Sweet potato pectin with high intestinal fermentation characteristic based on magnetic induction electric field as well as preparation method and application of sweet potato pectin

Abstract

The invention belongs to the technical field of agricultural and sideline food processing, and discloses sweet potato pectin with high intestinal fermentation characteristic based on a magnetic induction electric field, and a preparation method and application thereof. The preparation method comprises the following steps: S1, mixing starch-removed sweet potato residues with an acid solution, performing magnetic induction electric field treatment, and centrifugally collecting supernate; s2, mixing and stirring the supernate obtained in the step S1 and an ethanol water solution, then carrying out alcohol precipitation standing treatment, and centrifugally collecting a precipitate; mixing the precipitate with water, and performing dialysis and concentration treatment to obtain a concentrate; and carrying out freeze drying treatment on the concentrate to obtain the sweet potato pectin. According to the method, a magnetic induction electric field technology is combined with traditional acid solution extraction, so that the intestinal fermentation characteristic of the sweet potato pectin is effectively enhanced.

Description

Technical Field

[0001] This invention belongs to the field of agricultural and sideline food processing technology, and more specifically, relates to a sweet potato pectin with high intestinal fermentation characteristics based on a magnetic induction electric field, its preparation method, and its application. Background Technology

[0002] Sweet potatoes are mainly used for starch extraction, making vermicelli and sweet potato noodles, and developing sweet potato beverages. During processing, a large amount of sweet potato residue is generated, accounting for approximately 10%-14% of the raw materials. Fresh sweet potato residue has a high water content (up to 80%), making it difficult to store and transport. It also rots and produces a foul odor, easily causing serious environmental pollution. Currently, most sweet potato residue is used as animal feed or discarded directly, failing to be fully utilized and hindering the extension and expansion of the sweet potato industry chain.

[0003] Pectin is a naturally occurring acidic heteropolysaccharide used in the food industry as a gelling agent, stabilizer, and thickener. Furthermore, pectin is a type of polysaccharide that is not digested and absorbed by the upper digestive tract, possessing the potential to enter the colon and interact with intestinal microorganisms, thereby producing health benefits. Studies have shown that sweet potato residue contains 30-40% dietary fiber, of which pectin content is approximately 20-30% (on a dry basis). To improve processing adaptability, numerous studies have optimized the physicochemical properties of sweet potato residue pectin through modification methods, but have neglected its regulatory role in the intestinal flora as a dietary nutrient. Therefore, preparing pectin with intestinal probiotic effects from sweet potato residue can effectively increase the added value of sweet potato residue.

[0004] Currently, commonly used pectin extraction methods mainly include acid extraction, alkali extraction, salt extraction, and enzymatic extraction. Among these, acid extraction is the most commonly used method for commercial pectin extraction. However, the extraction rate of sweet potato pectin using traditional acid extraction is only about 5%, which is lower than the actual pectin content in sweet potato residue. In addition, sweet potato pectin extracted using traditional acid extraction also exhibits relatively poor intestinal fermentation characteristics. Therefore, this invention proposes a sweet potato pectin with high intestinal fermentation characteristics based on a magnetically induced electric field, its preparation method, and its application. Summary of the Invention

[0005] The purpose of this invention is to address the shortcomings of existing technologies by proposing a method for preparing sweet potato pectin with enhanced intestinal fermentation properties based on a magnetically induced electric field, along with its applications. This invention combines magnetically induced electric field technology with traditional acid solution extraction, effectively enhancing the intestinal fermentation characteristics of sweet potato pectin.

[0006] To achieve the above objectives, the first aspect of the present invention provides a method for preparing sweet potato pectin with high intestinal fermentation characteristics based on a magnetically induced electric field, the preparation method comprising the following steps: S1: The sweet potato residue after starch removal is mixed with acid solution and then subjected to magnetic induction electric field treatment. The supernatant is collected by centrifugation. S2: The supernatant obtained in step S1 is mixed with an ethanol-water solution and stirred, then subjected to alcohol precipitation and allowed to stand. The precipitate is collected by centrifugation. The precipitate is mixed with water and then subjected to dialysis and concentration to obtain a concentrate. The concentrate is freeze-dried to obtain sweet potato pectin.

