Dual-frequency ultrasonic-assisted extraction method of ficoll polysaccharide and application

Abstract

The application discloses a double-frequency ultrasonic-assisted extraction method of fig polysaccharide and application, and belongs to the technical field of natural product extraction. The method comprises the following steps: S1, preparing an ethanol solution of fig powder; S2, placing the solution in a double-frequency ultrasonic device for ultrasonic-assisted extraction, and the ultrasonic conditions comprise the following: an ultrasonic frequency of 40 kHz and 25 kHz, an ultrasonic power of 345-525 W, and an ultrasonic time of 4-12 min; and S3, obtaining fig polysaccharide extract after filtration. The method is an efficient, rapid and simple fig polysaccharide extraction method, and is particularly suitable for an industrialized production scene with strict requirements on extraction time, and the extracted fig polysaccharide has good in-vitro antioxidant activity, can be used for preparing antioxidant-related functional food, medicine and cosmetics, and has a good development prospect in the field of health products.

Description

Technical Field

[0001] This invention belongs to the field of natural product extraction technology, specifically relating to a dual-frequency ultrasound-assisted extraction method for fig polysaccharides and its application. Background Technology

[0002] The fig (Ficus carica L.) is a plant belonging to the genus Ficus in the family Moraceae. Also known as the "tomorrow's fruit," "honey fruit," or "hidden fig," it originated in Central Asia and the Mediterranean coast of Europe and is one of the oldest tree species in the world. Figs are widely cultivated in my country, mainly distributed in Xinjiang, Jiangsu, Shandong, and Zhejiang provinces, with southern Xinjiang being particularly famous. Figs can be eaten and used medicinally, possessing properties such as strengthening the stomach and intestines, reducing swelling and detoxifying, dispelling rheumatism, and preventing cancer. It is a natural health-promoting fruit with both edible and medicinal uses. Studies have shown that figs have excellent therapeutic effects, being rich in polysaccharides, flavonoids, superoxide dismutase (SOD), and furanocoumarin lactones. Fig polysaccharides (FCPs) are an important functional active ingredient that has received widespread attention in recent years due to their natural, safe, and non-toxic characteristics. Numerous studies have revealed that fig polysaccharides possess a variety of biological activities, including antioxidant, anti-inflammatory, anti-tumor, immunomodulatory, and hypoglycemic effects.

[0003] Polysaccharide extraction methods include hot water extraction, ultrasound-assisted extraction, microwave-assisted extraction, and enzymatic hydrolysis. Hot water reflux extraction is simple to operate and requires no special equipment, but it is gradually being phased out due to its energy consumption, time-consuming nature, and low polysaccharide yield. Microwave extraction is fast and has a high yield, but the violent reaction and high system temperature during microwave extraction can cause partial polysaccharide decomposition, and the resulting polysaccharides have poor antioxidant capacity. Enzymatic methods offer high yields and fast extraction speeds, but they are sensitive to environmental conditions such as temperature and acidity, requiring strict control. Ultrasonic extraction, with its simple equipment, mild extraction conditions, and high yield, is favored by many researchers. Ultrasonic-assisted extraction technology utilizes the thermal, mechanical vibration, and cavitation effects of ultrasound to rapidly break down plant cell walls, promoting the rapid release of active ingredients. Depending on the mode of action, ultrasound can produce two different effects on the sample: direct effects and indirect effects. Dual-frequency ultrasound can catalyze more bubbles, generating a stronger cavitation effect, while effectively overcoming cavitation shielding and avoiding problems such as uneven energy distribution and large standing wave area inherent in single-frequency ultrasound. This significantly improves the yield of plant polysaccharides and enhances their bioactivity. However, research on dual-frequency ultrasound-assisted extraction processes for fig polysaccharides is still in its early stages, especially regarding various key process parameters. Therefore, developing a simple, efficient, and parameter-defined dual-frequency ultrasound-assisted extraction method is of great significance for promoting the development of fig functional foods and related industries. Summary of the Invention

[0004] This invention provides a dual-frequency ultrasound-assisted extraction method and application for fig polysaccharides, aiming to solve the problems of the prior art.

[0005] The dual-frequency ultrasound-assisted extraction method for fig polysaccharides according to the present invention includes the following steps: S1. Prepare an ethanol solution of fig powder; S2. Place the above solution in a dual-frequency ultrasonic device for ultrasonic-assisted extraction. The ultrasonic conditions include: ultrasonic frequency of 40kHz and 25kHz, ultrasonic power of 345-525W, and ultrasonic time of 4-12min. S3. After filtration, a fig polysaccharide extract is obtained.

