A method for simultaneously extracting and separating polyphenols and flavonoids from lotus seed powder

Abstract

The application discloses a method for simultaneously extracting and separating polyphenols and flavones from lotus seed peel powder, which comprises the following steps: 1) husking, peeling and sieving lotus seeds to obtain lotus seed peel powder; 2) adding the lotus seed peel powder into a mixed solution of ethanol and water, ultrasonically extracting the lotus seed peel powder at a temperature of 65-75 DEG C, and then centrifuging to obtain supernatant; wherein the volume concentration of the ethanol is 40-70 %, and the mass-volume ratio of the lotus seed peel powder and the mixed solution is 1:30-50 g / ml; 3) adjusting the pH of the supernatant obtained in the step 2) to 2.8-3.2, and standing to make the flavones precipitate completely, and then centrifuging to obtain precipitate and supernatant; 4) rotary-evaporating and concentrating the supernatant obtained in the step 3), and vacuum freeze-drying to obtain polyphenols; and vacuum freeze-drying the precipitate obtained in the step 3) to obtain flavones. The method has the advantages of simple operation, convenience, low cost, simultaneous extraction and separation of polyphenols and flavones, high extraction rate and purity, reutilization of waste, and industrial application potential.

Description

Technical Field

[0001] This invention belongs to the field of deep processing of agricultural by-products, and specifically relates to a method for simultaneously extracting and separating polyphenols and flavonoids from lotus seed peel powder. Background Technology

[0002] Lotus is a perennial aquatic herbaceous plant belonging to the genus *Nelumbo nucifera* of the family Herbaceous plant. Its mature fruit is called lotus seed. my country is a major lotus-producing country, with a lotus seed production of 154,800 tons in 2018. Currently, lotus seeds are mainly processed into food products after drying, shelling (fruit peel), removing the seed coat, and removing the embryo. The mechanical peeling process of red lotus seeds (removing the seed coat) produces a large amount of lotus seed peel wagte (LSPW), also known as lotus seed peel powder, red skin powder, or outer skin powder. It mainly consists of the seed coat and some lotus kernel, accounting for about 15-20% of the total lotus seed weight. There is currently no effective way to utilize it, but it may be rich in flavonoids, phenolic acids, and other polyphenolic substances, making it a potential source.

[0003] Currently, lotus seed powder is mainly used as a high-protein feed for animals, as well as a raw material or ingredient for brewing lotus seed wine. Every year, a large amount of powder is treated as waste.

[0004] Therefore, extracting usable nutrients from lotus seed powder is a problem that needs to be solved to turn lotus seed processing byproducts into valuable resources and achieve high-value utilization. Summary of the Invention

[0005] The purpose of this invention is to provide a method for simultaneously extracting and separating polyphenols and flavonoids from lotus seed powder. This method is simple, convenient, quick, and low in cost. It can simultaneously extract and separate polyphenols and flavonoids with high extraction rate and purity, and is beneficial for waste recycling.

[0006] To solve the above-mentioned technical problems, the present invention adopts the following technical solution:

[0007] A method for simultaneously extracting and separating polyphenols and flavonoids from lotus seed powder is provided, comprising the following steps:

[0008] 1) Remove the shells from the lotus seeds, grind them, and sift them to obtain lotus seed powder;

[0009] 2) Add the lotus seed powder obtained in step 1) to a mixture of ethanol and water, extract by ultrasonication at 65-75℃, and then centrifuge to obtain the supernatant; wherein the volume concentration of ethanol is 40-70%, and the mass-volume ratio of lotus seed powder to the mixture is 1:30-50g / ml;

[0010] 3) Adjust the pH of the supernatant obtained in step 2) to 2.8-3.2, let it stand to allow the flavonoids to precipitate completely, and centrifuge to obtain the precipitate and supernatant;

[0011] 4) The supernatant obtained in step 3) is concentrated by rotary evaporation and then freeze-dried under vacuum to obtain polyphenols; the precipitate obtained in step 3) is freeze-dried under vacuum to obtain brass.

