Colon-targeting microcapsule, preparation method and application thereof

Abstract

This invention relates to the field of intestinal health technology, specifically to a colon-targeted microcapsule, its preparation method, and its application. The microcapsule uses resistant dextrin as the wall material and is prepared by encapsulating lutein through an emulsification-spray drying process. The resistant dextrin maintains its structural integrity in the stomach and small intestine, and is degraded by intestinal flora upon entering the colon, thereby triggering the targeted release of lutein. In vitro simulated digestion experiments show that the cumulative release rate of the microcapsule in simulated gastric and intestinal fluids is less than 15%, while the release rate in simulated colonic fluid is greater than 89% after 6 hours. This invention's microcapsule promotes the production of short-chain fatty acids, stimulates intestinal peristalsis, and increases fecal water content through the prebiotic effect of resistant dextrin, while simultaneously reducing colonic oxidative stress through the antioxidant effect of lutein. These two factors synergistically achieve the effect of promoting bowel movements.

Description

Technical Field

[0001] This invention relates to the field of gut health technology, specifically to a colon-targeted microcapsule, its preparation method, and its application. Background Technology

[0002] Constipation, a common functional gastrointestinal disorder, affects approximately 10% to 20% of the adult population worldwide, with a particularly high incidence among the elderly and women. Long-term constipation not only causes discomfort such as bloating and abdominal pain, but is also closely related to complications such as melanosis coli, hemorrhoids, and intestinal obstruction, seriously affecting the quality of life of patients. Currently, the commonly used laxative strategies in clinical practice mainly include the following categories: (1) Stimulant laxatives (such as bisacodyl and senna leaf extract), which enhance peristalsis by stimulating the nerves of the intestinal wall, but long-term use can easily lead to drug dependence, electrolyte imbalance and intestinal nerve damage; (2) Osmotic laxatives (such as polyethylene glycol and lactulose), which promote defecation by increasing the osmotic pressure of the intestinal lumen, but may cause bloating, diarrhea and intestinal flora imbalance; (3) Dietary fiber supplements (such as wheat bran and fruit and vegetable fiber), although they have a high safety profile, they are slow to take effect, require large intake, and have limited effect on patients with severe constipation. In addition, most commercially available laxative products focus on short-term relief and lack comprehensive regulatory functions for intestinal microecological balance, oxidative stress relief and long-term intestinal health.

[0003] Lutein, a natural fat-soluble carotenoid, is widely found in dark green vegetables and flowers. Recent studies have shown that, in addition to its clear role in visual protection, lutein also exhibits significant anti-inflammatory, antioxidant, and intestinal regulatory potential. Its conjugated double bond system can efficiently quench singlet oxygen, scavenge free radicals, and reduce intestinal oxidative damage. Simultaneously, lutein can inhibit intestinal inflammatory responses by regulating signaling pathways such as NF-κB. However, lutein has extremely poor water solubility, making it difficult to disperse effectively in gastrointestinal fluids; it is sensitive to light, heat, and oxygen, and is prone to cis-trans isomerization and degradation during processing and storage; more importantly, lutein has low bioavailability in the acidic environment of the stomach, with most of its active ingredients being degraded or absorbed in the upper digestive tract, making it difficult to reach the colon to exert local regulatory effects. These inherent limitations severely restrict the direct application of lutein in the prevention and treatment of functional intestinal diseases.

[0004] Resistant dextrin is a water-soluble dietary fiber prepared from starch through acid-thermal depolymerization and enzymatic recombination. Its structure contains numerous α-1,2 and α-1,3 glycosidic bonds, which resist hydrolysis by human digestive enzymes, allowing it to directly enter the colon and be fermented and utilized by probiotics. As a high-quality prebiotic, resistant dextrin can significantly increase the production of short-chain fatty acids (especially butyrate) in the intestine, lower intestinal pH, inhibit the growth of pathogenic bacteria, and gently stimulate intestinal peristalsis. However, the laxative effect of using resistant dextrin alone has drawbacks such as significant individual variability and slow onset of action, and it cannot achieve synergistic delivery and protection of fat-soluble active ingredients.

