Folium mori polyphenol subsection alcohol extraction blood sugar reducing process

Abstract

The invention provides a mulberry leaf polyphenol subsection alcohol extraction blood sugar reducing process. The preparation method comprises the following steps: S1, removing impurities from mulberry leaves, cleaning, drying and crushing to obtain a raw material to be extracted; and S2, sequentially extracting the raw materials to be extracted by adopting a food-grade alcohol solvent according to a gradient extraction method from low to high to obtain at least two alcohol extraction sections with different polarities. According to the segmented alcohol extraction and blood glucose reduction process for mulberry leaf polyphenol, accurate graded enrichment of polyphenol components with different polarities is achieved, tedious multi-step concentration and high-temperature drying are not needed, the total polyphenol yield and the purity of key functional components are remarkably improved, oxidative degradation and structural damage of polyphenol in the extraction, concentration and drying processes are inhibited to the maximum extent, and the yield of the polyphenol is improved. Meanwhile, the preparation method is simple in process, low in energy consumption and easy for industrial large-scale production.

Description

Technical Field

[0001] This invention relates to the field of food and medicine homology technology, specifically a fractional alcohol extraction process for mulberry leaf polyphenols to lower blood sugar. Background Technology

[0002] In existing technologies, mulberry leaves are widely used to develop products for lowering blood sugar, anti-oxidation, and anti-inflammation due to their medicinal and edible properties and rich content of polyphenols such as flavonoids, anthocyanins, and phenolic acids. Currently, commonly used extraction processes include: water extraction using water as a solvent, which is simple to operate but has low polyphenol dissolution efficiency and insufficient purity; single-stage alcohol extraction using 70%-80% ethanol as a solvent, which can improve the overall extraction rate but cannot fractionally enrich different polar components; ultrasonic or microwave-assisted extraction technology, which can shorten the time and increase the yield, but requires large equipment investment and fine-tuning of process parameters affects component stability, making it difficult to scale up production; and supercritical CO2 extraction, which can better protect heat-sensitive components but has limited extraction efficiency for polar polyphenols and is costly, hindering large-scale application.

[0003] The above methods struggle to achieve a balance between improving extraction efficiency, separation purity, production costs, and scalability: active ingredients are prone to degradation or structural damage during multiple concentration and drying processes; at the same time, existing processes cannot meet the dual standards of food-grade safety and pharmaceutical-grade quality consistency, and thus cannot fully realize the application potential of mulberry leaf polyphenols in the field of blood sugar reduction and health care. Summary of the Invention

[0004] To address the shortcomings of existing technologies, this invention provides a fractional alcohol extraction process for mulberry leaf polyphenols to lower blood sugar. This process solves the problem of how to achieve efficient fractional enrichment and activity protection of mulberry leaf polyphenols of different polarities by combining low-medium-high gradient alcohol extraction, buffered instantaneous acidification protection, macroporous resin fractional elution, one-time low-temperature vacuum concentration, and nitrogen inert and mild drying, while meeting both food-grade and pharmaceutical-grade quality standards.

[0005] To achieve the above objectives, the present invention provides the following technical solution: a fractional alcohol extraction process for mulberry leaf polyphenols to lower blood sugar, comprising:

[0006] S1. Remove impurities from mulberry leaves, wash, dry, and crush them to obtain the raw material to be extracted;

[0007] S2. The raw material to be extracted is sequentially extracted using a food-grade alcohol solvent in a gradient extraction method from low to high polarity to obtain at least two alcohol extraction stages with different polarities;

[0008] S3. Before entering the adsorption separation, the alcohol extraction section is first subjected to instantaneous acidification protection by an edible buffer system and then passed into a macroporous adsorption resin. Under inert gas protection, it is eluted according to different acidity and alkalinity, and the corresponding polyphenol enriched fractions are collected respectively.

[0009] S4. The polyphenol enriched fractions are combined and concentrated to a solid level suitable for drying under low temperature vacuum conditions in one step to obtain mulberry leaf polyphenol pre-drying extract, so as to avoid repeated heating;

[0010] S5. The mulberry leaf polyphenol extract is gently dried under inert gas protection to obtain mulberry leaf polyphenol powder. The characteristic components of the polyphenols, residual solvents and related quality indicators are tested in accordance with pharmaceutical and food safety standards to obtain a product that can be used for both medicinal and food applications.

