Starch-based soft capsules and a method for their production

Abstract

The application belongs to the technical field of soft capsules, and discloses a starch-based soft capsule material and a preparation method thereof. The preparation method comprises the following steps: mixing wheat starch and deionized water, adding a sodium periodate solution to react, so as to obtain dialdehyde starch; reacting the dialdehyde starch with glycidyl methacrylate and triethylamine, so as to obtain grafted modified starch; mixing the grafted modified starch with modified nano-silicon dioxide, and reacting after ultrasonic oscillation, so as to obtain nano-silicon dioxide composite modified starch; mixing the composite modified starch with polyvinyl alcohol and polyvinylpyrrolidone, so as to obtain a film forming solution; and after the film forming solution is cast and dried, hot pressing is performed, so that the starch-based soft capsule material is finally obtained. The starch is subjected to multiple hydrophobic modifications, so that the hydrophilic performance is reduced, and the stability of the soft capsule is improved.

Description

Technical Field

[0001] This invention relates to the field of soft capsule technology, specifically to a starch-based soft capsule and its preparation method. Background Technology

[0002] In the pharmaceutical and food industries, soft capsules play a vital role as a common carrier of drugs and nutrients. Traditional soft capsules are mostly made from gelatin; however, gelatin sources have limitations, such as the risk of animal disease outbreaks, and its biodegradability and environmental performance are relatively insufficient. With the growing demand for green and sustainable materials, starch-based soft capsules have emerged. Starch is widely available, inexpensive, and has good biodegradability, making it one of the ideal alternatives to gelatin.

[0003] However, starch-based soft capsules face serious problems in practical applications, namely, the strong hydrophilicity of starch itself. This hydrophilicity makes starch-based soft capsules highly susceptible to absorbing moisture during storage and use. During storage, moisture absorption causes the soft capsules to soften, deform, and even stick together, significantly affecting the product's appearance and quality stability. In the pharmaceutical field, moisture absorption may accelerate drug degradation, reduce efficacy, and shorten shelf life; in the food industry, moisture absorption can trigger oxidative rancidity of oils and fats, microbial growth, and other problems, leading to food spoilage and affecting taste and nutritional value.

[0004] Furthermore, soft capsules need to maintain their structural integrity under specific conditions, such as in the gastrointestinal tract, where they must prevent premature disintegration in gastric juices while simultaneously releasing their contents smoothly in intestinal juices. The high hydrophilicity of starch makes its structural stability deteriorate in humid environments, making it difficult to meet these complex application requirements. Improving the hydrophobicity of starch in starch-based soft capsules and reducing its hydrophilicity could effectively improve the storage stability of soft capsules, extend product shelf life, broaden their application range under different humidity conditions, and improve product quality and safety, thus possessing significant application value and market potential. However, how to efficiently and stably achieve hydrophobic modification of starch to meet the requirements of industrial production and practical applications of soft capsules remains a key technical challenge that urgently needs to be solved in this field. Summary of the Invention

[0005] The purpose of this invention is to solve the above-mentioned technical problems by proposing a starch-based soft capsule and its preparation method. This invention involves multiple hydrophobic modifications to starch to reduce its hydrophilicity, thereby improving the stability of the soft capsule.

[0006] To achieve the above-mentioned objectives, the present invention adopts the following technical solution:

[0007] A method for preparing a starch-based soft capsule material includes the following steps:

[0008] (1) Wheat starch was added to deionized water to prepare starch milk, sodium periodate solution was added dropwise, the mixture was stirred and reacted, and after centrifugation, washing and drying, dialdehyde starch was obtained;

[0009] (2) Add dialdehyde starch to deionized water to prepare starch milk, then add glycidyl methacrylate and triethylamine, heat and stir under nitrogen protection, and after washing, filtration and drying, obtain grafted modified starch;

[0010] (3) Add the grafted modified starch to deionized water, stir and disperse to obtain a dispersion, then add modified nano silica, ultrasonically vibrate and disperse evenly, heat and stir to react, and obtain nano silica composite modified starch;

[0011] (4) Add nano-silica composite modified starch to deionized water, then add polyvinyl alcohol and polyvinylpyrrolidone, heat and stir to obtain film-forming solution;

[0012] (5) The film-forming solution is uniformly cast onto a preheated polytetrafluoroethylene plate and dried to form a pre-formed film. Then the pre-formed film is transferred between two stainless steel plates and hot-pressed to solidify and form the final product.