[0005] In terms of active ingredient encapsulation and targeted delivery technology, existing microencapsulation methods mainly include spray drying, agglomeration, and liposome encapsulation. However, these methods suffer from problems such as complex processes, high costs, and the fact that chitosan is easily dissolved and released in the acidic environment of the stomach, making it difficult to achieve colon-targeted delivery.

[0006] In summary, the current technological field has the following significant gaps: (1) a lack of microcapsule systems that can simultaneously achieve efficient protection of lutein, colon-targeted release, and synergistic effects with prebiotics; (2) existing laxative products mostly focus on physical excretion promotion, neglecting the dual regulation of intestinal oxidative stress and microecology; and (3) natural, safe, and simple colon-targeted delivery systems have not yet been effectively applied in functional foods. Therefore, developing a colon-targeted microcapsule based on lutein and resistant dextrin, and constructing a laxative beverage with multiple functions of promoting excretion, anti-inflammation, and regulating bacteria, has significant clinical and market value. Summary of the Invention

[0007] The purpose of this invention is to provide a colon-targeted microcapsule, its preparation method, and its application. It is prepared by emulsification spray drying to achieve colon-targeted release and is used in a laxative beverage. It has the synergistic effects of promoting excretion, anti-oxidation, and regulating gut microbiota.

[0008] To achieve the above-mentioned technical objectives and effects, the present invention is implemented through the following technical solution: A colon-targeting microcapsule, comprising: Wall materials composed of water-soluble dietary fiber, and Carotenoid core material encapsulated by the wall material; The microcapsules are microparticles obtained by spray drying an oil-in-water emulsion. The rate at which the microcapsules release carotenoids in the colonic environment due to the degradation of the wall material by intestinal flora is higher than the rate at which they release carotenoids through diffusion in the gastric and intestinal fluid environments.

[0009] Furthermore, the wall material is resistant dextrin, and / or The core material is lutein.

[0010] Furthermore, the cumulative release rate of carotenoids in simulated gastric fluid for 2 hours and simulated intestinal fluid for 4 hours is not higher than 20%, and the cumulative release rate in simulated colonic fluid for 6 hours is not lower than 75%.

[0011] Furthermore, the resistant dextrin has a number-average molecular weight of 2000 Da to 5000 Da.

[0012] Furthermore, the wall material is inulin or polydextrose, and the core material is zeaxanthin.

[0013] On the other hand, the present invention provides a method for preparing the above-mentioned microcapsules, comprising: Preparation of an aqueous solution of water-soluble dietary fiber. Preparation of an oil solution of carotenoids in food-grade oils. The oil solution is dispersed in the aqueous solution to form an oil-in-water emulsion. The emulsion is spray-dried, and the powder is collected.

[0014] Furthermore, the dispersion employs high-shear homogenization, with a rotation speed of 8000 rpm to 15000 rpm and a temperature of 40°C to 50°C; the inlet air temperature of the spray drying is 155°C to 165°C, and the outlet air temperature is 75°C to 85°C.

[0015] On the other hand, the present invention proposes a laxative composition containing the above-mentioned microcapsules and a food-acceptable carrier.

[0016] Furthermore, the composition is an oral preparation selected from beverages, solid beverages, jellies, compressed candies, or capsules.

[0017] Furthermore, the beverage contains 1.0 g to 3.0 g of the microcapsules per 200 mL.

[0018] The beneficial effects of this invention are: This invention achieves colon-targeted delivery of lutein. Resistant dextrin, a water-soluble dietary fiber, contains numerous α-1,2 and α-1,3 glycosidic bonds in its molecular structure, enabling it to resist hydrolysis by digestive enzymes in gastric and small intestinal juices. During emulsification, lutein is uniformly dispersed in the resistant dextrin solution to form an oil-in-water emulsion, which is then spray-dried and solidified into microcapsules. This allows the resistant dextrin to form a continuous matrix phase within the microcapsules, encapsulating the lutein. When the microcapsules are orally administered into the digestive tract, the matrix maintains its structural integrity in the stomach and small intestine, effectively protecting the encapsulated lutein. Upon reaching the colon, specific enzymes produced by intestinal flora degrade the glycosidic bonds of the resistant dextrin, leading to matrix dissolution and triggering lutein release. In vitro simulated digestion experiments confirmed the above delivery mechanism: the cumulative release rate of the microcapsules in simulated gastric and intestinal fluids was only 14.77±0.65%, while the cumulative release rate in simulated colonic fluids reached 89.2±1.28% within 6 hours. This indicates that the microcapsules have good colon-targeted release characteristics, which solves the technical problem that lutein is difficult to directly act on the colon due to its poor water solubility and acid sensitivity.