[0006] Specifically, in step S1, the liquid-to-solid ratio of fig powder to ethanol is 10-50 mL / g; preferably, the liquid-to-solid ratio is 25-40 mL / g; and most preferably, the liquid-to-solid ratio is 28 mL / g.

[0007] Specifically, in step S2, preferably, the ultrasonic power is 435-525W; most preferably, the ultrasonic power is 480W.

[0008] Specifically, in step S2, preferably, the ultrasound time is 8-12 min; most preferably, the ultrasound time is 10.1 min.

[0009] The present invention also provides a fig polysaccharide extracted by the above method, which exhibits significant activity in in vitro antioxidant activity tests and has the potential to be used as a natural antioxidant.

[0010] This invention also provides an application of the above-mentioned fig polysaccharide as an antioxidant, which can be used to prepare antioxidant-related functional foods, pharmaceuticals and cosmetics, and has good development prospects in the field of health products.

[0011] The beneficial effects of this invention are as follows: 1. The dual-frequency ultrasound-assisted extraction method of the present invention has an extraction rate of up to 69.59±0.51%, which is not only far superior to traditional hot water extraction (8.52%) and compound enzyme method (7.98%), but also significantly higher than subcritical water extraction (56.48%) and existing single-frequency ultrasound-assisted technology (up to 41.58%), thus achieving efficient extraction of polysaccharide components.

[0012] 2. Compared with traditional processes that take several hours, the method of this invention significantly shortens the operation time, requires no high temperature and high pressure, and does not require the addition of chemical reagents or biological enzymes. The process is simpler and safer, easier to scale up industrially, and significantly improves extraction efficiency.

[0013] 3. The fig polysaccharides extracted by the method of this invention have been shown to have significant in vitro antioxidant activity, proving that the method of this invention can effectively preserve the biological activity of natural products, providing a good foundation for their application in functional foods, pharmaceuticals and cosmetics. Attached Figure Description

[0014] Figure 1 : Glucose standard curve.

[0015] Figure 2 Figure: Effect of ultrasound time on the extraction rate of fig polysaccharides.

[0016] Figure 3 Figure: Effect of liquid-to-solid ratio on fig polysaccharide extraction rate.

[0017] Figure 4 Figure: Effect of ultrasonic power on the extraction rate of fig polysaccharides.

[0018] Figure 5 Contour plot (A) and 3D response surface plot (B) showing the effects of ultrasonic time and liquid-to-solid ratio on extraction rate; Contour plot (C) and 3D response surface plot (D) showing the effects of ultrasonic time and ultrasonic power on extraction rate; Contour plot (E) and 3D response surface plot (F) showing the effects of liquid-to-solid ratio and ultrasonic power on extraction rate.

[0019] Figure 6 Figure: DPPH free radical scavenging test results of fig polysaccharides.

[0020] Figure 7 Figure: ABTS free radical scavenging test results of fig polysaccharides.

[0021] Figure 8 Figure: Results of hydroxyl radical scavenging test of fig polysaccharides.

[0022] Figure 9 Figure: Results of iron reducing power test for fig polysaccharides. Detailed Implementation

[0023] The present invention will now be described in detail with reference to specific embodiments.

[0024] As used herein, the terms “prepared from” and “comprising” are synonymous. The terms “comprising,” “including,” “having,” “containing,” or any other variations thereof, as used herein, are intended to cover non-exclusive inclusion. For example, a composition, step, method, article, or apparatus that includes the listed elements is not necessarily limited to those elements, but may include other elements not expressly listed or elements inherent to such composition, step, method, article, or apparatus.

[0025] When a mass, concentration, temperature, time, or other value or parameter is expressed as a range, a preferred range, or a range defined by a series of upper and lower preferred values, it should be understood as specifically disclosing all ranges formed by any pair of any upper or preferred value with any lower or preferred value, regardless of whether the range is disclosed individually. For example, the range 1-50 should be understood to include any number, combination of numbers, or subranges selected from 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, 30, 31, 32, 33, 34, 35, 36, 37, 38, 39, 40, 41, 42, 43, 44, 45, 46, 47, 48, 49, or 50, as well as all decimal values ​​between the integers mentioned above, such as 1.1, 1.2, 1.3, 1.4, 1.5, 1.6, 1.7, 1.8, and 1.9. Regarding subranges, specifically consider "nested subranges" extending from any endpoint of the range. For example, nested sub-ranges of the exemplary range 1-50 may include 1-10, 1-20, 1-30 and 1-40 in one direction, or 50-40, 50-30, 50-20 and 50-10 in another direction.

