Method for extracting amygdalin, amygdalin and total flavonoids of bitter almonds from bitter almond debittering liquid

Abstract

The present invention relates to a method for extracting amygdalin, amygdalin and total flavonoids of bitter almonds from bitter almond debittering liquid, so as to solve the technical problems of low recovery rate, high production cost and disadvantageous industrial production in the prior art. The method comprises: 1. Passing the bitter almond debittering liquid through an impurity adsorbent to obtain a bitter almond debittering liquid extract with a specific gravity of 1.15-1.25; 2. Adding an organic solvent, adjusting the pH value to 3-5, filtering and collecting a first filtrate and a first precipitate; 3. After adjusting the pH value of the first filtrate to 5-6, adding an organic solvent again, stirring, refrigerating for 12 hours, filtering and collecting a second filtrate and a second precipitate; recrystallizing from the second precipitate to obtain amygdalin; obtaining total flavonoids of bitter almonds from the second filtrate; 4. Obtaining amygdalin from the first precipitate. The method is safe, simple, high-yield, low-cost, and the solvent system is simple and easy to recover.

Description

Technical Field

[0001] The invention relates to a method for simultaneously extracting amygdalin, amygdalin and total flavonoids of bitter almonds, and in particular to a method for extracting amygdalin, amygdalin and total flavonoids of bitter almonds from debittered bitter almond liquid. Background Art

[0002] Amygdalin is the main active ingredient in the traditional Chinese medicine bitter almonds. It is easily soluble in water and boiling ethanol, but has low solubility in cold ethanol. Amygdalin is very easy to hydrolyze, especially in the presence of acid or enzymes. It can be decomposed to produce D-glucose and the extremely unstable intermediate product amygdalin. Benzoic acid and hydrocyanic acid are generated under heating or enzyme action. Hydrocyanic acid can calm the respiratory center, play an antitussive and antiasthmatic role, and can be used to treat cough and asthma of various symptoms. In addition, amygdalin has good anti-tumor effects and is often used as an auxiliary drug for the treatment of cancer. Bitter almond protein contains 18 kinds of amino acids needed by the human body, such as leucine, isoleucine, lysine, methionine, threonine, phenylalanine, valine, etc. It is a good protein nutrition enhancer and a plant protein that can be used as both medicine and food.

[0003] When industrially producing and processing bitter almonds, they must go through two key processes: peeling and debittering. Both the peeling and debittering processes will produce a large amount of wastewater. Studies have shown that 1 ton of bitter almonds can be processed to obtain 0.75 ton of debittered almonds, with a loss of 0.25 ton and 20 ton of wastewater (including 100 kg dietary fiber, 20 kg amygdalin, 30 kg almond flavonoids, 50 kg bitter almond protein, etc.). On the one hand, a large number of functional food ingredients become waste, and on the other hand, the organic matter content in the peeling and debittering wastewater exceeds the standard. The wastewater of the current production process is not utilized, but enters sewage treatment, and is directly discharged after meeting the standards. A large amount of active substances are disposed of, resulting in a waste of available resources.

[0004] The Chinese patent with publication number CN 107556347 B mentions the use of alcohol / inorganic salt two-phase aqueous extraction, ultrasound-assisted synergistic enhancement and other steps to achieve the separation and recovery of amygdalin in the bitter almond debittering concentrate. Through this process, the content of recovered amygdalin can reach 60-70%.

[0005] A Chinese patent with publication number CN 107759644 B relates to a method for recovering amygdalin from debittered bitter almond water by a macroporous resin method. Through separation by macroporous adsorption resin, the recovered amygdalin content can reach about 61%, and the recovery rate of the effective component can reach 88%.

[0006] A Chinese patent with publication number CN 109133398 A relates to a method for resource processing of bitter almond debittered water, which uses membrane separation technology to separate amygdalin and protein in the bitter almond debittered water.