[0019] This invention achieves multi-target regulation of intestinal function through the synergistic effect of lutein and resistant dextrin. Resistant dextrin, acting as a prebiotic, enters the colon and is preferentially fermented and utilized by beneficial bacteria such as Bifidobacteria and Lactobacillus, metabolizing it into short-chain fatty acids such as butyrate. These short-chain fatty acids inhibit the proliferation of pathogenic bacteria by lowering the pH of the colonic lumen and serve as energy substrates for intestinal epithelial cells, promoting epithelial repair. Simultaneously, they exert a laxative effect through peristalsis and water retention by stimulating intestinal smooth muscle contraction and increasing intestinal osmotic pressure. Lutein, released synchronously with the degradation of resistant dextrin, reaches the colon and utilizes the strong antioxidant activity of its conjugated polyene chains to quench excess reactive oxygen species generated by impaired intestinal barrier function due to constipation. Furthermore, it alleviates oxidative stress damage to the intestinal mucosa by regulating inflammatory signaling pathways such as NF-κB, thereby improving the intestinal microenvironment. The synergistic effect described above was manifested in animal experiments as a comprehensive improvement in multiple indicators: after administering the microcapsules of this invention to constipated mice, the number of fecal pellets increased by 39.0±1.0%, the small intestinal propulsion rate increased by 26.2±4.2%, and the water content of colonic contents increased by 13.13±0.65%. Moreover, all indicators in the high-dose group returned to near-normal levels, demonstrating the technical advantages of the microcapsules in comprehensively regulating intestinal motility, flora balance, and oxidative microenvironment through physical excretion promotion dominated by resistant dextrin and chemical repair dominated by lutein.

[0020] This invention achieves green preparation and excellent storage stability of microcapsules through a simplified three-step process of dissolution-emulsification-spray drying. The preparation process uses only water as a solvent and edible soybean oil as the oil phase carrier, eliminating the need for organic solvents or chemical cross-linking agents and avoiding the risk of harmful substance residues, thus meeting the clean production requirements of functional foods. In the emulsification stage, the oil phase is uniformly dispersed in the resistant dextrin aqueous phase as tiny droplets by controlling the shear rate, forming a water-in-oil emulsion with a concentrated particle size distribution. In the spray drying stage, the inlet and outlet air temperatures are controlled to rapidly evaporate moisture while preventing excessive degradation of heat-sensitive lutein, and the droplets instantly solidify into microcapsules. The resulting dense wall structure not only provides protection in the digestive tract but also continuously blocks oxygen and light from eroding the core material during storage, thereby delaying the oxidative degradation of lutein. Accelerated stability tests show that the lutein retention rate of the microcapsules remains above 80% after 49 days of storage at room temperature in the dark, demonstrating excellent shelf stability. The simplified process and stable product performance together form the technical foundation for the transformation of this invention from laboratory research to large-scale production and market application.

[0021] Of course, any product implementing this invention does not necessarily need to achieve all of the advantages described above at the same time. Attached Figure Description

[0022] To more clearly illustrate the technical solutions of the embodiments of the present invention, the accompanying drawings used in the description of the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0023] Figure 1 This is a schematic diagram illustrating the cumulative release rate of microcapsules in an in vitro simulated gastrointestinal tract. Figure 2 This is a schematic diagram of the propulsion rate of the small intestine in mice. Figure 3 A schematic diagram showing the cumulative number of fecal pellets excreted by mice over 7 days; Figure 4 A schematic diagram showing the water content of mouse colon contents; Figure 5 This is a schematic diagram showing the lutein retention rate during the accelerated stability test of microcapsules. Detailed Implementation

[0024] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. 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.

