A method for extracting polyphenols and flavonoids from the starch residue, stems, leaves, and fine roots of taro.

Abstract

This invention discloses a method for extracting polyphenols and flavonoids from banana taro residue, stems, leaves, and fine roots, belonging to the field of natural active substance extraction technology. The method uses banana taro processing by-products (residue, stems, leaves, and fine roots) as raw materials, and involves pretreatment, ultrasonic-assisted enzymatic hydrolysis extraction, centrifugal filtration, macroporous adsorption resin purification, vacuum concentration, and vacuum freeze-drying to simultaneously obtain high-purity polyphenol and flavonoid extracts. This invention features a mild and efficient process, high extraction rate, and complete preservation of active ingredients, achieving high-value comprehensive utilization of banana taro by-products. It is environmentally friendly, suitable for industrial production, and the obtained products can be widely used in food, health products, cosmetics, and pharmaceutical fields.

Description

Technical Field

[0001] This invention belongs to the field of natural active substance extraction technology, specifically relating to a method for simultaneously extracting polyphenols and flavonoids from banana taro starch residue, stems, leaves, and fine roots. Background Technology

[0002] Canna edulis Ker, also known as banana taro, is a perennial herbaceous plant belonging to the genus Canna in the family Cannaceae. It is widely cultivated in southwestern and southern my country and is a high-yield starch crop. However, the starch processing of Canna edulis produces a large amount of starch residue. Its stems, leaves, and fine roots are often discarded or used as low-grade animal feed, resulting in resource waste and potential environmental pollution.

[0003] Studies have shown that the starch residue, stems, leaves, and fine roots of banana taro are rich in natural active substances such as polyphenols and flavonoids, which possess antioxidant, anti-inflammatory, antibacterial, hypoglycemic, and hepatoprotective biological activities, and have high application value in the fields of food, health products, cosmetics, and medicine. Currently, the extraction of plant polyphenols and flavonoids is mostly based on single raw materials and single components. There are few reports on comprehensive and simultaneous extraction processes for all by-products of banana taro (starch residue, stems, leaves, and fine roots), and traditional processes suffer from low extraction efficiency, high energy consumption, easy destruction of active ingredients, and solvent residues, making it difficult to meet the needs of efficient industrial production.

[0004] Therefore, developing a simple, efficient, and environmentally friendly method to simultaneously extract polyphenols and flavonoids from banana taro residue, stems, leaves, and fine roots, thereby achieving high-value comprehensive utilization of banana taro by-products, has significant economic and environmental value. Summary of the Invention

[0005] This invention aims to overcome the shortcomings of existing technologies and provide a method for extracting polyphenols and flavonoids from banana taro residue, stems, leaves, and fine roots, thereby turning raw materials into valuable resources, reducing production costs, improving extraction efficiency and product purity, and providing a mild and controllable process suitable for large-scale industrial production.

[0006] To achieve the above objectives, the present invention provides the following technical solution: A method for extracting polyphenols and flavonoids from the starch residue, stems, leaves, and fine roots of taro, comprising the following steps: (1) Raw material pretreatment The banana taro starch residue, stems, leaves, and fine roots are washed and cleaned to remove impurities. They are then dried in an oven at 50-60℃ until constant weight, pulverized, and passed through a 40-60 mesh sieve. They are then mixed evenly in a mass ratio of 1:1:1:1 to obtain mixed raw material powder.

[0007] (2) Ultrasound-assisted enzymatic extraction Add 50%–70% (v / v) of ethanol aqueous solution to the mixed raw material powder, with a material-to-liquid ratio of 1:20–1:40 (g / mL); then add 0.3%–0.8% (w / v) of the compound enzyme by weight of the raw material, and adjust the pH value to 4.5–6.5; perform ultrasonic extraction at 40–60℃ using an ultrasonic power of 200–400W for 30–60 min; after extraction, raise the temperature to 85–95℃ to inactivate the enzyme for 10–15 min, and then cool to room temperature.

[0008] Note: The preferred compound enzyme is a mixture of cellulase, pectinase and xylanase in a mass ratio of 2:1:1; the ultrasound is performed in an intermittent mode, i.e., 3 seconds of ultrasound followed by a 2-second interval.

[0009] (3) Centrifugal filtration Centrifuge the enzymatic extract at 4000–6000 r / min for 15–20 min and collect the supernatant; repeat the extraction of the residue 1–2 times and combine all the supernatants.

[0010] (4) Concentration and purification The combined supernatant was concentrated under reduced pressure to remove ethanol, yielding a crude extract. The crude extract was then loaded onto an AB-8 macroporous adsorption resin column at a flow rate of 1–3 mL / min. Impurities were first eluted with deionized water, followed by elution with a 60%–80% (v / v) ethanol aqueous solution. The eluent was collected and concentrated under reduced pressure until no alcohol odor was detected, yielding a polyphenol-flavonoid mixed concentrate.

[0011] Note: The preferred diameter-to-height ratio of the AB-8 macroporous adsorption resin column is 1:8 to 1:12, and the sample loading amount is 1 / 3 to 1 / 2 of the resin column volume.