[0007] Although the above process can realize the recovery of amygdalin, the operation procedure is complicated, the production cycle is long, the solvent loss is large, the quality and recovery rate are low, and the obtained product is relatively single, which is not conducive to cost reduction. Summary of the invention

[0008] In order to solve the technical problems of low recovery rate, high production cost and disadvantageous industrial production in the prior art, the present invention provides a method for extracting amygdalin, amygdalin and total flavonoids of bitter almonds from bitter almond debittering liquid.

[0009] The technical solution provided by the present invention is:

[0010] A method for extracting amygdalin, amygdalin and total flavonoids from bitter almond debittered liquid, which is special in that it comprises the following steps:

[0011] S1. Adjust the bitter almond debittered liquid to a bitter almond debittered concentrated liquid with a specific gravity of 1.03-1.05, add an impurity adsorbent to the bitter almond debittered concentrated liquid for adsorption, filter and collect the debittered liquid filtrate, and concentrate the debittered liquid filtrate into a bitter almond debittered liquid extract with a specific gravity of 1.15-1.25;

[0012] S2, adding an organic solvent to the bitter almond debittered liquid extract, stirring at room temperature for more than 2 hours, adjusting the pH value to 3-5, refrigerating for 8-12 hours, and then filtering to collect the first filtrate and the first precipitate;

[0013] S3, after adjusting the pH value of the first filtrate to 5-6, concentrate it into a first filtrate concentrated extract with a specific gravity of 1.15-1.25, add the organic solvent again and stir it at room temperature for more than 5 hours, refrigerate it for more than 12 hours, filter and collect the second filtrate and the second precipitate;

[0014] Recrystallize the second precipitate with 60-80% by volume ethanol, and dry to obtain amygdalin;

[0015] The second filtrate is concentrated to be free of alcohol, and the total flavonoids of bitter almonds are obtained by separation using a macroporous adsorption resin or a membrane;

[0016] S4. Add 3-5 times the mass of pure water to the first precipitate obtained in step S2, dissolve it at 50-60°C, keep it warm for 30-40 minutes, refrigerate it for 3-5 hours, collect the third filtrate by centrifugation, slowly add acetonitrile-acetone mixture to the third filtrate, stir it, centrifuge it, collect the third precipitate, rinse the third precipitate with water, and then freeze-dry it to obtain almond protein.

[0017] The order of step S3 and step S4 can be swapped.

[0018] Further, in step S1, the adsorbent is added to the bitter almond debitterized concentrated solution for adsorption as follows:

[0019] The adsorbent is activated carbon and activated clay;

[0020] The amount of activated carbon added is 1-3% of the mass of the bitter almond debittered concentrated solution, and the amount of activated clay added is 0.5-1% of the mass of the bitter almond debittered concentrated solution;

[0021] The adsorption temperature is 50-60°C and the adsorption time is 1-3h.

[0022] Activated clay is a polar adsorbent, which is often used to absorb polar impurities. Activated carbon is a non-polar adsorbent, which is often used to adsorb non-polar impurities. Adding activated carbon and activated clay as adsorbents at the same time can better adsorb impurities in the bitter almond debittering concentrate and increase the content of active substances extracted subsequently.

[0023] Further, in step S2, the organic solvent is any one of methanol, ethanol or isopropanol;

[0024] To adjust the pH value, use citric acid or acetic acid.

[0025] Furthermore, in step S2, the volume fraction of the methanol, ethanol or isopropanol is 90%-100%, and the volume mass ratio of the organic solvent to the debittered bitter almond extract is 10-30%;

[0026] The mass concentration of the citric acid or glacial acetic acid is 5-10%.

[0027] In this step, the addition of the organic solvent is a process of removing "impurities (almond protein)" in the first filtrate, and is also a process of precipitating almond protein. If the volume-to-mass ratio of the organic solvent is less than 10%, the precipitation of almond protein is incomplete, resulting in the presence of almond protein in amygdalin and total flavonoids of bitter almonds; if the volume-to-mass ratio of the organic solvent is greater than 30%, amygdalin will also be partially precipitated, resulting in an increase in the impurity content and a decrease in purity during the subsequent extraction of almond protein.

