Plant-based soft capsule

Abstract

A plant-based soft capsule comprising a film-forming composition, the film-forming composition being used for forming a soft capsule shell and comprising 1-15 parts by weight of a first edible gum, 1-15 parts by weight of a second edible gum, 10-50 parts by weight of a plasticizer, and a certain amount of a pH adjusting agent, wherein the amount of the pH adjusting agent is such that the pH value of the soft capsule shell is less than 5 when formulated into a 5wt % aqueous solution, preferably 3-4.5, and the first edible gum is gellan gum and the second edible gum is pectin. The soft capsule has a pleasant texture when chewed, ruptures easily when bitten, is brittle yet palatable, and is suitable for consumption by children and the elderly.

Description

A plant-based soft capsule

[0001] This application claims priority to Chinese patent application filed on June 18, 2024, with application number 202410792567.0 and entitled "A Plant-Based Soft Capsule". Technical Field

[0002] This invention belongs to the field of pharmaceutical and dietary supplement manufacturing, and specifically relates to a film-forming composition and its application in plant-based soft capsules. Background Technology

[0003] Existing chewable soft capsules have a poor chewing texture, being hard and tough. Certain groups, such as children and the elderly, cannot bite through these capsules, and the product does not provide a crisp and palatable experience, severely impacting the user experience and consumer demand for chewable soft capsules.

[0004] WO2023036581A1 discloses a film-forming composition comprising high-ester pectin, water, and a plasticizer. The addition of a second gelling agent (starch) results in a film-forming composition capable of preparing soft capsules or hard capsule shells. Essentially, WO2023036581A1 is a film-forming composition using only high-ester pectin, water, and a plasticizer without the addition of a second gelling agent (starch). This composition can only produce a thin film. Only with the addition of a second gelling agent (starch) can the film-forming composition exhibit sufficient adhesive strength to bond two soft capsule films together during the soft capsule forming process, thereby producing a soft capsule. In the film-forming composition of WO2023036581A1, the high-ester pectin requires high levels of coexisting starch and a low pH (pH 3.26) to provide the gelling properties required for soft capsule formation. Furthermore, its gelling properties are brittle, resulting in low strength and poor toughness of the formed capsule shell. During the soft capsule forming process, the capsule shell cannot expand or contract significantly, resulting in low shell utilization, high costs, and a tendency for oil leakage. Furthermore, the chewable soft capsules prepared with this formula have a tough texture, and the shell becomes very hard after drying, making it difficult for consumers to bite through, thus making it unsuitable for manufacturing chewable soft capsules.

[0005] Existing plant-based gum soft capsules primarily utilize plant-based colloids combined with starch to achieve low oil leakage rates and controllable costs. For example, commercially available products combine carrageenan and starch, as well as gellan gum and starch. However, the carrageenan-starch combination, due to the presence of carrageenan, faces controversy among some consumers, and its high cost limits its development. The gellan gum-starch combination technology is a rising star, offering stable production and moderate pricing, and represents one of the future development paths. The pectin-starch combination technology is still immature and suffers from drawbacks such as high oil leakage rates and high costs.

[0006] Therefore, it is urgent to develop a soft capsule technology that has a low oil leakage rate, stable production, controllable cost, excellent chewing taste, and is easy to bite through. Summary of the Invention

[0007] This invention reveals that existing film-forming composition techniques produce soft capsule shells with poor chewability, high toughness, and difficulty in biting through. Experiments show that films prepared using gellan gum, pectin, water, and a plasticizer as the film-forming composition have a crisp and palatable texture and are easy to bite through, but the formed shells have poor adhesion, making it impossible to produce soft capsules. Further adjustments to the ratio and amount of gellan gum and pectin failed to improve the adhesion and toughness of the film formed by the film-forming composition. However, unexpectedly, it was found that by adjusting the pH of the soft capsule shell solution in addition to gellan gum, pectin, water, and a plasticizer, when the pH of a 5% soft capsule shell solution is between 3.0 and 4.5, the film formed by the film-forming composition exhibits excellent toughness and adhesion. This not only ensures sufficient elasticity of the shell during molding but also demonstrates strong adhesion at the seams of the pressed soft capsules. Furthermore, the film formed by the film-forming composition of this invention has a smooth surface, and the pressed soft capsules do not leak oil, making it suitable for large-scale production. This invention discovers a soft capsule film-forming composition that is soft, brittle, and easy to bite through. Compared with film-forming compositions of carrageenan and starch, the soft capsules prepared by this composition have a better chewing texture, are easier to bite through, and are crisp and delicious, making them especially suitable for children and the elderly.

[0008] In one aspect, a film-forming composition is provided for forming soft capsule shells, comprising 1-15 parts by weight of a first edible gum, 1-15 parts by weight of a second edible gum, 10-50 parts by weight of a plasticizer, and a certain amount of a pH adjuster, wherein the amount of the pH adjuster is such that the soft capsule shell has a pH value <5 when formulated into a 5 wt% aqueous solution, and the first edible gum is gellan gum, and the second edible gum is pectin. In one embodiment, the amount of the pH adjuster is such that the soft capsule shell has a pH value of 3 to 4.5 when formulated into a 5 wt% aqueous solution.

[0009] In one embodiment, the film-forming composition comprises water. In another embodiment, the film-forming composition comprises 20-60 parts by weight of water.

[0010] In one embodiment, the film-forming composition comprises 0-24 parts by weight of one or more of starch, dextrin, cellulose, and pullulan.

[0011] In one embodiment, the film-forming composition comprises one or more of a pigment, an opacifier, a fragrance, and a sweetener.

[0012] In one embodiment, the film-forming composition comprises a third edible gum, which is one or more of carrageenan, agar, sodium alginate, konjac gum, xanthan gum, and locust bean gum.

[0013] In one embodiment, the film-forming composition does not contain gelatin.

[0014] In one embodiment, gellan gum is one or more of partially deacylated gellan gum and high-acylated gellan gum.

[0015] In one embodiment, a partially deacylated gellan gum is a gellan gum in which each repeating unit contains 25%-40% or 30-40% acetyl groups and 15%-45% or 15%-40% or 15%-30% or 15%-26% glyceryl groups.

[0016] In one embodiment, each repeating unit of gellan gum contains more than 40% acetyl groups and more than 45% glyceryl groups.

[0017] In one embodiment, the pectin is a high-ester pectin. In another embodiment, the pectin is a pectin with an esterification degree of 50-70%, 52%-65%, or 52%-60%.

[0018] In one embodiment, the plasticizer is one or more of glycerol, sorbitol, mannitol, erythritol, xylitol, and maltitol.

[0019] In one embodiment, the pH adjuster is one or more of citrate, carbonate, bicarbonate, phosphate, pyrophosphate, sodium hydroxide, potassium hydroxide, citric acid, malic acid, acetic acid, hydrochloric acid, or phosphoric acid.

[0020] In one embodiment, the citrate is sodium citrate and / or potassium citrate. In one embodiment, the phosphate is sodium phosphate and / or potassium phosphate. In one embodiment, the pyrophosphate is sodium pyrophosphate. In one embodiment, the carbonate is sodium carbonate and / or potassium carbonate. In one embodiment, the bicarbonate is sodium bicarbonate or potassium bicarbonate.

[0021] In one embodiment, the starch is one or more of natural starch and modified starch.

[0022] In one embodiment, the modified starch is one or more of hydroxypropyl starch, hydroxypropyl distarch phosphate, oxidized starch, acetate starch, oxidized hydroxypropyl starch, acetylated oxidized starch, acetylated distarch phosphate, or acid-modified starch.

[0023] In one embodiment, the film-forming composition comprises 2-10 parts by weight, 3-8 parts by weight, or 4-6 parts by weight of gellan gum.

[0024] In one embodiment, the film-forming composition comprises 2-10 parts by weight, 5-9 parts by weight, or 6-8 parts by weight of pectin.

[0025] In one embodiment, the film-forming composition comprises 15-50 parts by weight, 20-45 parts by weight, or 25-45 parts by weight of a plasticizer.

[0026] In one embodiment, the film-forming composition comprises 0.05-1.3 parts by weight, 0.1-1 parts by weight, or 0.2-1 parts by weight of a pH adjuster.

