Microwave combined foam separation and enrichment device and separation method thereof

Abstract

The invention belongs to the technical field of saponin extraction, and particularly relates to a microwave combined foam separation and enrichment device and a separation method thereof. According to the separation and enrichment device, microwave-assisted water extraction is combined with foam separation and enrichment, the method effectively promotes saponin leaching, the extraction rate is close to that of a traditional ethanol extraction method, the extraction time is greatly shortened to be within 5 min and is far shorter than that of traditional hot reflux ethanol extraction and hot water extraction, and no organic solvent is needed. An extracting solution obtained by microwave-assisted water extraction is directly used as a feeding solution for foam separation, and microwave heating not only accelerates the adsorption of saponin on bubbles, but also reduces the solution viscosity, reduces bubble interstitial liquid and remarkably improves the enrichment ratio. Meanwhile, the amphipathy of the saponin and intramolecular vibration under the action of microwaves further enhance the adsorption of the saponin on bubbles, so that the enrichment ratio reaches up to 1.6 or above, which is obviously superior to the enrichment ratio of the combination of the traditional method and the foam separation enrichment method.

Description

Technical Field

[0001] The present invention belongs to the technical field of saponin extraction, and more specifically, relates to a microwave-combined foam separation and enrichment device and a separation method thereof. Background Art

[0002] The chemical composition of the soapberry shell is relatively rich, and its main compound type is triterpenoid saponins, which have multiple pharmacological effects such as anti-tumor, antibacterial, anti-inflammatory, antioxidant, hypoxia resistance, protection of myocardial ischemia and hemolysis, etc., and can also be used in the daily chemical industry as a detergent. Although the soapberry shell is rich in triterpenoid saponins, it has not been mass-produced and marketed due to factors such as the lack of scientific and technological research and development, shortage of raw materials, and high production costs, making it difficult to commercialize.

[0003] Traditional saponin extraction methods mainly include heating reflux method, water extraction and alcohol precipitation method and ultrasonic extraction method. Although these methods can achieve the extraction of saponins to a certain extent, they have many defects, such as low extraction efficiency, serious loss of effective ingredients, high impurity content, long extraction time, etc. For example, the heating reflux method requires long-term heating, high energy consumption and easy to cause degradation of effective ingredients; the water extraction and alcohol precipitation method requires multiple washing and alcohol precipitation, which is cumbersome to operate and has a low yield.

[0004] In order to break through the limitations of traditional extraction methods, researchers have explored a series of innovative extraction technologies in recent years. Microwave-assisted extraction stands out for its high efficiency and speed. Through microwave heating, efficient extraction of saponins can be achieved in a short time, significantly improving extraction efficiency and yield. For example, Chinese patent application CN108403741A discloses a method for microwave-assisted extraction of ginsenosides, which changes the traditional production process and combines biological fermentation and microwave-assisted ethanol extraction to extract saponins from ginseng, which can significantly increase the extraction content of ginsenosides. However, this method also faces the environmental and cost issues that may be caused by the long biological fermentation time (usually more than 35 hours) and ethanol as an extraction solvent.

[0005] In summary, there are still many challenges in the extraction and application of saponins in existing technologies. The lag in scientific and technological research and development, the tight supply of raw materials and the high production costs have limited its commercialization process; and the traditional extraction methods are difficult to meet actual needs due to their low efficiency and cumbersome operation. Therefore, there is an urgent need to develop more efficient, environmentally friendly and low-cost extraction technologies for the commercial application of natural products such as saponins. Summary of the invention

[0006] The technical problem to be solved by the present invention is to overcome the defects and shortcomings of the conventional extraction methods in the prior art, such as low efficiency and complicated operation, and to provide a microwave-combined foam separation and enrichment device.

[0007] Another object of the present invention is to provide application of the microwave-combined foam separation and enrichment device in the field of separation and purification.

[0008] Another object of the present invention is to provide a method for separating saponins by microwave-assisted water extraction combined with foam, wherein the method uses the microwave-combined foam separation and enrichment device.

[0009] Another object of the present invention is to provide a method for separating saponins by microwave-assisted water extraction combined with foam.