[0028] Furthermore, in step S3, the reagent used to adjust the pH value of the first filtrate to 5-6 is sodium carbonate or potassium carbonate with a mass concentration of 3-5%;

[0029] The reason for using low mass concentration of sodium carbonate or potassium carbonate is that the amygdalin in the first filtrate is unstable. If an alkaline solution with too high concentration is added, the local pH in the first filtrate will be too high, and the amygdalin will be degraded, resulting in a decrease in the extraction rate.

[0030] The organic solvent is methanol, ethanol or isopropanol with a volume fraction of 90%-100%, and the volume mass ratio of the organic solvent to the first filtrate concentrated extract is 80-150%.

[0031] If the volume mass ratio of the organic solvent to the concentrated extract of the first filtrate is too high, greater than 150%, the second precipitate will contain some total flavonoids of bitter almonds, thereby reducing the content of amygdalin; if the volume mass ratio of the organic solvent to the concentrated extract of the first filtrate is too small, less than 80%, amygdalin cannot be completely precipitated, thereby reducing the yield of amygdalin.

[0032] Furthermore, in step S4, the added volume of the acetonitrile-acetone mixed solution is 10-30% of the volume of the third filtrate.

[0033] The acetonitrile-acetone mixed solvent can be selected to selectively dissolve the impurities in the third filtrate, so that the bitter almond protein precipitation effect is better and the content is higher.

[0034] Furthermore, in step S4, the volume ratio of acetonitrile to acetone in the acetonitrile-acetone mixture is (3-8):1, and the acetonitrile-acetone mixture is pre-frozen at -20°C to -4°C for more than 8 hours before being added to the third filtrate.

[0035] The volume ratio of acetonitrile to acetone in the acetonitrile-acetone mixture is preferably (3-8):1. If the ratio of acetonitrile is higher than 8 or lower than 3, the polarity of the acetonitrile-acetone mixture cannot dissolve impurities well, resulting in a high impurity content in the third precipitate and reducing the purity of the bitter almond protein.

[0036] Furthermore, in step S1, the amount of activated carbon added is 2% of the mass of the bitter almond debitterized concentrated solution, and the amount of activated clay added is 1% of the mass of the bitter almond debitterized concentrated solution;

[0037] In step S2, the volume mass ratio of the organic solvent to the debittered bitter almond extract is 20%;

[0038] In step S3, the organic solvent is added again, specifically, the volume mass ratio of the organic solvent to the first filtrate concentrated extract is 100-120%;

[0039] In step S4, in the acetonitrile-acetone mixed solution, the volume ratio of acetonitrile to acetone is 5:1.

[0040] Beneficial effects of the present invention:

[0041] 1. According to the difference in solubility of amygdalin in ethanol-water mixed solvent systems with different proportions, the present invention adopts two alcohol precipitations combined with double pH treatment to achieve the separation and purification of amygdalin, amygdalin and almond flavonoids. This process not only achieves the purification of amygdalin, but also obtains two by-products, amygdalin and total flavonoids, which can reduce the production cost of a single substance, is simple to operate, has a high recovery rate, can achieve resource processing of bitter almond debittering concentrated liquid, and is more conducive to industrial production.

[0042] 2. The present invention adopts heat treatment to remove part of the impurities, and then adds acetonitrile-acetone mixed solvent, which is more conducive to the separation of almond protein and water-soluble impurities, thereby improving the purification efficiency of almond protein.

[0043] 3. The recovery rate of the active ingredient of amygdalin can reach about 85%, which is safer, simpler, more productive, and lower in cost than the known methods. The solvent system is simple and easy to recover, and is more suitable for large-scale industrial production.

[0044] 4. The purity of the amygdalin product produced by the method provided by the present invention is high, all above 98%. BRIEF DESCRIPTION OF THE DRAWINGS

[0045] Figure 1 The liquid phase spectrum of the bitter almond debittering liquid used in Example 1 of the present invention;

[0046] Figure 2 This is the liquid phase spectrum of the amygdalin product extracted in Example 1 of the present invention. DETAILED DESCRIPTION

[0047] The method provided by the present invention is further illustrated by specific examples below. It is worth noting that the present embodiment uses purchased bitter almond debittering concentrate with a solid content of 55-60%. It can be understood that whether the waste liquid after bitter almond debittering is used directly or the purchased bitter almond debittering concentrate is used, as long as the specific gravity is adjusted to the required range, the method provided by the present invention can be used.