[0027] In one embodiment, the film-forming composition comprises 1-24 parts by weight, 1-12 parts by weight, or 1-5 parts by weight of starch.

[0028] In one embodiment, the film-forming composition comprises no more than 4 parts by weight of pigment.

[0029] In one embodiment, the film-forming composition comprises no more than 5 parts by weight of a light-blocking agent.

[0030] In one embodiment, the film-forming composition comprises no more than 2 parts by weight of fragrance.

[0031] In one embodiment, the film-forming composition comprises no more than 3 parts by weight of a sweetener.

[0032] In one embodiment, the ratio of the insoluble particle content Mu of the soft capsule shell to the gel dosage Mj of the film-forming composition is 0-2.

[0033] The insoluble particle content Mu is the sum of the content of small insoluble particles m1 and the content of large insoluble particles m2 in the capsule shell;

[0034] The content of small insoluble matter m1 was determined as follows: the capsule shell was placed in a 2% calcium chloride solution to solidify for 2 hours, and the dissolved small insoluble matter suspension was dried to remove moisture. The weight of the small insoluble matter was the content of small insoluble matter m1.

[0035] The content of large insoluble matter m2 was determined as follows: After the soft capsule shell was completely dissolved, the turbid liquid of the dissolved soft capsule shell was centrifuged at 4000 rpm for 15 min. After the upper liquid was removed, the bottom precipitate was thoroughly dried. The weight of the bottom precipitate was the content of large insoluble matter m2.

[0036] The gelling agent content Mj is the sum of the amounts of edible gum used.

[0037] In one embodiment, the pigment is selected from one or more of titanium dioxide, Allura Red, Brilliant Blue, Tartrazine, Sunset Yellow, Cochineal, Turmeric, Natura Orange, Gardenia Yellow, Gardenia Blue, Safflower Yellow, Vegetable Carbon Black, Carotene, and Sodium Copper Chloride.

[0038] In one implementation, the fragrance is selected from one or more of the following: peach flavoring, strong strawberry flavoring, cherry flavoring, cantaloupe flavoring, apple flavoring, grape flavoring, banana flavoring, lemon flavoring, papaya whitening flavoring, blueberry flavoring, fruit acid flavoring, grapefruit flavoring, olive flavoring, sweet orange flavoring, or milk flavoring.

[0039] In one embodiment, the sweetener is selected from one or more of sucralose, aspartame, alitame, sodium saccharin, acesulfame potassium, allulose, adventitia, cyclamate, sematrandezine, steviol glycosides, mogrosides, isomaltulose, ammonium glycyrrhizate, monopotassium and tripotassium glycyrrhizate, D-mannitol, xylitol, erythritol, maltitol, and lactitol.

[0040] In another aspect, a method for preparing soft capsule shells from the film-forming compositions described herein is provided, comprising one or more of the following steps:

[0041] 1) Sol: A) First, heat and stir the gellan gum, pectin, plasticizer and water in the formula amount, or the gellan gum, pectin, starch, plasticizer and water in the formula amount at 60-98°C until all materials are dissolved; B) Remove the air bubbles to obtain the sol;

[0042] 2) Shot pressing: Using a soft capsule production line, the glue solution is transported to the glue box of the soft capsule filling machine. The glue solution is cooled on the surface of the drum to form a capsule shell, which is then pressed into shape by the encapsulation filler and can be further shaped in the drum.

[0043] 3) Drying: After the capsules have been shaped or rotated, dry them until the moisture content of the capsule skin is 8-20%.

[0044] In another aspect, soft capsule shells are provided that comprise the film-forming composition described herein or prepared by the methods described herein.

[0045] In another aspect, soft capsules are provided, which contain the soft capsule shell and contents described herein.

[0046] In one embodiment, the contents include one or more of vitamins, microorganisms, enzymes, vegetable or animal oils, protein powder, minerals, and plant extracts.

[0047] In one implementation, the vitamin is one or more of vitamin A, vitamin D, or vitamin K.

[0048] In one embodiment, the microorganism is a probiotic strain, preferably one or more of Bifidobacterium, lactic acid bacteria, or yeast.

[0049] In one embodiment, the enzyme preparation is one or more of glucose oxidase, oxidase, transglutaminase, protease, α-amylase, β-amylase, papain, pepsin, trypsin, lactase, invertase, maltase, or lipase.

[0050] In one embodiment, the vegetable oil or animal fat is an oil containing unsaturated fatty acids, preferably one or more of Omega-3 fatty acids, Omega-6 fatty acids, and Omega-9 fatty acids.

[0051] In one embodiment, the protein powder is one or more of fish meal, meat and bone meal, egg powder, or soy powder.

[0052] In one embodiment, the vegetable oil or animal fat is one or more of the following: DHA algal oil, fish oil, flaxseed oil, rice bran oil, evening primrose oil, borage oil, wheat germ oil, conjugated linoleic acid, Ganoderma lucidum spore oil, pear oil, krill oil, garlic oil, almond oil, perilla seed oil, olive oil, squalene, sesame oil, pumpkin seed oil, safflower seed oil, shea butter oil, camellia oil, saw palm extract oil, walnut oil, castor oil, grapeseed oil, cottonseed oil, peanut oil, soybean oil, corn oil, sunflower seed oil, rapeseed oil, and palm oil.

[0053] In one implementation, the minerals are one or more mineral salts and oxides containing calcium, magnesium, potassium, manganese, iron, zinc, selenium, and copper.

[0054] In one embodiment, the plant extract is one or more of lutein, lutein ester, zeaxanthin, Haematococcus pluvialis, elderberry, blueberry, acerola cherry, chicken gizzard lining, honeysuckle, poria cocos, hawthorn, yam, millet, and tangerine peel extract.

[0055] In another aspect, the use of the film-forming compositions or soft capsules described herein in pharmaceuticals, food, or cosmetics is provided. Preferably, the food is a health food.

[0056] The advantages of this invention include:

[0057] 1. The soft capsules and capsule shells prepared by the film-forming composition described in this article have a better taste, are easier to bite, and are crisp and delicious, making them especially suitable for children and the elderly.

[0058] 2. The soft capsules prepared by the film-forming composition described in this article have smooth capsule shells, and the pressed soft capsules do not have the problem of content leakage (e.g., oil leakage), making them suitable for large-scale production. Attached Figure Description

[0059] Figure 1 shows the fracture surface morphology of a soft capsule shell containing gellan gum and starch (Comparative Example 5) under a 400x optical microscope.

[0060] Figure 2 shows the fracture surface morphology of the soft capsule shell (composition 1) containing gellan gum and pectin under a 400x optical microscope.

[0061] Figure 3 is a diagram of the occlusal stress-stroke distance of the soft capsule shell prepared by composition 1.

[0062] Figure 4 shows the occlusal stress-stroke distance diagram of the soft capsule shell prepared in Comparative Example 1. Detailed Implementation

[0063] The present invention will be further described in detail below with reference to specific embodiments. The present invention can be implemented in many different forms and is not limited to the embodiments described herein. Rather, these embodiments are provided to provide a thorough and complete understanding of the disclosure of the present invention.

[0064] Unless otherwise defined, 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 invention pertains.

[0065] This invention, through experiments, discovered that using gellan gum, pectin, water, and a plasticizer as a film-forming composition cannot produce soft capsules. Adjusting the ratio and amount of gellan gum and pectin did not improve the adhesion and toughness of the film formed by the film-forming composition. However, unexpectedly, this invention found that by combining gellan gum with pectin and adjusting the pH value of the film-forming composition, improved film adhesion and toughness could be achieved. Specifically, this invention found that when the pH value of a 5% soft capsule shell solution is between 3.0 and 4.5, the film formed by the film-forming composition exhibits excellent toughness and adhesion, ensuring sufficient elasticity of the capsule shell during molding and strong adhesion at the seams of the pressed soft capsules. The film formed by this type of film-forming composition has a smooth surface, and the pressed soft capsules do not experience leakage of contents (e.g., oil leakage), making it suitable for large-scale production.