[0007] According to the present invention, preferably, the method for preparing the sweet potato residue after starch removal includes: After washing and cutting the sweet potatoes into pieces, they are mixed with water and then pressed and crushed. The residue is then filtered and collected. The residue is then washed, dried and crushed in sequence to obtain sweet potato residue before starch removal. The sweet potato residue before starch removal is mixed with water and gelatinized to obtain a gelatinized product; The gelatinized material was mixed with a heat-resistant α-amylase and subjected to the first enzymatic hydrolysis treatment to obtain the first enzymatic hydrolysate. The first enzymatic hydrolysate is mixed with a saccharifying enzyme and subjected to a second enzymatic hydrolysis process to obtain a second enzymatic hydrolysate. After centrifugation, (ethanol) washing, drying and pulverizing, the starch-removed sweet potato residue is obtained.

[0008] According to the present invention, preferably, the gelatinization time is 25-35 minutes.

[0009] According to the present invention, preferably, the operating conditions for the first step of enzymatic hydrolysis include: temperature ≤ 95℃, pH 5.5-6.5, and hydrolysis time 25-35 min.

[0010] According to the present invention, preferably, the operating conditions for the second enzymatic hydrolysis treatment include: temperature ≤ 60℃, pH 3-5, and enzymatic hydrolysis time 85-95 min.

[0011] According to the present invention, preferably, the ratio of the amount of sweet potato residue after starch removal to the acid solution is (0.5-3.5):(25-45) g / mL.

[0012] According to the present invention, preferably, the operating conditions for the magnetic induction electric field processing include: The alternating frequency of the magnetic induction electric field is 45-55kHz; The flow rate of the mixture of the starch-removed sweet potato residue and the acid solution entering the magnetic induction electric field treatment area is 5-15 L / h. The initial temperature of the mixture of the starch-removed sweet potato residue and the acid solution entering the magnetic induction electric field treatment area is 20-25℃. The excitation voltage intensity is 100-500V; The magnetic induction electric field treatment time is 100-150 minutes.

[0013] In this invention, the extraction rate of sweet potato pectin shows a continuous upward trend as the excitation voltage intensity of the magnetic induction electric field treatment increases, reaching its highest level at an excitation voltage intensity of 500V. However, when the excitation voltage intensity is increased above 500V, it is found that high excitation voltage intensity causes excessive heat effect and changes in the physical structure of the sample, resulting in excessively rapid expansion of the sweet potato pectin and blockage of the flow path. Therefore, it is impossible to continuously and stably transport the mixture of starch-removed sweet potato residue and acid solution into the magnetic induction electric field treatment area.

[0014] In this invention, the term "magnetic induction electric field treatment" refers to treating the mixed system sample of sweet potato residue after starch removal and acid solution with a magnetic induction electric field. The magnetic induction electric field induces the movement of free ions in the electrolyte, strengthens the interaction between ions and pectin, and at the same time, the current generates a volume heating effect through the acidic medium, which accelerates the release and depolymerization of sweet potato pectin from the plant cell wall.

[0015] In this invention, the magnetic induction electric field treatment time is preferably 120 minutes. Within this time, the magnetic induction electric field treatment enables the mixture of starch-removed sweet potato residue and acid solution under different excitation voltage intensities to achieve continuous and stable flow sampling (flow sampling: the continuous transport process into the magnetic induction electric field treatment area). Furthermore, the temperature under different excitation voltage intensities can stabilize after continuous increase. The inventors have discovered that as the excitation voltage intensity increases, the mixture of starch-removed sweet potato residue and acid solution continuously heats up, with different heating rates for different excitation voltage intensities. When the excitation voltage intensity is too high, the heating rate is too fast, causing the mixture to swell rapidly, ultimately leading to unstable flow sampling. Therefore, this invention limits the initial temperature of the mixture of starch-removed sweet potato residue and acid solution entering the magnetic induction electric field treatment area to 20-25°C.

[0016] According to the present invention, preferably, while performing the magnetic induction electric field treatment, the mixture system after the starch-removed sweet potato residue and the acid solution is also stirred at a stirring rate of 750-850 rpm.

[0017] According to the present invention, preferably, the concentration of the ethanol aqueous solution is 90-95%.

[0018] According to the present invention, preferably, the volume ratio of the supernatant to the aqueous ethanol solution is (0.5-1.5):(3.5-4.5).

[0019] According to the present invention, preferably, the alcohol precipitation and settling time is 12-24 hours, so that the sweet potato pectin settles.

