Medium-chain inulin, preparation method therefor, and use thereof

Abstract

The present invention belongs to the technical field of plant extraction. Disclosed are a medium-chain inulin, a preparation method therefor, and the use thereof. The unique inulin structure and chain length disclosed in the present invention reshape the gut microbiome and metabolome, and in particular, selectively modulate key microorganisms such as Faecalibacterium, Bifidobacterium, Parabacteroides, Clostridium_sensu_stricto_1 and Akkermansia, and metabolites such as nicotinamide, taurocholic acid, aldosterone, corticosterone, 2-(1H-indol-3-yl)acetic acid, 5-hydroxy-L-tryptophan, 5α-DHT and maltose, thereby promoting the amelioration of obesity and the improvement of the overall health of a host. The core microorganisms and metabolites identified by the technical solution represent potential therapeutic targets for preventing or treating obesity and related metabolic symptoms. These findings support the development of inulin-based nutritional strategies to effectively manage body weight by modulating specific microbiota and the metabolome.

Description

A medium-chain inulin, its preparation method and application Technical Field

[0001] This invention relates to the field of plant extraction technology, and in particular to a medium-chain inulin, its preparation method, and its application. Background Technology

[0002] Obesity is a global health problem affecting millions of people worldwide, and the global prevalence of obesity continues to rise. According to the World Health Organization (WHO), in 2022, more than 2.5 billion adults were overweight, of whom more than 890 million were classified as obese. Furthermore, obesity is often accompanied by a variety of metabolic diseases, including diabetes, hypertension, cardiovascular disease (CVD), and musculoskeletal disorders. The primary cause of obesity is an imbalance between energy intake and expenditure, leading to excessive fat storage in white adipose tissue. High-fat diets (HFD) are prevalent in both developed and developing countries and are a major contributor to the global obesity epidemic. HFD typically lacks sufficient dietary fiber, disrupting the gut microbiota, affecting physiological processes, and contributing to obesity, hyperlipidemia, and other metabolic problems. Therefore, in contemporary society, the prevention of obesity and its complications caused by high-fat diets and insufficient dietary fiber has garnered increasing attention.

[0003] Inulin is a natural dietary fiber composed of linear β-2,1-linked fructose and terminal α-1,2-linked glucose residues, with a degree of polymerization (DP) ranging from 2 to 60. Due to its unique glycosidic bonds, inulin is not easily digested by amylases in the proximal gastrointestinal tract. However, almost 90% of inulin reaches the colon and is fermented by beneficial bacteria, producing a variety of metabolites, including short-chain fatty acids (SCFAs), amino acids, and vitamins. This is considered the main pathway by which inulin exerts its biological activity. However, inulin with different chain lengths (different DP values) specifically regulates different microbial communities, resulting in different metabolites and exhibiting different biological effects. The biological activity of inulin is closely related to its DP value, and current research in this field suggests that medium-chain inulin with a chain length between 10 and 20 has a wide range of biological effects. However, the targeted extraction of medium-chain inulin and the exploration of its biological effects are currently lacking. Exploring the targeted extraction technology of medium-chain inulin and its biological effects, especially its therapeutic effects on obesity and metabolic syndrome, is of great significance for the development of natural functional foods and biomedicine. Summary of the Invention

[0004] The purpose of this invention is to provide a medium-chain inulin, its preparation method, and its application, in order to solve the problems existing in the prior art.

[0005] To achieve the above objectives, the present invention provides the following solution:

[0006] One of the technical solutions of this invention is a method for preparing medium-chain inulin, comprising the following steps:

[0007] (1) Jerusalem artichoke was ground into a pulp, and water was added for extraction. Then, crude polysaccharide was obtained by filtration, concentration, protein removal, and alcohol precipitation.

[0008] (2) The crude polysaccharide was dialyzed and concentrated using a semi-permeable membrane, and then freeze-dried to obtain the medium-chain inulin.

[0009] The second technical solution of the present invention is a medium-chain inulin prepared by the above preparation method, wherein the medium-chain inulin is composed of fructose linked by 2,1 glycosidic bonds and has an average degree of polymerization of 12.

[0010] The third technical solution of the present invention is the application of the medium-chain inulin in the preparation of products for preventing and treating obesity.

[0011] The fourth technical solution of the present invention is a product for preventing and treating obesity, comprising the aforementioned medium-chain inulin.