[0010] The above-mentioned purpose of the present invention is achieved through the following technical solutions:

[0011] The present invention protects a microwave-combined foam separation and enrichment device, comprising an air pump, a buffer device, an airflow meter, a reaction vessel, a microwave device, a foam separation device and a foam collector, wherein the air pump, the buffer device, the airflow meter, the foam separation device and the foam collector are connected in sequence through a gas pipeline; the foam separation device is directly connected to the microwave device through an opening; a reaction vessel is arranged in the microwave device, and a feed port of the foam separation device is connected to the inner space of the reaction vessel.

[0012] The present invention also protects the application of the microwave-combined foam separation and enrichment device in the field of separation and purification.

[0013] The present invention also protects a method for separating saponins by microwave-assisted water extraction combined with foam, and the microwave-combined foam separation and enrichment device is used to extract saponins.

[0014] When microwave-assisted water extraction of saponins is performed, the foam separation device and the gas pipeline are removed. Only the microwave device is used to perform microwave heating extraction on the raw water mixture containing saponins (contained in the reaction vessel) to obtain a crude saponin extract. When microwave-assisted foam separation is performed to enrich saponins, the air pump, buffer device, airflow meter, microwave device, reaction vessel, foam separation device and foam collector are connected through a gas pipeline. The air pump is turned on and air is blown into the crude saponin extract in the reaction vessel. The surface-active saponins will be adsorbed on the bubbles, overflow from the foam separation tube, and be collected by the foam collector to obtain a saponin enriched solution.

[0015] Furthermore, the microwave device is a microwave oven.

[0016] The present invention also protects a method for separating saponins by microwave-assisted water extraction combined with foam, comprising the following steps:

[0017] S1. Add the saponin-containing raw material to water, mix well, perform microwave extraction under microwave conditions, and post-treat to obtain a crude saponin extract;

[0018] S2. The crude saponin extract obtained in step S1 is used as the original feed solution for foam separation, and foam separation is performed under microwave conditions to obtain a saponin enriched solution.

[0019] The present invention adopts the combination of microwave heating and water as a solvent to extract saponins: microwave heating can quickly shorten the time required for saponin extraction, and the energy utilization efficiency is high; combined with water extraction, the use of organic solvents can be avoided, thereby avoiding the risk of explosion and environmental pollution caused by the use of organic solvents, and can also avoid the appearance of excessive non-polar impurities (such as flavonoids, polyphenols, pigments, etc.) in the extract.

[0020] Combined microwave heating and foam separation and enrichment technology: Heating can increase the adsorption rate of saponins on the bubble surface, while reducing the viscosity of the solution, reducing the amount of interstitial fluid carried by the bubbles and increasing the enrichment ratio. In addition, saponins are amphiphilic polar molecules, which undergo intramolecular vibrations under the action of microwaves, further increasing their adsorption rate on the bubble surface and further increasing the enrichment ratio.

[0021] Furthermore, the enrichment ratio is used to evaluate the change in the relative content or concentration of the target component in the sample after the extraction process. Specifically, the enrichment ratio refers to the ratio between the content (or concentration) of the target component after the extraction operation and its original content (or concentration) before the operation.

[0022] Preferably, in step S1, the microwave power of the microwave extraction is 500-2000W, more preferably 600-1400W, most preferably 1000W.

[0023] Preferably, in step S1, the microwave extraction time is ≤5 min, more preferably 0.5 to 2 min.

[0024] Preferably, in step S1, the mass ratio of the saponin-containing raw material to water is 1: (10-80) g / mL, preferably (20-60) g / mL.

[0025] Preferably, in step S2, the microwave power for foam separation is 100-800 W, more preferably 200-600 W, most preferably 300 W.

[0026] Preferably, in step S2, the gas flow rate of the foam separation is 50 to 1000 mL / min, more preferably 200 to 600 mL / min, and most preferably 400 mL / min.

[0027] Furthermore, the saponin-containing raw material includes Gleditsia sinensis husk and / or Gleditsia sinensis spines.

[0028] Furthermore, the pretreatment includes washing, drying, crushing and screening.

[0029] Specifically, the pretreatment is to wash the saponin-containing raw material and dry it at 50-120°C (preferably 105°C), grind it into powder after drying, sieve it through 50-20 mesh (preferably 100 mesh), and store it in a sealed state under dry conditions.