[0012] (5) Drying The polyphenol-flavonoid mixture was freeze-dried under vacuum to obtain the banana taro polyphenol and flavonoid extract.

[0013] Note: Preferred freeze-drying conditions: cold trap temperature -50 to -40°C, vacuum degree 10 to 20 Pa, drying time 24 to 36 h.

[0014] Compared with the prior art, the beneficial effects of the present invention are: Efficient utilization of resources: By using the by-products of banana taro processing (powder residue, stems, leaves, and fine roots) as raw materials, we can turn waste into treasure, significantly reduce raw material costs, and reduce environmental pollution, resulting in significant economic and ecological benefits.

[0015] Highly efficient and gentle extraction: The extraction process employs a combination of "ultrasound-assisted + compound enzymatic hydrolysis" to synergistically break down plant cell walls, thereby accelerating the dissolution of active ingredients. The extraction time is short and the energy consumption is low. The extraction temperature is gentle, which effectively avoids the thermal decomposition of polyphenols and flavonoids, thus preserving their complete biological activity.

[0016] Excellent purification effect: Purification by AB-8 macroporous adsorption resin can effectively remove impurities such as polysaccharides and proteins, and improve the total purity of polyphenols and flavonoids in the extract; the process is simple to operate, the solvent can be recycled and reused, and it is green and environmentally friendly.

[0017] The invention has broad application prospects: the process steps are simple and the conditions are easy to control, and the extraction rate and purity are both high. The extracted extract can be widely used in food antioxidants, health products, cosmetic additives, pharmaceutical raw materials and other fields. Detailed Implementation

[0018] To make the technical means, creative features, and achieved objectives and effects of this invention easier to understand, the invention is further described below with reference to specific embodiments. However, the following embodiments are only preferred embodiments of this invention and not all embodiments. Other embodiments obtained by those skilled in the art based on the embodiments described herein without creative effort are all within the protection scope of this invention. Unless otherwise specified, the experimental methods in the following embodiments are conventional methods, and the materials and reagents used in the following embodiments are commercially available unless otherwise specified.

[0019] (I) Example 1 1. Raw material pretreatment: Clean and remove impurities from banana taro starch residue, stems, leaves and fine roots, dry at 55℃ to constant weight, crush and pass through a 50-mesh sieve, and mix evenly at a mass ratio of 1:1:1:1.

[0020] 2. Ultrasonic-assisted enzymatic hydrolysis: Add 60% ethanol aqueous solution at a material-to-liquid ratio of 1:30 (g / mL); add 0.5% of the raw material mass of a compound enzyme (cellulase: pectinase: xylanase = 2:1:1), and adjust the pH to 5.5; extract at 50℃ with intermittent ultrasound at 300W (3s ultrasound, 2s interval) for 45min; inactivate the enzyme at 90℃ for 12min, and cool to room temperature.

[0021] 3. Centrifugation and filtration: Centrifuge at 5000 r / min for 18 min and collect the supernatant; repeat the extraction of the residue twice and combine the supernatants.

[0022] 4. Concentration and purification: The supernatant is concentrated under reduced pressure to remove ethanol, resulting in a crude extract. The crude extract is then loaded onto an AB-8 resin column with a diameter-to-height ratio of 1:10 at a flow rate of 2 mL / min, with the loading volume being 1 / 2 of the resin column volume. After eluting impurities with deionized water, the column is eluted with 70% ethanol aqueous solution. The eluent is collected and concentrated under reduced pressure until no alcohol odor is detected.

[0023] 5. Drying: Under the conditions of cold trap temperature -45℃ and vacuum degree 15Pa, the banana taro polyphenol and flavonoid extracts were obtained by vacuum freeze drying for 30h.

[0024] Test results: Polyphenol extraction rate 3.26%, flavonoid extraction rate 2.89%, total purity of polyphenols and flavonoids in the extract 82.3%.

[0025] (II) Example 2 1. Raw material pretreatment: Dry at 50℃ to constant weight, pulverize and pass through a 40-mesh sieve, and mix in a ratio of 1:1:1:1.

[0026] 2. Ultrasonic-assisted enzymatic hydrolysis: Add 50% ethanol aqueous solution, material-to-liquid ratio 1:20; add 0.3% compound enzyme, pH 4.5; sonicate at 40℃ and 200W for 60 min; inactivate enzyme at 85℃ for 15 min, then cool.

[0027] 3. Centrifugation and filtration: Centrifuge at 4000 r / min for 20 min, extract the residue once, and combine the supernatants.

[0028] 4. Concentration and purification: Load the sample into an AB-8 resin column with a diameter-to-height ratio of 1:8, at a flow rate of 1 mL / min, with a sample volume of 1 / 3 of the resin volume; wash with deionized water to remove impurities, then elute with 60% ethanol and concentrate until no alcohol odor remains.

[0029] 5. Drying: Freeze-dry at -50℃ and 10Pa for 36 hours to obtain the target extract.