[0012] The fifth technical solution of the present invention is the application of the medium-chain inulin in the preparation of products that regulate intestinal flora.

[0013] The sixth technical solution of the present invention is the application of the medium-chain inulin in the preparation of products that upregulate Faecalibaculum, Bifidobacterium, Parasutterella, Muribauculum, Clostridium sensu stricto, and Akkermansia.

[0014] Based on the above technical solution, the present invention has the following technical effects:

[0015] The unique inulin structure and specific chain length disclosed in this invention remodel the gut microbiome and metabolome, particularly selectively modulating key microorganisms such as *Femtobacterium faecium*, *Bifidobacterium*, *Pseudomonas*, *Clostridium sensustricto*, and *Akkermansia*, as well as metabolites such as nicotinamide, taurine, aldosterone, corticosterone, 2-(1H-indole-3-yl)acetic acid, 5-hydroxy-L-tryptophan, 5α-DHT, and maltose, thereby promoting improvements in obesity and overall health. Furthermore, the identified key microorganisms and metabolites represent promising therapeutic targets for the prevention or treatment of obesity. These findings support the development of inulin-based nutritional strategies aimed at modulating specific microbiomes and metabolomes for effective weight management. Attached Figure Description

[0016] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0017] Figure 1 shows the structural characteristics of medium-chain inulin. A represents the ion chromatography (IC) of medium-chain inulin. B shows the trends of multi-angle laser scattering (LS), refractive index (RI), and fitted molar mass signals of medium-chain inulin. The red line represents the LS trend with retention time, and the green line represents the RI trend of medium-chain inulin. The trends of the red and green lines indicate the size and relative proportion of polysaccharide molecules in the test sample. The blue line represents the trend of the fitted molar mass of inulin with retention time, based on the LS and RI signals. C shows the Fourier transform infrared (FT-IR) spectrum of medium-chain inulin. D shows the proposed chemical and structural formula of medium-chain inulin. E shows scanning electron microscopy (SEM) images of inulin. E.1 shows the overall appearance of inulin under SEM scanning; E.2 shows the composition of inulin spheres observed at 200x magnification under SEM; E.3 shows inulin observed at 1000x magnification under SEM. F shows the three-dimensional spatial structure of inulin images fitted with determined structural parameters. F.1 is spherical inulin; F.2 is the three-dimensional structure of inulin molecules with DP=12; F.3 is long-chain inulin with DP=60; G is a transmission electron microscope (TEM) scan of inulin, G.1 is a spherical conformation formed by inulin of different chain lengths coiled together at 70,000x magnification; G.2 is a network woven from long-chain inulin at 30,000x magnification; G.3 is a single long chain of inulin at 30,000x magnification.

[0018] Figure 2 shows that supplementing C57BL / 6 mice with medium-chain inulin for 12 weeks prevented HFD-induced obesity and improved lipid deposition. A and B represent the experimental design and obese phenotypes in HFD or HFD+ mice; C represents weekly weight changes and body weight changes in mice fed HFD or HFD+ inulin during the experiment; D represents tissue weight changes in liver tissue, white adipose tissue (epididymal fat pad), and brown adipose tissue (bats) fed HFD or HFD+ inulin; E represents serum lipid levels; F represents fasting blood glucose (FBG) and serum urea levels; G represents the extent of liver fat accumulation and distribution as shown in Oil Red stained sections. H indicates the percentage (%) of the corresponding section showing positive Oil Red stained liver area (G), and I represents the liver lipid profile. An asterisk indicates significant differences: *P<0.05, **P<0.01, ***P<0.001.

[0019] Figure 3 shows that medium-chain inulin restored SCFA content in C57BL / 6 mice and alleviated intestinal damage caused by HFD feeding. A. SCFA content in feces. B. BCFA content in feces. C. Overview of total fatty acids (TFA), short-chain fatty acids (SCFAs), and branched-chain fatty acids (BCFAs) in feces. DF. Ileal morphology and quantitative analysis. After staining with hematoxylin and eosin (H&E), ileal villus height, crypt depth, and villus height / crypt depth ratio (V / C) were observed under a ×100 magnifying glass. GI: ​​Quantitative determination of colon morphology and related parameters, including crypt depth, intestinal wall thickness, intestinal contents, pH value, and representative images of colon sections from the five experimental groups. *P<0.05, **P<0.01.

