A high-efficiency purification method for purple corn anthocyanins and application thereof in preparation of effervescent tablets

Abstract

This invention discloses a highly efficient purification method for anthocyanins from purple corn leaves and its application in the preparation of effervescent tablets, belonging to the field of natural product extraction and purification technology. The method involves filtering and concentrating the crude anthocyanin extract obtained from soaking to remove impurities, followed by fractional purification using simulated moving bed chromatography with six functional zones. The purified anthocyanins are then concentrated and dried to obtain the final product. This process can be continuously operated, significantly improving the purity and yield of anthocyanins, providing reliable technical support for the industrial-scale, high-value utilization of anthocyanins from purple corn leaves.

Description

Technical Field

[0001] This invention relates to the field of natural product extraction and purification technology, and in particular to a highly efficient purification method for anthocyanins from purple corn leaves and its application in the preparation of effervescent tablets. Background Technology

[0002] Purple corn is a specialty crop rich in anthocyanins. Its leaves contain abundant flavonoids and anthocyanin-like active substances, which possess excellent antioxidant, anti-inflammatory, and free radical scavenging functions, showing broad application prospects in food, health products, and cosmetics. With the increasing market demand for natural active ingredients, the extraction and purification technology of anthocyanins from purple corn leaves has attracted widespread attention.

[0003] Currently, the main purification methods for anthocyanins from purple corn leaves include solvent extraction, gel filtration chromatography, and conventional column chromatography. Solvent extraction is simple but has low purification efficiency and carries the risk of solvent residue. Gel filtration chromatography offers high separation precision but has low throughput and long elution cycles, making it difficult to achieve continuous industrial production. Conventional column chromatography is cumbersome to operate, has low adsorbent utilization, resulting in low product yields, and cannot effectively fractionate different active components.

[0004] Simulated moving bed chromatography (SMB) is a highly efficient continuous chromatographic separation technique with advantages such as high separation efficiency, large throughput, and low solvent consumption, and has been applied in the purification of substances such as sugars and amino acids. However, the current application of SMB in the purification of anthocyanins from purple corn leaves has the following shortcomings: First, the column partitioning design is unreasonable, and the column ratio in each zone is not optimized according to the polarity characteristics of anthocyanins; second, parameters such as feed concentration, eluent gradient, flow rate, and switching time lack systematic matching, making it difficult to simultaneously improve purity and yield; third, it cannot achieve targeted separation of different antioxidant anthocyanin components, limiting the differentiated application of the product. In addition, in existing purification methods, the pretreatment step fails to effectively remove macromolecular impurities and colloidal substances, easily causing column blockage, affecting separation efficiency and equipment lifespan.

[0005] Therefore, developing a highly efficient purification method for anthocyanins from purple corn leaves that features optimized processes, high purification efficiency, fractionation of active components, and suitability for industrial production, and solving problems such as low purity, low yield, and low continuity in existing technologies, has significant practical importance and application value. Summary of the Invention

[0006] The purpose of this invention is to provide a highly efficient purification method for anthocyanins from purple corn leaves and its application in the preparation of effervescent tablets, so as to solve the problems existing in the prior art.

[0007] To achieve the above objectives, the present invention provides the following solution: This invention provides a method for purifying anthocyanins from purple corn leaves, comprising the following steps: (1) Soak purple corn leaves in water to extract crude anthocyanin extract; (2) The crude anthocyanin extract was sequentially filtered, concentrated and purified; the extraction was performed using a nanofiltration membrane; the nanofiltration membrane had a molecular weight cutoff of 5000-10000 Da; (3) Adjust the concentration of the extract after step (2) to 5-10 mg / mL and perform continuous separation and purification using a simulated moving bed chromatography system; the simulated moving bed chromatography system contains 24 chromatographic columns connected in series and is divided into an adsorption zone, a purification zone, a desorption zone 1, a desorption zone 2, a regeneration zone and a water washing zone in sequence. (4) Collect the effluent from desorption zone 1 and / or desorption zone 2, concentrate and freeze dry to obtain purple corn leaf anthocyanins with a purity of 80%–90% and a yield of 80%–90%.

[0008] The concentration temperature in step (4) is 40℃-50℃.