[0012] According to the above scheme, in step 1), the sample is passed through an 80-mesh sieve.

[0013] According to the above scheme, in step 2), the ultrasonic power is 320-400W; the extraction time is 35-45min.

[0014] According to the above scheme, in step 2), the centrifugation conditions are: 6000-8000 rpm, 20-40℃ for 15-30 min.

[0015] According to the above scheme, in step 3), the settling time is 2-3 hours.

[0016] According to the above scheme, in step 3), the centrifugation conditions are 5000-10000 rpm and 4-10℃ for 15-20 min.

[0017] According to the above scheme, in step 3), the pH is adjusted using a 0.1-1 mol / L HCl solution.

[0018] According to the above scheme, in step 4), the supernatant is desolventized and concentrated on a rotary evaporator at 70-77℃ until constant weight.

[0019] According to the above scheme, in step 4), the precipitate is washed with water until neutral and then subjected to vacuum freeze drying.

[0020] The beneficial effects of this invention are as follows:

[0021] This invention provides a method for simultaneously extracting and separating polyphenols and flavonoids from lotus seed peel powder. Using a suitable mixture of ethanol and water as the extraction solvent, ultrasonic extraction is performed at a specific temperature, which can efficiently extract flavonoids and polyphenols simultaneously. Then, by simply adjusting the pH and allowing the mixture to stand, the flavonoids precipitate, thus achieving effective separation of flavonoids and polyphenols. This method is simple, convenient, quick, and low-cost, and can simultaneously extract and separate polyphenols and flavonoids with high extraction rates and purity. It is also beneficial for waste recycling and has potential for industrial application. Attached Figure Description

[0022] Figure 1 This is the absorption spectrum of the lotus seed peel powder extract in Example 1 of the present invention. Detailed Implementation

[0023] The technical solutions in the embodiments of the present invention will be clearly and completely described below. 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.

[0024] Example 1

[0025] A method for simultaneously extracting polyphenols and flavonoids from lotus seed powder is provided, comprising the following steps:

[0026] (1) After the lotus seeds are shelled, the powder ground by the machine is passed through an 80-mesh sieve;

[0027] (2) Take 2g of the sieved powder obtained in step (1) and put it into a beaker. Add 100mL of a mixture of ethanol and water in a volume ratio of 1:1. Place the beaker in an ultrasonic extractor at a temperature of 70℃ and a power of 320W for 40min. Centrifuge at 6000rpm and 20℃ for 15min and collect the supernatant.

[0028] (3) Adjust the pH of the supernatant collected in step (2) with 0.1 mol / L HCl solution to 3, let it stand for 3 h to allow the flavonoids to precipitate completely, and centrifuge at 6000 rpm and 4℃ for 15 min.

[0029] (4) The supernatant collected in step (3) is concentrated on a rotary evaporator at 70°C until constant weight is achieved. The concentrated liquid is then freeze-dried under vacuum to obtain polyphenols with a mass of 0.258g.

[0030] (5) The precipitate collected in step (3) was washed with water until neutral and then freeze-dried under vacuum to obtain flavonoids with a mass of 0.062g.

[0031] Spectral property determination of the product:

[0032] Weigh 0.01g of the dried extract obtained in steps (4) and (5), and prepare solutions with 70% ethanol aqueous solution to contain 0.10g / L of flavonoids and polyphenols. Using the same solvent (70% ethanol aqueous solution) as a reference, scan the spectrum in the range of 200-800nm ​​on a UV-Vis spectrophotometer to obtain the absorption spectrum of the lotus root bark extract. See details below. Figure 1 .

[0033] From the appendix Figure 1 It can be seen that there are two relatively obvious absorption peaks near wavelengths of 300nm and 360nm in the ultraviolet region, which are typical absorption peaks of polyphenols and flavonoids.