[0020] Figure 4 shows the overview of the gut microbiome and the screening of differentially expressed microorganisms after the addition of inulin. In the figure, A represents the flavonoid index, an indicator of gut microbiome diversity; B represents the beta diversity of the gut microbiome; C represents the abundance ratio of the major gut bacteria, Firmicutes and Bacteroides; D represents differentially expressed microorganisms at the phylum level; E represents differentially expressed microorganisms at the genus level; F is a bar chart of differentially expressed microorganisms obtained by the LEfse analysis method; and G is an evolutionary clade diagram of the gut microbiome obtained by the LEfse analysis method.

[0021] Figure 5 shows the metabolomic profiles and differentially expressed metabolites among the experimental groups. A. Heatmap showing the effects of HFD feeding and inulin supplementation on intestinal metabolites in mice. B. Orthogonal projection of Potential Structure Discriminant Analysis (OPLS-DA) showing the distribution of intestinal metabolites in different groups. C. OPLS-DA S-plot showing the distribution of differentially expressed metabolites. Red dots represent metabolites with VIP ≥ 1, and blue dots represent metabolites with VIP < 1. D~H. Volcano plots showing the differences in metabolites among the HFD, ND, and inulin-supplemented groups. I. Upregulation and downregulation of differentially expressed metabolites in the inulin-supplemented group and the HFD-fed group.

[0022] Figure 6 shows the correlations between inulin addition and changes in health parameters, microbiota, and metabolites. In Figures A, B, and C, red text indicates significant upregulation of microbiota or metabolites after inulin addition. A. Correlation between health parameters and different gut microbiota. B. Correlation between health parameters and diverse metabolites. C. Correlation between different gut microbiota and metabolites. D. Analysis of metabolic pathway regulation by HFD feeding and / or inulin addition, comparing the ND group with the HFD group, and between the HFD+1%, HFD+3%, or HFD+5% inulin groups and the HFD group. The metabolic pathways in D are shown below. In HFD vs. ND, 1 represents biotin metabolism, 2 represents the interconversion of pentose and gluconate, 3 represents tryptophan metabolism, 4 represents arachidonic acid metabolism, 5 represents steroid hormone biosynthesis, 6 represents tyrosine metabolism, 7 represents starch and sucrose metabolism, 8 represents lysine degradation, 9 represents galactose, 10 represents glutathione, and 11 represents cysteine ​​and methionine metabolism. In the HFD vs. HFD+1% inulin group, 1 represents starch / sucrose metabolism, 2 represents arachidonic acid metabolism, and 3 represents steroid hormone biosynthesis. In the HFD vs. HFD+3% inulin group, 1 represents arachidonic acid metabolism, 2 represents nicotinic acid / nicotinamide metabolism, 3 represents steroid hormone metabolism, and 4 represents primary bile acid biosynthesis. In the HFD vs. HFD+5% inulin group, 1 represents arachidonic acid metabolism, 2 represents tryptophan metabolism, and 3 represents primary bile acid biosynthesis.

[0023] Figure 7 shows the correlations between metabolic pathways significantly altered by inulin supplementation based on differential metabolites and KEGG pathways. Metabolites connected by solid lines represent direct conversions, while those connected by dashed lines represent indirect conversions via biochemical processes. Red text indicates increased concentrations, while blue text indicates decreased concentrations due to dietary inulin supplementation. Rounded rectangles of different colors represent pathways enriched by KEGG analysis. Pink-marked metabolic pathways are upregulated, while light blue indicates downregulated pathways. Light yellow rectangles represent physiological and / or biochemical processes affected by inulin-regulated metabolic pathways.

[0024] Figure 8 shows the co-occurrence network of gut microbiota and metabolites with body weight (BW) and short-chain fatty acids (SCFAs). Light blue dashed lines indicate negative correlations (mutually exclusive, mu-) between two nodes, while light pink solid lines indicate positive correlations (co-) between two nodes. A. Correlation between microbiota, body weight, and short-chain fatty acids (SCFAs). B. Correlation between metabolites, body weight, and SCFAs. Detailed Implementation

[0025] Various exemplary embodiments of the present invention will now be described in detail. This detailed description should not be considered as a limitation of the present invention, but rather as a more detailed description of certain aspects, features, and embodiments of the present invention.