[0048] Example 1

[0049] See also Figure 1 , is the liquid phase spectrum of the bitter almond debittered liquid used in the experiment, wherein the content of amygdalin is 17.47%; the specific gravity of 10 kg of bitter almond debittered liquid is adjusted to 1.03-1.05, activated carbon and activated clay adsorbents are added, the amount of activated carbon added is 1% of the mass of the bitter almond debittered liquid, and the amount of activated clay added is 1% of the mass of the bitter almond debittered liquid; the adsorption temperature is 60°C, the adsorption time is 1h, the debittered liquid filtrate is filtered and collected, and the debittered liquid filtrate is concentrated into a bitter almond debittered liquid extract with a specific gravity of 1.15;

[0050] Adding a 90% ethanol solution by volume to the debittered bitter almond extract, wherein the volume mass ratio of the ethanol solution to the debittered bitter almond extract is 30%, stirring at room temperature for more than 2 hours, adding 5% citric acid by mass concentration to adjust the pH value to 3.0, refrigerating for 12 hours, and then filtering to collect a first filtrate and a first precipitate;

[0051] After adjusting the pH value of the first filtrate to 5.0 with 3% sodium carbonate, the first filtrate was concentrated into a first filtrate concentrated extract with a specific gravity of 1.15, and an ethanol solution with a volume fraction of 100% was added again, and the volume mass ratio of the ethanol solution to the first filtrate concentrated extract was 80%, and the mixture was stirred at room temperature for more than 5 hours, and refrigerated for more than 12 hours, and then the second filtrate and the second precipitate were filtered and collected; the second precipitate was recrystallized with 60% ethanol by volume, and dried to obtain 1.527 kg of amygdalin with a content of 98.9%, see Figure 2 , which is the liquid phase spectrum measurement result of the amygdalin product; the second filtrate is concentrated to be alcohol-free, and 147.3 g of total flavonoids of bitter almonds are obtained by macroporous adsorption resin or membrane separation, with a content of 41.8%;

[0052] Add 5 times the mass of pure water to the first precipitate, dissolve it at 50°C, keep it warm for 30 minutes, refrigerate it for 3 hours, collect the third filtrate by centrifugation, slowly add acetonitrile-acetone mixed solution to the third filtrate and stir it, the added volume of acetonitrile-acetone mixed solution is 10% of the volume of the third filtrate, the volume ratio of acetonitrile to acetone in the acetonitrile-acetone mixed solution is 3:1, and it is pre-frozen at -20°C to -4°C for more than 8 hours; centrifuge to collect the third precipitate, rinse the third precipitate with water and then freeze-dry it to obtain 0.838 kg of bitter almond protein with a content of 85.4%.

[0053] Example 2

[0054] The specific gravity of 10 kg of bitter almond debittered liquid is adjusted to 1.03-1.05, and activated carbon and activated clay adsorbents are added, wherein the amount of activated carbon added is 3% of the mass of the bitter almond debittered liquid, and the amount of activated clay added is 0.5% of the mass of the bitter almond debittered liquid; the adsorption temperature is 50° C., the adsorption time is 3 hours, the debittered liquid filtrate is filtered and collected, and the debittered liquid filtrate is concentrated into a bitter almond debittered liquid extract with a specific gravity of 1.25;

[0055] Adding 100% ethanol solution by volume to the debittered bitter almond extract, wherein the volume mass ratio of the ethanol solution to the debittered bitter almond extract is 10%, stirring at room temperature for more than 2 hours, adding 5% acetic acid by mass concentration to adjust the pH value to 4.5, refrigerating for 8 hours and then filtering, collecting a first filtrate and a first precipitate;