[0009] Furthermore, the number of chromatographic columns in the adsorption zone, purification zone, desorption zone 1, desorption zone 2, regeneration zone, and water washing zone are 6, 3, 4, 4, 3, and 4, respectively; Furthermore, the eluents used in each region of the simulated moving bed chromatography system are as follows: Adsorption zone: Pretreated purple corn leaf anthocyanin extract; Refining area: 5%-10% ethanol aqueous solution; Desorption zone 1: 40%-50% ethanol aqueous solution; Desorption zone 2: 60%-70% ethanol aqueous solution; Regeneration zone: 90%-100% ethanol aqueous solution; Washing area: Deionized water.

[0010] Furthermore, each zone has one inlet and one outlet, controlled by a rotary valve. The inlets for the adsorption zone, purification zone, desorption zone 1, desorption zone 2, and regeneration zone are the first column in that zone (clockwise), while the inlet for the water washing zone is the last column in that zone (clockwise). Furthermore, the flow rates in each zone of the simulated moving bed chromatography system are as follows: adsorption zone: 1-3 BV / h; purification zone, desorption zone 1, desorption zone 2, and regeneration zone: 5-10 BV / h; water washing zone: 5-12 BV / h.

[0011] Furthermore, the switching time of the simulated moving bed chromatography system is 1000-1500s, the operating temperature is 30-40℃, and the stationary phase of the chromatographic column is AB-8 resin or X-5 resin.

[0012] The present invention also provides an effervescent tablet containing purple corn leaf anthocyanins, which is composed of the following components by weight percentage: The ingredients include 5%-8% anthocyanins from purple corn leaves, 50%-60% of a mixture of citric acid and sodium bicarbonate, 25%-35% fillers, 2%-4% sweeteners, 2%-3% binders, and 0.3%-0.7% lubricants. The anthocyanins from purple corn leaves were prepared using the method described above.

[0013] Specifically, the filler includes mannitol, the sweetener includes steviol glycosides, the binder includes povidone K30, and the lubricant includes PEG6000.

[0014] Furthermore, the mass ratio of citric acid to sodium bicarbonate is 1.2:1 to 1.4:1.

[0015] The present invention discloses the following technical effects: This invention achieves efficient separation and purification of anthocyanins from purple corn leaves through a synergistic process of immersion-concentration-simulated moving bed chromatography. This process can operate continuously and stably, accurately separating two refined anthocyanin components with distinct antioxidant activities, effectively improving product purity and yield, and offering significant advantages over traditional purification methods. Using this high-quality refined anthocyanin as the active ingredient, combined with scientifically proportioned excipients, effervescent tablets prepared through standardized processes meet relevant standards in all physicochemical properties. The product has a uniform texture and smooth surface, rapidly disintegrates in water to form a clear and homogeneous solution, and has a harmonious and pleasant taste, combining good practicality and user experience. This provides a reliable technical guarantee for the industrial transformation and high-value application of anthocyanins from purple corn leaves. Detailed Implementation

[0016] Various exemplary embodiments of the present invention will now be described in detail. This detailed description should not be considered as a limitation of the present invention, but rather as a more detailed description of certain aspects, features, and embodiments of the present invention.

[0017] It should be understood that the terminology used in this invention is merely for describing particular embodiments and is not intended to limit the invention. Furthermore, with respect to numerical ranges in this invention, it should be understood that each intermediate value between the upper and lower limits of the range is also specifically disclosed. Any stated value or intermediate value within a stated range, as well as each smaller range between any other stated value or intermediate value within said range, is also included in this invention. The upper and lower limits of these smaller ranges may be independently included or excluded from the range.

[0018] Unless otherwise stated, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art. While only preferred methods and materials have been described herein, any methods and materials similar or equivalent to those described herein may be used in the implementation or testing of this invention. All references to this specification are incorporated by way of citation to disclose and describe methods and / or materials associated with those references. In the event of any conflict with any incorporated reference, the content of this specification shall prevail.

[0019] Various modifications and variations can be made to the specific embodiments described in this specification without departing from the scope or spirit of the invention, as will be apparent to those skilled in the art. Other embodiments derived from this specification will also be readily apparent to those skilled in the art. This specification and embodiments are merely exemplary.

[0020] The terms “include,” “including,” “have,” “contain,” etc., used in this article are all open-ended terms, meaning that they include but are not limited to.

[0021] It should be noted that any aspects not described in detail in this invention are conventional practices in the field and are not the focus of this invention.