[0026] It should be understood that the terminology used in this invention is merely for describing particular embodiments and is not intended to limit the invention. Furthermore, with respect to numerical ranges in this invention, it should be understood that each intermediate value between the upper and lower limits of the range is also specifically disclosed. Every smaller range between any stated value or intermediate value within a stated range, and any other stated value or intermediate value within said range, is also included in this invention. The upper and lower limits of these smaller ranges may be independently included or excluded from the range.

[0027] Unless otherwise stated, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art. While only preferred methods and materials have been described herein, any methods and materials similar or equivalent to those described herein may be used in the implementation or testing of this invention. All references to this specification are incorporated by way of citation to disclose and describe methods and / or materials associated with those references. In the event of any conflict with any incorporated reference, the content of this specification shall prevail.

[0028] Various modifications and variations can be made to the specific embodiments described in this specification without departing from the scope or spirit of the invention, as will be apparent to those skilled in the art. Other embodiments derived from this specification will also be obvious to those skilled in the art. This application specification and embodiments are merely exemplary.

[0029] The terms “include,” “including,” “have,” “contain,” etc., used in this article are all open-ended terms, meaning that they include but are not limited to.

[0030] Unless otherwise specified, the technical solutions described in this invention are all conventional solutions in the field, and the reagents or raw materials used are all purchased from commercial channels or are publicly available unless otherwise specified.

[0031] This invention provides a method for preparing medium-chain inulin, comprising the following steps:

[0032] (1) Jerusalem artichoke was ground into a pulp, and water was added for extraction. Then, crude polysaccharide was obtained by filtration, concentration, protein removal, and alcohol precipitation.

[0033] (2) The crude polysaccharide was dialyzed and concentrated using a semi-permeable membrane, and then freeze-dried to obtain the medium-chain inulin.

[0034] In some specific implementations, in step (1), the conditions for water extraction are: the volume ratio of the slurry to water is 1:30, the extraction temperature is 80°C, and the time is 3 hours;

[0035] The concentration specifically refers to concentrating to 30% of the original volume;

[0036] The method for removing protein is as follows: add an equal volume of 5% trichloroacetic acid solution, let stand for 60 minutes, centrifuge at 8000 rpm and 20°C for 10 minutes to remove the precipitate;

[0037] The method for alcohol precipitation is as follows: add 4 times the volume of anhydrous ethanol, let stand for 8-12 hours, centrifuge at 6000 rpm and 20°C for 10 minutes, and discard the supernatant.

[0038] In some specific implementations, in step (2), the dialysis conditions are: membrane pore diameter D = 3500 Daltons.

[0039] This invention also provides medium-chain inulin prepared by the above preparation method, wherein the medium-chain inulin is composed of fructose linked by 2,1 glycosidic bonds and has an average degree of polymerization of 12.

[0040] This invention also provides the application of the medium-chain inulin in the preparation of products for preventing and treating obesity.

[0041] This invention also provides a product for preventing and treating obesity, including the aforementioned medium-chain inulin.

[0042] This invention also provides the application of the medium-chain inulin in the preparation of products that regulate gut microbiota.

[0043] This invention also provides the application of the medium-chain inulin in the preparation of products that upregulate Faecalibaculum, Bifidobacterium, Parasutterella, Muribauculum, Clostridium sensu stricto, and Akkermansia.

[0044] This invention extracts inulin from Jerusalem artichoke and eliminates small molecules, including monosaccharides or some oligosaccharides with a DP value less than 10, by dialysis through a semi-permeable membrane (molar mass > 3,000 D). Structural characterization analysis indicates that the extraction process produces medium-chain inulin (DP = 12). This invention proposes the following hypotheses: (1) inulin with a DP in the range of 10 to 20 can selectively promote beneficial gut microbiota and affect metabolomics / metabolic pathways; and (2) inulin can alleviate obesity and related complications in HFD-fed mice. The purpose of this invention is to investigate the effects and mechanisms of medium-chain inulin supplementation on obesity, particularly by modulating the gut microbiome and metabolome of diet-induced obese (DIO) mice.