[0026] The singular form includes the plural objects of discussion unless the context clearly indicates otherwise. "Optional" or "any one" means that the matter or event described thereafter may or may not occur, and the description includes both the possibility that the event occurs and the possibility that the event does not occur.

[0027] Approximate terms used in the specification and claims to modify quantities indicate that the invention is not limited to that specific quantity, but also includes acceptable modifications close to that quantity that do not alter the relevant essential function. Correspondingly, the use of "about," "approximately," etc., to modify a numerical value means that the invention is not limited to that precise value. In some instances, approximate terms may correspond to the precision of the instrument used to measure the value. In this application's specification and claims, scope definitions can be combined and / or interchanged, unless otherwise stated, these scopes include all subscopes contained therein.

[0028] Furthermore, the indefinite articles “a” and “an” preceding the elements or components of this invention do not impose any limitation on the quantity requirement (i.e., the number of times) of the elements or components. Therefore, “an” or “a” should be interpreted as including one or at least one, and the singular form of an element or component also includes the plural form, unless the quantity clearly refers to the singular form.

[0029] The present invention will be further described below with reference to specific embodiments.

[0030] In this embodiment of the invention, a series of glucose standard solutions of different concentrations were prepared. The standard curve of glucose was determined by the phenol-concentrated sulfuric acid method, and the linear relationship between its concentration and absorbance was investigated. The specific method is as follows: 10.0 mg of glucose was accurately weighed, dissolved in deionized water, and diluted to 10.0 mL to prepare a glucose standard solution with a mass concentration of 0.1 mg / mL. Then, 0.2, 0.4, 0.6, 0.8, 1.0, and 1.2 mL of the glucose standard solution were respectively placed in test tubes, diluted to 2.0 mL with distilled water, and shaken well. Using distilled water as a blank control, 1.0 mL of 5% phenol solution was added to a test tube, shaken well, and then 5.0 mL of concentrated sulfuric acid was slowly added along the wall. After shaking well, the solution was allowed to stand for 20 min, and the absorbance was measured at 490 nm. The standard curve is shown below. Figure 1 As shown, from Figure 1 As can be seen, glucose exhibits good linearity within the concentration range of 0.01-0.06 mg / mL, with the standard equation being y = 9.6619x - 0.0161, R0. 2 =0.9996.

[0031] Example 1: This example 1 prepared a series of fig polysaccharide extracts under different ultrasonic times (4, 6, 8, 10, 12 min). The specific preparation steps are as follows: S1. Preparation of ethanol solution of fig powder: Fresh figs (harvested from Xinjiang) were washed, air-dried, and then pulverized using a pulverizer. After passing through a 40-mesh sieve, 1.0 g of fig powder was mixed with 30 mL of ethanol to prepare an ethanol solution of fig powder with a liquid-to-solid ratio of 30 mL / g; S2. The above solution was placed in a dual-frequency ultrasonic device (KQ-600DE type CNC ultrasonic cleaner) for ultrasonic-assisted extraction. The ultrasonic conditions were: ultrasonic frequency 40 kHz and 25 kHz, ultrasonic power 480 W (300 W for fixed tank ultrasonic and 180 W for changing probe ultrasonic), and ultrasonic times of 4, 6, 8, 10, and 12 min, respectively; S3. The extract was centrifuged at 5500 rpm for 10 min, filtered, and the series of fig polysaccharide extracts of Example 1 were obtained.

[0032] The extraction rate of fig polysaccharides in Example 1 above was calculated, and the results are as follows: Figure 2 As shown, the extraction rate of fig polysaccharides initially increased and then decreased with increasing ultrasonic time, reaching a maximum extraction rate of 68.25% at 10 minutes. This indicates that as ultrasonic time increases, fig polysaccharides continuously diffuse into the solvent. However, with excessively long ultrasonic times, the ultrasonic shearing effect degrades the fig polysaccharides. Furthermore, the thermal effect caused by this process may raise the solution temperature, leading to further degradation of the fig polysaccharides. Therefore, the optimal ultrasonic time is 10 minutes.