[0030] Test results: Polyphenol extraction rate 2.91%, flavonoid extraction rate 2.57%, total purity 79.6%.

[0031] (III) Example 3 1. Raw material pretreatment: Dry at 60℃, pulverize and pass through a 60-mesh sieve, and mix in a ratio of 1:1:1:1.

[0032] 2. Ultrasonic-assisted enzymatic hydrolysis: Add 70% ethanol aqueous solution, material-to-liquid ratio 1:40; add 0.8% compound enzyme, pH 6.5; sonicate at 60℃ and 400W for 30 min; inactivate enzyme at 95℃ for 10 min, then cool.

[0033] 3. Centrifugation and filtration: Centrifuge at 6000 r / min for 15 min, extract the residue twice, and combine the supernatants.

[0034] 4. Concentration and purification: Load the sample into an AB-8 resin column with a diameter-to-height ratio of 1:12, at a flow rate of 3 mL / min, with a sample volume of 1 / 2 resin volume; wash with deionized water to remove impurities, then elute with 80% ethanol and concentrate until no alcohol odor remains.

[0035] 5. Drying: Freeze-dry at -40℃ and 20Pa for 24 hours to obtain the target extract.

[0036] Test results: Polyphenol extraction rate 3.18%, flavonoid extraction rate 2.83%, total purity 81.7%.

[0037] (iv) Comparative Example 1. Comparative Example 1 (without complex enzyme): The steps are the same as in Example 1, except that no complex enzyme is added.

[0038] Results: The polyphenol extraction rate was 1.72%, and the flavonoid extraction rate was 1.45%, which was significantly lower than that of Example 1.

[0039] 2. Comparative Example 2 (without ultrasound): The steps are the same as in Example 1, except that ultrasound assistance is not used, and only static enzymatic hydrolysis is performed.

[0040] Results: The polyphenol extraction rate was 2.05%, and the flavonoid extraction rate was 1.83%, which was lower than that of Example 1.

[0041] Conclusion: Ultrasound and combined enzymatic hydrolysis have a synergistic effect, and the combination of the two can significantly improve the extraction efficiency of polyphenols and flavonoids from banana taro by-products.

[0042] The foregoing has shown and described the basic principles, main features, and advantages of the present invention. Those skilled in the art should understand that the present invention is not limited to the above embodiments. The embodiments and descriptions in the specification are merely preferred examples and are not intended to limit the invention. Various changes and modifications can be made to the invention without departing from its spirit and scope, and all such changes and modifications fall within the scope of the present invention as claimed. The scope of protection of the present invention is defined by the appended claims and their equivalents.

Claims

1. A method for extracting polyphenols and flavonoids from the starch residue, stems, leaves, and fine roots of taro, characterized in that, Includes the following steps: S1: Raw material pretreatment: Wash and remove impurities from the banana taro powder residue, stems, leaves and fine roots, dry them to constant weight, crush and sieve them, and mix them evenly in a mass ratio of 1:1:1:1 to obtain mixed raw material powder; S2: Ultrasonic-assisted enzymatic extraction: Add 50%–70% (v / v) of ethanol aqueous solution to the mixed raw material powder, with a material-to-liquid ratio of 1:20–1:40 (g / mL), add 0.3%–0.8% (w / v) of compound enzyme, adjust the pH to 4.5–6.5, and perform ultrasonic extraction at 40–60℃ and 200–400W for 30–60 min. After enzyme inactivation, cool to room temperature. S3: Centrifugation and filtration: Centrifuge the enzymatic extract, collect the supernatant, and repeat the extraction of the residue 1-2 times, then combine the supernatants. S4: Concentration and purification: The supernatant is concentrated under reduced pressure to remove ethanol, resulting in a crude extract; the crude extract is loaded onto an AB-8 macroporous adsorption resin column at a flow rate of 1-3 mL / min, and after eluting impurities with deionized water, it is eluted with a 60%-80% (v / v) ethanol aqueous solution. The eluent is collected and concentrated under reduced pressure until there is no alcohol odor. S5: Drying: The concentrate was freeze-dried under vacuum to obtain banana taro polyphenol and flavonoid extracts.

2. The method according to claim 1, characterized in that, In step S1, the drying temperature is 50-60℃, and the powder is then passed through a 40-60 mesh sieve.

3. The method according to claim 1, characterized in that, The complex enzyme mentioned in step S2 is a mixture of cellulase, pectinase and xylanase in a mass ratio of 2:1:

1.

4. The method according to claim 1, characterized in that, In step S2, the ultrasonic extraction is performed in an intermittent mode, with 3 seconds of ultrasound followed by a 2-second interval.

5. The method according to claim 1, characterized in that, In step S4, the diameter-to-height ratio of the AB-8 macroporous adsorption resin column is 1:8 to 1:12, and the sample loading amount is 1 / 3 to 1 / 2 of the resin column volume.

6. The method according to claim 1, characterized in that, The vacuum freeze-drying conditions in step S5 are: cold trap temperature -50 to -40°C, vacuum degree 10 to 20 Pa, and drying time 24 to 36 h.