[0045] Inulin is a natural dietary fiber with various bioactivities. However, few studies have focused on the effects of medium-chain inulin (degree of polymerization = 12) on diet-induced obesity (HFD) in mice. This invention verifies whether medium-chain inulin intake (1%, 3%, and 5% of diet) can counteract HFD-fed obesity in mice by modulating gut microbiota and metabolome. The structural characteristics and spatial conformation of inulin were examined by determining its structural parameters. Forty 3-week-old male C57BL / 6 mice were randomly divided into 5 groups (n = 8 / group), fed a standard diet or an HFD diet supplemented with 1%, 3%, and 5% inulin, respectively, for 12 consecutive weeks. Obesity and health status were assessed by examining body weight, serum biochemical and physiological indicators, and the gut microbiota and metabolome to elucidate the underlying mechanisms. Medium-chain inulin is mainly composed of fructose linked by 2,1 glycosidic bonds, with an average degree of polymerization of 12. Inulin supplementation (3% or 5%) prevented diet-induced obesity (DIO) and metabolic disorders in mice. Furthermore, dietary inulin remodeled the gut microbiota, increasing the abundance of Bacteroidetes, Faecalibacteria, Bifidobacteria, Parabacteria, Lactobacilliaceae, Bacteroidetes, Clostridium, and Akkermansia. Simultaneously, dietary inulin selectively increased the concentration of 11 key metabolites in the intestinal contents of HFD-fed mice, which are directly related to energy utilization pathways. Overall, medium-chain inulin mitigated DIO by specifically remodeling key gut microbiota and metabolites and modulating energy utilization-related metabolic pathways. Therefore, medium-chain inulin may serve as a potential functional food or therapeutic agent for the prevention or treatment of host DIO.

[0046] Example 1

[0047] 1. Inulin extraction and structural characterization

[0048] The medium-chain inulin used in this experiment was extracted from Jerusalem artichoke and dialyzed through a semi-permeable membrane (molar mass > 3,000 D) to remove free monosaccharides or some oligosaccharides with a DP value less than 10. The monosaccharide components, molar mass, glycosidic bonds, and structural characteristics of C and H spectra were determined.

[0049] The specific steps are as follows: (1) Water extraction at a suitable temperature: Grind dried Jerusalem artichoke slices or fresh Jerusalem artichoke into a paste, add distilled water (material-to-water volume ratio 1:30) to a stainless steel pot, extract at 80℃ for 3 hours, cool and filter twice with a polyester fiber mesh (mesh size <1cm) to remove residue, and mix the filtrate. (2) Concentration: Use a vacuum low-temperature concentrator to concentrate the filtrate to 30% of the original extract volume at 60-80℃. (3) Protein removal: After cooling the concentrate, add an equal volume of 5% trichloroacetic acid solution and let stand for 60 minutes. Centrifuge at 8000 rpm and 20℃ for 10 minutes to remove the precipitate. The supernatant is a polysaccharide solution without protein. (4) Alcohol precipitation of polysaccharides: Based on the characteristic that polysaccharides are insoluble in ethanol solutions, transfer the protein-free polysaccharide solution to a 5000ml beaker and add 4 times the volume of anhydrous ethanol as the polysaccharide solution. After soaking in alcohol for 8 hours or standing overnight, centrifuge at 6000 rpm and 20°C for 10 minutes, discard the supernatant, and precipitate crude polysaccharide. (5) Dialysis: Dissolve the extracted crude polysaccharide solution in deionized water at a ratio of 1:1.5, put the crude polysaccharide solution into the prepared dialysis bag (membrane pore diameter D=3500 Daltons, intercepted molecular weight>3500D), rinse the surface of the dialysis bag, clamp one end of the dialysis bag with a special clamp for dialysis bags, add 70% volume of crude polysaccharide solution into the dialysis bag, then clamp the other end with a large clamp, place the sealed dialysis bag in deionized water for dialysis, change the deionized water at 3, 9 and 18 hours, and collect the solution in the dialysis bag after 40 hours. (6) Freeze-drying: After dialysis, collect the liquid in the dialysis bag, concentrate it to one-tenth of the volume, freeze-dry it, and obtain medium-chain inulin with a degree of polymerization greater than 10.

[0050] 2. Experimental Design for Validating the Biological Functions of Medium-Chain Inulin

[0051] Forty male C57BL / 6 mice (3 weeks old, 11-13 g; SPF grade) were purchased from Jinan Pengyue Laboratory Animal Breeding Co., Ltd. (Jinan, China). All experiments were approved by the Animal Use Ethics Committee of Shandong Agricultural University (Program No. 20200526). Mice were housed in the environmentally controlled enclosure of the Animal Center of Shandong Agricultural University (temperature 22±2℃, relative humidity 55–60%, 12 / 12-hour light / dark cycle). During the experiment, mice had free access to water and food, were weighed weekly to monitor weight changes, and their food intake was measured daily. All experiments were approved by the Animal Use Ethics Committee of Shandong Agricultural University (Program No. 20200526).