[0033] Example 2: In this example, a series of fig polysaccharide extracts with different liquid-to-solid ratios (10, 20, 30, 40, 50 mL / g) were prepared. The specific preparation steps are as follows: S1. Preparation of ethanol solutions of fig powder: Fresh figs (harvested from Xinjiang) were washed, air-dried, and then pulverized with a pulverizer. After passing through a 40-mesh sieve, 1.0 g of fig powder was mixed with ethanol to prepare a series of fig powder ethanol solutions with liquid-to-solid ratios of 10, 20, 30, 40, 50 mL / g. S2. The above solutions were placed in a dual-frequency ultrasonic device (KQ-600DE type CNC ultrasonic cleaner) for ultrasonic-assisted extraction. The ultrasonic conditions were: ultrasonic frequency 40kHz and 25kHz, ultrasonic power 480W (300W for fixed tank ultrasonic and 180W for changing probe ultrasonic), and ultrasonic time 10min. S3. The extract was centrifuged at 5500rpm for 10min and filtered to obtain a series of fig polysaccharide extracts of Example 2.

[0034] The extraction rate of fig polysaccharides in Example 2 above was calculated, and the results are as follows: Figure 3 As shown, the extraction rate of fig polysaccharides generally increased and then decreased with the increase of the liquid-to-solid ratio, reaching a peak of 69.12% at 30 mL / g. Subsequently, the extraction rate of FCPs began to decline as the liquid-to-solid ratio continued to increase. This may be because at low liquid-to-solid ratios, the solvent is insufficient to fully wet the material, making it difficult for polysaccharide molecules to be released from the cell structure. Increasing the liquid-to-solid ratio increases the solvent volume, reduces the immediate concentration of polysaccharides in the solvent, strengthens the concentration gradient inside and outside the cell, and accelerates the diffusion process. In addition, an appropriate liquid-to-solid ratio results in moderate solvent viscosity and good fluidity, which is conducive to maximizing the mass transfer efficiency of polysaccharide molecules at the solid-liquid interface. However, excessive solvent may cause excessive swelling of plant cells, thereby blocking the polysaccharide release channels. Furthermore, an excessively high liquid-to-solid ratio will disperse the ultrasonic energy density, reduce the cavitation effect, and weaken the cell disruption effect. Therefore, the optimal liquid-to-solid ratio is 30 mL / g.

[0035] Example 3: In this example, a series of fig polysaccharide extracts were prepared under different ultrasonic powers (345, 390, 435, 480, 525 W). The specific preparation steps are as follows: S1. Preparation of ethanol solution of fig powder: Fresh figs (harvested from Xinjiang) were washed, air-dried, and then pulverized using a pulverizer. After passing through a 40-mesh sieve, 1.0 g of fig powder was mixed with 30 mL of ethanol to prepare an ethanol solution of fig powder with a liquid-to-solid ratio of 30 mL / g; S2. The above solution was placed in a dual-frequency ultrasonic device (KQ-60) respectively. Ultrasonic extraction was performed using an ODE type CNC ultrasonic cleaner. The ultrasonic conditions were as follows: ultrasonic frequencies of 40kHz and 25kHz, ultrasonic powers of 345, 390, 435, 480, and 525W (300W for fixed tank ultrasonic and 45W, 90W, 135W, 180W, and 225W for changing probe ultrasonic), and ultrasonic time of 10min. S3. The extract was centrifuged at 5500rpm for 10min and filtered to obtain a series of fig polysaccharide extracts of Example 3.

[0036] The extraction rate of fig polysaccharides in Example 3 above was calculated, and the results are as follows: Figure 4 As shown, the extraction yield of fig polysaccharides initially increased and then decreased as the ultrasonic power increased from 345W to 480W. Appropriate ultrasonic power can disrupt the plant's cell walls, thereby promoting the rapid and abundant release of polysaccharides from the cells within a short period. Conversely, excessive ultrasonic power generates a strong ultrasonic shearing effect and releases a large amount of heat, causing polysaccharide degradation and reducing the overall extraction content. Therefore, the optimal ultrasonic power is 480W.

[0037] Example 4: Optimization of dual-frequency ultrasonic extraction process of fig polysaccharides using response surface methodology.

[0038] In this example, Example 4 uses ultrasonic time, liquid-to-solid ratio, and ultrasonic power as independent variables, and polysaccharide extraction rate as the response value. A three-factor, three-level Box-Behnken experiment was designed using Design-Expert 10.0.1 software to prepare a series of fig polysaccharide extracts under different factors (ultrasonic power, liquid-to-solid ratio, ultrasonic time). The specific preparation steps are as follows: S1. Preparation of ethanol solutions of fig powder: Fresh figs (harvested in Xinjiang) are washed, naturally dried, and then pulverized using a pulverizer. After passing through a 40-mesh sieve, 1.0g of fig powder is mixed with ethanol to prepare fig powder ethanol solutions with different liquid-to-solid ratios (20, 30, 40mL / g); S2. The above solutions are then... The extract was placed in a dual-frequency ultrasonic device (KQ-600DE type CNC ultrasonic cleaner) for ultrasonic-assisted extraction. The ultrasonic conditions were: ultrasonic frequency 40kHz and 25kHz, ultrasonic power 435, 480, and 525W respectively (300W for fixed tank ultrasonic and 135W, 180W, and 225W for changing probe ultrasonic), and ultrasonic time 8, 10, and 12 min. S3. The extract was centrifuged at 5500 rpm for 10 min and filtered to obtain a series of fig polysaccharide extracts of Example 4.