[0056] After adjusting the pH value of the first filtrate to 6.0 with potassium carbonate of 3% by mass, the first filtrate is concentrated into a first filtrate concentrated extract with a specific gravity of 1.25, and an ethanol solution with a volume fraction of 90% is added again, the volume mass ratio of the ethanol solution to the first filtrate concentrated extract is 150%, and the mixture is stirred at room temperature for more than 5 hours, refrigerated for more than 12 hours, and then the second filtrate and the second precipitate are filtered and collected; the second precipitate is recrystallized with ethanol of 80% by volume, and filtered and dried to obtain 1.541 kg of amygdalin with a content of 98.2%; the second filtrate is concentrated to be alcohol-free, and 140.7 g of total flavonoids of bitter almonds with a content of 43.3% are obtained by separation with a macroporous adsorption resin or a membrane;

[0057] Add 3 times the mass of pure water to the first precipitate, dissolve it at 60°C, keep it warm for 40 minutes, refrigerate it for 5 hours, collect the third filtrate by centrifugation, slowly add acetonitrile-acetone mixed solution to the third filtrate and stir it, the added volume of acetonitrile-acetone mixed solution is 30% of the volume of the third filtrate, the volume ratio of acetonitrile to acetone in the acetonitrile-acetone mixed solution is 8:1, and it is pre-frozen at -20°C to -4°C for more than 8 hours; centrifuge to collect the third precipitate, rinse the third precipitate with water and then freeze-dry to obtain 0.832 kg of bitter almond protein with a content of 85.3%.

[0058] Example 3

[0059] The specific gravity of 10 kg of bitter almond debittered liquid is adjusted to 1.03-1.05, and activated carbon and activated clay adsorbents are added, wherein the amount of activated carbon added is 2% of the mass of the bitter almond debittered liquid, and the amount of activated clay added is 1% of the mass of the bitter almond debittered liquid; the adsorption temperature is 60° C., the adsorption time is 2 hours, the debittered liquid filtrate is filtered and collected, and the debittered liquid filtrate is concentrated into a bitter almond debittered liquid extract with a specific gravity of 1.20;

[0060] Adding 95% ethanol solution by volume to the debittered bitter almond extract, wherein the volume mass ratio of the ethanol solution to the debittered bitter almond extract is 20%, stirring at room temperature for more than 2 hours, adding 10% acetic acid by mass concentration to adjust the pH value to 4.0, refrigerating for 8 hours and then filtering, collecting a first filtrate and a first precipitate;

[0061] The pH value of the first filtrate is adjusted to 5.3 by using 5% potassium carbonate, and then concentrated into a first filtrate concentrated extract with a specific gravity of 1.21, and an ethanol solution with a volume fraction of 95% is added again, and the volume mass ratio of the ethanol solution to the first filtrate concentrated extract is 100%, and the mixture is stirred at room temperature for more than 5 hours, and refrigerated for more than 12 hours, and then the second filtrate and the second precipitate are filtered and collected; the second precipitate is recrystallized by using 70% ethanol by volume, and filtered and dried to obtain 1.538 kg of amygdalin with a content of 99.5%; the second filtrate is concentrated to be alcohol-free, and 143.5 g of total flavonoids of bitter almonds with a content of 45.0% are obtained by using a macroporous adsorption resin or membrane separation;

[0062] Add 4 times the mass of pure water to the first precipitate, dissolve it at 60°C, keep it warm for 35 minutes, refrigerate it for 5 hours, collect the third filtrate by centrifugation, slowly add acetonitrile-acetone mixed solution to the third filtrate and stir it, the added volume of acetonitrile-acetone mixed solution is 20% of the volume of the third filtrate, the volume ratio of acetonitrile to acetone in the acetonitrile-acetone mixed solution is 5:1, and it is frozen at -20°C to -4°C for more than 8 hours in advance; centrifuge, collect the third precipitate, rinse the third precipitate with water and then freeze-dry it to obtain 0.829 kg of bitter almond protein with a content of 87.4%.