[0011] Preferably, the gradient extraction method employs at least three food-grade alcohol-water solvents with increasing volume fractions for sequential extraction. The low-gradient alcohol segment preferentially dissolves highly polar polyphenols, mainly phenolic acids; the medium-gradient alcohol segment dissolves moderately polar polyphenols, mainly glycoside flavonoids; and the high-gradient alcohol segment dissolves low-polarity components, mainly hydrophobic flavonoids, thereby obtaining a polarized chromatographic alcohol extraction segment.

[0012] Preferably, the edible buffer system is selected from the citric acid / sodium citrate buffer system, which is used to acidify the alcohol extraction section before adsorption separation to the chemically stable range of the polyphenol structure, so as to inhibit oxidative browning, ester bond hydrolysis and self-polymerization reaction.

[0013] Preferably, the macroporous adsorption resin is a non-ionic, food-grade neutral adsorption resin. After the macroporous adsorption resin has finished adsorbing, it is sequentially eluted with acidic eluent, neutral eluent and weakly alkaline eluent to enrich the acidic polyphenol fraction, the near-neutral polyphenol fraction and the bound polyphenol fraction released by weak dissociation, respectively.

[0014] Preferably, the inert gas is nitrogen, used to reduce dissolved oxygen content and inhibit polyphenol oxidation, wherein the eluent and the mulberry leaf polyphenol pre-drying extract are transported and processed in a closed system.

[0015] Preferably, the process control in steps S4 and S5 uses the polyphenol activity retention index as the evaluation parameter, and the model formula for the polyphenol activity retention index H is:

[0016]

[0017] In the formula, C i,in C i,out The concentrations of the i-th marker polyphenol before and after step S4 are w, respectively. i Let be the weighting coefficient of the i-th type of polyphenol. α i T is the sensitivity amplification index. max T is the highest temperature measured throughout the concentration-drying process. s To correspond to the structural thermosensitive threshold temperature of polyphenols, DO intγ is the dimensionless value of the equivalent oxygen exposure intensity, and β and γ are empirical attenuation constants.

[0018] Preferably, the release of the mulberry leaf polyphenol powder obtained in step S5 is based on the drug-food dual consistency score Q. du The determination is based on the following model formula:

[0019]

[0020] In the formula, Q fo Q dr These are the quality scores for food and pharmaceuticals, respectively, where m and n are the weighted indices for food and pharmaceutical quality, and σ is the weighted index for food and pharmaceutical quality. b λ is the dimensionless value of the relative coefficient of variation of key quality attributes in consecutive batches, and λ is the inter-batch variation penalty coefficient, which is used to reduce the overall score of inconsistent samples.

[0021] Preferably, the polyphenolic characteristic components are selected from at least one or more of phenolic acids, flavonoids, and anthocyanins, and a liquid chromatography fingerprint reference library is established to achieve batch-to-batch consistency monitoring and product traceability.

[0022] This invention provides a fractional alcohol extraction process for mulberry leaf polyphenols to lower blood sugar. It has the following beneficial effects:

[0023] This fractional alcohol extraction and blood sugar reduction process for mulberry leaf polyphenols achieves precise fractionation and enrichment of polyphenol components with different polarities through a "low → high" gradient alcohol extraction combined with edible buffer instantaneous acidification protection and macroporous resin fractional elution. It eliminates the need for cumbersome multi-step concentration and high-temperature drying, significantly improving the total polyphenol yield and the purity of key functional components. Under inert gas protection and one-time low-temperature vacuum concentration conditions, the oxidative degradation and structural damage of polyphenols during extraction, concentration, and drying are suppressed to the greatest extent, ensuring the bioactivity and stability of the product. At the same time, the process is simple, energy-efficient, and easy to scale up for industrial production.

[0024] This solution uses a two-way quantitative evaluation of the process and finished product quality through the polyphenol activity retention index and the dual consistency score between food and medicine. Combined with liquid chromatography fingerprinting and residual solvent detection, it achieves consistent control of food-grade safety and pharmacopoeia-grade quality. Feedback from multiple batches can guide the optimization of process parameters, ensuring that the quality fluctuations between batches are minimized, thereby meeting the strict standards for using food and medicine homologous products as raw materials for health foods and excipients for traditional Chinese medicine formula granules. Attached Figure Description

[0025] Figure 1 This is a flowchart illustrating the process of realizing the invention;

[0026] Figure 2 This is a diagram illustrating the working principle of the gradient extraction method. Detailed Implementation

[0027] 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.