[0052] Forty male C57BL / 6 mice (3 weeks old, 11-13 g; SPF grade) were purchased from Jinan Pengyue Laboratory Animal Breeding Co., Ltd. (Jinan, China). All experiments were approved by the Animal Use Ethics Committee of Shandong Agricultural University (Agreement No.: 20200526). Mice were housed in an environmentally controlled indoor environment (temperature, 22±2℃; relative humidity 55-60%; regular 12 / 12 h light / dark cycles at the Animal Center of Shandong Agricultural University), with free access to water and food (normal diet) during the experiment.

[0053] After the purchased mice acclimatized to the housing environment and diet for one week, they were randomly divided into 5 groups (n=8, 4 mice / cage). They were fed a normal diet (normal group), a high-fat diet (HFD), and HFD diets supplemented with 1%, 3%, and 5% inulin, respectively, for 12 consecutive weeks. The mice had free access to food and water, were weighed weekly, and their food intake was monitored daily.

[0054] 3. Sample Collection and Measurement

[0055] For the last three days of the experiment, fresh feces were collected, and short-chain fatty acid (SCFA) levels were determined using high-performance gas chromatography (HPGC97, Zhejiang Fuli). At the end of the experiment, fasting blood glucose (FBG) was measured from the tail vein using a rapid blood glucose meter before sacrifice. Blood samples were collected from the eyes of each mouse to determine serum biochemical parameters, and the mice were then sacrificed by cervical dislocation. After opening the abdominal cavity, the contents of the hindgut (from the cecum to the rectum) were collected into two sterile tubes for each mouse and immediately frozen in liquid nitrogen to determine the microbiome and metabolome. Liver, abdominal white adipose tissue (WAT), and scapular brown adipose tissue (BAT) were collected, weighed, immediately frozen in liquid nitrogen, and then stored at -80°C for further analysis. A 3 cm segment of intestine was cut from the middle of the colon and ileum using surgical scissors to prepare histological sections. Collected intestinal samples were rinsed with physiological saline (9 g / L, w / v) and fixed in formaldehyde-phosphate buffer (100 g / L, w / v) for at least 24 hours, followed by paraffin sectioning. For each intestinal sample, 5–10 observation samples (5 µm thick sections) were sequentially cut using a microtome and stained with hematoxylin and eosin (H&E). Intestinal morphology was assessed by measuring villus height (V), crypt depth (C), and villus-to-crypt ratio (V:C) using an optical microscope (BX-51, Olympus, Tokyo, Japan) equipped with Image-Pro Plus software (version 6.0, Motic Images software, Motic China Group Co., Ltd., Xiamen, China). Each sample was measured 10 times.

[0056] 4. Identification of the cecal microbiota using 16S rDNA amplicon sequencing

[0057] Microbiota identification was performed using the IonS5™ XL sequencing platform (Novogene, Beijing, China). DNA was extracted from cecal chyme samples using the QIAamp DNA fecal mini kit (Qiagen Inc., Hilden, Germany); then, the V3-V4 hypervariable region of the 16S rRNA gene was amplified. The amplicon library was sequenced on the IonS5™ XL sequencing platform (Novogene, Beijing, China), with single-end reads of 400 and 600 bp (SE400 and SE600). Detailed procedures are listed in the supplementary materials.

[0058] 5. Determination of the metabolomics of cecal digests

[0059] Quantitative measurements of the cecal metabolome were performed using liquid chromatography-tandem mass spectrometry (LC-MS / MS) (Beijing Novogene Technology Co., Ltd.). The measurement process consisted of three main steps: (1) metabolite extraction; (2) quantitative analysis of metabolites in the digesta by ultra-high performance liquid chromatography-tandem mass spectrometry (UHPLC-MS / MS); and (3) data processing and metabolite identification.

[0060] 6. Statistical Analysis

[0061] Statistical analysis was performed using one-way ANOVA with multiple comparisons based on Dunn's method using IBM SPSS Statistics 23. Histograms were generated using GraphPad Prism 8.0 to represent the results. Linear discriminant analysis (LDA) was used to analyze the effect size of gut microbiota changes using the BIC online program (http: / / www.ehbio.com / Cloud_Platform / front / # / ), with p < 0.05 considered statistically significant. MetaboAnalyst 4.0 online software and the KEGG pathway database (https: / / www.metaboanalyst.ca / ) were used for enrichment of metabolic pathways and analysis of differentially expressed metabolic pathways. Spearman analysis was used to analyze the correlations between differentiated microbes, metabolites, and health parameters, and the results were presented as heatmaps using Heatmap Illustrator (version 1.0.3.7).