[0063] Example 4

[0064] The specific gravity of 10 kg of bitter almond debittered liquid is adjusted to 1.03-1.05, and activated carbon and activated clay adsorbents are added, wherein the amount of activated carbon added is 2.5% of the mass of the bitter almond debittered liquid, and the amount of activated clay added is 0.8% of the mass of the bitter almond debittered liquid; the adsorption temperature is 55° C., the adsorption time is 2 hours, the debittered liquid filtrate is filtered and collected, and the debittered liquid filtrate is concentrated into a bitter almond debittered liquid extract with a specific gravity of 1.18;

[0065] Adding a methanol solution with a volume fraction of 95% to the debittered bitter almond extract, wherein the volume mass ratio of the methanol solution to the debittered bitter almond extract is 20%, stirring at room temperature for more than 2 hours, adding citric acid with a mass concentration of 10% to adjust the pH value to 5.0, refrigerating for 8 hours and then filtering to collect a first filtrate and a first precipitate;

[0066] After adjusting the pH value of the first filtrate to 5.5 with 5% sodium carbonate, the first filtrate is concentrated into a first filtrate concentrated extract with a specific gravity of 1.23, and a methanol solution with a volume fraction of 95% is added again, the volume mass ratio of the methanol solution to the first filtrate concentrated extract is 120%, and the mixture is stirred at room temperature for more than 5 hours, and refrigerated for more than 12 hours, and then the second filtrate and the second precipitate are filtered and collected; the second precipitate is recrystallized with 60% ethanol by volume, and dried to obtain 1.532 kg of amygdalin with a content of 99.2%; the second filtrate is concentrated to be alcohol-free, and 145.9 g of total flavonoids of bitter almonds with a content of 43.9% are obtained by separation with a macroporous adsorption resin or membrane;

[0067] Add 5 times the mass of pure water to the first precipitate, dissolve it at 55°C, keep it warm for 35 minutes, refrigerate it for 4 hours, collect the third filtrate by centrifugation, slowly add acetonitrile-acetone mixed solution to the third filtrate and stir it, the added volume of acetonitrile-acetone mixed solution is 25% of the volume of the third filtrate, the volume ratio of acetonitrile to acetone in the acetonitrile-acetone mixed solution is 6:1, and it is pre-frozen at -20°C to -4°C for more than 8 hours; centrifuge to collect the third precipitate, rinse the third precipitate with water and then freeze-dry it to obtain 0.831 kg of bitter almond protein with a content of 86.6%.

[0068] Example 5

[0069] The specific gravity of 10 kg of bitter almond debittered liquid is adjusted to 1.03-1.05, and activated carbon and activated clay adsorbents are added, wherein the amount of activated carbon added is 1.5% of the mass of the bitter almond debittered liquid, and the amount of activated clay added is 0.6% of the mass of the bitter almond debittered liquid; the adsorption temperature is 50° C., the adsorption time is 2 hours, the debittered liquid filtrate is filtered and collected, and the debittered liquid filtrate is concentrated into a bitter almond debittered liquid extract with a specific gravity of 1.19;

[0070] Adding a 100% volume fraction of isopropanol solution to the debittered bitter almond extract, wherein the volume mass ratio of the isopropanol solution to the debittered bitter almond extract is 15%, stirring at room temperature for more than 2 hours, adding 8% mass concentration of citric acid to adjust the pH value to 3.5, refrigerating for 10 hours and then filtering, collecting a first filtrate and a first precipitate;

[0071] After adjusting the pH value of the first filtrate to 5.0 with sodium carbonate at a mass concentration of 4%, the first filtrate is concentrated into a first filtrate concentrated extract with a specific gravity of 1.22, and an isopropanol solution with a volume fraction of 95% is added again, the volume mass ratio of the isopropanol solution to the first filtrate concentrated extract is 130%, and the mixture is stirred at room temperature for more than 5 hours, refrigerated for more than 12 hours, and then the second filtrate and the second precipitate are filtered and collected; the second precipitate is recrystallized with ethanol at a volume fraction of 65%, and dried to obtain 1.529 kg of amygdalin with a content of 98.7%; the second filtrate is concentrated to be alcohol-free, and 148.2 g of total flavonoids of bitter almonds with a content of 40.7% are obtained by separation with a macroporous adsorption resin or membrane;