[0028] like Figure 1-2 As shown, this embodiment of the invention provides a fractional alcohol extraction process for mulberry leaf polyphenols to lower blood sugar, including: S1. removing impurities, washing, drying and pulverizing mulberry leaves to obtain the raw material to be extracted.

[0029] S2. The raw material to be extracted is sequentially extracted using a gradient extraction method with food-grade alcohol solvents, from low to high polarity, to obtain at least two alcohol extraction segments with different polarities. The gradient extraction method uses at least three food-grade alcohol-water solvents with increasing volume fractions for sequential extraction. The low-gradient alcohol segment preferentially dissolves highly polar polyphenols, mainly phenolic acids; the medium-gradient alcohol segment dissolves moderately polar polyphenols, mainly glycoside flavonoids; and the high-gradient alcohol segment dissolves low-polarity components, mainly hydrophobic flavonoids, thereby obtaining a polarized chromatographic alcohol extraction segment.

[0030] The specific implementation method is as follows:

[0031] Take 100g of mulberry leaf powder with a moisture content ≤10% and pulverized to 80–100 mesh, and perform reflux extraction three times at a material-to-liquid ratio of 1:10:

[0032] First, a 30% (v / v) food-grade ethanol aqueous solution was refluxed at 50°C for 90 minutes. After filtration, concentration and drying, 6.2 g of high polarity fraction extract was obtained, corresponding to an extraction rate of 6.2%. The total polyphenol content was determined to be 120 mg GAE / g.

[0033] The same residue was then repeatedly extracted by reflux with 60% ethanol for 90 minutes. After treatment with the same method, 8.1g of the medium polar fraction extract was obtained, with a total polyphenol content of 150mg GAE / g.

[0034] Finally, the residue was refluxed with 90% ethanol for 90 minutes to obtain 4.5g of low-polarity extract with a total polyphenol content of 80mg GAE / g.

[0035] High-performance liquid chromatography fingerprint analysis showed that:

[0036] The 30% segment is mainly enriched in phenolic acids, such as chlorogenic acid.

[0037] The 60% fraction is mainly enriched with glycoside flavonoids, such as quercetin-3-O-glucoside.

[0038] 90% of the fraction is mainly enriched with hydrophobic flavonoids, such as quercetin.

[0039] S3. Before entering the adsorption separation, the alcohol extraction section is first subjected to instantaneous acidification protection by an edible buffer system and then passed into the macroporous adsorption resin. Under inert gas protection, it is eluted according to different acidity and alkalinity, and the corresponding polyphenol enriched fractions are collected respectively.

[0040] The edible buffer system is selected from the citric acid / sodium citrate buffer system, which is used to acidify the alcohol extraction section before adsorption separation to the chemically stable range of polyphenol structure, so as to inhibit oxidative browning, ester bond hydrolysis and self-polymerization reaction.

[0041] The macroporous adsorption resin is a non-ionic, food-grade, neutral adsorption resin. After the macroporous adsorption resin has completed adsorption, it is sequentially eluted with acidic eluent, neutral eluent, and weakly alkaline eluent to enrich the acidic polyphenol fraction, the near-neutral polyphenol fraction, and the bound polyphenol fraction released by weak dissociation, respectively.

[0042] Nitrogen is used as the inert gas to reduce dissolved oxygen content and inhibit polyphenol oxidation. The eluent and the pre-drying extract of mulberry leaf polyphenols are transported and processed in a closed system.

[0043] The specific implementation method is as follows:

[0044] The following example uses the polar fraction extract in 60% ethanol to demonstrate how transient acidification protection, resin adsorption, and fractional elution are performed under nitrogen protection, and provides data on the yield and total polyphenol content of each fraction.

[0045] Buffer acidification:

[0046] Place 500 mL of the B-segment alcohol extract in a nitrogen atmosphere chamber, slowly add 100 mL of 0.1 M citric acid / sodium citrate buffer to rapidly adjust the pH to 4.00 ± 0.05, and let stand and stir for 10 min to passivate the phenolic hydroxyl groups in the polyphenol molecules and inhibit oxidative browning and self-polymerization.