[0066] In this document, the term "film-forming composition" refers to a composition of materials that forms the capsule shell. In this document, the film-forming composition is used to form the shell of soft capsules. The film-forming composition may contain edible gums, plasticizers, and pH adjusters.

[0067] The film-forming composition may further comprise one or more of starch, dextrin, cellulose, and pullulan. Alternatively, the film-forming composition may not comprise one or more of starch, dextrin, cellulose, and pullulan. Preferably, the starch is one or more of natural starch and modified starch. Preferably, the modified starch is one or more of hydroxypropyl starch, hydroxypropyl distarch phosphate, oxidized starch, acetate starch, oxidized hydroxypropyl starch, acetylated oxidized starch, acetylated distarch phosphate, or acid-modified starch.

[0068] The film-forming composition described herein may comprise a first edible gum, a second edible gum, and optionally a third edible gum. The first edible gum may be gellan gum, and the second edible gum may be pectin. Gellan gum may be one or more of partially deacylated gellan gum and high-acylated gellan gum. Preferably, the partially deacylated gellan gum contains 25%-40% (e.g., 25%, 26%, 27%, 28%, 29%, 30%, 31%, 32%, 33%, 34%, 35%, 36%, 37%, 38%, 39%, 40%) or 30-40% acetyl groups and 15%-45% (e.g., 15%, 16%, 17%, 18%, 19%) of each repeating unit of gellan gum. Gellan gum containing 20%, 21%, 22%, 23%, 24%, 25%, 26%, 27%, 28%, 29%, 30%, 31%, 32%, 33%, 34%, 35%, 36%, 37%, 38%, 39%, 40%, 41%, 42%, 43%, 44%, 45%) or 15%-40%, 15%-30%, or 15%-26% glyceryl acyl groups. Preferably, each repeating unit of the gellan gum contains more than 40% acetyl groups and more than 45% glyceryl acyl groups. Preferably, the pectin is a high-ester pectin, and more preferably a pectin with a degree of esterification of 50%-70% (e.g., 50%, 51%, 52%, 53%, 54%, 55%, 56%, 57%, 58%, 59%, 60%, 61%, 62%, 63%, 64%, 65%, 66%, 67%, 68%, 69% or 70%) or 52-65%, or 52%-60%.

[0069] The third edible gum may be one or more of carrageenan, agar, sodium alginate, konjac gum, xanthan gum, and locust bean gum. The film-forming composition may not contain gelatin. The film-forming composition herein may contain 1-15 parts by weight of a first edible gum, for example, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, or 15 parts by weight of a first edible gum. The film-forming composition herein may contain 1-15 parts by weight of a second edible gum, for example, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, or 15 parts by weight of a second edible gum.

[0070] The film-forming composition described herein may contain 10-50 parts by weight of a plasticizer, such as 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, 30, 31, 32, 33, 34, 35, 36, 37, 38, 39, 40, 41, 42, 43, 44, 45, 46, 47, 48, 49, or 50 parts by weight of a plasticizer. The plasticizer may be one or more of glycerol, sorbitol, mannitol, erythritol, xylitol, and maltitol.

[0071] The film-forming composition described herein may contain a certain amount of a pH adjuster, wherein the amount of the pH adjuster is such that the pH value of the soft capsule shell is <5 when prepared into a 5 wt% aqueous solution, preferably 3 to 4.5. For example, the pH value of the soft capsule shell when prepared into a 5 wt% aqueous solution is 3.1, 3.2, 3.3, 3.4, 3.5, 3.6, 3.7, 3.8, 3.9, 4, 4.1, 4.2, 4.3, 4.4, 4.5, 4.6, 4.7, 4.8, or 4.9.

[0072] The film-forming composition described herein may also contain water, for example 20-60 parts by weight, such as 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, 30, 31, 32, 33, 34, 35, 36, 37, 38, 39, 40, 41, 42, 43, 44, 45, 46, 47, 48, 49, 50, 51, 52, 53, 54, 55, 56, 57, 58, 59 or 60 parts by weight.

[0073] Depending on the material differences in the film-forming compositions described herein, different types of food pH adjusters can be selected. For example, the pH adjuster may be one or more of citrate, carbonate, bicarbonate, phosphate, pyrophosphate, sodium hydroxide, potassium hydroxide, citric acid, malic acid, acetic acid, hydrochloric acid, or phosphoric acid. Preferably, the citrate is sodium citrate and / or potassium citrate. Preferably, the phosphate is sodium phosphate and / or potassium phosphate. Preferably, the pyrophosphate is sodium pyrophosphate. Preferably, the carbonate is sodium carbonate and / or potassium carbonate. Preferably, the bicarbonate is sodium bicarbonate or potassium bicarbonate.

[0074] In the film-forming composition described herein, the ratio of the insoluble particle content Mu of the soft capsule shell to the gel dosage Mj of the film-forming composition is 0-2, for example, 0.1, 0.2, 0.3, 0.4, 0.5, 0.6, 0.7, 0.8, 0.9, 1.1, 1.2, 1.3, 1.4, 1.5, 1.6, 1.7, 1.8, 1.9, or 2. The insoluble particle content Mu refers to the sum of the content of small insoluble particles m1 and the content of large insoluble particles m2. The content of small insoluble particles m1 can be determined by a method comprising the following steps: placing 100 mg of dried soft capsule shell in a 2% calcium chloride solution for 2 hours to solidify, drying the dissolved small insoluble particle suspension to remove moisture, and the weight of the small insoluble particles is the content of small insoluble particles m1. The content of large insoluble particles, m2, can be determined by the following steps: 100 mg of dried soft capsule shells are completely dissolved in water (e.g., deionized water, such as 15 g of deionized water) (e.g., completely dissolved at 75°C). The turbid solution of the dissolved soft capsule shells is centrifuged at 4000 rpm for 15 min. The supernatant is removed, and the bottom precipitate is thoroughly dried. The weight of the precipitate is the content of large insoluble particles, m2. The gelling agent content, Mj, can be the sum of the amounts of edible gum used.

[0075] The film-forming composition may also contain one or more excipients commonly used in the soft capsule industry, such as pigments, opacifiers, flavorings, and sweeteners. The film-forming composition may contain no more than 4 parts by weight, for example, 0, 1, 2, 3, or 4 parts by weight of pigment. The film-forming composition may contain no more than 5 parts by weight, for example, 0, 1, 2, 3, 4, or 5 parts by weight of opacifier. The film-forming composition may contain no more than 2 parts by weight, for example, 0, 1, or 2 parts by weight of flavoring. The film-forming composition may contain no more than 3 parts by weight, for example, 0, 1, 2, or 3 parts by weight of sweetener. The pigment may be selected from one or more of titanium dioxide, Allura Red, Brilliant Blue, Tartrazine, Sunset Yellow, Cochineal, Turmeric, Natura Orange, Gardenia Yellow, Gardenia Blue, Safflower Yellow, Vegetable Carbon Black, Carotene, and Sodium Copper Chloride. The flavoring can be selected from one or more of the following: peach flavoring, strong strawberry flavoring, cherry flavoring, cantaloupe flavoring, apple flavoring, grape flavoring, banana flavoring, lemon flavoring, papaya whitening flavoring, blueberry flavoring, fruit acid flavoring, grapefruit flavoring, olive flavoring, sweet orange flavoring, or milk flavoring. The sweetener can be selected from one or more of the following: sucralose, aspartame, alitane, sodium saccharin, acesulfame potassium, allulose, adventitia, cyclamate, sematrandezidine, steviol glycosides, mogrosides, isomaltulose, ammonium glycyrrhizate, monopotassium and tripotassium glycyrrhizate, D-mannitol, xylitol, erythritol, maltitol, and lactitol.