[0025] The method for preparing colon-targeted microcapsules as described in this embodiment includes: Step 1: Preparation of resistant dextrin solution Take 10 g of food-grade resistant dextrin (molecular weight approximately 2000-5000 Da), add it to 100 mL of deionized water at 50℃, and stir magnetically at 300 rpm for 30 minutes until completely dissolved to obtain a 10% (w / w) transparent solution.

[0026] Step 2: Preparation of Lutein Oil Phase Weigh 0.5 g of lutein crystals (purity ≥90%) and add them to 5 g of edible soybean oil. Place the mixture in a 60°C water bath and stir at 200 rpm for 15 minutes until the lutein is completely dissolved and a uniform lutein oil phase is formed.

[0027] Step 3: Emulsification and Microencapsulation The lutein oil phase was slowly added dropwise to the resistant dextrin solution and emulsified using a high-speed shear emulsifier (10,000 rpm, 5 minutes) to form a stable oil-in-water (O / W) emulsion. The system temperature was maintained at 40-50℃ during the emulsification process.

[0028] Step 4: Spray drying into capsules The above emulsion was processed by a spray dryer (inlet air temperature 160±5℃, outlet air temperature 80±5℃, atomization pressure 0.3MPa), and the dried powder was collected, which is the lutein-resistant dextrin microcapsule.

[0029] Step 5: Preparation of the laxative drink Take 2.0 g of the above microcapsule powder, 5.0 g of fructooligosaccharide, 0.1 g of citric acid and 0.02 g of potassium sorbate, add them to 200 mL of purified water, stir well, pasteurize (70℃, 10 minutes) and fill into a container to obtain the bowel-regulating beverage (Lut-RD).

[0030] Example 1

[0031] In this embodiment, lutein-resistant dextrin microcapsules are first prepared, comprising: Weigh 10.0 g of resistant dextrin (molecular weight approximately 3500 Da, trade name Fibersol-2, Matsutani Chemical Industry Co., Ltd., Japan). Slowly add it to 90 mL of deionized water at 50°C and dissolve for 40 minutes under magnetic stirring at 300 rpm. Then, add water to bring the total mass to 100 g, obtaining a 10% (w / w) clear aqueous solution. Separately, take 0.5 g of lutein crystals with a purity of not less than 90% and add them to 5.0 g of edible soybean oil. Place the solution in a 60°C water bath and stir at 200 rpm for 15 minutes to completely dissolve the lutein and form a homogeneous oil phase. Under continuous stirring at 500 rpm, slowly add the lutein oil phase dropwise to the resistant dextrin aqueous solution. Then, emulsify using a high-shear emulsifier at 10000 rpm for 5 minutes, controlling the system temperature at 45±2°C during emulsification to form a stable oil-in-water emulsion. The resulting emulsion was immediately spray-dried with an inlet air temperature of 160±2℃, an outlet air temperature of 80±2℃, an atomization pressure of 0.3 MPa, and a feed flow rate of 10 mL / min. The dried pale yellow powder was collected to obtain lutein-resistant dextrin microcapsules.

[0032] To evaluate the colon-targeted release performance of the microcapsules, this embodiment used an in vitro simulated gastrointestinal digestion model for testing. The process included: first, incubating the microcapsule samples in simulated gastric juice containing pepsin at pH 1.2 for 2 hours; then transferring them to simulated intestinal juice containing pancreatin at pH 6.8 for 4 hours; and finally, incubating them in simulated colonic juice containing fermented rat cecal contents at pH 7.2 for 6 hours. The entire digestion process was conducted in a 37°C constant-temperature shaking water bath at 100 rpm. The release of lutein was measured at different time points, and the cumulative release rate of three parallel batches of samples is shown in Table 1.