[0030] Further, as a preferred embodiment, the microwave-combined foam separation and enrichment device is used to perform step S1 and step S2.

[0031] Compared with the prior art, the present invention has the following beneficial effects:

[0032] The present invention adopts microwave-assisted water extraction combined with foam separation enrichment method, which effectively promotes the leaching of saponins, and its extraction rate is close to that of traditional ethanol extraction method, while the time is greatly shortened to less than 5min, which is much lower than the time of traditional hot reflux ethanol extraction and hot water extraction, and no organic solvent is needed. The extract obtained by microwave-assisted water extraction is directly used as the feed liquid for foam separation. Microwave heating not only accelerates the adsorption of saponins on bubbles, but also reduces the viscosity of the solution, reduces the interstitial liquid of bubbles, and significantly improves the enrichment ratio. At the same time, the amphiphilicity of saponins and the intramolecular vibration under the action of microwaves further enhance their adsorption on bubbles, making the enrichment ratio as high as 1.6 and above, which is significantly better than the enrichment ratio of the traditional method combined with the foam separation enrichment method. BRIEF DESCRIPTION OF THE DRAWINGS

[0033] Figure 1 Schematic diagram of the microwave-coupled foam separation and enrichment device. DETAILED DESCRIPTION

[0034] The present invention is further described below in conjunction with the accompanying drawings and specific examples, but the examples do not limit the present invention in any form. Unless otherwise specified, the reagents, methods and equipment used in the present invention are conventional reagents, methods and equipment in the art.

[0035] Unless otherwise specified, the reagents and materials used in the following examples are commercially available.

[0036] Gleditsia sinensis (the Gleditsia sinensis required for the experiment was collected from the Qianzhi Mingguang Gleditsia sinensis rice processing base in Maochang Town, Zhijin County, Bijie City, Guizhou Province)

[0037] Preparation of honey locust shell powder: wash the honey locust shell and dry it in an oven at 105°C, grind it into powder with a grinder, pass it through a 100-mesh sieve to obtain the honey locust shell powder, put it into a sealed bag and store it in a drying dish for later use.

[0038] Example 1 Microwave-assisted water extraction method to extract saponins from Gleditsia sinensis

[0039] The confirmation process of the optimal extraction conditions for extracting saponins from Gleditsia sinensis by microwave-assisted water extraction is as follows:

[0040] (1) Process and evaluation indicators

[0041] Weigh the powder of the soapberry shell, add deionized water and stir evenly, microwave for a certain time, let stand for 30 minutes, and then filter to obtain the soapberry shell water extract. The water extract is concentrated by rotary evaporation, anhydrous ethanol is added, shaken and left to stand for 1 hour, and then filtered into a round-bottom flask. This step can remove the proteins and sugars insoluble in ethanol in the soapberry shell water extract to obtain a preliminary purified soapberry shell surfactant crude extract. After the soapberry shell surfactant crude extract is concentrated under reduced pressure, it is dried in an oven at 105°C until the quality is stable, and the yield of the soapberry shell surfactant extract is calculated (since the surfactant extracted from the soapberry shell is mainly saponin, but pure saponin cannot be directly obtained during the extraction process, therefore, the present invention indirectly indicates the efficiency of this extraction process by calculating the yield of the surfactant extract to reflect the level of the saponin yield). The yield of the surfactant extract is calculated as shown in formula (1).

[0042]

[0043] (2) Single factor test

[0044] Taking W1 as the evaluation index, the effects of raw material particle size, microwave power, microwave time, and liquid-to-solid ratio on W1 were explored, and each reaction was performed three times in parallel.

[0045] (3) Response surface experiment

[0046] The microwave time (A), microwave power (B) and liquid-to-solid ratio (C) were taken as the experimental factors and W1 was taken as the response value. The Box-Behnken design response surface experiment was carried out using Design-Expert 8.0.6.