[0047] Resin column packing and sample loading:

[0048] Food-grade nonionic neutral macroporous adsorption resin was selected, and 20g of wet resin was packed into a 2cm diameter glass column. Under nitrogen protection, 300mL of pH 4.0 segment B buffer solution was added to the resin column at a flow rate of 1mL / min.

[0049] Pre-washing inside the column:

[0050] After resin loading, rinse with 200 mL of deionized water to remove unadsorbed impurities at a flow rate of 1 mL / min, and discard the eluent.

[0051] Graded elution:

[0052] Acidic elution:

[0053] Adjust the pH to 4.0 with 50% (v / v) ethanol aqueous solution, elute with 300 mL of solution at a flow rate of 1.2 mL / min, and label the collected fraction as BA.

[0054] Neutral elution:

[0055] Elute with 300 mL of 70% ethanol aqueous solution to pH 7.0 at a flow rate of 1.2 mL / min, and collect BN.

[0056] Weakly alkaline elution:

[0057] Adjust the pH to 9.0 with 90% ethanol aqueous solution, elute with 300 mL of solution at a flow rate of 1.2 mL / min, and collect BB.

[0058] Fraction Recovery and Detection:

[0059] The three fractions were each rotary evaporated to dryness under nitrogen protection to obtain:

[0060] BA acidic fraction extract 2.0g; total polyphenol content determined to be 142mgGAE / g.

[0061] 2.5g of neutral BN fraction; total polyphenol content 180mg GAE / g.

[0062] BB weakly alkaline fraction 0.5g; total polyphenol content 85mgGAE / g.

[0063] High performance liquid chromatography analysis showed that the BA segment was mainly composed of phenolic acids, the BN segment was mainly composed of glycoside flavonoids, and the BB segment was mainly composed of a small amount of hydrophobic flavonoids and bound polyphenols, which verified the separation efficiency of fractional elution.

[0064] S4. Combine the polyphenol enrichment fractions and concentrate them in one step under low temperature vacuum conditions to a solid level suitable for drying, to obtain mulberry leaf polyphenol pre-drying extract, in order to avoid repeated heating.

[0065] The process control in steps S4 and S5 uses the polyphenol activity retention index as the evaluation parameter. The model formula for the polyphenol activity retention index H is:

[0066]

[0067] In the formula, C i,in C i,out The concentrations of the i-th marker polyphenol before and after step S4 are w, respectively. i Let be the weighting coefficient of the i-th type of polyphenol. α i T is the sensitivity amplification index. max T is the highest temperature measured throughout the concentration-drying process. s To correspond to the structural thermosensitive threshold temperature of polyphenols, DO intγ is the dimensionless value of the equivalent oxygen exposure intensity, and β and γ are empirical attenuation constants.

[0068] The specific implementation method is as follows:

[0069] Fraction merging:

[0070] The acidic fraction (2.0 g), neutral fraction (2.5 g), and weakly basic fraction (0.5 g) obtained in step S3, totaling 5.0 g, were dissolved in 600 mL of 60% (v / v) food-grade ethanol and placed in the feed tank of the thin-film evaporator. A nitrogen purging line was connected between the feed tank and the evaporator, and the inert gas flow rate was maintained at 0.2 L / min to ensure that the dissolved oxygen content in the system remained below 1 mg / L.

[0071] Low-temperature vacuum concentration:

[0072] Under vacuum conditions of -0.08 MPa and jacket temperature ≤40℃, the material is concentrated by flash evaporation in a thin-film evaporator in a single pass, without the need for intermediate reflux or secondary heating. The entire concentration process takes about 30 minutes, concentrating the material to a solid content of about 35%. The concentrated extract is collected in one go under the same nitrogen protection system, and the weight of the extracted extract is 4.85 g.

[0073] Retention of active ingredients:

[0074] Chlorogenic acid: The total chlorogenic acid content in the combined fractions was approximately 260 mg, and the content after concentration was 245 mg, with a retention rate of 94.2%.

[0075] Quercetin-3-O-glucoside: The content in the combined fraction was approximately 435 mg, and the content after concentration was 415 mg, with a retention rate of 95.4%.

[0076] Extract characteristics:

[0077] The extract was a dark brown, viscous liquid with a moisture content of 32% and a pH of approximately 4.2, suitable for proceeding to the next step of gentle drying. No coking or discoloration occurred during any of the concentration processes, demonstrating that the low-temperature vacuum and inert atmosphere effectively inhibited the thermal degradation and oxidative polymerization of polyphenols.