[0013] In existing technologies, starch-based soft capsules face a serious problem in practical applications: starch itself has strong hydrophilicity. This hydrophilicity makes starch-based soft capsules highly susceptible to absorbing moisture during storage and use. During storage, moisture absorption causes the soft capsules to soften, deform, and even stick together, significantly affecting the product's appearance and quality stability. To address these technical problems, this invention improves the stability of starch soft capsule materials in humid environments from the following three aspects:

[0014] 1) Under the action of sodium periodate, the vicinal diol structure in wheat starch molecules is oxidized to a dialdehyde structure. The formation of the dialdehyde structure changes the chemical structure and polarity of the starch molecule, reducing the number of hydrophilic groups such as hydroxyl groups in the molecule, thereby reducing the hydrophilicity of the starch; 2) Dialdehyde starch undergoes a graft copolymerization reaction with glycidyl methacrylate under triethylamine catalysis and nitrogen protection. Glycidyl methacrylate is grafted onto the dialdehyde starch molecule, introducing hydrophobic organic groups into the starch molecule, increasing the hydrophobicity of the starch molecule; 3) By incorporating food-grade nano-silica into the soft capsule material, the food-grade nano-silica and the grafted modified starch form a nanocomposite structure through physical adsorption and chemical bonding. The nanostructure can fill the gaps between starch molecules, preventing water molecules from penetrating into the soft capsule material, thereby further improving the stability of starch soft capsules in humid environments.

[0015] As a preference, in step (1), the mass ratio of sodium periodate to wheat starch is 1:10-15.

[0016] As a preference, in step (2), the mass ratio of dialdehyde starch to glycidyl methacrylate is 1:0.3-0.5.

[0017] As a preference, in step (2), the amount of triethylamine added is 0.5-3.0% of the mass of the dialdehyde starch.

[0018] Preferably, in step (3), the method for preparing modified nano-silica includes the following steps:

[0019] Nano-silica was added to anhydrous ethanol and stirred to disperse it evenly. Then, silane coupling agent hydrolysate was added, and the mixture was heated and stirred to react. Polyvinyl alcohol was then added, and the mixture was heated and stirred to react. After centrifugation, washing, and drying, modified nano-silica was obtained.

[0020] In the technical solution of this invention, as described above, the stability of starch soft capsule materials in humid environments is improved using the aforementioned series of methods. However, a further problem encountered is that the flexibility of the soft capsule material decreases, making it more brittle and prone to breakage during processing or use. Research by the invention team revealed that nano-silica has a significant impact on the flexibility of the soft capsule material. This may be because nano-silica, due to its high surface energy, agglomerates. These agglomerates act like rigid particles, hindering the relative sliding of starch molecular chains when the material is subjected to external forces, thus limiting the flexible extension of the molecular chains and leading to a decrease in the flexibility of the soft capsules. To further solve this technical problem, this invention further modifies the nano-silica by grafting polyvinyl alcohol (PVA) onto the surface of the nano-silica using a silane coupling agent. After PVA is grafted onto the surface of the nano-silica, the hydroxyl groups on its molecular chains can interact with the hydroxyl groups in starch molecules through intermolecular forces such as hydrogen bonds. This interaction builds a "bridge" between the nano-silica and starch, allowing the nano-silica to be more uniformly dispersed in the starch matrix, effectively improving the interfacial compatibility between the two. Uniformly dispersed nano-silica no longer acts as an agglomerate hindering the movement of starch molecular chains, providing a more favorable environment for the flexible movement of starch molecular chains, thereby improving the flexibility of soft capsules. Furthermore, nano-silica grafted with polyvinyl alcohol, due to its uniform dispersion and good interaction with starch molecules, can more effectively disperse and transfer stress. When the material is subjected to external force, the stress can be evenly distributed throughout the system, avoiding excessive stress concentration in localized areas. This reduces brittle fracture caused by stress concentration, further improving the flexibility and deformation resistance of soft capsules.

[0021] Preferably, the amount of modified nano-silica added is 1.5-3.0% of the mass of the grafted modified starch.

[0022] As a preference, in step (4), polyvinyl alcohol 400 is selected.

[0023] As a preference, in step (4), the mass ratio of nano-silica composite modified starch to polyvinyl alcohol is 1:0.5-1.0.