[0033] Table 1. Cumulative release rate (%) of microcapsules during simulated gastrointestinal digestion. As shown in Table 1, at the end of 2 hours of simulated gastric juice and 4 hours of simulated intestinal juice (i.e., a total digestion time of 6 hours), the cumulative release rates of the three batches of samples were 15.4%, 14.8%, and 14.1%, respectively, with an average of only 14.8 ± 0.7%. This indicates that the microcapsules have good resistance to digestion in the gastric and small intestinal environments, effectively protecting lutein from premature release. After transfer to simulated colonic juice, lutein was rapidly released. After 6 hours of incubation in colonic juice (i.e., a total digestion time of 12 hours), the cumulative release rates of the three batches of samples reached 90.3%, 89.5%, and 87.8%, respectively, with an average of 89.2 ± 1.3%, confirming that the microcapsules of this invention possess excellent colon-targeted release characteristics. Compared to existing technologies that achieve colon targeting through complex enteric coating or chemical cross-linking, this invention achieves highly efficient colon targeting through a simple emulsification-spray drying process, utilizing resistant dextrin as a special wall material. Its mechanism of action does not depend on pH changes, but rather on the specific degradation of resistant dextrin by the unique microbial environment of the colon. This microbial-triggered release mechanism is not only greener and simpler in its process, but also more physiologically selective in its release, avoiding the problem of incomplete release due to individual pH differences.

[0034] Data are expressed as mean ± standard deviation, and all experiments were repeated three times. It should be understood that the release data presented in this embodiment only represent the test results of this batch of samples. Appropriate adjustments to different batches or process parameters may cause data fluctuations, but none of them deviate from the colon-targeted release characteristics defined in this invention.

[0035] Example 2

[0036] To further increase the content of active ingredients per unit dose, this embodiment optimized the preparation process based on Example 1. Specifically, the concentration of the resistant dextrin solution was increased to 15% (w / w), and the concentration of lutein in the oil phase was increased to 100 mg / mL, with soybean oil still used as the carrier. The oil phase and aqueous phase were mixed at a mass ratio of 1:10. A two-step emulsification method was adopted: first, high-shear dispersion at 8000 rpm for 2 minutes, followed by high-shear emulsification at 15000 rpm for 3 minutes. The entire emulsification process was carried out under nitrogen protection, and the system temperature was controlled at 45±2℃. The spray drying process parameters were adjusted to an inlet air temperature of 160±2℃, an outlet air temperature of 80±2℃, and a feed flow rate of 8 mL / min. The obtained microcapsules, observed by scanning electron microscopy, were spherical, intact, and had a smooth surface, with an encapsulation rate greater than 92%.

[0037] The in vitro digestion experiment was conducted according to the method described in Example 1, and the cumulative release rate results of three batches of parallel samples are shown in Table 2.

[0038] Table 2. Cumulative release rate (%) of high drug loading microcapsules during simulated gastrointestinal digestion. As shown in Table 2, the average cumulative release rate of the high drug-load microcapsules described in this embodiment in simulated gastric and intestinal fluids was 14.2 ± 0.4%, and the average release rate in simulated colonic fluid over 6 hours was 89.2 ± 0.8%, which is comparable to the results of Example 1, indicating that increasing the drug loading did not affect its colon-targeting performance. Those skilled in the art will understand that the process parameters of this embodiment can be appropriately adjusted according to production scale and equipment characteristics, as long as the stable formation of the oil-in-water emulsion and spray drying can be achieved.

[0039] Example 3

[0040] Take 20.0 g of the high drug loading microcapsules obtained in Example 2, mix them evenly with 50.0 g of fructooligosaccharides, 1.0 g of citric acid, 0.1 g of sucralose and 0.05 g of edible orange flavoring, slowly add them to 1 L of purified water at 60°C, stir until completely dissolved, cool and filter through a 0.22 μm filter membrane, aseptically fill into glass bottles, seal and pasteurize at 70°C for 10 minutes to obtain a laxative drink. Each 200 mL of the drink contains approximately 2.0 g of microcapsules.

[0041] The laxative effect of the obtained beverage was evaluated using a loperamide-induced mouse constipation model. SPF-grade male ICR mice, weighing 18-22 g, were randomly divided into four groups (n=10 per group) after one week of acclimatization: a blank control group, a model control group, a low-dose group, and a high-dose group. The blank control group received normal drinking water, while the other groups were administered loperamide by gavage at a dose of 10 mg / kg to establish a constipation model. The low-dose group was administered the diluted beverage solution by gavage to achieve a microcapsule dose of 100 mg / kg; the high-dose group was administered the diluted beverage solution by gavage to achieve a microcapsule dose of 200 mg / kg. Gavage was continued for 7 days. After the last administration, mice were fasted but allowed free access to water for 12 hours. All mice, except the blank control group, were administered loperamide by gavage. Thirty minutes later, ink was administered by gavage. Small intestinal propulsion rate, the cumulative number of fecal pellets over 7 days, and the water content of colonic contents were measured. All data are expressed as mean ± standard deviation. One-way ANOVA was performed using SPSS 22.0 software. LSD method was used for comparisons between groups. p < 0.05 was considered statistically significant.