[0078] S5. Mulberry leaf polyphenol extract is gently dried under inert gas protection to obtain mulberry leaf polyphenol powder. The characteristic components of polyphenols, residual solvents and related quality indicators are tested in accordance with pharmaceutical and food safety standards to obtain a product that can be used for both medicinal and food applications.

[0079] The release of the mulberry leaf polyphenol powder obtained in step S5 is based on the drug-food dual consistency score Q. du The determination is based on the following model formula:

[0080]

[0081] In the formula, Q fo Q dr These are the quality scores for food and pharmaceuticals, respectively, where m and n are the weighted indices for food and pharmaceutical quality, and σ is the weighted index for food and pharmaceutical quality. b λ is the dimensionless value of the relative coefficient of variation of key quality attributes in consecutive batches, and λ is the inter-batch variation penalty coefficient, which is used to reduce the overall score of inconsistent samples.

[0082] The characteristic components of polyphenols are selected from at least one or more of phenolic acids, flavonoids, and anthocyanins, and a liquid chromatography fingerprint reference library is established to achieve batch-to-batch consistency monitoring and product traceability.

[0083] The specific implementation method is as follows:

[0084] Application scenario: Mild drying and quality release under spray drying conditions.

[0085] Drying equipment and process parameters:

[0086] It adopts a spray drying tower with dual rotating atomizing nozzles, the tower body is lined with corrosion-resistant stainless steel, and it is equipped with a nitrogen replacement system.

[0087] Inlet temperature: 110℃; outlet temperature: 60℃; feed flow rate: 10L / h; atomization pressure: 0.3MPa; relative humidity inside the tower: ≤10%.

[0088] Adjust the extract obtained in step S4 to a solids content of 35% (w / w) and a viscosity of approximately 2.5 Pa·s, and load it into the feed pump. Initiate nitrogen protection and continuously monitor dissolved oxygen levels at the drying chamber inlet to ensure they remain below 1 mg / L.

[0089] Yield and powder properties:

[0090] On average, three batches are produced continuously, with a feed amount of 600mL per batch, yielding approximately 4.55g of powder after drying, resulting in an overall yield of 91%.

[0091] The resulting powder is brownish-brown in color, uniform and fine, with good flowability. The average particle size is 8 μm, and SEM shows that the spherical particles have slightly wrinkled surfaces, making them suitable for rapid dissolution.

[0092] Chemical and microbiological indicators:

[0093] Total polyphenol content: 147±2.3mgGAE / g.

[0094] Chlorogenic acid: content 6.1±0.2mg / g.

[0095] Quercetin-3-O-glucoside: 9.0±0.3 mg / g. Fingerprint similarity: 98.5%.

[0096] Residual solvent: 980 ppm ethanol.

[0097] Moisture content: 4.0 ± 0.2%. Water activity: 0.32.

[0098] Heavy metals: Pb < 0.1 mg / kg, As < 0.2 mg / kg, Hg and Cd were not detected.

[0099] Residue detection: all were below the detection limit.

[0100] Microbial limits: Total colony count 3.1 × 10⁻⁶ 3 CFU / g, yeast 1.2×10 2 CFU / g, coliform bacteria, Salmonella, and Staphylococcus aureus were not detected.

[0101] Stability and release criteria:

[0102] Accelerated stability: Total polyphenol retention rate ≥92%, appearance color and fingerprint similarity changes <1%.

[0103] Long-term exposure at room temperature: Polyphenol content decreases by <5%, while water content and water activity remain stable.

[0104] Based on the dual scoring matrix of pharmacopoeia and food safety, the spray-dried powder meets the standards in all key indicators, complies with the release requirements for products that are both food and medicine, and can be directly used in traditional Chinese medicine formula granules or health food ingredients.

[0105] Example 2

[0106] Unlike Example 1, the application scenario of this example is mild drying and quality release under freeze-drying conditions.

[0107] Drying equipment and process parameters:

[0108] A fully automatic tray freeze dryer was used. Pre-freezing was carried out at -40℃ for 6 hours, followed by primary drying at -20℃ under a vacuum of ≤5Pa for 24 hours, and then secondary drying was carried out at 20℃ for 12 hours. Gradual temperature increase was used throughout the process to prevent heat-sensitive degradation of polyphenols.