[0020] In this invention, the centrifugation speed and time in the preparation method are not limited. Those skilled in the art can select appropriate centrifugation conditions according to the scale of sweet potato pectin being processed, all of which are within the protection scope of this application. As a preferred embodiment, the centrifugation speed is 4000-10000 rpm and the centrifugation time is 10-20 min.

[0021] The second aspect of the present invention provides sweet potato pectin prepared by the preparation method described above.

[0022] The third aspect of this invention provides the application of the aforementioned sweet potato pectin in the preparation of fermented food ingredients.

[0023] The beneficial effects of the technical solution of the present invention are as follows: This invention combines magnetic induction electric field technology (regulating the excitation voltage intensity of the magnetic induction electric field) with traditional acid solution extraction (acid extraction), which can enhance the dissolution of sweet potato pectin under the combination of thermal and non-thermal effects, effectively enhance the intestinal fermentation characteristics of sweet potato pectin, and improve the extraction rate of sweet potato pectin.

[0024] The test data (pH value, short-chain fatty acid (SCFA) content, total sugar content, and reducing sugar content of the fermentation supernatant) show that the low-esterification sweet potato pectin extracted by the method of this invention has better fermentation characteristics than commercially available pectin. Pectin with these characteristics can stably perform thickening, gelling, and biocompatibility functions in the acidic environment of fermented foods, and can be used as a core functional ingredient for improving the texture of fermented foods.

[0025] The magnetic induction electric field (MIEF) assisted extraction method of the present invention obtains a potential difference through the variable magnetic flux of the coil and the iron core. Compared with the high voltage pulse electric field, the magnetic induction electric field (MIEF) assisted extraction method of the present invention does not use traditional metal electrodes. Therefore, the magnetic induction electric field (MIEF) assisted extraction method of the present invention can overcome the problems of electrode corrosion and adverse electrochemical reactions contaminating the sample.

[0026] This invention enables the reuse of waste sweet potato residue in the production and processing of sweet potato starch, effectively avoiding resource waste and environmental pollution, and is suitable for industrial application.

[0027] Other features and advantages of the present invention will be described in detail in the following detailed description section. Attached Figure Description

[0028] The above and other objects, features and advantages of the present invention will become more apparent from the more detailed description of exemplary embodiments of the invention in conjunction with the accompanying drawings.

[0029] Figure 1The extraction rates of sweet potato pectin obtained by the preparation methods of Examples 1-6 of the present invention are shown (“Excitationvoltage” refers to the excitation voltage intensity, and “Yield” refers to the extraction rate; different letters in the figure indicate significant differences between different groups (p<0.05)).

[0030] Figure 2 The degree of esterification of sweet potato pectin obtained by the preparation methods of Examples 1-6 of the present invention is shown (different letters in the figure represent significant differences between different groups (p<0.05)).

[0031] Figure 3 The figure shows the relative total sugar content of the fermentation supernatant measured in Test Example 2 of the present invention (“Relative total sugar content” means relative total sugar content, “Sample” means each sample tested for relative total sugar content, different uppercase letters in the figure indicate significant differences between different groups at the same time (p<0.05), and different lowercase letters indicate significant differences within the same group at different times (p<0.05)).

[0032] Figure 4 The reducing sugar content of the fermentation supernatant measured in Test Example 2 of the present invention is shown (“Reducing sugar content” refers to the reducing sugar content; different uppercase letters in the figure indicate significant differences between different groups at the same time (p<0.05), and different lowercase letters indicate significant differences within the same group at different times (p<0.05)). Detailed Implementation

[0033] Preferred embodiments of the invention will now be described in more detail. While preferred embodiments of the invention are described below, it should be understood that the invention can be implemented in various forms and should not be limited to the embodiments set forth herein. Rather, these embodiments are provided so that the invention will be thorough and complete, and will fully convey the scope of the invention to those skilled in the art.

