylated modified gelatin is used for preparing vitamin microcapsules, preferably for preparing vitamin A microcapsules.

6. A method for preparing vitamin A microcapsules, wherein the vitamin A microcapsules are prepared with the glycosylated modified gelatin prepared by the method described in any one of claims 1 - 3, or with the glycosylated modified gelatin described in claim 4, and the preparation method is as follows: S1: Dissolve the glycosylated modified gelatin to form an aqueous phase; S2: Melt vitamin A crystals and an antioxidant to prepare an oil phase; S3: Add the oil phase to the aqueous phase for emulsification, and dry to obtain vitamin A microcapsules.

7. The method according to claim 6, wherein The temperature in S1 is 40 - 70 °C; And / or, the mass ratio of vitamin A crystals to the antioxidant in S2 is 1:0.01 - 0.05; Preferably, the antioxidant is one or more of ethoxyquinoline and / or 2,6-di-tert-butyl-4-methylphenol BHT; And / or, the melting temperature in S2 is 50 - 70 °C; And / or, the mass ratio of vitamin A crystals to the modified gelatin in S3 is 1:0.1 - 1; And / or, the drying method in S3 is spray drying; Preferably, the drying temperature is 150 - 200 °C; And / or, the emulsion particle size D90 prepared in S3 reaches 0.3 - 1.0 μm, the oil loading rate > 45%, and the embedding rate of the dried product ≥ 99%.

8. A vitamin A microcapsule, wherein the vitamin A microcapsule is prepared with the glycosylated modified gelatin prepared by the method described in any one of claims 1 - 3, or with the glycosylated modified gelatin described in claim 4, or is obtained by the preparation method described in claim 6 or 7.

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