[0062] 7. Experimental Results

[0063] 7.1 Structural characteristics of medium-chain inulin

[0064] The molecular structure of inulin is shown in Figure 1. Ion chromatography (IC) analysis revealed that inulin molecules are composed of two monosaccharides, fructose (Fru) and glucose (Glc), with a molar ratio of 82.61%:17.39% (Figure 1A, Table 1). The average molecular weight (Mw), number-average molecular weight (Mn), and Z-average molecular weight (Mz) of inulin are 1.30 × 10⁻⁶. 3 1.80×10 3 and 2.40×10 3 g / mol (Table 1). The polydispersity coefficients of inulin were 1.35 (Mw / Mn) and 2.10 (Mz / Mn), indicating a relatively narrow molar mass distribution range. Furthermore, the weight-average radius (Rw), number-average radius (Rn), and Z-average radius (Rz) of inulin were calculated to be 14.1, 14.0, and 13.6 nm, respectively. The molecular weight characteristics of inulin were examined using the molar mass variation trend curve (B in Figure 1). The results showed that the laser scattering (LS) curve (red line) decreased rapidly, while the refractive index (RI) curve (green line) gradually increased. With the extension of retention time, the molar mass line (blue line) at 10 3 ~10 4 Variation within the g / mol range. Fourier transform infrared spectroscopy (FT-IR) indicates the presence of hydroxyl (-OH) groups (3,600~3,200 cm⁻¹) in the inulin structure. -1 3,490 cm -1 The peak at the peak clearly indicates the OH stretching vibration, further confirming the presence of polysaccharides. According to GC-MS analysis, the inulin molecule consists of 12 monosaccharide residues linked by three different types of glycosidic bonds, involving non-reducing terminal t-Fruf and t-Glcp (molar ratios of 16.44% and 16.33%, respectively), and intrachain residues of 2,1-Fruf and 1,6-Fruf (molar ratios of 66.68% and 0.55%, respectively) (Table 2). This indicates that the ratio of Fru to Glc residues is 83.68%:16.33%, consistent with the compositional analysis. NMR spectroscopy analysis revealed the inulin molecule to be a medium-length PS with 12 monosaccharide residues (D in Figure 1). Combining all structural parameters, the potential spatial conformation of the inulin molecule was further fitted. The three-dimensional molecular structure shows that the inulin molecule is spherical, with few branches, and contains a small number of rod-shaped macromolecules (F.1~F.3 in Figure 1). Furthermore, images obtained from scanning electron microscopy (SEM) show that inulin molecules are spherical with smooth surfaces (E.1–E.3 in Figure 1). In addition, transmission electron microscopy (TEM) images show that the inulin sample contains both long-chain and short-chain molecules, and inulin molecules of different chain lengths form spherical or interconnected network spatial conformations through folding and curling (G.1–G.3 in Figure 1).

[0065] Table 1 Monosaccharide composition and molecular weight parameters

[0066]

[0067] Table 2. Glycosidic bond residue structure and molar ratio

[0068]

[0069] 7.2 Effects of medium-chain inulin supplementation on diet-induced obesity (DIO) in mice

[0070] As shown in Figure 2A, C57BL / 6 mice were fed a normal diet (ND), HFD, or HFD supplemented with different concentrations (w / w: 1%, 3%, and 5%) of medium-chain inulin. After a 12-week experimental period, compared with ND-fed mice, HFD-fed mice had a significantly increased body weight (BW) (P<0.05), while inulin supplementation significantly inhibited HFD-induced BW increase in a dose-dependent manner (Figure 2B and C). As shown in Figure 2D, compared with ND-fed mice, HFD-fed mice had a significantly increased liver weight (liver weight to body weight ratio, w / w), while inulin supplementation inhibited the increase in liver weight in HFD-fed mice (P<0.05). Similarly, HFD feeding led to an increase in white adipose tissue (WAT) and epididymal fat pad weight, but a decrease in brown adipose tissue (BAT) weight, while inulin supplementation reduced the proportion of WAT and increased the proportion of BAT in the body.