[0034] Example 1

[0035] This embodiment provides a method for preparing sweet potato pectin with high intestinal fermentation characteristics based on a magnetically induced electric field. The preparation method includes the following steps: S1: (1) Preparation of sweet potato residue after starch removal: After washing and cutting the sweet potatoes into chunks, they were placed in a juicer with an appropriate amount of water for pressing and pulverizing. The residue was collected through a filter screen and washed several times with an aqueous solution to remove soluble starch. Then, it was dried at 65°C and pulverized to obtain sweet potato residue before starch removal. The sweet potato residue before starch removal was mixed with deionized water in a certain proportion and gelatinized for 30 minutes to obtain a gelatinized product. The gelatinized product was mixed with a thermoresistant α-amylase and subjected to the first enzymatic hydrolysis treatment (95°C, pH 6, hydrolysis for 30 minutes) to obtain the first hydrolysate. The first hydrolysate was mixed with a saccharifying enzyme and subjected to the second enzymatic hydrolysis treatment (60°C, pH 4.5, hydrolysis for 90 minutes) to obtain the second hydrolysate. The precipitate was then collected by centrifugation, washed with ethanol, and collected by centrifugation again. Finally, it was dried and pulverized to obtain the sweet potato residue after starch removal. (2) Extraction of sweet potato pectin: The starch-removed sweet potato residue was mixed with an acid solution (hydrochloric acid aqueous solution) and then subjected to magnetic induction electric field treatment. The mixture was centrifuged (8000 rpm for 15 min), and the supernatant (i.e., the extract containing sweet potato pectin) was collected. Among them: The ratio of the amount of sweet potato residue after starch removal to the acid solution is 1:30 g / mL, and the pH of the mixture system after mixing the sweet potato residue after starch removal and the acid solution is 1.8. The operating conditions for the magnetic induction electric field processing include: The alternating frequency of the magnetic induction electric field is 50kHz; The flow rate of the mixture of the starch-removed sweet potato residue and the acid solution entering the magnetic induction electric field treatment area is 10 L / h. The initial temperature of the mixture of the starch-removed sweet potato residue and the acid solution entering the magnetic induction electric field treatment area is 25°C. The excitation voltage intensity is 500V; The magnetic induction electric field processing time is 120 minutes; While performing the magnetic induction electric field treatment, the mixture of the starch-removed sweet potato residue and the acid solution was also stirred at a stirring speed of 800 rpm.

[0036] S2: Purified sweet potato pectin: The supernatant obtained in step S1 was mixed with a 95% ethanol aqueous solution (the volume ratio of the supernatant to the 95% ethanol aqueous solution was 1:4), stirred, and then subjected to alcohol precipitation and allowed to stand for 12 hours. The precipitate was collected by centrifugation (4000 rpm, 15 min). The precipitate was mixed with deionized water and dialyzed for 3 days. The dialyzed solution was then concentrated by rotary evaporation to obtain a concentrate. The concentrate was freeze-dried (-60℃, 72 h) to obtain sweet potato pectin HSP-500.

[0037] Example 2

[0038] The only difference between this embodiment and Embodiment 1 is that the excitation voltage intensity is 0V, and sweet potato pectin HSP-0 is obtained.

[0039] Example 3

[0040] The only difference between this embodiment and Embodiment 1 is that the excitation voltage intensity is 100V, and sweet potato pectin HSP-100 is obtained.

[0041] Example 4

[0042] The only difference between this embodiment and Embodiment 1 is that the excitation voltage intensity is 200V, and sweet potato pectin HSP-200 is obtained.

[0043] Example 5

[0044] The only difference between this embodiment and Embodiment 1 is that the excitation voltage intensity is 300V, and sweet potato pectin HSP-300 is obtained.

[0045] Example 6

[0046] The only difference between this embodiment and Embodiment 1 is that the excitation voltage intensity is 400V, and sweet potato pectin HSP-400 is obtained.

[0047] Test Example 1

[0048] This test example calculates the extraction rate and esterification degree of sweet potato pectin in Examples 1-6.

[0049] The formula for calculating the extraction rate of sweet potato pectin is as follows: Pectin extraction rate (%) = M1 / M2 × 100%; In the formula: M1 is the mass of sweet potato residue after starch removal, mg; M2 is the mass of sweet potato pectin obtained by the preparation method of this invention, mg.

[0050] The degree of esterification (DE) of sweet potato pectin was determined by Fourier transform infrared spectroscopy (FT-IR). The formula for calculating the degree of esterification of sweet potato pectin is as follows: DE (%) = A 1740 / (A 1740 +A 1630 )×100%; In the formula: A 1740 and A 1630 They represent 1740 cm respectively -1 and 1630 cm -1 Peak area at that location.

[0051] See results Figure 1 , Figure 2 :Depend on Figure 1 It can be seen that the extraction rate of sweet potato pectin extracted by this invention significantly increases with the increase of the excitation voltage intensity of the magnetic induction electric field; Figure 2 It can be seen that the extracted sweet potato pectin is all low-esterification pectin.