[0024] As a preference, in step (4), the mass ratio of nano-silica composite modified starch to polyvinylpyrrolidone is 1:0.05-0.15.

[0025] A starch-based soft capsule material is prepared by the method described above.

[0026] The present invention has the following beneficial effects:

[0027] (1) The starch soft capsule material has undergone a series of modifications, which greatly reduces its hydrophilicity and gives it excellent stability in a humid environment;

[0028] (2) Starch soft capsule material has good flexibility and is not easy to break during processing or use. Detailed Implementation

[0029] The technical solutions in the embodiments of the present invention will be clearly and completely described below. 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.

[0030] Example 1: A method for preparing a starch-based soft capsule material, comprising the following steps:

[0031] (1) Wheat starch was added to deionized water at a mass-volume ratio of 1 g / 10 mL to prepare starch milk. The milk was placed in a reaction vessel equipped with a stirrer and a thermometer. A sodium periodate solution with a mass concentration of 30% was slowly added dropwise under a 45°C water bath. The mass ratio of sodium periodate to wheat starch was 1:14. The mixture was stirred and reacted for 5 h. After centrifugation, washing and drying, dialdehyde starch was obtained.

[0032] (2) Dialdehyde starch was added to deionized water at a mass-volume ratio of 1 g / 5 mL to prepare starch milk. The starch milk was added to the reaction vessel, and then glycidyl methacrylate and triethylamine were added. The mass ratio of dialdehyde starch to glycidyl methacrylate was 1:0.45, and the amount of triethylamine added was 2.5% of the mass of dialdehyde starch. Under nitrogen protection, the mixture was heated to 60°C and stirred for 6 h. After washing, filtration and drying, grafted modified starch was obtained.

[0033] (3) Grafted modified starch was added to deionized water at a mass-volume ratio of 1g / 5mL, stirred and dispersed to obtain a dispersion, and then modified nano silica was added. The amount of modified nano silica added was 2.5% of the mass of grafted modified starch. The mixture was ultrasonically dispersed, heated to 70℃, stirred and reacted for 2h, and then washed, filtered and dried to obtain nano silica composite modified starch.

[0034] (4) Add nano-silica composite modified starch to deionized water at a mass-volume ratio of 1g / 7mL, then add polyvinyl alcohol 400 and polyvinylpyrrolidone. The mass ratio of nano-silica composite modified starch to polyvinyl alcohol 400 is 1:0.9, and the mass ratio of nano-silica composite modified starch to polyvinylpyrrolidone is 1:0.12. Heat to 80℃ and stir for 3h to obtain film-forming solution.

[0035] (5) The film-forming solution is uniformly cast onto a polytetrafluoroethylene plate preheated to 50°C and dried to form a pre-formed film. Then, the pre-formed film is transferred between two stainless steel plates preheated to 60°C and hot-pressed for 5 minutes under a pressure of 1.8 MPa to solidify and form the film.

[0036] The preparation method of modified nano-silica includes the following steps:

[0037] Add 50 mL of anhydrous ethanol and 5 mL of deionized water to a 250 mL three-necked flask, stir well, add 3 g of KH-570 silane coupling agent, and then add glacial acetic acid to adjust the pH value to 4-5. Stir and hydrolyze for 1 h in a 40 °C water bath to obtain the coupling agent hydrolysate.

[0038] 5g of nano-silica was added to 100mL of anhydrous ethanol and stirred for 30min to ensure uniform dispersion, yielding a nano-silica dispersion. This dispersion was then added to a coupling agent hydrolysate, and the mixture was heated to 70℃ and stirred for 3h to allow the silane coupling agent to condense with the hydroxyl groups on the nano-silica surface, completing the surface silanization treatment of the nano-silica. Subsequently, 5g of polyvinyl alcohol was added, the temperature was raised to 90℃, and the reaction was continued for 5h. After centrifugation, washing, and drying, modified nano-silica was obtained.

[0039] Example 2: A method for preparing a starch-based soft capsule material, comprising the following steps:

[0040] (1) Wheat starch was added to deionized water at a mass-volume ratio of 1 g / 10 mL to prepare starch milk. The milk was placed in a reaction vessel equipped with a stirrer and a thermometer. A sodium periodate solution with a mass concentration of 30% was slowly added dropwise under a water bath at 45°C. The mass ratio of sodium periodate to wheat starch was 1:11. The mixture was stirred and reacted for 5 h. After centrifugation, washing and drying, dialdehyde starch was obtained.