[0042] The results of the small intestinal propulsion rate measurement are shown in Table 3.

[0043] Table 3. Small intestinal propulsion rate (%) in each group of mice As shown in Table 3, the average small intestinal propulsion rate of the high-dose group mice was 68.5±0.6%, which was 26.2 percentage points higher than that of the model control group (42.3±1.0%), and the difference was statistically significant (p<0.01). Moreover, there was no significant difference between the high-dose group and the blank control group (71.2±0.8%) (p>0.05), indicating that the beverage described in this example can significantly promote intestinal peristalsis in constipated mice and restore it to a near-normal level.

[0044] The results of the cumulative number of stool particles over 7 days are shown in Table 4.

[0045] Table 4. Cumulative number of fecal pellets excreted by mice in each group over 7 days As shown in Table 4, the average number of fecal pellets excreted by mice in the high-dose group over 7 days was 125±1 pellets, which was 39 pellets more than the 86±1 pellets in the model control group, representing an increase of 45.3%, and the difference was statistically significant (p<0.01). The low-dose group also showed significant improvement (p<0.05), which showed a dose-dependent effect.

[0046] The results of the determination of water content in colon contents are shown in Table 5.

[0047] Table 5. Moisture content (%) of colon contents in mice of each group As shown in Table 5, the average water content of the colon contents of mice in the high-dose group was 70.1±0.7%, which was 12.5 percentage points higher than that of the model control group (57.6±0.7%). The difference was statistically significant (p<0.01), indicating that the beverage described in this embodiment can effectively increase the water content of the intestine and soften the feces.

[0048] The above data confirms that the laxative beverage containing the microcapsules of this invention can significantly promote intestinal peristalsis, increase defecation frequency and fecal water content in constipated mouse models, and the effect is dose-dependent. It should be understood that animal experimental data provides a scientific basis for efficacy evaluation, but individual differences may lead to slight variations in actual results.

[0049] Example 4

[0050] The microcapsule powder prepared in Example 1 was sealed in an aluminum foil bag and stored at room temperature (25±2℃) for 49 days, protected from light. Lutein retention was determined periodically. The lutein content was determined by high-performance liquid chromatography (HPLC), and the retention rate was calculated with the initial content as 100%. The retention rates of three parallel batches of samples at each time point are shown in Table 6.

[0051] Table 6. Lutein retention rate (%) of microcapsules in accelerated stability test As shown in Table 6, after 49 days of storage, the lutein retention rates of the three batches of samples were 85.5%, 83.9% and 84.8%, respectively, with an average of 84.7 ± 0.8%, which is still greater than 80%. This indicates that the microcapsules have a good protective effect on lutein and effectively delay its oxidative degradation during storage.

[0052] Example 5

[0053] Following the method described in Example 1, the wall materials were replaced with inulin and polydextrose, respectively. Inulin had a number-average molecular weight of approximately 5000 Da and was purchased from Orafti, Belgium; polydextrose had a number-average molecular weight of approximately 4000 Da and was purchased from Danisco, USA. The core material was replaced with zeaxanthin, with a purity of not less than 90%. Microcapsule samples were prepared accordingly. In vitro digestion experiments were conducted according to the method in Example 1. The results showed that the microcapsules with inulin as the wall material had a cumulative release rate of less than 20% in simulated gastric and intestinal fluids, and a release rate of 78.6 ± 2.3% in simulated colonic fluid after 6 hours. The microcapsules with polydextrose as the wall material had a release rate of 81.2 ± 1.9% in simulated colonic fluid after 6 hours, both exhibiting good colon-targeting characteristics, with colonic release rates not less than 75%. The release behavior of the microcapsules with zeaxanthin as the core material in simulated colonic fluid was similar to that of the lutein microcapsules described in Example 1, with a release rate exceeding 85%. Those skilled in the art will understand that the above-described extended applications verify the versatility of the technical solution of the present invention, that is, the microcapsule system described in the present invention can be applied to a combination of various water-soluble dietary fiber wall materials and carotenoid core materials, but the specific combination still needs to be optimized and selected according to the target efficacy and process adaptability.