[0109] Both the freezing and heating processes were carried out under nitrogen inert protection to limit oxygen exposure.

[0110] Yield and powder properties:

[0111] Each batch of 600mL extract was fed, with an average powder yield of 4.88g and a yield of 98%.

[0112] The powder is a milky white porous microparticle with a loose density of 0.18 g / mL and a dense density of 0.24 g / mL. The porous structure created by water vaporization enhances its solubility and hygroscopic buffering properties. The average particle size is 12 μm, and the angle of rest is 28°.

[0113] Chemical and microbiological indicators:

[0114] Total polyphenol content: 152±1.8mgGAE / g.

[0115] Chlorogenic acid: 6.4±0.2 mg / g. Quercetin-3-O-glucoside: 9.3±0.4 mg / g, fingerprint similarity 99.2%.

[0116] Residual solvent: Not detected. Moisture content: 1.1 ± 0.1%. Water activity: 0.18.

[0117] Heavy metals and pesticide residues: Same as in Example 1.

[0118] Microbial limits: Total colony count 1.7 × 10⁻⁶ 3 CFU / g, yeast 7.0×10 1 CFU / g, no other pathogens detected.

[0119] Stability and release criteria:

[0120] Accelerated stability: Total polyphenol retention rate ≥95%.

[0121] Long-term exposure at room temperature: Polyphenol content decreases by <4%, water activity decreases by <0.20.

[0122] With the dual advantages of low moisture content and no residual solvent, freeze-dried powder exhibits batch-to-batch deviations of less than 3%, demonstrating superior consistency compared to spray drying. Based on dual quality release standards, freeze-dried powder can be used as a higher-grade raw material for medicinal and edible herbs and health products.

[0123] Example 3

[0124] Unlike Example 1, the application scenario of this example is mild drying and quality release under low-temperature vacuum belt drying conditions.

[0125] Equipment and process flow:

[0126] A continuous low-temperature vacuum belt dryer is used, with the machine body divided into a preheating zone, a drying zone, and a cooling zone. The belt width is 500 mm, and the vacuum degree is adjustable from -0.02 to -0.08 MPa. The extract obtained in step S4 is homogenized by a premixing homogenizer pump and then introduced into the belt dryer in a tunnel manner with nitrogen purging, with an inert gas flow rate of 0.15 L / min.

[0127] Process parameters:

[0128] The preheating zone temperature is set to 30℃ and the belt speed is 1m / min to allow the material layer to initially solidify.

[0129] The temperature in the drying zone gradually increases to 45℃, with a total residence time of approximately 20 minutes.

[0130] After the temperature in the cooling zone drops to 25°C, the discharge section automatically scrapes off the dried material in flake form.

[0131] The entire process is carried out under a vacuum of -0.05 MPa and a pure nitrogen atmosphere to ensure that the oxygen content is <0.5%.

[0132] Yield and pre-powder properties:

[0133] Each batch of 600mL extract is loaded with a drying belt, and after drying, 4.70g of dried slices can be collected, with a yield of 94%.

[0134] The dried flakes were pulverized under a machine and sieved through a 200-mesh sieve to obtain 4.50g of powder, with a yield of 90%.

[0135] The powder is dark brown in color, with a loose packing density of 0.28 g / mL, an average particle size of 10 μm, and an angle of repose of 33°.

[0136] Physicochemical and functional index testing:

[0137] Total polyphenol content: 148±2.0mgGAE / g.

[0138] Chlorogenic acid: 6.2±0.2 mg / g. Quercetin-3-O-glucoside: 8.8±0.3 mg / g.

[0139] Melting point test: No obvious endothermic peak was observed, indicating that no crystals were precipitated and the polyphenols remained in a monodisperse state.

[0140] Solubility test: Completely dissolved in water at 25℃ for 5 minutes, showing excellent performance.

[0141] Residual solvent: 720 ppm of ethanol residue.

[0142] Moisture content: 3.2%. Water activity: 0.28.

[0143] Microbiological and safety testing:

[0144] Total bacterial count: 2.8 × 10⁻⁶ 3 CFU / g, yeast 1.0×10 2 CFU / g.

[0145] Heavy metals, pesticide residues, and pathogens all meet the limits set by the National Food and Pharmacopoeia.