[0041] (2) Dialdehyde starch was added to deionized water at a mass-volume ratio of 1 g / 5 mL to prepare starch milk. The starch milk was added to the reaction vessel, and then glycidyl methacrylate and triethylamine were added. The mass ratio of dialdehyde starch to glycidyl methacrylate was 1:0.35, and the amount of triethylamine added was 1.0% of the mass of dialdehyde starch. Under nitrogen protection, the mixture was heated to 60°C and stirred for 6 h. After washing, filtration and drying, grafted modified starch was obtained.

[0042] (3) Grafted modified starch was added to deionized water at a mass-volume ratio of 1g / 5mL, stirred and dispersed to obtain a dispersion, and then modified nano silica was added. The amount of modified nano silica added was 2.0% of the mass of grafted modified starch. The mixture was ultrasonically dispersed, heated to 70℃, stirred and reacted for 2h, and then washed, filtered and dried to obtain nano silica composite modified starch.

[0043] (4) Add nano-silica composite modified starch to deionized water at a mass-volume ratio of 1g / 7mL, then add polyvinyl alcohol 400 and polyvinylpyrrolidone. The mass ratio of nano-silica composite modified starch to polyvinyl alcohol 400 is 1:0.6, and the mass ratio of nano-silica composite modified starch to polyvinylpyrrolidone is 1:0.08. Heat to 80℃ and stir for 3h to obtain film-forming solution.

[0044] (5) The film-forming solution is uniformly cast onto a polytetrafluoroethylene plate preheated to 50°C and dried to form a pre-formed film. Then, the pre-formed film is transferred between two stainless steel plates preheated to 60°C and hot-pressed for 5 minutes under a pressure of 1.8 MPa to solidify and form the film.

[0045] The preparation method of modified nano-silica includes the following steps:

[0046] Add 50 mL of anhydrous ethanol and 5 mL of deionized water to a 250 mL three-necked flask, stir well, add 3 g of KH-570 silane coupling agent, and then add glacial acetic acid to adjust the pH value to 4-5. Stir and hydrolyze for 1 h in a 40 °C water bath to obtain the coupling agent hydrolysate.

[0047] 5g of nano-silica was added to 100mL of anhydrous ethanol and stirred for 30min to ensure uniform dispersion, yielding a nano-silica dispersion. This dispersion was then added to a coupling agent hydrolysate, and the mixture was heated to 70℃ and stirred for 3h to allow the silane coupling agent to condense with the hydroxyl groups on the nano-silica surface, completing the surface silanization treatment of the nano-silica. Subsequently, 5g of polyvinyl alcohol was added, the temperature was raised to 90℃, and the reaction was continued for 5h. After centrifugation, washing, and drying, modified nano-silica was obtained.

[0048] Example 3: A method for preparing a starch-based soft capsule material, comprising the following steps:

[0049] (1) Wheat starch was added to deionized water at a mass-volume ratio of 1 g / 10 mL to prepare starch milk. The milk was placed in a reaction vessel equipped with a stirrer and a thermometer. A sodium periodate solution with a mass concentration of 30% was slowly added dropwise under a water bath at 45°C. The mass ratio of sodium periodate to wheat starch was 1:12. The mixture was stirred and reacted for 5 h. After centrifugation, washing and drying, dialdehyde starch was obtained.

[0050] (2) Dialdehyde starch was added to deionized water at a mass-volume ratio of 1 g / 5 mL to prepare starch milk. The starch milk was added to the reaction vessel, and then glycidyl methacrylate and triethylamine were added. The mass ratio of dialdehyde starch to glycidyl methacrylate was 1:0.4, and the amount of triethylamine added was 1.5% of the mass of dialdehyde starch. Under nitrogen protection, the mixture was heated to 60°C and stirred for 6 h. After washing, filtration and drying, grafted modified starch was obtained.

[0051] (3) Grafted modified starch was added to deionized water at a mass-volume ratio of 1g / 5mL, stirred and dispersed to obtain a dispersion, and then modified nano silica was added. The amount of modified nano silica added was 2.2% of the mass of grafted modified starch. The mixture was ultrasonically dispersed, heated to 70℃, stirred and reacted for 2h, and then washed, filtered and dried to obtain nano silica composite modified starch.