[0022] In this invention, the eluent used in each region is of volume concentration.

[0023] Example 1 A highly efficient purification method for anthocyanins from purple corn leaves, comprising the following steps: (1) Extraction: Purple corn leaves were bagged and soaked three times in sequence, each soaking time was 4 hours. After each soaking, the water was changed and the soaking liquid was collected to obtain crude anthocyanin extract from purple corn leaves. (2) Purification: a. Metal membrane filtration: The crude extract is filtered through a metal membrane (0.5μm pore size) to remove insoluble impurities; b. Nanofiltration membrane concentration: A nanofiltration membrane with a pore size of 5000 Da is used to remove macromolecular substances, and the filtrate is concentrated to obtain a concentrated solution; (3) Simulated moving bed chromatographic fractionation: a. Feed solution preparation: After filtering the concentrate, prepare an anthocyanin extract with deionized water to a concentration of 5 mg / mL; b. SMB Chromatographic Purification: This simulated moving bed chromatography system contains 24 chromatographic columns (25 mm inner diameter, 1000 mm length), divided into 6 zones: adsorption zone, purification zone, desorption zone 1, desorption zone 2, regeneration zone, and water washing zone. The number of chromatographic columns is 6, 3, 4, 4, 3, and 4, respectively. The zones are connected in series, and each zone has one inlet and one outlet, controlled by a rotary valve. The feed inlets for the adsorption zone, purification zone, desorption zone 1, desorption zone 2, and regeneration zone are the first column in that zone (clockwise), while the feed inlet for the water washing zone is the last column in that zone (clockwise). During operation, all zones work simultaneously, with a switching time of 1260 seconds. Continuous operation is achieved by moving the column position clockwise. The feed solution for the adsorption zone is 5 mg / mL purple corn leaf anthocyanin extract; for the purification zone, it is 10% ethanol aqueous solution; for desorption zone 1, it is 40% ethanol aqueous solution; for desorption zone 2, it is 60% ethanol aqueous solution; for the regeneration zone, it is 95% ethanol aqueous solution; and for the water washing zone, it is deionized water. The flow rates for each zone are 2.0 BV / h, 5.0 BV / h, 5.0 BV / h, 5.0 BV / h, 5.0 BV / h, and 7.0 BV / h, respectively. The stationary phase is AB-8 macroporous resin, and the operating temperature is 30℃. (4) Post-processing: Collect the eluent from desorption zone 1 and desorption zone 2, concentrate them under vacuum at 45°C, and freeze-dry them after concentration to obtain two refined anthocyanin components.

[0024] The purity of the desorption zone 1 component was 78.6%, the yield was 82.5%, and the anti-DPPH activity was 65.7%; the purity of the desorption zone 2 component was 83.8%, the yield was 80.6%, and the anti-DPPH activity was 79.3%.

[0025] Example 2 A highly efficient purification method for anthocyanins from purple corn leaves, comprising the following steps: (1) Extraction: Purple corn leaves were bagged and soaked three times in sequence, each soaking time was 4 hours. After each soaking, the water was changed and the soaking liquid was collected to obtain crude anthocyanin extract from purple corn leaves. (2) Purification: a. Metal membrane filtration: The crude extract is filtered through a metal membrane (0.5μm pore size) to remove insoluble impurities; b. Nanofiltration membrane concentration: A nanofiltration membrane with a pore size of 5000 Da is used to remove macromolecular substances, and the filtrate is concentrated to obtain a concentrated solution; (3) Simulated moving bed chromatographic fractionation: a. Feed solution preparation: After filtering the concentrate, prepare an anthocyanin extract with deionized water to a concentration of 5 mg / mL; b. SMB Chromatographic Purification: This simulated moving bed chromatography system contains 24 chromatographic columns (25 mm inner diameter, 1000 mm length), divided into 6 zones: adsorption zone, purification zone, desorption zone 1, desorption zone 2, regeneration zone, and water washing zone. The number of chromatographic columns is 6, 3, 4, 4, 3, and 4, respectively. The zones are connected in series, and each zone has one inlet and one outlet, controlled by a rotary valve. The feed inlets for the adsorption zone, purification zone, desorption zone 1, desorption zone 2, and regeneration zone are the first column in that zone (clockwise), while the feed inlet for the water washing zone is the last column in that zone (clockwise). During operation, all zones work simultaneously, with a switching time of 1080 seconds. Continuous operation is achieved by moving the column position clockwise. The feed solution for the adsorption zone is 5 mg / mL purple corn leaf anthocyanin extract; for the purification zone, it is 10% ethanol aqueous solution; for desorption zone 1, it is 50% ethanol aqueous solution; for desorption zone 2, it is 70% ethanol aqueous solution; for the regeneration zone, it is 95% ethanol aqueous solution; and for the water washing zone, it is deionized water. The flow rates for each zone are 1.5 BV / h, 7.0 BV / h, 5.0 BV / h, 7.0 BV / h, 5.0 BV / h, and 6.0 BV / h, respectively. The stationary phase is AB-8 macroporous resin, and the operating temperature is 35℃. (4) Post-processing: Collect the eluent from desorption zone 1 and desorption zone 2, concentrate them under vacuum at 45°C, and freeze-dry them after concentration to obtain two refined anthocyanin components.