[0039] The test factors and levels are shown in Table 1, and the test scheme and test results are shown in Table 2. A total of 17 groups were tested, of which 12 groups were three-dimensional factorial points composed of ultrasonic time, liquid-to-material ratio and ultrasonic power independent variables at different levels, and the remaining 5 groups were response surface center repeat experimental points.

[0040] Table 1: Test factors and levels of fig polysaccharides

[0041] Table 2: Response Surface Experiment Design and Test Results

[0042] The data in Table 2 were fitted, and the fitting results are shown in Table 3 below. The model shows a low P-value (<0.0001, highly significant) and a high F-value (61.26), confirming that the quadratic polynomial fitting equation is ideal and that the model has high significance. The lack-of-fit term (P=0.4011 >0.05) is not significant, indicating that it has a good variance fit and small error, verifying the feasibility of the established regression model. In addition, the R-value of this model is... 2 The value is 0.9875, R 2The adj value is 0.9713, indicating that the model fits the experimental results well, and the deviation between the actual results and the predicted values ​​is small. Furthermore, the precision (Adeq Precisior) is as high as 23.143, all of which demonstrate that the model has good correlation and the experimental design is feasible. Meanwhile, the results show that A, B, C, and A... 2 B 2 C 2 The effect on polysaccharide extraction rate was significant (P < 0.05), and the significance of C was higher than that of A and B. Therefore, the order of polysaccharide extraction strength was: liquid-to-solid ratio > ultrasonic time > ultrasonic power. The quadratic model fitted by this invention is highly significant and effective.

[0043] The regression equation is as follows: Y=68.94+3.27A-2.27B-4.39C+3.84AB+4.66AC-2.15BC-15.64A 2 -9.40B 2 - 8.61C 2 (A: Ultrasonic time, B: Liquid-to-material ratio, C: Ultrasonic power) Table 3: Multiple Regression Fit Analysis

[0044] Note: ns, not significant; **, significant and p < 0.001; *, significant and p < 0.05. (Notes lacking *** need to be modified to correspond with those in the table.) Figure 5 Two-dimensional contour plots (A, C, E) and three-dimensional response surface plots (B, D, F) are shown for dual-frequency ultrasound-assisted extraction of fig polysaccharides. The slope of the response surface plots determines the influence of these two factors on the response values; a larger slope indicates a more significant interaction between the two factors. It can be seen that the contour plot of the BC interaction does not show a clear ellipse shape, but is closer to a circle, indicating that their interaction is not significant, consistent with the results of the analysis of variance. The interaction plots of AB and AC in the figure are nearly elliptical, indicating that their interaction is significant.

[0045] Differentiating the model equations and finding the extreme values, the optimal extraction conditions for fig polysaccharides under the coordination of three factors were determined to be: ultrasonic time 10.12 min, liquid-to-solid ratio 27.73 mL / g, ultrasonic power 476.31 W, and extraction rate 69.630%. Considering actual production factors, the optimal ultrasonic time for the dual-frequency ultrasonic-assisted extraction method of fig polysaccharides described in this invention is 10.1 min, liquid-to-solid ratio 28 mL / g, and ultrasonic power 480 W.

[0046] The present invention will be further described below with reference to application examples.

[0047] Application Example 1: Extraction of fig polysaccharides using a dual-frequency ultrasound-assisted extraction method Example 1 of this application uses a dual-frequency ultrasonic-assisted extraction method to extract fig polysaccharides. The specific steps are as follows: S1. Prepare an ethanol solution of fig powder: Wash fresh figs (harvested from Xinjiang), air dry them, then crush them with a pulverizer. After passing through a 40-mesh sieve, take 1.0g of fig powder and mix it with 28mL of ethanol to prepare an ethanol solution of fig powder with a liquid-to-solid ratio of 28mL / g; S2. Place the above solution in a dual-frequency ultrasonic device (KQ-600DE type CNC ultrasonic cleaner) for ultrasonic-assisted extraction. The ultrasonic conditions are: ultrasonic frequency 40kHz and 25kHz, ultrasonic power 480W (300W for fixed tank ultrasonic and 180W for changing probe ultrasonic), and ultrasonic time 10.1min; S3. Centrifuge the extract at 5500rpm for 10min, filter, and obtain the fig polysaccharide extract of Example 1.