[0052] (4) Add nano-silica composite modified starch to deionized water at a mass-volume ratio of 1g / 7mL, then add polyvinyl alcohol 400 and polyvinylpyrrolidone. The mass ratio of nano-silica composite modified starch to polyvinyl alcohol 400 is 1:0.7, and the mass ratio of nano-silica composite modified starch to polyvinylpyrrolidone is 1:0.1. Heat to 80℃ and stir for 3h to obtain film-forming solution;

[0053] (5) The film-forming solution is uniformly cast onto a polytetrafluoroethylene plate preheated to 50°C and dried to form a pre-formed film. Then, the pre-formed film is transferred between two stainless steel plates preheated to 60°C and hot-pressed for 5 minutes under a pressure of 1.8 MPa to solidify and form the film.

[0054] The preparation method of modified nano-silica includes the following steps:

[0055] Add 50 mL of anhydrous ethanol and 5 mL of deionized water to a 250 mL three-necked flask, stir well, add 3 g of KH-570 silane coupling agent, and then add glacial acetic acid to adjust the pH value to 4-5. Stir and hydrolyze for 1 h in a 40 °C water bath to obtain the coupling agent hydrolysate.

[0056] 5g of nano-silica was added to 100mL of anhydrous ethanol and stirred for 30min to ensure uniform dispersion, yielding a nano-silica dispersion. This dispersion was then added to a coupling agent hydrolysate, and the mixture was heated to 70℃ and stirred for 3h to allow the silane coupling agent to condense with the hydroxyl groups on the nano-silica surface, completing the surface silanization treatment of the nano-silica. Subsequently, 5g of polyvinyl alcohol was added, the temperature was raised to 90℃, and the reaction was continued for 5h. After centrifugation, washing, and drying, modified nano-silica was obtained.

[0057] Example 4: A method for preparing a starch-based soft capsule material, comprising the following steps:

[0058] (1) Wheat starch was added to deionized water at a mass-volume ratio of 1 g / 10 mL to prepare starch milk. The milk was placed in a reaction vessel equipped with a stirrer and a thermometer. A sodium periodate solution with a mass concentration of 30% was slowly added dropwise in a 45°C water bath. The mass ratio of sodium periodate to wheat starch was 1:15. The mixture was stirred and reacted for 5 h. After centrifugation, washing and drying, dialdehyde starch was obtained.

[0059] (2) Dialdehyde starch was added to deionized water at a mass-volume ratio of 1 g / 5 mL to prepare starch milk. The starch milk was added to the reaction vessel, and then glycidyl methacrylate and triethylamine were added. The mass ratio of dialdehyde starch to glycidyl methacrylate was 1:0.5, and the amount of triethylamine added was 3.0% of the mass of dialdehyde starch. Under nitrogen protection, the mixture was heated to 60°C and stirred for 6 h. After washing, filtration and drying, grafted modified starch was obtained.

[0060] (3) Grafted modified starch was added to deionized water at a mass-volume ratio of 1g / 5mL, stirred and dispersed to obtain a dispersion, and then modified nano silica was added. The amount of modified nano silica added was 3.0% of the mass of grafted modified starch. The mixture was ultrasonically dispersed, heated to 70℃, stirred and reacted for 2h, and then washed, filtered and dried to obtain nano silica composite modified starch.

[0061] (4) Add nano-silica composite modified starch to deionized water at a mass-volume ratio of 1g / 7mL, then add polyvinyl alcohol 400 and polyvinylpyrrolidone. The mass ratio of nano-silica composite modified starch to polyvinyl alcohol 400 is 1:1.0, and the mass ratio of nano-silica composite modified starch to polyvinylpyrrolidone is 1:0.15. Heat to 80℃ and stir for 3h to obtain film-forming solution.

[0062] (5) The film-forming solution is uniformly cast onto a polytetrafluoroethylene plate preheated to 50°C and dried to form a pre-formed film. Then, the pre-formed film is transferred between two stainless steel plates preheated to 60°C and hot-pressed for 5 minutes under a pressure of 1.8 MPa to solidify and form the film.

[0063] The preparation method of modified nano-silica includes the following steps:

[0064] Add 50 mL of anhydrous ethanol and 5 mL of deionized water to a 250 mL three-necked flask, stir well, add 3 g of KH-570 silane coupling agent, and then add glacial acetic acid to adjust the pH value to 4-5. Stir and hydrolyze for 1 h in a 40 °C water bath to obtain the coupling agent hydrolysate.