[0026] The purity of the desorption zone 1 component was 82.9%, the yield was 87.3%, and the anti-DPPH activity was 71.2%; the purity of the desorption zone 2 component was 86.7%, the yield was 76.3%, and the anti-DPPH activity was 86.1%.

[0027] Example 3 A highly efficient purification method for anthocyanins from purple corn leaves, comprising the following steps: (1) Extraction: Purple corn leaves were bagged and soaked three times in sequence, each soaking time was 4 hours. After each soaking, the water was changed and the soaking liquid was collected to obtain crude anthocyanin extract from purple corn leaves. (2) Purification: a. Metal membrane filtration: The crude extract is filtered through a metal membrane (0.5μm pore size) to remove insoluble impurities; b. Nanofiltration membrane concentration: A nanofiltration membrane with a pore size of 5000 Da is used to remove macromolecular substances, and the filtrate is concentrated to obtain a concentrated solution; (3) Simulated moving bed chromatographic fractionation: a. Feed solution preparation: After filtering the concentrate, prepare an anthocyanin extract with deionized water to a concentration of 5 mg / mL; b. SMB Chromatographic Purification: This simulated moving bed chromatography system contains 24 chromatographic columns (25 mm inner diameter, 1000 mm length), divided into 6 zones: adsorption zone, purification zone, desorption zone 1, desorption zone 2, regeneration zone, and water washing zone. The number of chromatographic columns is 6, 3, 4, 4, 3, and 4, respectively. The zones are connected in series, and each zone has one inlet and one outlet, controlled by a rotary valve. The feed inlets for the adsorption zone, purification zone, desorption zone 1, desorption zone 2, and regeneration zone are the first column in that zone (clockwise), while the feed inlet for the water washing zone is the last column in that zone (clockwise). During operation, all zones work simultaneously, with a switching time of 1080 seconds. Continuous operation is achieved by moving the column position clockwise. The feed solution for the adsorption zone is 5 mg / mL purple corn leaf anthocyanin extract; for the purification zone, it is 5% ethanol aqueous solution; for desorption zone 1, it is 40% ethanol aqueous solution; for desorption zone 2, it is 70% ethanol aqueous solution; for the regeneration zone, it is 100% ethanol aqueous solution; and for the water washing zone, it is deionized water. The flow rates for each zone are 2.0 BV / h, 5.0 BV / h, 6.0 BV / h, 5.0 BV / h, 7.0 BV / h, and 9.0 BV / h, respectively. The stationary phase is X-5 macroporous resin, and the operating temperature is 40℃. (4) Post-processing: Collect the eluent from desorption zone 1 and desorption zone 2, concentrate them under vacuum at 45°C, and freeze-dry them after concentration to obtain two refined anthocyanin components.

[0028] The purity of the desorption zone 1 component was 78.6%, the yield was 82.5%, and the anti-DPPH activity was 65.7%; the purity of the desorption zone 2 component was 84.5%, the yield was 82.3%, and the anti-DPPH activity was 84.6%.