[0047] (4) Test results

[0048] Through the analysis of the response surface test results, the optimal extraction process conditions were obtained as follows: microwave time 33s, microwave power 1000W, liquid-to-solid ratio 35:1 (mL / g). Under these conditions, the predicted W1 value was 63.91%. Due to the limitations of the microwave device, the microwave time of the extraction process was adjusted to 30s. Three parallel tests were carried out according to the adjusted optimal extraction process conditions, and the W1 was measured to be 60.40%, with a relative error of 3.51% with the model prediction value, indicating that the optimized process conditions are more reliable.

[0049] Example 2 Microwave-assisted water extraction combined with foam separation to enrich Gleditsia saponins

[0050] (1) Design of microwave-assisted foam separation and enrichment device

[0051] According to the microwave-coupled foam separation and enrichment device Figure 1As shown, when microwave-assisted water extraction combined with foam separation is used to enrich saponins of Gleditsia sinensis, the air pump 1, the buffer device 3, the airflow meter 4, the reaction vessel 5, the microwave device (the microwave device in the embodiment is a microwave oven) 6, the foam separation device 7 (including the feed port 9) and the foam collector 8 are connected through the gas pipeline 2, and the microwave oven at this time serves as a heating device for foam separation. Among them, the foam separation device is directly connected to the microwave oven 6 through the top opening of the microwave oven; the reaction vessel 5 is placed in the microwave oven 6, and the feed port 9 of the foam separation device 7 is connected to the internal space of the reaction vessel 5.

[0052] (2) Quantification of Gleditsia saponins and enrichment ratio test

[0053] The crude extract of surfactant substances from the husk of Gleditsia sinensis obtained by the optimal process adjusted in Example 1 was used as the original feed liquid for foam separation by the perchloric acid-vanillin-glacial acetic acid colorimetric method.

[0054] Place the reaction container in a microwave oven, turn on the air pump, adjust the gas flowmeter to change the gas flow rate, and turn on the microwave power to the rated power. The gas is introduced from the lower end of the foam separation tube and bubbles are generated through the glass orifice plate. Due to the surface activity of saponin, saponin is enriched around the foam to stabilize the bubbles. Bubbles are continuously generated and move upward, forming a foam layer on the upper layer of the liquid, and finally collected by the foam collector. The foam separation enrichment method uses the enrichment ratio as the evaluation index, and its calculation is shown in formula (2).

[0055]

[0056] Where: E——enrichment ratio; Cf——mass concentration of saponin in feed liquid, mg / mL; CO——mass concentration of saponin in foam layer, mg / mL.

[0057] (3) Orthogonal test

[0058] Through the experimental results of single-factor experiments, the experimental factors with no significant differences were eliminated, and the gas flow rate (L) and microwave power (M) were used as the independent variable E as the response value. The Box-Behnken design-response surface experiment was carried out using Design-Expert 8 and the experimental results were analyzed.

[0059] (4) Test results

[0060] Through the analysis of the response surface test results, the optimal extraction process conditions for the enrichment of saponins by foam separation were obtained as follows: gas flow rate 400 mL / min, microwave power 300 W. The enrichment ratio under the optimal conditions was 1.832.

[0061] Example 3 Microwave-assisted water extraction combined with foam separation to enrich Gleditsia saponins

[0062] The powder of Gleditsia sinensis shell was added to deionized water and stirred to form a suspension with a liquid-solid ratio of 20:1 (mL / g), heated for 120s at a microwave power of 600W, and filtered to obtain the Gleditsia sinensis shell water extract after standing for 30min. The yield of the surfactant extract was determined to be 59.48%.

[0063] According to the method of embodiment 2, microwave-coupled foam enrichment and separation is carried out, the above-mentioned gained Gleditsia husk water extract is placed in a microwave reaction furnace, the air pump is turned on, the gas flow rate is adjusted to 200mL / min, and the microwave oven is turned on to make its power 200W. Gas is passed from the lower end of the foam separation tube, and bubbles are produced through the glass orifice plate. Due to the surface activity of Gleditsia saponin, Gleditsia saponin is enriched in the foam and bubbles are made stable around the foam. Bubbles are constantly produced and move upwards, and form a foam layer in the upper liquid strata, and are finally collected by a foam collector, and its enrichment ratio is measured to be (1.623) through a perchloric acid-vanillin-glacial acetic acid colorimetric method.