[0052] Test Example 2

[0053] This test example uses in vitro fermentation experiments on sweet potato pectin, low-esterification commercial pectin (CP), and inulin (INL) from Examples 1-6 to characterize the fermentation characteristics of the sweet potato pectin of the present invention.

[0054] The in vitro fermentation experiment includes the following steps: 1. Preparation of basal culture medium for in vitro anaerobic fermentation: Sweet potato pectin, low-esterification commercial pectin (CP), and inulin (INL) from Examples 1-6 were dissolved in basal culture medium at a concentration of 10 mg / mL. (The composition of the basal culture medium (1L) is: yeast extract 2.0 g, peptone 2.0 g, NaCl 0.1 g, K2HPO4 0.04 g, KH2PO4 0.04 g, CaCl2) 0.01g of 6H₂O, MgSO₄ The following solutions were prepared in three replicates: 0.01 g of 7H2O, 2 g of NaHCO3, 0.5 g of cysteine ​​hydrochloride, 0.02 g of heme chloride, 0.5 g of porcine bile salts, 2 mL of Tween-80, 1.0 mL of 1% resazurin solution, and 10 μL of vitamin K. After sterilization at high temperature (121℃, 30 min), the solutions were used for subsequent in vitro fermentation experiments. 2. Fresh stool samples were collected from three volunteers (in good health and who had not taken probiotics or antibiotics in the past three months). 5g of stool was placed in a sterile centrifuge tube and 45mL of sterile saline (containing 0.5g / L cysteine ​​hydrochloride) was added. After stirring thoroughly, the mixture was centrifuged at low speed to remove insoluble stool particles. The supernatant was then combined in a laminar flow hood to obtain a 10% (w / w) stool suspension. 3. Finally, take 9 mL of the culture medium sample solution prepared in step 1 into a 25 mL sterile conical flask and add 1 mL of the fecal suspension from step 2; seal the sterile conical flask with a sterile breathable sealing film and transfer it into an anaerobic fermentation box, add the anaerobic gas generator, and quickly seal it and place it in a 37℃ incubator for fermentation for 24 hours to obtain the fermentation supernatant and precipitate.

[0055] The pH value of the fermentation supernatant was measured using a pH meter, and the results are shown in Table 1.

[0056] The content of short-chain fatty acids (SCFAs) in the fermentation supernatant after 24 h of fermentation was determined by gas chromatography. In addition, the lactic acid content was determined by a lactic acid assay kit. The results are shown in Table 2.

[0057] The relative total sugar content of the fermentation supernatant was determined at 490 nm using the phenol-sulfuric acid method. The results are shown in [Figure number missing]. Figure 3 .

[0058] The reducing sugar content of the fermentation supernatant was determined at 540 nm using the 3,5-dinitrosalicylic acid (DNS) method. The results are shown in [Figure number missing]. Figure 4 .

[0059] Table 1. pH changes at different fermentation time points

[0060] Note: Different letters in the same column indicate significant differences between different groups (p < 0.05).

[0061] As can be seen from Table 1, compared with commercial pectin with low esterification (CP), the pH of sweet potato pectin in Examples 1-6 of this invention showed a trend of first decreasing and then increasing between 6 and 24 hours, and the pH of HSP-500 was the lowest in Examples 1-6; while the pH of commercial pectin with low esterification (CP) showed a trend of decreasing to stabilizing.

[0062] Table 2

[0063] Note: Different letters in the same column indicate significant differences between different groups (p < 0.05).

[0064] As can be seen from Table 2, after 24 hours of fermentation, the short-chain fatty acid content of Examples 1-6 was significantly higher than that of low-esterification commercial pectin (CP), and the propionic acid content of Example 1 was significantly higher than that of Examples 2-6 and low-esterification commercial pectin (CP).

[0065] Depend on Figure 3 It can be seen that the relative total sugar content of Examples 1-6 is significantly lower than that of low-esterification commercial pectin (CP) and inulin (INL); and in Examples 1-6, the utilization rate of HSP (sweet potato pectin) as the sole carbon source is better (relative total sugar content is lower) as the excitation voltage intensity increases.