[0029] Example 4 A highly efficient purification method for anthocyanins from purple corn leaves, comprising the following steps: (1) Extraction: Purple corn leaves were bagged and soaked three times in sequence, each soaking time was 4 hours. After each soaking, the water was changed and the soaking liquid was collected to obtain crude anthocyanin extract from purple corn leaves. (2) Purification: a. Metal membrane filtration: The crude extract is filtered through a metal membrane (0.5μm pore size) to remove insoluble impurities; b. Nanofiltration membrane concentration: A nanofiltration membrane with a pore size of 5000 Da is used to remove macromolecular substances, and the filtrate is concentrated to obtain a concentrated solution; (3) Simulated moving bed chromatographic fractionation: a. Feed solution preparation: After filtering the concentrate, prepare an anthocyanin extract with deionized water to a concentration of 5 mg / mL; b. SMB Chromatographic Purification: The simulated moving bed chromatography system consists of 24 columns (25 mm inner diameter, 1000 mm length), divided into 6 zones: adsorption zone, purification zone, desorption zone 1, desorption zone 2, regeneration zone, and washing zone. The number of columns in each zone is 6, 3, 4, 4, 3, and 4, respectively. The zones are connected in series, and each zone has one inlet and one outlet, controlled by a rotary valve. The feed inlets for the adsorption zone, purification zone, desorption zone 1, desorption zone 2, and regeneration zone are the first column in that zone (clockwise), while the feed inlet for the water washing zone is the last column in that zone (clockwise). During operation, all zones work simultaneously, with a switching time of 1200 seconds. Continuous operation is achieved by moving the column position clockwise. The feed solution for the adsorption zone is 5 mg / mL purple corn leaf anthocyanin extract; for the purification zone, it is 10% ethanol aqueous solution; for desorption zone 1, it is 50% ethanol aqueous solution; for desorption zone 2, it is 70% ethanol aqueous solution; for the regeneration zone, it is 100% ethanol aqueous solution; and for the water washing zone, it is deionized water. The flow rates for each zone are 1.0 BV / h, 6.0 BV / h, 7.0 BV / h, 7.0 BV / h, 7.0 BV / h, and 10.0 BV / h, respectively. The stationary phase of the chromatographic column is X-5 macroporous resin, and the operating temperature is 30℃. (4) Post-processing: Collect the eluent from desorption zone 1 and desorption zone 2, concentrate them under vacuum at 45°C, and freeze-dry them after concentration to obtain two refined anthocyanin components.

[0030] The purity of the desorption zone 1 component was 81.2%, the yield was 87.7%, and the anti-DPPH activity was 69.8%; the purity of the desorption zone 2 component was 83.2%, the yield was 73.5%, and the anti-DPPH activity was 84.8%.

[0031] Comparative Example 1 This embodiment provides a method for purifying anthocyanins from purple corn leaves, the steps of which are as follows: (1) Extraction: Purple corn leaves were bagged and soaked three times in sequence, each soaking time was 4 hours. After each soaking, the water was changed and the soaking liquid was collected to obtain crude anthocyanin extract from purple corn leaves. (2) Purification: a. Metal membrane filtration: The crude extract is filtered through a metal membrane (0.5μm pore size) to remove insoluble impurities; b. Nanofiltration membrane concentration: A nanofiltration membrane with a pore size of 5000 Da is used to remove macromolecular substances, and the filtrate is concentrated to obtain a concentrated solution; (3) Simulated moving bed chromatographic fractionation: a. Feed solution preparation: After filtering the concentrate, prepare an anthocyanin extract with deionized water to a concentration of 5 mg / mL; b. SMB Chromatographic Purification: The simulated moving bed chromatography equipment consists of 12 chromatographic columns with an inner diameter of 25 mm and a length of 1000 mm. All chromatographic columns are divided into four functional areas: adsorption zone, desorption zone 1, desorption zone 2, and water washing zone. The number of chromatographic columns corresponding to each zone are 4, 3, 3, and 2, respectively. The zones are connected in series, with each zone having one inlet and one outlet. The inlets for the adsorption zone, desorption zone 1, and desorption zone 2 are the first column of their respective zones (clockwise), and the outlets are the last column of their respective zones (clockwise). The inlet and outlet for the washing zone are the first and last columns of that zone, respectively (clockwise). During operation, the adsorption zone, desorption zone 1, desorption zone 2, and washing zone work synchronously. When the set switching time is reached, each column moves one column position clockwise, and this cycle continues to operate continuously, achieving continuous operation of the purification process. The feed solution for the adsorption zone was a pretreated 5 mg / mL anthocyanin extract from purple corn leaves; the feed solution for desorption zone 1 was a 20% ethanol aqueous solution; the feed solution for desorption zone 2 was a 70% ethanol aqueous solution; and the feed solution for the washing zone was deionized water. The stationary phase of the chromatographic column was D101 macroporous resin. The operating temperature throughout the purification process was controlled at 30℃. The flow rate was set to 2.0 BV / h for the adsorption zone, 5.5 BV / h for desorption zone 1, 6.5 BV / h for desorption zone 2, and 8.0 BV / h for the washing zone. The switching time was set to 800 s.