[0064] Example 4 Microwave-assisted water extraction combined with foam separation to enrich Gleditsia saponins

[0065] Weigh the powder of Gleditsia sinensis shell, add deionized water and stir evenly to form a suspension with a liquid-to-solid ratio of 60:1 (mL / g), heat it at a microwave power of 1400W for 30s, let it stand for 30min, and then filter to obtain the Gleditsia sinensis shell water extract. The yield of its surface active extract was determined to be 58.60%.

[0066] According to the method of embodiment 2, microwave-coupled foam enrichment and separation was carried out, the above-mentioned obtained Gleditsia husk water extract was placed in a microwave reaction furnace, the air pump was turned on, the gas flow rate was adjusted to 600mL / min, and the microwave oven was turned on to make its power 600W. Gas was introduced from the lower end of the foam separation tube, and bubbles were generated through the glass orifice plate. Due to the surface activity of Gleditsia saponin, Gleditsia saponin was enriched around the foam and the bubbles became stable. Bubbles were continuously generated and moved upward, forming a foam layer on the upper layer of the liquid, and finally collected by the foam collector. Its enrichment ratio was (1.767) measured by the perchloric acid-vanillin-glacial acetic acid colorimetric method.

[0067] Comparative Example 1: Extraction of Gleditsia saponin by traditional hot reflux ethanol extraction method

[0068] The confirmation process of the optimal extraction conditions for extracting saponins from Gleditsia sinensis using the traditional hot reflux ethanol extraction method is as follows:

[0069] (1) Process and evaluation indicators

[0070] Weigh 100-mesh honey locust powder, add different volumes and concentrations of ethanol solutions respectively, stir evenly, reflux at a certain reflux extraction temperature for a certain time, and filter under reduced pressure to obtain a crude extract of the surfactant substance of the honey locust shell. After the crude extract of the surfactant substance of the honey locust shell is evaporated under reduced pressure, it is dried in an oven at 105°C until the quality is stable, and the yield of the surfactant extract of the honey locust shell is calculated. The yield of the surfactant extract is calculated as shown in formula (1).

[0071] Formula: W1 is the yield of the surfactant extract of Gleditsia sinensis husk, %. m is the weight of the Gleditsia sinensis husk powder, g. m1 is the weight of the round-bottom flask dried at 105° C., g. m2 is the total weight of the surfactant solids and the round-bottom flask dried at 105° C., g.

[0072] (2) Single factor test

[0073] Taking W1 as the evaluation index, the effects of four factors, namely ethanol concentration, reflux extraction temperature, liquid-to-solid ratio and reflux time, on W1 were investigated, and each reaction was performed three times in parallel.

[0074] (3) Response surface experiment

[0075] Through the experimental results of single-factor experiments, the experimental factors with no significant differences were eliminated, and the response surface experiment was carried out with ethanol concentration (E), liquid-to-solid ratio (F), and reflux time (G) as independent variables and W1 as the response value. The Box-Behnken design-response surface experiment was carried out using Design-Expert 8.

[0076] (4) Test results

[0077] Through the analysis of the response surface test results, the optimal extraction process conditions of the traditional hot reflux ethanol extraction method were obtained as follows: reflux time 60min, liquid-to-solid ratio 35:1 (mL / g), ethanol concentration 60%. Under these conditions, the W1 value predicted by Design-Expert8.0 was 64.13%.

[0078] After adjusting the optimal extraction process conditions according to the actual situation, three parallel tests were carried out, and the actual W1 was 63.59%, which was 0.8% relative to the model prediction value, indicating that the optimized process conditions were more reliable.

[0079] The confirmation process of the optimal extraction conditions for extracting saponins from Gleditsia sinensis by hydrothermal extraction is as follows:

[0080] (1) Process and evaluation indicators

[0081] Weigh 100-mesh soapberry powder, add different volumes of deionized water, extract at a certain temperature for a certain time, and filter under reduced pressure to obtain a crude extract of surfactant substances from soapberry shells. The water extract is concentrated by rotary evaporation, anhydrous ethanol is added, shaken and allowed to stand for 1 hour, and filtered into a round-bottom flask. This step can remove the ethanol-insoluble proteins and sugars in the soapberry shell water extract to obtain a preliminary purified crude extract of surfactant substances from soapberry shells. After the crude extract of surfactant substances from soapberry shells is evaporated under reduced pressure, it is dried in an oven at 105°C until the quality is stable, and the yield of surfactant extract from soapberry shells is calculated. The yield of surfactant extract is calculated as shown in formula (1).