[0076] The film-forming composition described herein can be used to prepare soft capsule shells. Those skilled in the art can routinely select suitable methods for preparing soft capsule shells. In this document, the method for preparing soft capsule shells from the film-forming composition includes one or more of the following steps: 1) Sol-gel: A) Heat and stir the formulated amounts of gellan gum, pectin, plasticizer, and water, or the formulated amounts of gellan gum, pectin, starch, plasticizer, and water, at 60–98°C until all materials are dissolved; B) Remove air bubbles to obtain the gel solution; 2) Capsule compression: Using a soft capsule production line, the gel solution is conveyed to the capsule box of a soft capsule filling machine. The gel solution cools on the surface of the drum to form a capsule shell, which is then pressed into shape by encapsulation filler and can be further shaped in a drum; 3) Drying: The shaped or drum-shaped capsules are dried until the shell moisture content is 8–20%. The soft capsule shells described herein may contain the film-forming composition described herein or be prepared by the methods described herein. The moisture content of the soft capsule shells described herein can be 8–20%.

[0077] The soft capsule shell described herein can be made into a soft capsule. The soft capsule may contain contents. The contents may contain one or more of the following: vitamins, microorganisms, enzymes, vegetable or animal fats, protein powder, minerals, and plant extracts. Vitamins may be one or more of vitamin A, vitamin D, or vitamin K. Microorganisms may be probiotic strains, preferably one or more of bifidobacteria, lactic acid bacteria, or yeast. Enzymes may be one or more of glucose oxidase, oxidase, transglutaminase, protease, α-amylase, β-amylase, papain, pepsin, trypsin, lactase, invertase, maltase, or lipase. Vegetable or animal fats may be oils containing unsaturated fatty acids, preferably one or more of Omega-3, Omega-6, and Omega-9 fatty acids. Protein powder may be one or more of fish meal, meat and bone meal, egg powder, or soy flour. Vegetable oils or animal fats may be one or more of the following: DHA algal oil, fish oil, flaxseed oil, rice bran oil, evening primrose oil, borage oil, wheat germ oil, conjugated linoleic acid, Ganoderma lucidum spore oil, pear oil, krill oil, garlic oil, almond oil, perilla seed oil, olive oil, squalene, sesame oil, pumpkin seed oil, safflower seed oil, shea butter, camellia oil, saw palm extract oil, walnut oil, castor oil, grapeseed oil, cottonseed oil, peanut oil, soybean oil, corn oil, sunflower seed oil, rapeseed oil, and palm oil. Minerals may be one or more of the following: mineral salts and oxides containing calcium, magnesium, potassium, manganese, iron, zinc, selenium, and copper. Plant extracts may be one or more of the following: lutein, lutein esters, zeaxanthin, Haematococcus pluvialis, elderberry, blueberry, acerola cherry, chicken gizzard lining, honeysuckle, poria cocos, hawthorn, yam, millet, and tangerine peel extract. The film-forming compositions, soft capsule shells, or soft capsules described herein can be used in pharmaceuticals, food (e.g., health foods), or cosmetics.

[0078] The embodiments of the present invention will be described in detail below with reference to examples. It should be understood that these embodiments are for illustrative purposes only and are not intended to limit the scope of the invention. For experimental methods in the following embodiments where specific conditions are not specified, please refer to the guidelines given in this invention, or follow experimental manuals or conventional conditions in the art, or follow the conditions recommended by the manufacturer, or refer to experimental methods known in the art.

[0079] Example

[0080] The following description is further illustrated with specific embodiments and comparative examples. Unless otherwise specified, the raw materials involved in the following specific embodiments and comparative examples are all commercially available. Unless otherwise specified, the instruments used are all commercially available. Unless otherwise specified, the processes involved are conventionally selected by those skilled in the art.

[0081] Materials and methods

[0082] 1. All materials used in the examples are commercially available. The material specifications are as follows.

[0083] Pectin: High-ester pectin with a degree of esterification of 59.7%.

[0084] Partially deacylated gellan gum: Each repeating unit of gellan gum contains 31% acetyl groups and 39% glyceryl groups.

[0085] Starch: Hydroxypropyl starch.

[0086] 2. The preparation method of soft capsules is as follows:

[0087] 1) Sol: A) First, heat and stir the gellan gum, pectin, starch (if any), plasticizer and water in the prescribed amounts at 60-98°C until all materials are dissolved; B) Remove the air bubbles to obtain the sol;

[0088] 2) Shot pressing: Using a soft capsule production line, the glue solution is transported to the glue box of the soft capsule filling machine. The glue solution is cooled on the surface of the drum to form a capsule shell, which is then pressed into shape by the encapsulation filler and can be further shaped in the drum.

[0089] 3) Drying: After the capsules are shaped or rotated and fixed, dry them until the moisture content of the capsule skin is 8-20%.

[0090] 3. Testing Methods

[0091] 3.1 Insoluble particle content Mu:

[0092] (1) Content of small insoluble particles m1: 100 mg of dried soft capsule shells were placed in a 2% calcium chloride solution for 2 hours to solidify. During this time, the gellan gum molecules in the capsule shells swelled and solidified in the calcium chloride solution, forming a gel structure. The solidified gellan gum molecules did not dissolve, and the network structure dispersed the long chain segments in the network structure. Large insoluble particles were bound, so only small insoluble particles were dissolved. The dissolved small insoluble particle suspension was dried to remove water, and the final content of small insoluble particles m1 (i.e., the absolute mass of small insoluble particles in 100 mg of dried capsule shells) could be obtained. The particles separated in this process are defined as small insoluble particles.

[0093] (2) Content of large insoluble particles m2: 100mg of dried soft capsule shells were dissolved in 15g of deionized water at 75℃ for 30 minutes, and stirred repeatedly during the process to ensure that the shells were completely dissolved. The turbid liquid of the dissolved soft capsule shells was then centrifuged at 4000rpm for 15min. After centrifugation under these conditions, the large insoluble particles were basically completely in the centrifugal precipitate. After removing the upper liquid (mainly soluble colloids and small insoluble particles), the bottom precipitate was dried thoroughly. The content of the precipitate was the content of large insoluble particles m2 (i.e., the absolute mass of large insoluble particles in 100mg of dried capsule shells). The precipitate obtained in this process was defined as large insoluble particles.

[0094] The insoluble particle content Mu = m1 + m2 is calculated.

[0095] 3.2 Gelation agent content Mj: The sum of all gelling agents (total amount of edible gum).

[0096] 3.3 Insoluble particles: gelling agent ratio: Mu:Mj.

[0097] 4. pH of a 5wt% aqueous solution of the product capsule shell:

[0098] The pH of the 5wt% aqueous solution of the product peel was determined as follows: 5wt% of the peel was mixed with water and stirred at 5000 rpm for 5 minutes at room temperature using a high-speed blender (CCC certified Hehui Liquid Food Blender H6y) to obtain a solution. The peel mass to water ratio was calculated to be 1:20. Subsequently, the pH of the solution was measured at 25°C using a pH meter (Mettler-Toledo Instruments (Shanghai) Co., Ltd. - FE20 Plus). The test result was used as the pH of the 5wt% aqueous solution of the peel.

[0099] 5. Ease of Capsule Bite-Breaking: The test was conducted using the HDP / VB bite-breaking clamp of a texture analyzer. A soft capsule was cut along the seam, and a rectangular sample measuring 8cm wide and 20cm long was cut using a measuring tool. The thickness depended on the thickness of the soft capsule itself. The sample was placed in the middle of the clamp, ensuring that the upper clamp (10cm wide) was centered along the longitudinal axis of the rectangular sample, i.e., the center point of the 8cm width coincided with the center point of the upper clamp. The test speed was 1.00mm / sec, and the trigger mode used a force of 5g. The test ends when the deformation reaches 100% (if the capsule breaks, the deformation is 100%, which can be understood as the capsule breaking into two pieces. If the capsule cannot be broken, it is compressed to its maximum value, at which point the deformation is less than 100%, and the capsule does not break into two pieces; it remains a complete capsule. However, the test ends when the probe deformation reaches 100%. Even if the capsule does not break, the instrument assumes that 100% has been reached, and therefore the test ends). The test records three indicators: the maximum pressure (i.e., the maximum biting force required to break), the distance from trigger start to end (i.e., capsule thickness), and whether the capsule breaks (i.e., confirming whether the capsule breaks into two pieces). These indicators are used to evaluate the ease of breaking the product.