[0032] (4) Post-processing: The eluents from desorption zone 1 and desorption zone 2 were collected and concentrated under vacuum at 45°C. After concentration, they were freeze-dried to obtain two refined anthocyanin components.

[0033] The purity of the desorption zone 1 component was 35.3%, the yield was 38.2%, the anti-DPPH activity was 28.4%, and the anti-ABTS activity was 31.5%; the purity of the desorption zone 2 component was 58.9%, the yield was 62.2%, the anti-DPPH activity was 56.8%, and the anti-ABTS activity was 65.7%.

[0034] Example 5 The purified anthocyanin component prepared in Example 1 was used to prepare effervescent tablets: The raw materials of the effervescent tablets are as follows by weight percentage: refined purple corn leaf anthocyanins 6%, a mixture of citric acid and sodium bicarbonate (1.3:1) 55%, PEG6000 0.5%, povidone K30 2.5%, steviol glycosides 3%, and mannitol 33%; The refined purple corn leaf anthocyanins are obtained by mixing the anthocyanins obtained from desorption zone 1 and desorption zone 2 at a mass ratio of 2:1.

[0035] The preparation steps for effervescent tablets are as follows: (1) Sieving: Citric acid, sodium bicarbonate, mannitol, steviol glycosides, PEG6000 and povidone K30 are pulverized by high-speed pulverizer and then put into a 100-mesh standard inspection sieve for sieving. The particles under the sieve are collected and the coarse particles that do not pass through the sieve are removed to ensure that the particle size of the raw materials is uniform. The refined purple corn leaf anthocyanin is directly sieved through a 100-mesh sieve for later use.

[0036] (2) Weighing: Weigh each raw material accurately according to the proportion. The weighing process shall be carried out in a dry environment (relative humidity 45%-55%) to avoid the raw materials absorbing moisture. (3) Mixing: First, add the weighed citric acid, sodium bicarbonate, mannitol and steviol glycosides to the three-dimensional mixer, set the mixing speed to 25 r / min and the mixing time to 15 min to ensure that the acidic components, alkaline components and fillers and sweeteners are initially mixed evenly; then add refined purple corn leaf anthocyanins and continue mixing for 10 min to make the anthocyanins evenly dispersed in the system; finally add PEG6000 and povidone K30, set the mixing speed to 30 r / min and the mixing time to 8 min to obtain a homogeneous mixture.

[0037] (4) Granulation and tableting: Add an appropriate amount of deionized water as a wetting agent to the mixture, and granulate it using a wet granulation machine (granulation speed 100 r / min, cutting speed 1500 r / min) to obtain wet granules; place the wet granules in a hot air circulating drying oven, set the drying temperature to 55℃, and the drying time to 2 hours until the moisture content of the granules is ≤3%; after drying, the granules are sieved through a 100-mesh sieve and then placed in a rotary tablet press for tableting (tableting pressure 8-10 MPa, tableting speed 20 r / min) to obtain round effervescent tablets (diameter 12 mm, thickness 3 mm).

[0038] The physicochemical properties of the effervescent tablets prepared in Example 5 were tested: 1. Soaking time: At 25℃±2℃, place the effervescent tablet into a 250mL beaker containing 100mL of distilled water, start an electronic stopwatch, and stop timing when the tablet has completely disintegrated and there is no solid residue.

[0039] Ten effervescent tablets were tested, and all of them met the standard of "soaking time ≤ 5 min".

[0040] 2. pH value: Take the above effervescent tablet disintegration solution, keep it at a constant temperature of 25℃±2℃, and test it with precision pH test paper. The results of 10 parallel measurements were all between 5.0 and 6.0, and the pH value was qualified.