[0082] (2) Single factor test

[0083] Taking W1 as the evaluation index, the effects of three factors, namely water extraction temperature, water extraction liquid-to-solid ratio and water extraction time, on W1 were investigated, and each reaction was carried out three times in parallel.

[0084] (3) Response surface experiment

[0085] Based on the experimental results of the single-factor experiment, the experimental factors with no significant difference were eliminated, and the response surface experiment was carried out with water extraction temperature (H), water extraction liquid-to-solid ratio (I), and water extraction time (J) as independent variables and W1 as the response value. The Box-Behnken design-response surface experiment was carried out using Design-Expert 8.

[0086] (4) Test results

[0087] Through the analysis of the response surface test results, the optimal extraction process conditions for extracting saponins by hydrothermal extraction were obtained as follows: extraction time 80min, extraction temperature 70℃, liquid-to-solid ratio 30:1 (mL / g). Under these conditions, the W1 value predicted by Design-Expert8.0 was 58.24%.

[0088] After adjusting the optimal extraction process conditions according to the actual situation, three parallel tests were carried out, and the actual W1 was measured to be 56.35%, with a relative deviation of 1.89% from the model prediction value, indicating that the optimized process conditions are more reliable.

[0089] Comparative Example 3 Microwave-assisted ethanol extraction of saponins from Gleditsia sinensis

[0090] The confirmation process of the optimal extraction conditions for extracting saponins from Gleditsia sinensis by microwave-assisted ethanol extraction is as follows:

[0091] (1) Process and evaluation indicators

[0092] Weigh the powder of Gleditsia sinensis shell and add different volumes of ethanol solutions of different concentrations, stir evenly, and microwave for a certain time. After the crude extract of the surfactant substance of the Gleditsia sinensis shell is concentrated under reduced pressure, it is dried in an oven at 105°C until the quality is stable, and the yield of the surfactant extract of the Gleditsia sinensis shell is calculated. The yield of the surfactant extract is calculated as shown in formula (1).

[0093] (2) Single factor test

[0094] Taking W1 as the evaluation index, the effects of ethanol concentration, microwave power, microwave time and liquid-to-solid ratio on W1 were explored, and each reaction was performed three times in parallel.

[0095] (3) Response surface experiment

[0096] The Box-Behnken response surface design experiment was carried out using Design-Expert 8.0.6, with microwave time (A), microwave power (B), liquid-to-solid ratio (C), and ethanol concentration (D) as the experimental factors and W1 as the response value.

[0097] (4) Test results

[0098] The results of response surface test showed that the optimal extraction process conditions were as follows: microwave time 57s, microwave power 800W, liquid-to-solid ratio 35:1 (mL / g), and ethanol concentration 60%. The predicted W1 value under these conditions was 65.74%. Due to the limitations of the microwave device, the microwave time of the extraction process was adjusted to 60s. Three parallel tests were conducted based on the adjusted optimal extraction process conditions, and the W1 was determined to be 64.44%, with a relative error of 1.30% with the model prediction value, indicating that the optimized process conditions are more reliable.

[0099] Comparative Example 4: Enrichment of Gleditsia saponins by conventional hot reflux ethanol extraction combined with foam separation

[0100] (1) Quantification of Gleditsia saponins and enrichment ratio test

[0101] According to the method described in Example 2, the crude extract of surfactant substances from the husk of Gleditsia sinensis obtained by the optimal process adjusted in Comparative Example 1 was used as the original feed liquid for foam separation by the perchloric acid-vanillin-glacial acetic acid color development method. At this time, the microwave oven ⑥ was replaced by a water bath heating pot.