[0072] Add 5 times the mass of pure water to the first precipitate, dissolve it at 60°C, keep it warm for 40 minutes, refrigerate it for 5 hours, collect the third filtrate by centrifugation, slowly add acetonitrile-acetone mixed solution to the third filtrate and stir it, the added volume of acetonitrile-acetone mixed solution is 15% of the volume of the third filtrate, the volume ratio of acetonitrile to acetone in the acetonitrile-acetone mixed solution is 4:1, and it is pre-frozen at -20°C to -4°C for more than 8 hours; centrifuge to collect the third precipitate, rinse the third precipitate with water and then freeze-dry to obtain 0.841 kg of bitter almond protein with a content of 85.2%.

[0073] Example 6

[0074] The specific gravity of 10 kg of bitter almond debittered liquid is adjusted to 1.03-1.05, and activated carbon and activated clay adsorbents are added, wherein the amount of activated carbon added is 1% of the mass of the bitter almond debittered liquid, and the amount of activated clay added is 0.5% of the mass of the bitter almond debittered liquid; the adsorption temperature is 60° C., the adsorption time is 3 hours, the debittered liquid filtrate is filtered and collected, and the debittered liquid filtrate is concentrated into a bitter almond debittered liquid extract with a specific gravity of 1.25;

[0075] Adding 100% ethanol solution by volume to the debittered bitter almond extract, wherein the volume mass ratio of the ethanol solution to the debittered bitter almond extract is 25%, stirring at room temperature for more than 2 hours, adding 8% citric acid by mass concentration to adjust the pH value to 4.0, refrigerating for 9 hours and then filtering to collect a first filtrate and a first precipitate;

[0076] After adjusting the pH value of the first filtrate to 5.5 with sodium carbonate of 4% by mass, the first filtrate is concentrated into a first filtrate concentrated extract with a specific gravity of 1.25, and an ethanol solution of 95% by volume is added again, the volume mass ratio of the ethanol solution to the first filtrate concentrated extract is 110%, and the mixture is stirred at room temperature for more than 5 hours, refrigerated for more than 12 hours, and then the second filtrate and the second precipitate are filtered and collected; the second precipitate is recrystallized with ethanol of 75% by volume, and dried to obtain 1.535 kg of amygdalin with a content of 99.0%; the second filtrate is concentrated to be alcohol-free, and 138.8 g of total flavonoids of bitter almonds with a content of 45.3% are obtained by separation with a macroporous adsorption resin or membrane;

[0077] Add 4 times the mass of pure water to the first precipitate, dissolve it at 60°C, keep it warm for 35 minutes, refrigerate it for 3.5 hours, collect the third filtrate by centrifugation, slowly add acetonitrile-acetone mixed solution to the third filtrate and stir it, the added volume of acetonitrile-acetone mixed solution is 20% of the volume of the third filtrate, the volume ratio of acetonitrile to acetone in the acetonitrile-acetone mixed solution is 7:1, and it is pre-frozen at -20°C to -4°C for more than 8 hours; centrifuge to collect the third precipitate, rinse the third precipitate with water and then freeze-dry it to obtain 0.828 kg of bitter almond protein with a content of 86.1%.