[0146] Stability assessment:

[0147] Accelerated stability: Total polyphenol retention rate ≥90%.

[0148] Room temperature storage: moisture and water activity fluctuation ≤0.5%, fingerprint similarity >97%.

[0149] Release criteria:

[0150] Based on the dual consistency scoring logic for medicine and food, the low-temperature vacuum belt-dried powder meets all the core quality attributes, with a score Q_dual > 0.95, which meets the release requirements for medicine and food homology preparations and health food raw materials.

[0151] Example 4

[0152] Unlike Example 1, the application scenario of this example is mild drying and quality release under microwave vacuum drying conditions.

[0153] Drying equipment and pretreatment:

[0154] This embodiment uses a laboratory-type microwave vacuum dryer, model MV-100, which has a built-in adjustable microwave source with a maximum power of 350 watts and a vacuum chamber. First, the extract obtained in step S4 is adjusted to a solid content of approximately 35%, placed in a pressure-resistant flat-bottomed tray, and pre-frozen at -20 degrees Celsius for four hours to enhance the uniform heating effect of the microwaves on the material's interior during the drying process. High-purity nitrogen is introduced into the drying chamber at a flow rate of 0.15 liters per minute. After the initial vacuuming, the system vacuum is maintained at -0.06 MPa to ensure the oxygen content remains below 0.2%.

[0155] Microwave vacuum drying parameters:

[0156] The microwave power was set to 200 watts, and an intermittent cyclic method was used: microwave heating was performed continuously for ten seconds, followed by a twenty-second pause to prevent surface overheating. The entire drying process lasted for forty-five minutes, with the cavity vacuum level monitored in real time to ensure it did not exceed -0.04 MPa.

[0157] Yield and powder morphology:

[0158] Each batch of extract was fed in a volume of 600 ml, and after drying, a powder weighing 4.75 g was obtained, with an overall yield of 95%. The dried powder was light brown, loosely granulated, with a bulk density of 0.27 g / ml and an angle of repose of 32 degrees. Scanning electron microscopy revealed that the powder surface had a porous, sponge-like structure, which facilitates rapid dissolution and improves bioavailability.

[0159] Chemical quality testing:

[0160] The moisture content, determined by the Karl Fischer method, was 2.0% ± 0.1%. The water activity was 0.25. The total polyphenol content was 143 mg gluconic acid equivalent per gram, with an activity retention rate of 97%. The chlorogenic acid content, determined by high-performance liquid chromatography at a wavelength of 325 nm, was 5.7 mg per gram, with a retention rate of 95%. The quercetin-3-O-glucoside content, determined at a wavelength of 360 nm, was 8.6 mg per gram, with a retention rate of 96%. The residual solvent ethanol content was 390 ppm, far below the national limit.

[0161] Microbiological and safety indicators:

[0162] The total bacterial count was 2.5 × 10⁻⁶. 3 CFU per gram, number of molds and yeasts: 1.8 × 10⁻⁶ 2 CFU per gram. Coliform bacteria, Salmonella, and Staphylococcus aureus were not detected. Heavy metal testing showed lead content less than 0.1 mg / kg, arsenic content less than 0.2 mg / kg, and cadmium and mercury were not detected. Pesticide residues, detected by full-spectrum scanning, were all below the detection limit.

[0163] Solubility and stability:

[0164] In water at room temperature (25°C), the powder dissolves completely within three minutes without leaving any suspended residue. Accelerated stability testing at 45°C and 75% relative humidity for one month showed a total polyphenol retention rate of no less than 92%. After six months of storage at room temperature (25°C) and 60% relative humidity, the total polyphenol content fluctuated by less than 4%, and the similarity of the powder particle structure and fingerprint spectrum did not change by more than 1%.

[0165] Release criteria:

[0166] Based on comprehensive indicators such as moisture content, water activity, total polyphenols and retention rate of key marker components, residual solvents, microbial limits, and batch-to-batch deviation, microwave vacuum-dried powder achieves a dual consistency score of over 0.95 in pharmaceutical and food safety, meeting the release requirements for granules of traditional Chinese medicine formulas that are both food and medicine and ingredients for health foods.

[0167] Although embodiments of the invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the appended claims and their equivalents.