[0041] 3. Tablet weight differences: Twenty effervescent tablets were randomly selected and equilibrated in a desiccator for 24 hours. Each tablet was then weighed individually using an electronic balance, and the weight of each tablet was recorded. The average weight of the 20 effervescent tablets was 1.02g, and the percentage difference in weight between individual tablets was between 2.1% and 3.8%, all ≤5%, indicating that the weight difference was acceptable.

[0042] 4. Hardness: Ten effervescent tablets were randomly selected, and their axial fracture pressure was measured using a tablet hardness tester. The measured results were 3.9kg, 4.1kg, 3.8kg, 4.2kg, 4.0kg, 3.7kg, 4.3kg, 3.9kg, 4.0kg, and 4.1kg, respectively. The average value was 4.0kg, which is between 3 and 5kg, indicating that the hardness is qualified.

[0043] 5. Appearance and taste: The effervescent tablets have a smooth and flat surface, free from cracks, missing corners, and spots, and have a uniform color (light purple). After disintegrating in water, the soup is clear and transparent, without turbidity, sediment, or flocculent matter. The solution is weakly acidic, with a harmonious sweet and sour taste and no off-flavors, meeting the sensory requirements of the product.

[0044] In summary, the effervescent tablets prepared based on refined purple corn leaf anthocyanins of this invention meet all the set standards in terms of physicochemical properties, and the product quality is stable and has excellent sensory qualities.

[0045] The embodiments described above are merely preferred embodiments of the present invention and are not intended to limit the scope of the present invention. Various modifications and improvements made by those skilled in the art to the technical solutions of the present invention without departing from the spirit of the present invention should fall within the protection scope defined by the claims of the present invention.

Claims

1. A method for purifying anthocyanins from purple corn leaves, characterized in that, Includes the following steps: (1) Soak purple corn leaves in water to extract crude anthocyanin extract; (2) The crude anthocyanin extract was sequentially filtered, concentrated, and purified; (3) Adjust the concentration of the extract after step (2) to 5-10 mg / mL and perform continuous separation and purification using a simulated moving bed chromatography system; the simulated moving bed chromatography system contains 24 chromatographic columns connected in series and is divided into an adsorption zone, a purification zone, a desorption zone 1, a desorption zone 2, a regeneration zone and a water washing zone in sequence. (4) Collect the effluent from desorption zone 1 and / or desorption zone 2, concentrate and freeze dry to obtain purple corn leaf anthocyanins.

2. The purification method for anthocyanins from purple corn leaves according to claim 1, characterized in that, The number of chromatographic columns in the adsorption zone, purification zone, desorption zone 1, desorption zone 2, regeneration zone, and water washing zone are 6, 3, 4, 4, 3, and 4, respectively.

3. The purification method for anthocyanins from purple corn leaves according to claim 1, characterized in that, The eluents used in each region of the simulated moving bed chromatography system are as follows: Adsorption zone: anthocyanin extract from purple corn leaves; Refining area: 5%-10% ethanol aqueous solution; Desorption zone 1: 40%-50% ethanol aqueous solution; Desorption zone 2: 60%-70% ethanol aqueous solution; Regeneration zone: 90%-100% ethanol aqueous solution; Washing area: Deionized water.

4. The purification method for anthocyanins from purple corn leaves according to claim 1, characterized in that, The flow rates in each zone of the simulated moving bed chromatography system are as follows: 1-3 BV / h in the adsorption zone; 5-10 BV / h in the purification zone, desorption zone 1, desorption zone 2, and regeneration zone; and 5-12 BV / h in the water washing zone.

5. The purification method for anthocyanins from purple corn leaves according to claim 1, characterized in that, The switching time of the simulated moving bed chromatography system is 1000-1500s, the operating temperature is 30-40℃, and the stationary phase of the chromatographic column is AB-8 resin or X-5 resin.

6. An effervescent tablet containing anthocyanins from purple corn leaves, characterized in that, It consists of the following components by weight percentage: The ingredients include 5%-8% anthocyanins from purple corn leaves, 50%-60% a mixture of citric acid and sodium bicarbonate, 25%-35% fillers, 2%-4% sweeteners, 2%-3% binders, and 0.3%-0.7% lubricants. The purple corn leaf anthocyanins were prepared using any one of the methods described in claims 1-5.

7. The effervescent tablet containing purple corn leaf anthocyanins as described in claim 6, characterized in that, The mass ratio of citric acid to sodium bicarbonate is 1.2:1 to 1.4:1.