[0065] 5g of nano-silica was added to 100mL of anhydrous ethanol and stirred for 30min to ensure uniform dispersion, yielding a nano-silica dispersion. This dispersion was then added to a coupling agent hydrolysate, and the mixture was heated to 70℃ and stirred for 3h to allow the silane coupling agent to condense with the hydroxyl groups on the nano-silica surface, completing the surface silanization treatment of the nano-silica. Subsequently, 5g of polyvinyl alcohol was added, the temperature was raised to 90℃, and the reaction was continued for 5h. After centrifugation, washing, and drying, modified nano-silica was obtained.

[0066] Example 5: A method for preparing a starch-based soft capsule material, comprising the following steps:

[0067] (1) Wheat starch was added to deionized water at a mass-volume ratio of 1 g / 10 mL to prepare starch milk. The milk was placed in a reaction vessel equipped with a stirrer and a thermometer. A sodium periodate solution with a mass concentration of 30% was slowly added dropwise under a 45°C water bath. The mass ratio of sodium periodate to wheat starch was 1:10. The mixture was stirred and reacted for 5 h. After centrifugation, washing and drying, dialdehyde starch was obtained.

[0068] (2) Dialdehyde starch was added to deionized water at a mass-volume ratio of 1 g / 5 mL to prepare starch milk. The starch milk was added to the reaction vessel, and then glycidyl methacrylate and triethylamine were added. The mass ratio of dialdehyde starch to glycidyl methacrylate was 1:0.3, and the amount of triethylamine added was 0.5% of the mass of dialdehyde starch. Under nitrogen protection, the mixture was heated to 60°C and stirred for 6 hours. After washing, filtration and drying, grafted modified starch was obtained.

[0069] (3) Grafted modified starch was added to deionized water at a mass-volume ratio of 1g / 5mL, stirred and dispersed to obtain a dispersion, and then modified nano silica was added. The amount of modified nano silica added was 1.5% of the mass of grafted modified starch. The mixture was ultrasonically dispersed, heated to 70℃, stirred and reacted for 2h, and then washed, filtered and dried to obtain nano silica composite modified starch.

[0070] (4) Add nano-silica composite modified starch to deionized water at a mass-volume ratio of 1g / 7mL, then add polyvinyl alcohol 400 and polyvinylpyrrolidone. The mass ratio of nano-silica composite modified starch to polyvinyl alcohol 400 is 1:0.5, and the mass ratio of nano-silica composite modified starch to polyvinylpyrrolidone is 1:0.05. Heat to 80℃ and stir for 3h to obtain film-forming solution.

[0071] (5) The film-forming solution is uniformly cast onto a polytetrafluoroethylene plate preheated to 50°C and dried to form a pre-formed film. Then, the pre-formed film is transferred between two stainless steel plates preheated to 60°C and hot-pressed for 5 minutes under a pressure of 1.8 MPa to solidify and form the film.

[0072] The preparation method of modified nano-silica includes the following steps:

[0073] Add 50 mL of anhydrous ethanol and 5 mL of deionized water to a 250 mL three-necked flask, stir well, add 3 g of KH-570 silane coupling agent, and then add glacial acetic acid to adjust the pH value to 4-5. Stir and hydrolyze for 1 h in a 40 °C water bath to obtain the coupling agent hydrolysate.

[0074] 5g of nano-silica was added to 100mL of anhydrous ethanol and stirred for 30min to ensure uniform dispersion, yielding a nano-silica dispersion. This dispersion was then added to a coupling agent hydrolysate, and the mixture was heated to 70℃ and stirred for 3h to allow the silane coupling agent to condense with the hydroxyl groups on the nano-silica surface, completing the surface silanization treatment of the nano-silica. Subsequently, 5g of polyvinyl alcohol was added, the temperature was raised to 90℃, and the reaction was continued for 5h. After centrifugation, washing, and drying, modified nano-silica was obtained.

[0075] Comparative Example 1

[0076] The difference between Comparative Example 1 and Example 1 is as follows:

[0077] Steps (1) and (2) are omitted in the preparation of starch-based soft capsule materials;

[0078] The remaining operating steps are the same as in Example 1.