[0048] Comparative Example 1: Extraction of fig polysaccharides by hot water extraction Comparative Example 1 uses hot water extraction to extract fig polysaccharides. The specific steps are as follows: the temperature is 100℃, the material-to-liquid ratio is 1:12, the extraction is performed twice, and the extraction time is 3 hours.

[0049] Comparative Example 2: Extraction of fig polysaccharides using ultrasound-assisted extraction method Comparative Example 2 uses ultrasound-assisted extraction to extract fig polysaccharides. The specific steps are as follows: 1. Solid-liquid ratio is 1:20 (g / mL), ultrasound temperature is 70℃, ultrasound time is 25min, and ultrasound-assisted extraction is performed four times. 2. Extraction time is 50min, extraction temperature is 75℃, and ultrasound power is 300W.

[0050] Comparative Example 3: Microwave-assisted extraction of fig polysaccharides Comparative Example 3 uses microwave-assisted extraction to extract fig polysaccharides. The specific steps are as follows: the material-to-liquid ratio is 1:10 (g / ml), the extraction time is 20 min, the microwave power is 556 W, and the pH value is 8.2.

[0051] Comparative Example 4: Extraction of fig polysaccharides using a compound enzyme extraction method Comparative Example 4 uses a compound enzyme extraction method to extract fig polysaccharides. The specific steps are as follows: the mass fractions of pectinase, papain, and cellulase are 1.5%, 1.5%, and 0.5%, respectively; the material-to-liquid ratio is 1:40 (g:mL); the extraction time is 54 min; the extraction temperature is 34℃; and the pH is 3.8.

[0052] Comparative Example 5: Extraction of fig polysaccharides by subcritical water extraction Comparative Example 5 uses subcritical water extraction to extract fig polysaccharides. The specific steps are as follows: extraction time 17 min, extraction temperature 150℃, material-to-liquid ratio 1:30 (g / mL), and extraction pressure 1.5 MPa.

[0053] Comparative Example 6: Extraction of fig polysaccharides using an aqueous two-phase solvent-ultrasonic extraction method Comparative Example 6 uses an aqueous two-phase solvent-ultrasonic extraction method to extract fig polysaccharides. The specific steps are as follows: 12% PEG and 16% (NH4)2SO4 are used as the aqueous two-phase extraction solvent, the material-liquid ratio is 1:22 (g / mL), the ultrasonic power is 360W, the ultrasonic time is 25min, and the ultrasonic extraction temperature is 50℃.

[0054] Comparative Example 7: Extraction of fig polysaccharides using ultrasound-microwave assisted extraction method Comparative Example 7 used an ultrasonic-microwave assisted extraction method to extract fig polysaccharides. The specific steps were as follows: ultrasonic treatment time 21.35 minutes, microwave power 580.9 watts, irradiation time 11.67 minutes, and solid-liquid ratio 24.66 mL / g.

[0055] Comparative Example 8: Extraction of fig polysaccharides by supercritical carbon dioxide extraction Comparative Example 8 used supercritical carbon dioxide extraction to extract fig polysaccharides. The specific steps are as follows: fig polysaccharides were extracted at 78.5℃, 33.4 MPa, and for 96.2 min. (Complete steps are required for the above test method.) The extraction rates of Application Example 1 and Comparative Examples 1-8 were tested, and their process efficiency was analyzed. The results are shown in Table 4 below: Table 4: Extraction Rate and Efficiency Analysis of Fig Polysaccharide Extraction Process

[0056] The above results demonstrate that the dual-frequency ultrasound-assisted method described in this invention stands out as the optimal process choice in this field due to its superior extraction efficiency and industrialization potential. After precise optimization using a response surface methodology and fine-tuning based on actual production needs, the method achieves an extraction rate as high as 69.59 ± 0.51%. This figure not only far exceeds that of traditional hot water extraction (8.52%) and compound enzyme extraction (7.98%), but also significantly outperforms subcritical water extraction (56.48%) and single-frequency ultrasound-assisted technology (up to 41.58%). In addition to its extremely high yield, the dual-frequency ultrasound-assisted method also exhibits an absolute advantage in production efficiency, completing the extraction process in just 10.1 minutes. Compared to traditional processes that take several hours or supercritical carbon dioxide extraction that takes nearly 100 minutes, this greatly reduces time costs and improves equipment turnover. Furthermore, this process operates under relatively mild atmospheric pressure, avoiding the harsh conditions of high temperature and high pressure required for subcritical water or supercritical extraction, making it more equipment-friendly and safer. The liquid-to-solid ratio and power settings have been scientifically verified, achieving a balance between solvent consumption and energy input. In summary, the dual-frequency ultrasonic-assisted method minimizes energy consumption and time costs while ensuring extremely high extraction rates, fully embodying the core concepts of "high efficiency, energy saving, and precision" in modern green chemistry. It has extremely high scientific research reference value and broad prospects for industrial application.