[0100] If the capsule skin breaks into two pieces after the bite test, in its bite stress-stroke distance graph, after the highest bite force, the capsule skin is bitten off, causing the bite stress to drop rapidly, and the distance continues to increase until the two molds come into contact, i.e., consistent with the thickness of the capsule skin, at which point the test ends, and a stress peak appears in the bite stress-stroke distance graph. At this point, the bite type is easy to bite off, and the bite coefficient ε is 1. The test data obtained by testing the capsule skin prepared by composition 1 according to the above method is shown in Figure 3.

[0101] If the capsule skin does not break into two halves after the bite test, and only a crease is left in the bite portion, then in its bite stress-travel distance graph, when the bite stress is at its maximum, the maximum formation distance is also reached. Therefore, no stress peak appears, and the bite type is "unbreakable," and the bite coefficient ε is 0. The test data obtained by testing the capsule skin of Comparative Example 1 using the above method is shown in Figure 4.

[0102] 6. Molding adhesion

[0103] Adhesion of the forming seams: Cut open the soft capsule on the non-seam side, squeeze out the contents, and then cut a ring with two seams from the middle while keeping it perpendicular to the seams. Place the ring on a glass slide and place the cross-sections of the two seams parallel on the glass slide. Measure the thickness of the two seams and the thickness of the capsule shell under an optical microscope. Calculate the ratio P (%) of the thinnest seam thickness to the thickness of the capsule shell. The corresponding scores are shown in Table 1.

[0104] Table 1: Evaluation Criteria for the Forming Adhesion and Maximum Biting Force of Soft Capsules

[0105] The adhesiveness of soft capsule molding is the most direct indicator for judging the feasibility of soft capsule production. Good adhesiveness means stable production during the soft capsule production process and low leakage rate (e.g., oil leakage rate).

[0106] The bite test of softgel capsule shells is the most important indicator for determining whether a product is suitable as a chewable softgel. The results of the bite test are divided into two categories. The first category is where the shell is easily bitten through; the maximum biting force required after biting through is used to assess the ease of biting through the shell, therefore the coefficient ε for this category is 1. The second category is where the shell cannot be bitten through. Products with this type of shell are generally unsuitable for chewable softgel applications, regardless of how low the maximum biting force measured by the instrument is. In other words, the shell is too tough and cannot provide the user with a crisp and palatable chewing experience; therefore, the coefficient ε for this type is 0.

[0107] The comprehensive evaluation index is composed of 50% for molding adhesion and 50% for capsule shell bite-off. The capsule shell bite-off is the product of the bite-off coefficient and the maximum bite force. The two indicators are added together to obtain the final comprehensive evaluation, namely, the comprehensive product evaluation P = molding capsule shell adhesion CX50% + bite-off coefficient εX bite force scoreFX50%. Furthermore, the comprehensive evaluation P must be greater than 6 to achieve the industrial production of soft capsule products.

[0108] 7. Microscopic observation

[0109] Figure 1 is an optical micrograph of the gel solution prepared in Comparative Example 5, placed between two glass slides. The solution was heated and pressurized to form a thin film at 95°C. After cooling, the resulting capsule skin was stained with iodine solution. The magnification factor is 600 (detailed image of the 266.1 μm wide film is shown). The particles are microstructures of insoluble particles such as starch, separated by centrifugation, and constitute 5% of the mass of the soft capsule skin. Figure 1 shows a relatively large number of starch particles distributed in the capsule skin. Lines 1-3 represent particle sizes measured using a ruler.

[0110] Figure 2 is an optical micrograph showing the gel prepared by composition 1 placed between two glass slides, heated and pressurized to form a thin film at 95°C, cooled to form a capsule skin, and then stained with iodine solution. The magnification factor of the image is 600 (detailed view of the film with a width of 266.1 μm is shown). No obvious particles are visible in Figure 2.

[0111] Example 1: The effect of insoluble particles in the capsule skin

[0112] Based on the formulation composition in Table 2 and the above-described soft capsule preparation method, corresponding soft capsule shells were prepared from compositions 1-5 and Comparative Example 1. The units of measurement for the compositions in Table 2 are in grams (the same applies to the examples below). For the soft capsule shells, the content of small insoluble particles (m1), the content of large insoluble particles (m2), and the insoluble particle:gel ratio (Mu:Mj) were determined according to the method described above. The pH of a 5 wt% aqueous solution of the shell, the adhesiveness (C) of the formed shell, and the bite-off difficulty index were also determined according to the method described above.

[0113] Table 2: Effect of insoluble particles

[0114] Chewable soft capsules were prepared according to the ingredients and contents described in Table 2, and the soft capsule process and product were tested and characterized. The test results are shown in Table 2.

[0115] Table 2 shows that the colloids constituting the gel network in compositions 1-5 are all formed by the combined use of high-ester pectin and gellan gum. This invention has discovered that when the ratio of the amount of insoluble particles in the product capsule shell is between 0 and 2, the soft capsule product capsule shell exhibits an easy-to-break bite type, i.e., a bite coefficient ε of 1, and the formed capsule shell has good adhesion properties, with an overall evaluation higher than 6.

[0116] In particular, the soft capsules made from Composition 1 exhibit excellent molding properties; the capsule skin is easy to bite through, and the maximum biting force is relatively small, requiring minimal chewing force to break the skin. Figure 2 shows an optical micrograph of the gel solution prepared from Composition 1 placed between two glass slides, heated and pressurized to form a thin film at 95°C, and then cooled to form the capsule skin. Iodine solution was then added to this film for staining. The magnification factor of the image is 600 (detailed view of the film with a width of 266.1 μm is shown). No obvious particles are visible in Figure 2.

[0117] For compositions 2-5, the addition of insoluble particulate matter not only maintains the adhesiveness of the formed capsule skin, but also ensures that the capsule skin remains easily bitten, i.e., the bite force ε is 1. Although the maximum bite force is increased, it can still be bitten through.

[0118] As the proportion of insoluble particles increases to the ratio of insoluble particles Mu to gelling agent Mj of 2.083 (i.e., the ratio of insoluble particles to colloids forming the gel network in Comparative Example 1 is greater than 2), although the adhesion of the formed capsule shell is good, when the bite-breaking type of the product capsule shell becomes unbiteable and the bite-breaking coefficient ε is 0, the overall evaluation P of the capsule shell is 4.5 (less than 6), so it is not suitable for industrial production as a chewable soft capsule product.

[0119] This invention discovers that for film-forming compositions containing high-ester pectin and gellan gum, chewable soft capsules with good adhesion of the formed capsule shell can be formed by controlling the pH of a 5 wt% aqueous solution of the product shell to 3.75-3.88. Starch can be appropriately added to this film-forming composition, but the addition of starch reduces the chewiness of the capsule shell. Unexpectedly, this invention finds that when the addition of starch results in an insoluble particle Mu: gelling agent Mj ratio of 2.083, chewable soft capsules cannot be obtained.

[0120] Example 2: Effect of pH on the capsule skin

[0121] Based on the formulation composition in Table 3 and the above-described soft capsule preparation method, corresponding soft capsule shells were prepared from compositions 6-9 and comparative examples 2-3. For the soft capsule shells, the content of small insoluble particles (m1), the content of large insoluble particles (m2), and the ratio of insoluble particles to gelling agent (Mu:Mj) were determined according to the method described above. The pH of a 5 wt% aqueous solution of the shell, the adhesiveness (C) of the formed shell, and the bite-off difficulty index were also determined according to the method described above.

[0122] Table 3: Effect of pH on the cystic membrane

[0123] In Example 2, the effect of pH of a 5 wt% aqueous solution of the product capsule shell on the adhesion of the formed capsule shell was investigated. It was found that when the pH of the 5 wt% aqueous solution of the product capsule shell was between 3.00 and 4.50, the adhesion of the product to the formed capsule shell remained at a high level, and the adhesion C of the formed capsule shell was greater than or equal to 6, indicating that the formed soft capsule shell was firmly adhered and the probability of leakage (e.g., oil leakage) was low.

[0124] In the formulations in Table 3, within the pH range of 3.00-4.50, high-ester pectin cannot reach the gelation conditions. Its role in the capsule shell is only in the form of self-entanglement of pectin molecular chains. Macroscopically, pectin plays an adhesive role in the capsule shell and cannot assist the gellan gum in the solution to form a stronger network structure. This also provides an effective guarantee for the adhesion of the formed capsule shell.