[0102] The reaction vessel is placed in a water bath with different temperatures for heating, the air pump is turned on, and the gas flow meter is adjusted to change the gas flow rate. The gas is introduced from the lower end of the foam separation tube and bubbles are generated through the glass orifice plate. Due to the surface activity of saponin, saponin is enriched around the foam to stabilize the bubbles. Bubbles are continuously generated and move upward, forming a foam layer on the upper layer of the liquid, and finally collected by the foam collector. However, due to the defoaming effect of ethanol, the adsorption performance of saponin on the bubble surface is reduced, and the foaming speed is slowed down. The surface foam separation and enrichment method of saponin uses the enrichment ratio as the evaluation index, and its calculation is shown in formula (2).

[0103] (2) Orthogonal experiment and its results

[0104] Taking the water bath temperature (K) and gas flow rate (L) as the experimental investigation factors, the optimal conditions tested by orthogonal experiment were 65°C and 300mL / min. The enrichment ratio under the optimal conditions was 1.136. Comparative Example 5: Enrichment of Gleditsia saponins by hydrothermal extraction combined with foam separation

[0105] (1) Quantification of Gleditsia saponins and enrichment ratio test

[0106] According to the method described in Example 2, the crude extract of surfactant substances from the husk of Gleditsia sinensis obtained by the optimal process adjusted in Comparative Example 2 was used as the original feed liquid for foam separation by a perchloric acid-vanillin-glacial acetic acid colorimetric method.

[0107] Place the reaction vessel in a water bath at different temperatures, turn on the air pump, and adjust the gas flowmeter to change the gas flow rate. The gas is introduced from the lower end of the foam separation tube and bubbles are generated through the glass orifice plate. Due to the surface activity of saponin, saponin is enriched around the foam to stabilize the bubbles. Bubbles are continuously generated and move upward, forming a foam layer on the upper layer of the liquid, and finally collected by the foam collector. The foam separation enrichment method uses the enrichment ratio as an evaluation index, and its calculation is shown in formula (2).

[0108] (2) Orthogonal experiment and its results

[0109] Taking the water bath temperature (K) and gas flow rate (L) as the experimental factors, the optimal conditions tested by orthogonal experiment were 70°C and 300mL / min. The enrichment ratio under the optimal conditions was 1.358. Comparative Example 6 Microwave-assisted ethanol extraction combined with foam separation to enrich saponins from Gleditsia sinensis

[0110] (1) Quantification of Gleditsia saponins and enrichment ratio test

[0111] According to the method described in Example 2, the crude extract of surfactant substances in the husk of Gleditsia sinensis obtained by the optimal process adjusted in Comparative Example 3 was used as the original feed liquid for foam separation by perchloric acid-vanillin-glacial acetic acid color development method.

[0112] Place the reaction container in a microwave oven, turn on the air pump, adjust the gas flowmeter to change the gas flow rate, and turn on the microwave power to the rated power. The gas is introduced from the lower end of the foam separation tube and bubbles are generated through the glass orifice plate. Due to the surface activity of saponin, saponin is enriched around the foam to stabilize the bubbles. Bubbles are continuously generated and move upward, forming a foam layer on the upper layer of the liquid, and finally collected by the foam collector. The foam separation enrichment method uses the enrichment ratio as the evaluation index, and its calculation is shown in formula (2).

[0113] (2) Orthogonal test

[0114] Through the experimental results of single-factor experiments, the experimental factors with no significant differences were eliminated, and the gas flow rate (L) and microwave power (M) were used as the independent variable E as the response value. The Box-Behnken design-response surface experiment was carried out using Design-Expert 8 and the experimental results were analyzed.

[0115] (3) Test results

[0116] Through the analysis of the response surface test results, the optimal extraction process conditions for microwave-assisted ethanol extraction combined with foam separation of saponins from Gleditsia sinensis were obtained as follows: gas flow rate 450 mL / min, microwave power 400 W. The enrichment ratio under the optimal conditions was 1.223.

[0117] Combining the results of the embodiments and comparative examples, it can be seen that the present invention utilizes microwave-assisted water extraction combined with foam separation and enrichment method to extract saponins. In the microwave-assisted water heating stage, the yield of the obtained surfactant extract (the main component is saponin) is 57% or more, which is close to the traditional method (Comparative Examples 1 to 3). The enrichment ratio of saponins obtained in the foam separation and enrichment stage reaches 1.6 or more, and the highest is as high as 1.832. The enrichment ratios of the traditional hot reflux ethanol extraction method (Comparative Example 4), the hydrothermal extraction method (Comparative Example 5), and the microwave-assisted alcohol extraction method (Comparative Example 6) combined with the foam separation and enrichment method are 1.136, 1.358 and 1.223, respectively, which are relatively low.