[0057] The present invention also conducted an in vitro antioxidant test on the fig polysaccharide extract prepared in the above application example 1. The test method is as follows: 1,1-Diphenyl-2-trinitrophenylhydrazine (DPPH) radical scavenging test: Prepare sample solutions of different concentrations (1.0, 1.5, 2.0, 2.5, 3.0 mg / mL). Take 2 mL of each solution into a 5 mL test tube, add 2 mL of DPPH solution (0.1 mmol / L), mix well, and react in the dark for 30 min. Measure the absorbance at 517 nm using a UV-Vis spectrophotometer. Using ascorbic acid (VC) as a positive control, the DPPH free radical scavenging rate is calculated using the following formula:

[0058] A1 is the absorbance of the sample after mixing with DPPH, A2 is the absorbance of the sample solution, and A0 is the absorbance of the DPPH solution.

[0059] 2,2'-Aza-bis-3-ethylbenzothiazoline-6-sulfonic acid (ABTS) radical scavenging test: Mix 7.4 mmol / L ABTS solution with 2.5 mmol / L potassium persulfate solution at a 1:1 ratio, and incubate in the dark for 12-16 hours to obtain ABTS• + Dilute the solution to a absorbance of 0.7 ± 0.02 at 734 nm for later use. Prepare sample solutions of different concentrations (1.0, 2.0, 3.0, 4.0, 0.5 mg / mL), take 1 mL in a 5 mL test tube, and add 3 mL of ABTS• + Mix thoroughly. After incubating at room temperature in the dark for 6 minutes, measure the absorbance at 734 nm using a UV-Vis spectrophotometer. Using VC as a positive control, the ABTS free radical scavenging rate is calculated using the following formula:

[0060] A1 is the sample and ABTS• + The absorbance after mixing, A2 is the absorbance of the sample solution, and A0 is the absorbance of ABTS• + The absorbance of the solution.

[0061] Hydroxyl radical scavenging test: Accurately weigh 0.0829 g of salicylic acid and dilute to 100 mL in a volumetric flask with ethanol to prepare a 6 mmol / L salicylic acid-ethanol solution. Accurately measure 68 μL of 30% hydrogen peroxide solution and dilute to 100 mL in a volumetric flask with water to prepare a 6 mmol / L hydrogen peroxide solution. Accurately weigh 0.1668 g of ferrous sulfate heptahydrate and dilute to 100 mL in a volumetric flask with water to prepare a 6 mmol / L ferrous sulfate solution. In a 10 mL test tube, add 1 mL each of the salicylic acid-ethanol solution, FeSO4 solution, sample solutions of different concentrations (1.0, 2.0, 3.0, 4.0, 5.0 mg / mL), and 6 mmol / L H2O2. Mix thoroughly and react at room temperature for 30 min. Then, allow to stand at room temperature in the dark for 25 min. Measure the absorbance A1 at 510 nm using a UV-Vis spectrophotometer. Using VC as a positive control, the hydroxyl radical scavenging rate is calculated using the following formula:

[0062] A1 is the absorbance of the sample after mixing with •OH, A2 is the absorbance of the sample solution, and A0 is the absorbance of the •OH solution.

[0063] Iron reducing power test: Different concentrations of sample solutions (1.0, 2.0, 3.0, 4.0, 5.0 mg / mL) were prepared using the potassium ferricyanide colorimetric method. 1 mL of each solution was placed in a 10 mL test tube, and 1 mL of 1% potassium ferricyanide solution and 1 mL of 0.2 mol / L phosphate buffer were added. The mixture was placed in a 50℃ water bath for 20 min, cooled under running water, and immediately 1 mL of 10% trichloroacetic acid was added. The mixture was centrifuged (3000 r / min) for 10 min. 2 mL of the supernatant was taken, and 2 mL of deionized water and 0.4 mL of 0.1% FeCl3 solution were added. After mixing thoroughly and standing for 10 min, the absorbance was measured at 700 nm using a UV-Vis spectrophotometer. Using VC as a positive control, the iron reducing power was calculated using the following formula:

[0064] A1 is the absorbance of the sample solution after mixing with FeCl3, and A0 is the absorbance of the sample solution.