[0066] Depend on Figure 4 It can be seen that the reducing sugars of pectin in Examples 1-6 and inulin (INL) after fermentation all showed a phenomenon of first increasing and then decreasing. Moreover, after 24 hours of fermentation, the reducing sugars of Example 1 were significantly higher than those of Examples 2-6 and low-esterification commercial pectin (CP).

[0067] The various embodiments of the present invention have been described above. These descriptions are exemplary and not exhaustive, nor are they limited to the disclosed embodiments. Many modifications and variations will be apparent to those skilled in the art without departing from the scope and spirit of the described embodiments.

Claims

1. A method for preparing sweet potato pectin with high intestinal fermentation characteristics based on a magnetically induced electric field, characterized in that, The preparation method includes the following steps: S1: The sweet potato residue after starch removal is mixed with acid solution and then subjected to magnetic induction electric field treatment. The supernatant is collected by centrifugation. S2: Mix the supernatant obtained in step S1 with an ethanol-water solution, stir, and then perform alcohol precipitation and allow it to stand. Centrifuge to collect the precipitate. The precipitate was mixed with water and then subjected to dialysis and concentration to obtain a concentrate. The concentrate was freeze-dried to obtain sweet potato pectin.

2. The method for preparing sweet potato pectin with high intestinal fermentation characteristics based on a magnetically induced electric field according to claim 1, wherein, The method for preparing the sweet potato residue after starch removal includes: After washing and cutting the sweet potatoes into pieces, they are mixed with water and then pressed and crushed. The residue is then filtered and collected. The residue is then washed, dried and crushed in sequence to obtain sweet potato residue before starch removal. The sweet potato residue before starch removal is mixed with water and gelatinized to obtain a gelatinized product; The gelatinized material was mixed with a heat-resistant α-amylase and subjected to the first enzymatic hydrolysis treatment to obtain the first enzymatic hydrolysate. The first enzymatic hydrolysate is mixed with a saccharifying enzyme and subjected to a second enzymatic hydrolysis process to obtain a second enzymatic hydrolysate. After centrifugation, washing, drying and pulverizing, the sweet potato residue after starch removal is obtained.

3. The method for preparing sweet potato pectin with high intestinal fermentation characteristics based on a magnetically induced electric field according to claim 2, wherein, The gelatinization time is 25-35 minutes; The operating conditions for the first step of enzymatic hydrolysis include: temperature ≤ 95℃, pH 5.5-6.5, and hydrolysis time 25-35 min; The operating conditions for the second step of enzymatic hydrolysis include: temperature ≤ 60℃, pH 3-5, and hydrolysis time 85-95 min.

4. The method for preparing sweet potato pectin with high intestinal fermentation characteristics based on a magnetically induced electric field according to claim 1, wherein, The ratio of the amount of sweet potato residue after starch removal to the acid solution is (0.5-3.5):(25-45) g / mL.

5. The method for preparing sweet potato pectin with high intestinal fermentation characteristics based on a magnetically induced electric field according to claim 1, wherein, The operating conditions for the magnetic induction electric field processing include: The alternating frequency of the magnetic induction electric field is 45-55kHz; The flow rate of the mixture of the starch-removed sweet potato residue and the acid solution entering the magnetic induction electric field treatment area is 5-15 L / h. The initial temperature of the mixture of the starch-removed sweet potato residue and the acid solution entering the magnetic induction electric field treatment area is 20-25℃. The excitation voltage intensity is 100-500V; The magnetic induction electric field treatment time is 100-150 minutes.

6. The method for preparing sweet potato pectin with high intestinal fermentation characteristics based on a magnetically induced electric field according to claim 1, wherein, While performing the magnetic induction electric field treatment, the mixture of the sweet potato residue after starch removal and the acid solution is also stirred at a stirring speed of 750-850 rpm.

7. The method for preparing sweet potato pectin with high intestinal fermentation characteristics based on a magnetically induced electric field according to claim 1, wherein, The concentration of the ethanol aqueous solution is 90-95%; The volume ratio of the supernatant to the ethanol-water solution is (0.5-1.5):(3.5-4.5).

8. The method for preparing sweet potato pectin with high intestinal fermentation characteristics based on a magnetically induced electric field according to claim 1, wherein, The alcohol precipitation and settling time is 12-24 hours.

9. Sweet potato pectin prepared by the preparation method according to any one of claims 1-8.

10. The application of the sweet potato pectin according to claim 9 in the preparation of fermented food ingredients.

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