[0118] It can be seen from the above results that the present invention utilizes microwave-assisted water extraction combined with foam separation and enrichment method to perform microwave-assisted water heating on the crushed saponin, which effectively promotes the leaching of saponin, and the extraction rate of its surface active components (the main component is saponin) is close to that of the traditional ethanol extraction method, while its extraction time (<1min) is much shorter than the extraction time (80min) required by the traditional hot reflux ethanol extraction method (60min) and the hot water extraction method, and avoids the use of organic solvents. The foam separation and enrichment method is further combined, and the extract obtained by the microwave-assisted water extraction method is used as the original feed liquid for foam separation. Microwave heating can enhance the extraction of saponin. The adsorption rate on the bubble surface is increased, and the viscosity of the solution is reduced, so that the amount of interstitial fluid carried by the bubbles is reduced, thereby improving the enrichment ratio; in addition, saponin is an amphiphilic polar molecule, which undergoes intramolecular vibration under the action of microwaves, which can further increase its adsorption rate on the bubble surface and further improve the enrichment ratio. The enrichment ratio can reach 1.6 or above, which is significantly higher than the enrichment ratios of traditional hot reflux ethanol extraction method (Comparative Example 4, the enrichment ratio is 1.136), hydrothermal extraction method (Comparative Example 5, the enrichment ratio is 1.358), and microwave-assisted alcohol extraction method (Comparative Example 6, the enrichment ratio is 1.223) respectively combined with foam separation enrichment method.

[0119] The above embodiments are preferred implementation modes of the present invention, but the implementation modes of the present invention are not limited to the above embodiments. Any other changes, modifications, substitutions, combinations, and simplifications that do not deviate from the spirit and principles of the present invention should be equivalent replacement methods and are included in the protection scope of the present invention.

Claims

1. A microwave-combined foam separation and enrichment device, characterized in that: The invention comprises an air pump (1), a buffer device (3), an airflow meter (4), a reaction container (5), a microwave device (6), a foam separation device (7) and a foam collector (8), wherein the air pump (1), the buffer device (3), the airflow meter (4), the foam separation device (7) and the foam collector (8) are connected in sequence via a gas pipeline (2); the foam separation device (7) is directly connected to the microwave device (6) via an opening; a reaction container (5) is arranged in the microwave device (6), and a feed port (9) of the foam separation device (7) is connected to the inner space of the reaction container (5).

2. Application of the microwave-coupled foam separation and enrichment device according to claim 1 in the field of separation and purification.

3. A method for separating saponins by microwave-assisted water extraction combined with foam, characterized in that: The microwave-combined foam separation and enrichment device according to claim 1 is used to extract saponins.

4. A method for separating saponins by microwave-assisted water extraction combined with foam, characterized in that: The steps include: S1. Add the saponin-containing raw material to water, mix well, perform microwave extraction under microwave conditions, and post-treat to obtain a crude saponin extract; S2. The crude saponin extract obtained in step S1 is used as the original feed solution for foam separation, and foam separation is performed under microwave conditions to obtain a saponin enriched solution.

5. The method according to claim 4, characterized in that: In step S1, the microwave power of the microwave extraction is 500-2000W.

6. The method according to claim 4, characterized in that: In step S1, the microwave extraction time is ≤5 min.

7. The method according to claim 4, characterized in that: In step S1, the mass ratio of the saponin-containing raw material to water is 1: (10-80) g / mL.

8. The method according to claim 4, characterized in that: In step S2, the microwave power for foam separation is 100-800W.

9. The method according to claim 4, characterized in that: In step S2, the gas flow rate of the foam separation is 50 to 1000 mL / min.

10. The method according to any one of claims 4 to 9, characterized in that: Step S1 and step S2 are carried out using the microwave-combined foam separation and enrichment device described in claim 1.

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