[0125] When the pH of the 5wt% aqueous solution of the product capsule shell is less than 3.00 or greater than 4.50, as in Comparative Examples 2 and 3, the adhesiveness of the product capsule shell is greatly reduced, resulting in the product capsule shell not adhering firmly during the molding process, and the capsule shell may even fail to adhere together, making it impossible to produce soft capsule products.

[0126] When the pH is less than 3.00, the gellan gum in the capsule shell cannot form a network structure under these conditions, which macroscopically manifests as the gellan gum failing to form a capsule shell with sufficient strength at low temperatures. When the pH is greater than 4.5, the gellan gum network structure exhibits greater gel strength with increasing pH. At this point, high-ester pectin cannot provide adhesive strength matching that of gellan gum, and during the molding process, the capsule shell gradually loses its adhesiveness, potentially leading to soft capsule leakage. This further illustrates that within this pH range, pectin plays a binding role, ensuring good adhesion of the soft capsule shell.

[0127] Example 3: Effects of the content and type of high-ester pectin and gellan gum on the capsule shell

[0128] Based on the formulations in Tables 4 and 5 and the soft capsule preparation method described above, corresponding soft capsule shells were prepared from compositions 10-18. For the soft capsule shells, the content of small insoluble particles (m1), the content of large insoluble particles (m2), and the insoluble particle:gel ratio (Mu:Mj) were determined according to the method described above. The pH of a 5 wt% aqueous solution of the shell, the adhesiveness (C) of the formed shell, and the bite-off difficulty index were also determined according to the method described above.

[0129] Table 4: Effects of high-ester pectin and gellan gum content on the pericarp

[0130] Table 5: Effects of different specifications of high-ester pectin colloid and gellan gum on capsule shell

[0131] As shown in Tables 4 and 5, when the pectin and gellan gum content falls within a certain range, the prepared capsule shell exhibits good adhesion, and the product capsule shell retains its easy-to-bite bite-off characteristic. Replacing the types of gellan gum and pectin with other materials also yields capsule shells with good adhesion and easy bite-off properties.

[0132] Example 4: Effects of different types of edible gums on capsule shell

[0133] Based on the formulation composition in Table 6 and the soft capsule preparation method described above, corresponding soft capsule shells were prepared from Comparative Examples 4-11. For the soft capsule shells, the content of small insoluble particles (m1), the content of large insoluble particles (m2), and the ratio of insoluble particles to gelling agent (Mu:Mj) were determined according to the method described above. The pH of a 5 wt% aqueous solution of the shell, the adhesiveness (C) of the formed shell, and the bite-off difficulty index were also determined according to the method described above.

[0134] Table 6: Effects of different types of edible gums on capsule shell

[0135] Table 6 explores the effects of different types of edible gums compared to Composition 1 on the adhesion and bite-hardness of the chewable soft capsule product. The present invention provides the following findings.

[0136] In Comparative Examples 4, 6, and 10, the edible gums constituting the gel network in Composition 1 were replaced with single pectin, gellan gum, and carrageenan, respectively. Insoluble particles: the colloid ratio constituting the gel network was less than 2, and the pH of the 5wt% aqueous solution of the product capsule shell was between 3.00 and 4.50, with the capsule shell exhibiting an easy-to-bite type. However, the adhesiveness of the formed capsule shells in all examples failed to meet the requirements for soft capsule molding, resulting in a lack of adhesion during the molding process. Therefore, Comparative Examples 4, 6, and 10 cannot meet the requirements for large-scale production of chewable soft capsules.

[0137] Comparative Example 8 uses gelatin as the colloid constituting the gel network. Although the ratio of insoluble particles to colloid constituting the gel network in Comparative Example 8 is less than 2, and the pH of the 5wt% aqueous solution of the product capsule shell is between 3.00 and 4.50, its capsule shell is non-bite-resistant. Despite the good adhesion of the molded capsule shell of Comparative Example 8, it cannot meet the requirements for large-scale production of chewable soft capsule products.

[0138] In Comparative Examples 5, 7, 9, and 11, the adhesiveness of the molded capsule shell was improved by adding starch. While this ensured that the product did not leak during molding and that the final insoluble particle to gel network colloid ratio was less than 2, it also failed to maintain the bite-hardness of the product capsule shell. Therefore, the compositions of Comparative Examples 5, 7, 9, and 11 are not suitable for the industrial production of chewable soft capsules.

[0139] Example 5: Examples of different pH adjusters

[0140] Based on the formulation composition in Table 7 and the above-described soft capsule preparation method, corresponding soft capsule shells were prepared from compositions 1 and 19-21. For the soft capsule shells, the content of small insoluble particles (m1), the content of large insoluble particles (m2), and the insoluble particle:gel ratio (Mu:Mj) were determined according to the method described above. The pH of a 5 wt% aqueous solution of the shell, the adhesiveness (C) of the formed shell, and the bite-off difficulty index were also determined according to the method described above.

[0141] Table 7: Effects of different pH adjusters on the skin of the capsule

[0142] Table 7 explores the effects of different pH adjuster types on the adhesion of the chewable soft capsule shell and the ease of biting the shell, compared to Example 1.

[0143] This invention discovers that by using one or more different types of pH adjusters to regulate the pH of a 5wt% aqueous solution of the product capsule shell, as long as the pH of the 5wt% aqueous solution of the product capsule shell is between 3.00 and 4.50, the formed capsule shell has good adhesion and the bite-break type of the capsule shell is also easy to bite, which is suitable for the large-scale production of chewable soft capsule products.

[0144] Example 6: Examples of different insoluble particles

[0145] Soft capsule shells were prepared according to the composition formulation in Table 8. The preparation method was as follows: Sol-gel: A) The components and water in the specified amounts were heated and stirred at 60–98°C until all materials dissolved; B) Air bubbles were removed to obtain the sol solution; Capsule pressing: Using a soft capsule production line, the sol solution was conveyed to the cassette of a soft capsule filling machine. The sol solution cooled on the surface of the drum to form the capsule shell, which was then pressed into shape after encapsulation and filling. Further shaping was possible in a rotating drum; Drying: The shaped or drum-shaped capsules were dried until the capsule shell moisture content reached 8–20%. For the soft capsule shells, the content of small insoluble matter (m1) and large insoluble matter (m2) was determined according to the method described above, and the insoluble particle:gel ratio (Mu:Mj) was also determined. According to the method described above, the pH of a 5 wt% aqueous solution of the capsule shell, the adhesiveness (C) of the formed capsule shell, and the bite-off difficulty index were also determined.

[0146] Table 8: Effects of different insoluble particles on the capsule shell

[0147] Table 8 explores the effects of other insoluble particle types or additional substances (e.g., flavorings, colorings, etc.) on the adhesion and bite-off ease of the chewable soft capsule product compared to Composition 3. It was found that using pullulan instead of starch, or adding colorings, flavorings, or opacifiers based on Example 3, as long as the pH of the 5wt% aqueous solution of the product capsule shell is between 3.00 and 4.50, and the ratio of insoluble particles to the colloids forming the gel network is less than 2, the capsule shell exhibits good adhesion and is of an easy-to-bite type, making it suitable for large-scale production of chewable soft capsule products.

[0148] Example 7: Effect of pH on starch-free film-forming compositions

[0149] Soft capsule shells were prepared according to the composition formulation in Table 9. The preparation method was as follows: Sol-gel: A) The components and water in the specified amounts were heated and stirred at 60–98°C until all materials dissolved; B) Air bubbles were removed to obtain the sol solution; Capsule pressing: Using a soft capsule production line, the sol solution was conveyed to the cassette of a soft capsule filling machine. The sol solution cooled on the drum surface to form the capsule shell, which was then pressed into shape after encapsulation and filling. Further shaping was possible in a rotating drum; Drying: The shaped or drum-shaped capsules were dried until the capsule shell moisture content reached 8–20%. For the soft capsule shells, the content of small insoluble particles (m1), the content of large insoluble particles (m2), and the insoluble particle:gel ratio (Mu:Mj) were determined according to the method described above. The pH of a 5 wt% aqueous solution of the capsule shell, the adhesiveness (C) of the formed capsule shell, and the bite-off difficulty index were also determined according to the method described above.