[0079] Comparative Example 2

[0080] The difference between Comparative Example 2 and Example 1 is as follows:

[0081] Step (3) is omitted in the preparation of starch-based soft capsule materials;

[0082] The remaining operating steps are the same as in Example 1.

[0083] Comparative Example 3

[0084] The difference between Comparative Example 3 and Example 1 is as follows:

[0085] Replace the modified nano silica in step (3) with ordinary nano silica;

[0086] The remaining operating steps are the same as in Example 1.

[0087] control sample

[0088] The control sample used ordinary wheat starch to prepare the soft capsule material.

[0089] Performance testing

[0090] Stability test of soft capsule materials: Medium-mass soft capsule materials from the examples and comparative examples were placed in a constant temperature and humidity chamber and left for 10 days. The moisture content was then determined using the toluene method. The humidity was controlled at 5%, 20%, 40%, 60%, and 80%, respectively. The moisture content (%) of the soft capsule materials was then tested after 10 days.

[0091]

[0092] Flexibility test of soft capsule materials: Place the starch capsule shell sample on the operating table and manually fold it multiple times, observing whether cracks or breaks appear on the sample surface. If obvious cracks or breaks only appear after a certain number of folds, it indicates good flexibility; if cracks or breaks appear after only a few folds, the flexibility is poor. Use a magnifying glass to observe the microstructural changes at the folds to help determine the flexibility.

[0093]

[0094] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A process for the preparation of a starch-based soft capsule material, characterized in that, The method comprises the following steps: (1) preparing a starch milk by adding wheat starch into deionized water, adding sodium periodate solution dropwise, stirring and reacting, and then performing centrifugal separation, washing and drying to obtain dialdehyde starch; (2) preparing a starch milk by adding the dialdehyde starch into deionized water, then adding glycidyl methacrylate and triethylamine, stirring and reacting under nitrogen protection, and then performing washing, suction filtration and drying to obtain grafted modified starch; (3) dispersing the grafted modified starch in deionized water to obtain a dispersion liquid, then adding modified nano-silicon dioxide, ultrasonic oscillation, uniform dispersion, and heating and stirring to obtain nano-silicon dioxide composite modified starch; The preparation method of the modified nano-silicon dioxide comprises the following steps: adding nano-silicon dioxide into anhydrous ethanol, stirring and uniformly dispersing, then adding silane coupling agent hydrolysis liquid, heating and stirring, then adding polyvinyl alcohol, heating and stirring, and then performing centrifugal separation, washing and drying to obtain modified nano-silicon dioxide; (4) adding the nano-silicon dioxide composite modified starch into deionized water, then adding polyvinyl alcohol and polyvinylpyrrolidone, and heating and stirring to obtain a film forming liquid; (5) uniformly casting the film forming liquid on a preheated polytetrafluoroethylene plate, drying to form a preliminarily formed film, then transferring the preliminarily formed film to between two stainless steel plates for heat pressing and curing to form a film.

2. A process for the preparation of a starch-based soft capsule material according to claim 1, characterized in that, In the step (1), the mass ratio of sodium periodate to wheat starch is 1:10-15.

3. A process for the preparation of a starch-based soft capsule material according to claim 1, characterized in that, In the step (2), the mass ratio of dialdehyde starch to glycidyl methacrylate is 1:0.3-0.

5.

4. A process for the preparation of a starch-based soft capsule material according to claim 1, characterized in that, In the step (2), the addition amount of triethylamine is 0.5-3.0% of the mass of the dialdehyde starch.

5. A process for the preparation of a starch-based soft capsule material according to claim 1, characterized in that, The addition amount of the modified nano-silicon dioxide is 1.5-3.0% of the mass of the grafted modified starch.

6. A process for the preparation of a starch-based soft capsule material according to claim 1, characterized in that, In the step (4), the polyvinyl alcohol is polyvinyl alcohol 400.

7. A process for the preparation of a starch-based soft capsule material according to claim 1, characterized in that, In the step (4), the mass ratio of the nano-silicon dioxide composite modified starch to polyvinyl alcohol is 1:0.5-1.

0.

8. A process for the preparation of a starch-based soft capsule material according to claim 1, characterized in that, In the step (4), the mass ratio of the nano-silicon dioxide composite modified starch to polyvinylpyrrolidone is 1:0.05-0.

15.

9. A starch-based softgel material, characterized in that, The film is prepared by the method of any one of claims 1-8.

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