[0054] In summary, this invention presents a colon-targeted microcapsule, its preparation method, and its application. The microcapsule uses resistant dextrin as the wall material and is prepared by encapsulating lutein through an emulsification-spray drying process. The resistant dextrin maintains its structural integrity in the stomach and small intestine, and is degraded by intestinal flora upon entering the colon, thereby triggering the targeted release of lutein. In vitro simulated digestion experiments show that the cumulative release rate of the microcapsule in simulated gastric and intestinal fluids is less than 15%, while the release rate in simulated colonic fluid is greater than 89% after 6 hours. This microcapsule promotes the production of short-chain fatty acids, stimulates intestinal peristalsis, and increases fecal water content through the prebiotic effect of resistant dextrin, while simultaneously reducing colonic oxidative stress through the antioxidant effect of lutein. These two factors synergistically achieve a laxative effect. A beverage formulated with this microcapsule and excipients such as fructooligosaccharides significantly increased the number of fecal pellets, improved small intestinal propulsion rate, and increased colonic water content in an animal constipation model. This invention features a simple preparation process, uses food-grade raw materials, and produces microcapsules with good storage stability, making it suitable for large-scale production in the functional food field.

[0055] The preferred embodiments of the present invention disclosed above are merely illustrative of the invention. These preferred embodiments do not exhaustively describe all details, nor do they limit the invention to the specific implementations described. Clearly, many modifications and variations can be made based on the content of this specification. This specification selects and specifically describes these embodiments to better explain the principles and practical applications of the invention, thereby enabling those skilled in the art to better understand and utilize the invention. The invention is limited only by the claims and their full scope and equivalents.

Claims

1. A colon-targeting microcapsule, characterized in that, include: Wall materials composed of water-soluble dietary fiber, and Carotenoid core material encapsulated by the wall material; The microcapsules are microparticles obtained by spray drying an oil-in-water emulsion. The rate at which the microcapsules release carotenoids in the colonic environment due to the degradation of the wall material by intestinal flora is higher than the rate at which they release carotenoids through diffusion in the gastric and intestinal fluid environments.

2. The microcapsule as described in claim 1, characterized in that, The wall material is resistant dextrin, and / or The core material is lutein.

3. The microcapsule as described in claim 1 or 2, characterized in that, The cumulative release rate of carotenoids in simulated gastric fluid for 2 hours and simulated intestinal fluid for 4 hours was not higher than 20%, and the cumulative release rate in simulated colonic fluid for 6 hours was not lower than 75%.

4. The microcapsule as described in claim 2, characterized in that, The resistant dextrin has a number-average molecular weight of 2000 Da to 5000 Da.

5. The microcapsule as described in claim 1, characterized in that, The wall material is inulin or polydextrose, and the core material is zeaxanthin.

6. A method for preparing the microcapsules according to any one of claims 1-5, comprising: Preparation of an aqueous solution of water-soluble dietary fiber. Preparation of an oil solution of carotenoids in food-grade oils. The oil solution is dispersed in the aqueous solution to form an oil-in-water emulsion. The emulsion is spray-dried, and the powder is collected.

7. The method as described in claim 6, characterized in that, The dispersion employs high-shear homogenization at a rotation speed of 8000 rpm to 15000 rpm and a temperature of 40°C to 50°C; the spray drying process uses an inlet air temperature of 155°C to 165°C and an outlet air temperature of 75°C to 85°C.

8. A laxative composition, characterized in that, It contains the microcapsules of any one of claims 1-6 and a food-acceptable carrier.

9. The composition according to claim 8, characterized in that, The composition is an oral preparation selected from beverages, solid beverages, jellies, compressed candies, or capsules.

10. The composition according to claim 10, characterized in that, The beverage contains 1.0 g to 3.0 g of the microcapsules per 200 mL.

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