[0150] Table 9

[0151] Table 9 investigates the effect of pH of a 5 wt% aqueous solution of the product capsule shell on the adhesiveness of the formed capsule shell, without the addition of insoluble particles such as starch. When the pH of the 5 wt% aqueous solution of the product capsule shell is between 3.00 and 4.50, the adhesiveness of the product in the formed capsule shell remains at a high level, with C values ​​greater than or equal to 6, indicating that the formed soft capsule shell is firmly bonded and the probability of oil leakage is low. When the pH of the 5 wt% aqueous solution of the product capsule shell is less than 3.00 or greater than 4.50, as in Comparative Examples 12 and 13, the adhesiveness of the formed capsule shell decreases significantly, resulting in weak adhesion during the forming process, and the capsule shell may even fail to adhere together, making it impossible to produce soft capsules. This further illustrates that within this pH range, pectin plays a binding role, resulting in good adhesion of the soft capsule shell.

[0152] Results and discussion

[0153] This invention proposes that when pectin and starch are used as the film-forming composition of soft capsules, pectin acts as a gelling agent in the soft capsule shell, while starch acts as a filler and provides adhesive strength to the shell during the soft capsule forming process, ensuring smooth formation and preventing oil leakage. According to existing technology, pectin requires a coexisting solute concentration above 55% and acidic conditions (pH < 3.6) to gel successfully. However, pectin alone can only form a film. For soft capsules to be effective, the shell needs sufficient adhesive strength. Only when starch accounts for more than 15% of the shell can sufficient adhesive strength be guaranteed to prevent oil leakage. However, adding such a high proportion of starch results in a tough and difficult-to-chew soft capsule shell after drying, making it unsuitable for chewable soft capsule products.

[0154] When soft capsule shells contain gellan gum and pectin, gellan gum acts as the primary gelling agent in the production of the soft capsules. Pectin, however, does not simultaneously meet the requirements of a coexisting solute concentration above 55% and acidic conditions (pH < 3.6) within the shell, preventing intermolecular gelation of pectin molecules. Therefore, pectin can provide adhesive forces to the soft capsules relative to gellan gum, and the addition of pectin can alter the gel network structure of gellan gum, promoting the formation of a three-dimensional interpenetrating network structure. This is not possible in combinations of gellan gum and carrageenan, nor in combinations of gellan gum and starch. These three combinations represent three different colloidal aggregate structures.

[0155] The first method involves combining carrageenan with gellan gum. Because these two colloids have inconsistent gelling properties, they are incompatible. When the mixed solution cools, the two gelling agents cannot form a homogeneous gel, failing to exhibit the gelling properties of the compound colloid. Ultimately, it is also impossible to produce a suitable capsule shell for soft capsule production.

[0156] The second method combines gellan gum with starch. Starch itself does not possess good gelling ability. When combined with gellan gum, it retains the gelling properties of gellan gum itself, neither increasing nor decreasing its gel strength. Instead, starch merely serves as a filler in the gel network and a source of adhesion for the capsule shell. Therefore, starch cannot synergistically enhance the gelling properties of gellan gum. The same principle applies to pectin combined with starch. As shown in Figure 1, the fracture surface morphology of the capsule shell containing pectin and starch reveals a large number of dispersed particles larger than 10 micrometers. These particles are large starch particles, and smaller starch particles are also embedded in the network structure in granular form. These particles provide all the adhesion force for the soft capsule shell during molding, resulting in a tough and rigid soft capsule shell that is not easily bitten through during chewing.

[0157] The third type is gellan gum combined with pectin, where both pectin and gellan gum can form three-dimensional gel network structures. As shown in Figure 2, the film-forming composition containing gellan gum and pectin forms a three-dimensional interpenetrating network structure in which the molecular weights of the two colloidal gels interpenetrate and intertwine. Compared to the gel network structure of gellan gum, pectin molecular chains penetrate the gellan gum gel network, rather than being embedded in the gellan gum network as starch granules. As can be seen from Figure 2, the fracture surface morphology of the capsule shell containing gellan gum and pectin is uniform, with no particles larger than 10 micrometers. Therefore, when gellan gum and pectin capsule shells are used as chewable soft capsule shells, they exhibit excellent gel properties, ensuring both the soft and brittle characteristics of the shell and good adhesion for soft capsule shell formation.

[0158] Pectin requires acidic and high-sugar conditions to gel. The invention revealed that adding acidic substances and highly coexisting solutes (such as starch) at different times effectively maintained the viscous properties of the pectin. This not only preserved the excellent gelling properties of gellan gum but also endowed the compounded colloid with good adhesive properties. Ultimately, the compounded colloid exhibited excellent soft capsule forming performance, possessing both good capsule shell gel strength and excellent adhesion properties at the forming seams.

[0159] The insoluble particles in the capsule shell are divided into large and small insoluble particles, and these particles exist in the gel network structure as single-property particles with molecular chain segments coiled together. The gel network structure is a three-dimensional network structure formed by multiple forces, including intermolecular forces and hydrogen bonds, between the dissolved and stretched colloidal molecular chains. Therefore, the colloidal molecules are mostly stretched molecular chain segments, which are fixed at the moment of gelation. When the insoluble particles embedded in the gel network in the capsule shell are smaller than the colloidal particles in the gel network, the capsule shell is mainly composed of the gel network, with a small proportion of insoluble particles. Gellan gum and pectin are not micron-sized particles, but rather dispersed molecular chain segments, and the two colloids are miscible in the dissolved state. During film formation, both geln gum and pectin are interpenetrating networks resulting from the interweaving of molecular chain segments. The network structure includes geln gum, while pectin itself does not act as a gel network, but merely shuttles through the geln gum gel network as long chain segments. This gives the capsule shell excellent adhesion. When the capsule shell is subjected to maximum compressive stress (during tooth occlusion), the particles constitute a smaller proportion of the gel network, resulting in fewer particles sliding within the gel network structure. This is primarily because the gel network is subjected to compressive stress, leading to brittle fracture under maximum compressive stress. Therefore, this improves the chewy texture of the dried capsule shell, causing it to break easily with a light bite. When the proportion of insoluble particles embedded in the gel network within the capsule shell is greater than that of the colloids composing the gel network, brittle fracture does not occur after maximum compressive stress. This is because, with increasing compressive stress, the insoluble particles in the dried gel network structure move within the capsule shell, releasing excess stress and increasing stress resistance, resulting in a ductile fracture – essentially improving toughness.

[0160] This invention provides a soft capsule shell composition formulation that is soft, crunchy, and easy to bite through. Compared with the film-forming composition formulation of carrageenan and starch, it has a better chewing texture, is easier to bite through, and is soft, crunchy, and delicious, making it especially suitable for children and the elderly.

[0161] Although the invention has been described with reference to illustrative embodiments, those skilled in the art will understand that various other changes, omissions, and / or additions can be made without departing from the spirit and scope of the invention, and that elements of the described embodiments can be substituted with substantially equivalents. Furthermore, many modifications can be made without departing from the scope of the invention to adapt particular situations or materials to the teachings of the invention. Therefore, this invention is not intended to be limited to the specific embodiments disclosed for carrying out the invention, but rather is intended to encompass all embodiments falling within the scope of the appended claims.

Claims

1. A film-forming composition for forming soft capsule shells, comprising 1-15 parts by weight of a first edible gum, 1-15 parts by weight of a second edible gum, 10-50 parts by weight of a plasticizer and a certain amount of a pH adjuster, wherein the amount of the pH adjuster is such that the pH of the soft capsule shell is <5 when prepared as a 5wt% aqueous solution, optionally 3-4.5, and the first edible gum is gellan gum and the second edible gum is pectin; Optionally, the film-forming composition satisfies one or more of the following conditions: i) The film-forming composition contains water, optionally 20-60 parts by weight; ii) The film-forming composition comprises 0-24 parts by weight of one or more of starch, dextrin, cellulose and pullulan; iii) The film-forming composition comprises one or more of a pigment, an opacifier, a fragrance, and a sweetener; iv) The film-forming composition includes a third edible gum, which is one or more of carrageenan, agar, sodium alginate, konjac gum, xanthan gum and locust bean gum; v) The film-forming composition does not contain gelatin.