[0034] Comparative Example 1

[0035] (1) After the lotus seeds are shelled, the powder ground by the machine is passed through an 80-mesh sieve;

[0036] (2) Take 2g of the sieved powder obtained in step (1) and place it in a beaker. Add 100mL of a mixture of ethanol and water in a volume ratio of 1:1. Place the beaker in a 70℃ water bath shaker and shake the powder to extract for 40min. Centrifuge and collect the supernatant.

[0037] (3) Adjust the pH of the supernatant collected in step (2) with 0.1 mol / L HCl solution to 3, let it stand for 3 h to allow the flavonoids to precipitate completely, and centrifuge at 4000 rpm and 4℃ for 15 min.

[0038] (4) The supernatant collected in step (3) is desolventized and concentrated in a rotary evaporator at 70°C. The concentrated liquid is then freeze-dried under vacuum to obtain polyphenols with a mass of 0.152g.

[0039] (5) The precipitate collected in step (3) is freeze-dried under vacuum to obtain flavonoids with a mass of 0.05g.

[0040] Comparative Example 2

[0041] (1) After the lotus seeds are shelled, the powder ground by the machine is passed through an 80-mesh sieve;

[0042] (2) Take 2g of the sieved powder obtained in step (1) and place it in a beaker. Add 100mL of a mixture of ethanol and water in a volume ratio of 1:1. Place the beaker in a 70℃ water bath shaker and shake the powder to extract for 30min.

[0043] (3) Place the beaker in an ultrasonic device with a temperature of 70℃ and a power of 320W, stir and extract the powder for 30 minutes, centrifuge, and collect the supernatant.

[0044] (4) Adjust the pH of the supernatant collected in step (3) with 0.1 mol / L HCl solution to 3, let it stand for 3 h to allow the flavonoids to precipitate completely, and centrifuge at 4000 rpm and 4℃ for 15 min.

[0045] (5) The supernatant collected in step (4) is desolventized and concentrated in a rotary evaporator at 70°C. The concentrated liquid is then freeze-dried under vacuum to obtain polyphenols with a mass of 0.218g.

[0046] (6) The precipitate collected in step (4) is freeze-dried under vacuum to obtain flavonoids with a mass of 0.056g.

[0047] The above are merely preferred embodiments of the present invention and are not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A method for simultaneously extracting and separating polyphenols and flavonoids from lotus seed powder, characterized in that, Includes the following steps: 1) Remove the shells from the lotus seeds, grind them, and sift them to obtain lotus seed powder; 2) Add the lotus seed powder obtained in step 1) to a mixture of ethanol and water, extract by ultrasonication at 65-75℃, and then centrifuge to obtain the supernatant; The volume concentration of ethanol is 40-70%, and the mass-volume ratio of lotus seed peeling powder to the mixed solution is 1:30-50 g / ml. 3) Adjust the pH of the supernatant obtained in step 2) to 2.8-3.2, let it stand for 2-3 hours to allow the flavonoids to precipitate completely, and centrifuge to obtain the precipitate and supernatant; 4) The supernatant obtained in step 3) is concentrated by rotary evaporation and then freeze-dried under vacuum to obtain polyphenols; the precipitate obtained in step 3) is freeze-dried under vacuum to obtain brass.

2. The method according to claim 1, characterized in that, In step 1), the sample is passed through an 80-mesh sieve.

3. The method according to claim 1, characterized in that, In step 2), the ultrasonic power is 320-400 W; the extraction time is 35-45 min.

4. The method according to claim 1, characterized in that, In step 2), the centrifugation conditions are: 6000-8000 rpm, 20-40℃ for 15-30 min.

5. The method according to claim 1, characterized in that, In step 3), the centrifugation conditions are 5000-10000 rpm and 4-10℃ for 15-20 min.

6. The method according to claim 1, characterized in that, In step 3), the pH is adjusted using a 0.1-1 mol / L HCl solution.

7. The method according to claim 1, characterized in that, In step 4), the supernatant is concentrated on a rotary evaporator at 70-77°C until constant weight is achieved.

8. The method according to claim 1, characterized in that, In step 4), the precipitate is washed with water until neutral and then subjected to vacuum freeze-drying.

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