Claims

1. A method for extracting amygdalin, amygdalin and total flavonoids from bitter almond debitterized liquid, characterized in that: The following steps are involved: S1. Adjust the bitter almond debittered liquid to a bitter almond debittered concentrated liquid with a specific gravity of 1.03-1.05, add an impurity adsorbent to the bitter almond debittered concentrated liquid for adsorption, filter and collect the debittered liquid filtrate, and concentrate the debittered liquid filtrate into a bitter almond debittered liquid extract with a specific gravity of 1.15-1.25; S2, adding an organic solvent to the bitter almond debittered liquid extract, stirring at room temperature for more than 2 hours, adjusting the pH value to 3-5, refrigerating for 8-12 hours, and then filtering to collect the first filtrate and the first precipitate; In step S2, the organic solvent is any one of methanol, ethanol or isopropanol; S3, after adjusting the pH value of the first filtrate to 5-6, concentrate it into a first filtrate concentrated extract with a specific gravity of 1.15-1.25, add the organic solvent again and stir it at room temperature for more than 5 hours, refrigerate it for more than 12 hours, filter and collect the second filtrate and the second precipitate; Recrystallize the second precipitate with 60-80% by volume ethanol, and dry to obtain amygdalin; The second filtrate is concentrated to be free of alcohol, and the total flavonoids of bitter almonds are obtained by separation using a macroporous adsorption resin or a membrane; In step S3, the organic solvent is 90%-100% by volume of methanol, ethanol or isopropanol; S4, adding 3-5 times the mass of pure water to the first precipitate obtained in step S2, dissolving at 50-60°C, keeping warm for 30-40 minutes, refrigerating for 3-5 hours, collecting the third filtrate by centrifugation, slowly adding acetonitrile-acetone mixture to the third filtrate, stirring, centrifuging, collecting the third precipitate, rinsing the third precipitate with water and freeze-drying to obtain almond protein; The order of step S3 and step S4 can be swapped.

2. The method for extracting amygdalin, amygdalin and total flavonoids of bitter almonds from the bitter almond debittering liquid according to claim 1, characterized in that: In step S1, the adsorbent is added to the bitter almond debitterized concentrated solution for adsorption as follows: The adsorbent is activated carbon and activated clay; The amount of activated carbon added is 1-3% of the mass of the bitter almond debittered concentrated solution, and the amount of activated clay added is 0.5-1% of the mass of the bitter almond debittered concentrated solution; The adsorption temperature is 50-60°C and the adsorption time is 1-3h.

3. The method for extracting amygdalin, amygdalin and total flavonoids of bitter almonds from the bitter almond debittering liquid according to claim 2, characterized in that: In step S2, citric acid or acetic acid is used to adjust the pH value.

4. The method for extracting amygdalin, amygdalin and total flavonoids of bitter almonds from the bitter almond debittering liquid according to claim 3, characterized in that: In step S2, the volume fraction of the methanol, ethanol or isopropanol is 90%-100%, and the volume mass ratio of the organic solvent to the debittered bitter almond extract is 10-30%; The mass concentration of the citric acid or acetic acid is 5-10%.

5. The method for extracting amygdalin, amygdalin and total flavonoids of bitter almonds from the bitter almond debittering liquid according to claim 4, characterized in that: In step S3, the pH value of the first filtrate is adjusted to 5-6 using a reagent having a mass concentration of 3-5% sodium carbonate or potassium carbonate; The volume mass ratio of the organic solvent to the concentrated extract of the first filtrate is 80-150%.

6. The method for extracting amygdalin, amygdalin and total flavonoids of bitter almonds from the debittered bitter almond liquid according to any one of claims 1 to 5, characterized in that: In step S4, the added volume of the acetonitrile-acetone mixed solution is 10-30% of the volume of the third filtrate.

7. The method for extracting amygdalin, amygdalin and total flavonoids of bitter almonds from the bitter almond debittering liquid according to claim 6, characterized in that: In step S4, the volume ratio of acetonitrile to acetone in the acetonitrile-acetone mixture is (3-8):1, and the acetonitrile-acetone mixture is pre-frozen at -20°C to -4°C for more than 8 hours before being added to the third filtrate.

8. The method for extracting amygdalin, amygdalin and total flavonoids of bitter almonds from the bitter almond debittering liquid according to claim 7, characterized in that: In step S1, the amount of activated carbon added is 2% of the mass of the bitter almond debitterized concentrated solution, and the amount of activated clay added is 1% of the mass of the bitter almond debitterized concentrated solution; In step S2, the volume mass ratio of the organic solvent to the debittered bitter almond extract is 20%; In step S3, the organic solvent is added again, specifically, the volume mass ratio of the organic solvent to the first filtrate concentrated extract is 100-120%; In step S4, in the acetonitrile-acetone mixed solution, the volume ratio of acetonitrile to acetone is 5:1.

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