2. The film-forming composition according to claim 1, wherein the film-forming composition satisfies one or more of the following conditions: vi) Gellan gum is one or more of partially deacylated gellan gum and high-acyl gellan gum; vii) Partially deacylated gellan gum is gellan gum in which each repeating unit contains 25%-40% or 30-40% acetyl groups and 15%-45% or 15%-40% or 15%-30% or 15%-26% glyceryl groups. viii) Each repeating unit of gellan gum contains more than 40% acetyl groups and more than 45% glyceryl groups; ix) The pectin is a high-ester pectin, optionally with an esterification degree of 50-70%, 52%-65% or 52%-60%; x) The plasticizer is one or more of glycerol, sorbitol, mannitol, erythritol, xylitol and maltitol; xi) The pH adjuster is one or more of the following: citrate, carbonate, bicarbonate, phosphate, pyrophosphate, sodium hydroxide, potassium hydroxide, citric acid, malic acid, acetic acid, hydrochloric acid, or phosphoric acid; xii) Citrate is sodium citrate and / or potassium citrate; xiii) Phosphates are sodium phosphate and / or potassium phosphate; xiv) Pyrophosphate is sodium pyrophosphate; xv) Carbonates are sodium carbonate and / or potassium carbonate; xvi) Bicarbonates are sodium bicarbonate or potassium bicarbonate; (xvii) Starch is one or more of natural starch and modified starch; (xviii) Modified starch is one or more of hydroxypropyl starch, hydroxypropyl distarch phosphate, oxidized starch, acetate starch, oxidized hydroxypropyl starch, acetylated oxidized starch, acetylated distarch phosphate, or acid-modified starch.

3. The film-forming composition according to claim 1 or 2, wherein the film-forming composition further satisfies one or more of the following conditions: The film-forming composition (xix) contains 2-10 parts by weight, 3-8 parts by weight, or 4-6 parts by weight of gellan gum; (xx) The film-forming composition contains 2-10 parts by weight, 5-9 parts by weight, or 6-8 parts by weight of pectin; (xxi) The film-forming composition contains 15-50 parts by weight, or 20-45 parts by weight, or 25-45 parts by weight of plasticizer; xxii) The film-forming composition contains 0.05-1.3 parts by weight, or 0.1-1 parts by weight, or 0.2-1 parts by weight of a pH adjuster; xxiii) The film-forming composition comprises 1-24 parts by weight, 1-12 parts by weight, or 1-5 parts by weight of starch; xxiv) The film-forming composition contains no more than 4 parts by weight of pigment; The film-forming composition (xxv) contains no more than 5 parts by weight of a light-blocking agent; (xxvi) The film-forming composition contains no more than 2 parts by weight of fragrance; (xxvii) The film-forming composition contains no more than 3 parts by weight of sweetener.

4. The film-forming composition according to any one of claims 1-3, wherein the ratio of the insoluble particle content Mu of the soft capsule shell to the gel dosage Mj of the film-forming composition is 0-2; The insoluble particle content Mu is the sum of the content of small insoluble particles m1 and the content of large insoluble particles m2 in the capsule shell; The content of small particulate insoluble matter m1 was determined by the following steps: 100 mg of dried capsule shell was placed in a 2% calcium chloride solution for 2 hours to solidify, and the dissolved small particulate insoluble matter suspension was dried to remove water. The weight of the small particulate insoluble matter was the content of small particulate insoluble matter m1. The content of large insoluble matter m2 was determined by the following steps: 100 mg of dried soft capsule shell was completely dissolved in water, for example, 15 g of deionized water. The turbid liquid of the dissolved soft capsule shell was centrifuged at 4000 rpm for 15 min. After removing the upper liquid, the bottom precipitate was thoroughly dried. The weight of the bottom precipitate was the content of large insoluble matter m2. The gelling agent content Mj is the sum of the amounts of edible gum used.

5. The film-forming composition according to any one of claims 1-4, wherein the film-forming composition satisfies one or more of the following conditions: (xxviii) The pigments are selected from one or more of the following: titanium dioxide, allure red, brilliant blue, tartrazine, sunset yellow, cochineal red, turmeric, annatto orange, gardenia yellow, gardenia blue, safflower yellow, vegetable carbon black, carotene, and sodium copper chlorophyllin. The fragrance of xxix is ​​selected from one or more of the following: peach, strawberry, cherry, cantaloupe, apple, grape, banana, lemon, papaya, blueberry, fruit acid, grapefruit, olive, sweet orange, or milk. The sweetener is selected from one or more of the following: sucralose, aspartame, alitame, sodium saccharin, acesulfame potassium, allulose, advans, cyclamate, sematrandez, steviol glycosides, mogrosides, isomaltulose, ammonium glycyrrhizate, monopotassium and tripotassium glycyrrhizate, D-mannitol, xylitol, erythritol, maltitol, and lactitol.

6. A method for preparing soft capsule shells from the film-forming composition of any one of claims 1-5, comprising one or more of the following steps: 1) Sol: A) First, heat and stir the gellan gum, pectin, plasticizer and water in the formula amount, or the gellan gum, pectin, starch, plasticizer and water in the formula amount at 60-98°C until all materials are dissolved; B) Remove the air bubbles to obtain the sol; 2) Shot pressing: Using a soft capsule production line, the glue solution is transported to the glue box of the soft capsule filling machine. The glue solution is cooled on the surface of the drum to form a capsule shell, which is then pressed into shape by the encapsulation filler and can be further shaped in the drum. 3) Drying: After the capsules have been shaped or rotated, dry them until the moisture content of the capsule skin is 8-20%.

7. A soft capsule shell comprising the film-forming composition of any one of claims 1-5 or prepared by the method of claim 6, optionally wherein the soft capsule shell has a moisture content of 8-20%.

8. A soft capsule comprising the soft capsule shell and contents of claim 7.

9. The soft capsule of claim 8, wherein the soft capsule satisfies one or more of the following conditions: i) The contents contain one or more of the following: vitamins, microorganisms, enzymes, vegetable or animal oils, protein powder, minerals, and plant extracts; ii) Among them, vitamins are one or more of vitamin A, vitamin D, or vitamin K; iii) Among them, the microbial category is a probiotic strain, which may be one or more of Bifidobacterium, lactic acid bacteria, or yeast; iv) The enzyme preparation is one or more of glucose oxidase, oxidase, transglutaminase, protease, α-amylase, β-amylase, papain, pepsin, trypsin, lactase, invertase, maltase, or lipase; v) Wherein, vegetable oil or animal fat is an oil containing unsaturated fatty acids, and may be one or more of Omega3 fatty acids, Omega6 fatty acids, and Omega9 fatty acids. vi) The protein powder is one or more of fish meal, meat and bone meal, egg powder, or soy powder; vii) Vegetable oils or animal fats include one or more of the following: DHA algal oil, fish oil, flaxseed oil, rice bran oil, evening primrose oil, borage oil, wheat germ oil, conjugated linoleic acid, Ganoderma lucidum spore oil, pear oil, krill oil, garlic oil, almond oil, perilla seed oil, olive oil, squalene, sesame oil, pumpkin seed oil, safflower seed oil, shea butter, camellia oil, saw palm extract, walnut oil, castor oil, grapeseed oil, cottonseed oil, peanut oil, soybean oil, corn oil, sunflower seed oil, rapeseed oil, and palm oil. viii) Minerals are one or more mineral salts and oxides containing calcium, magnesium, potassium, manganese, iron, zinc, selenium, and copper. ix) Plant extracts are one or more of the following: lutein, lutein esters, zeaxanthin, Haematococcus pluvialis, elderberry, blueberry, acerola cherry, chicken gizzard lining, honeysuckle, poria cocos, hawthorn, yam, millet, and tangerine peel extract.

10. Use of the film-forming composition of any one of claims 1-5 or the soft capsule of claim 8 or 9 in a pharmaceutical, food, or cosmetic product; optionally, the food product is a health food.

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