Claims

1. A fractional alcohol extraction process for mulberry leaf polyphenols to lower blood sugar, characterized in that, include: S1. Remove impurities from mulberry leaves, wash, dry, and crush them to obtain the raw material to be extracted; S2. The raw material to be extracted is sequentially extracted using a food-grade alcohol solvent in a gradient extraction method from low to high polarity to obtain at least two alcohol extraction stages with different polarities; S3. Before entering the adsorption separation, the alcohol extraction section is first subjected to instantaneous acidification protection by an edible buffer system and then passed into a macroporous adsorption resin. Under inert gas protection, it is eluted according to different acidity and alkalinity, and the corresponding polyphenol enriched fractions are collected respectively. S4. The polyphenol enriched fractions are combined and concentrated to a solid level suitable for drying under low temperature vacuum conditions in one step to obtain mulberry leaf polyphenol pre-drying extract; S5. The mulberry leaf polyphenol extract is gently dried under inert gas protection to obtain mulberry leaf polyphenol powder. The characteristic components of the polyphenols, residual solvents and related quality indicators are tested in accordance with pharmaceutical and food safety standards to obtain a product that can be used for both medicinal and food applications.

2. The fractional alcohol extraction process for lowering blood sugar from mulberry leaf polyphenols according to claim 1, characterized in that: The gradient extraction method employs at least three food-grade alcohol-water solvents with increasing volume fractions for sequential extraction. The low-gradient alcohol segment preferentially dissolves highly polar polyphenols, mainly phenolic acids; the medium-gradient alcohol segment dissolves moderately polar polyphenols, mainly glycoside flavonoids; and the high-gradient alcohol segment dissolves low-polarity components, mainly hydrophobic flavonoids, thereby obtaining a polarized chromatographic alcohol extraction segment.

3. The fractional alcohol extraction process for lowering blood sugar from mulberry leaf polyphenols according to claim 1, characterized in that: The edible buffer system is selected from the citric acid / sodium citrate buffer system, and is used to acidify the alcohol extraction section before adsorption separation to the range of polyphenol structural chemical stability.

4. The fractional alcohol extraction process for lowering blood sugar from mulberry leaf polyphenols according to claim 1, characterized in that: The macroporous adsorption resin is a non-ionic, food-grade neutral adsorption resin. After the macroporous adsorption resin has completed adsorption, it is sequentially eluted with acidic eluent, neutral eluent and weakly alkaline eluent to enrich acidic polyphenol fraction, near-neutral polyphenol fraction and bound polyphenol fraction released by weak dissociation, respectively.

5. The fractional alcohol extraction process for lowering blood sugar from mulberry leaf polyphenols according to claim 1, characterized in that: The inert gas is nitrogen, and the eluent and the mulberry leaf polyphenol extract before drying are transported and processed in a closed system.

6. The fractional alcohol extraction process for mulberry leaf polyphenols to lower blood sugar according to claim 1, characterized in that: The process control in steps S4 and S5 uses the polyphenol activity retention index as the evaluation parameter. The model formula for the polyphenol activity retention index H is: In the formula, C i,in C i,out The concentrations of the i-th marker polyphenol before and after step S4 are w, respectively. i Let ∑ be the weighting coefficient of the i-th type of polyphenol. i w i =1, α i T is the sensitivity amplification index. max T is the highest temperature measured throughout the concentration-drying process. s To correspond to the structural thermosensitive threshold temperature of polyphenols, DO int γ is the dimensionless value of the equivalent oxygen exposure intensity, and β and γ are empirical attenuation constants.

7. The fractional alcohol extraction process for mulberry leaf polyphenols to lower blood sugar according to claim 1, characterized in that: The release of the mulberry leaf polyphenol powder obtained in step S5 is based on the drug-food dual consistency score Q. du The determination is based on the following model formula: In the formula, Q fo Q dr These are the quality scores for food and pharmaceuticals, respectively, where m and n are the weighted indices for food and pharmaceutical quality, and σ is the weighted index for food and pharmaceutical quality. b λ is the dimensionless value of the relative coefficient of variation of key quality attributes in consecutive batches, and λ is the inter-batch variation penalty coefficient.

8. The fractional alcohol extraction process for lowering blood sugar from mulberry leaf polyphenols according to claim 1, characterized in that: The polyphenolic characteristic components are selected from at least one or more of phenolic acids, flavonoids, and anthocyanins, and a liquid chromatography fingerprint reference library is established.

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