[0065] Figure 6 The figure shows the DPPH free radical scavenging test results of fig polysaccharides prepared by the method of this invention. As can be seen from the figure, DPPH is a stable purple free radical with strong absorption at 517 nm. When an antioxidant provides hydrogen atoms to combine with DPPH, DPPH is reduced to a yellow non-free radical form. Within the range of 1.0-3.0 mg / mL, fig polysaccharides exhibit strong DPPH free radical scavenging ability, and the DPPH free radical scavenging rate of the sample solution increases significantly with increasing concentration, showing a concentration-dependent effect. At a sample concentration of 3 mg / mL, the scavenging rate reached 83.74%, indicating that fig polysaccharides have good antioxidant activity.

[0066] Figure 7 The figure shows the ABTS free radical scavenging test results of fig polysaccharides prepared by the method of this invention. As can be seen from the figure, fig polysaccharides exhibit strong DPPH free radical scavenging ability within the range of 1.0-3.0 mg / mL, and this ability is concentration-dependent, with the scavenging rate increasing with increasing sample concentration. At a sample concentration of 3 mg / mL, the scavenging rate reached 98.1%.

[0067] Figure 8 The figure shows the hydroxyl radical scavenging test results of fig polysaccharides prepared by the method of this invention. As can be seen from the figure, the experiment generates highly reactive •OH radicals via the Fenton reaction, and the antioxidant can competitively scavenge •OH radicals. The chromogenic agent salicylic acid can capture unremoved •OH radicals to generate a colored product, which is detected at 510 nm. Within the experimental concentration range, fig polysaccharides (1.0-5.0 mg / mL) all showed hydroxyl radical scavenging effects, and their scavenging ability was concentration-dependent, increasing with increasing concentration. At a sample solution concentration of 5 mg / mL, the hydroxyl radical scavenging rate was 89%.

[0068] Figure 9 The graph shows the iron reducing power test results of fig polysaccharides prepared by the method of this invention. As can be seen from the graph, the antioxidant can reduce Fe... 3+ Reduced to Fe 2+ The absorbance was measured at 593 nm. Within the sample concentration range of 1-5 mg / mL, the iron reducing power increased with increasing fig polysaccharide concentration, indicating that the fig extract possesses a certain reducing ability.

[0069] It is understood that the above specific embodiments are all further illustrations of the present invention and are not intended to limit the scope of protection of the present invention. For those skilled in the art, all other modifications and refinements obtained without creative effort are within the scope of protection of the present invention.

Claims

1. A method for dual-frequency ultrasound-assisted extraction of fig polysaccharides, characterized in that, Includes the following steps: S1. Prepare an ethanol solution of fig powder; S2. Place the above solution in a dual-frequency ultrasonic device for ultrasonic-assisted extraction. The ultrasonic conditions include: ultrasonic frequency of 40kHz and 25kHz, ultrasonic power of 345-525W, and ultrasonic time of 4-12min. S3. After filtration, a fig polysaccharide extract is obtained.

2. The method for dual-frequency ultrasound-assisted extraction of fig polysaccharides according to claim 1, characterized in that, In step S1, the ratio of fig powder to ethanol is 10-50 mL / g.

3. The method for dual-frequency ultrasound-assisted extraction of fig polysaccharides according to claim 2, characterized in that, The liquid-to-solid ratio is 25-40 mL / g.

4. The method for dual-frequency ultrasound-assisted extraction of fig polysaccharides according to claim 3, characterized in that, The liquid-to-solid ratio is 28 mL / g.

5. The method for dual-frequency ultrasound-assisted extraction of fig polysaccharides according to claim 1, characterized in that, In step S2, the ultrasonic power is 435-525W.

6. The method for dual-frequency ultrasound-assisted extraction of fig polysaccharides according to claim 5, characterized in that, The ultrasonic power is 480W.

7. The method for dual-frequency ultrasound-assisted extraction of fig polysaccharides according to claim 1, characterized in that, In step S2, the ultrasound time is 8-12 minutes.

8. The method for dual-frequency ultrasound-assisted extraction of fig polysaccharides according to claim 7, characterized in that, The ultrasound duration was 10.1 min.

9. Fig polysaccharide extracted by the dual-frequency ultrasound-assisted extraction method according to any one of claims 1-8.

10. The use of the fig polysaccharide according to claim 9 in the preparation of antioxidant functional foods, pharmaceuticals and cosmetics.

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