[0071] Furthermore, changes in blood lipid profiles, glucose, and urea levels are shown in Figures 2E and 2F. The levels of triglycerides (TG), total cholesterol (TCHO), and urea in the inulin-supplemented group were significantly lower than those in the HFD group. In addition, inulin supplementation increased serum high-density lipoprotein (HDL) levels and decreased serum low-density lipoprotein (LDL) levels, thereby improving the HDL / LDL ratio. As shown in Figure 2G, liver sections were stained with modified Oil Red O to observe the degree of lipid accumulation in the liver (Figure 2G, red stained areas represent lipid droplets). Lipid accumulation in the liver was significantly higher in the HFD group than in the ND group (P<0.01), while inulin supplementation significantly reduced liver lipid accumulation in a dose-dependent manner (P<0.05). Dietary supplementation with 3% inulin reduced HFD-induced lipid deposition to a level similar to that in the ND group, while 5% inulin supplementation significantly reduced the lipid accumulation area compared to the ND group (P<0.05) (Figure 2H). Finally, the present invention evaluated the liver lipid profile and found that inulin supplementation reduced the concentrations of triglycerides (TG), total cholesterol (TCHO), and low-density lipoprotein (LDL) (P<0.05), while increasing the level of high-density lipoprotein (HDL) and the HDL / LDL ratio in a dose-dependent manner (Figure 2, I).

[0072] 7.3 Effects of medium-chain inulin on intestinal development and short-chain fatty acid (SCFA) synthesis

[0073] As shown in Figures 3A-C, compared with the normal group (ND), feeding mice with HFD reduced (P<0.05) the levels of intestinal SCFAs, while inulin supplementation restored the levels of acetate, propionic acid, and butyric acid in a dose-dependent manner. Conversely, HFD feeding significantly increased (P<0.05) the levels of branched-chain fatty acids (BCFAs), such as isobutyric acid and isovaleric acid (P<0.05). However, dietary inulin supplementation reduced the production of BCFAs in a dose-dependent manner (P<0.05).

[0074] Furthermore, intestinal morphology studies showed that, compared with ND-fed mice, HFD-fed mice had increased crypt depth while decreasing villus height and V / C ratio (P<0.05) (Figure 3, D~F). Dietary inulin supplementation prevented this damage and instead promoted ileal growth and development, manifested as increased ileal villus height and V / C ratio (P<0.05) and decreased crypt depth (P<0.05). Similarly, HFD-fed mice increased crypt depth and pH while decreasing colonic wall thickness. Conversely, inulin supplementation reversed these effects, increasing intestinal wall thickness and decreasing crypt depth and pH in a dose-dependent manner (P<0.05) (Figure 3, G~I).

[0075] 7.4 Characteristics of the gut microbiota and differences in microorganisms among groups

[0076] Gut microbiota analysis showed that Firmicutes and Bacteroidetes were the dominant phyla in all groups. However, HFD feeding reshaped the differential gut microbiota, decreasing α-diversity (P<0.05) while increasing Firmicutes richness and F / B ratio (P<0.05) (Figure 4, A, B, C); conversely, dietary inulin supplementation enhanced (P<0.05) microbial diversity, especially Bacteroidetes richness and F / B ratio (Figure 4, C and D). Furthermore, principal coordinate analysis (PCoA) and group clustering showed that the ND group was completely separated from other groups, while the 3% and 5% inulin supplementation groups showed partial overlap, and the 1% inulin group and the HFD group clustered together (Figure 4, B).

[0077] Furthermore, inulin supplementation suppressed the increase in abundance of Lachnospiraceae_NK4A136_group, Alistipes, Dubosiella, and Coridextribacter induced by HFD feeding (P<0.05), and significantly increased the abundance of Faecalibaculum, Lactobacillus, Bifidobacterium, Akkermansia, Bacteroides, and Clostridium_sensu_stricto_1 (Figure 4, E). Linear discriminant analysis (LDA) effect size (LefSe) analysis (Figure 4, F and G) showed that HFD feeding increased the relative abundance of Fibrobacter, Fibrobacteres, Desulfobacterota, and unidentified bacteria (LDA score >4), while inulin supplementation increased the abundance of Verrucomicrobiota, Muribaculaceae, Lactobacillaceae, and Bifidobacteriaceae (LDA score >4.0), which was not observed in the HFD-fed group. Finally, the clade diagram shows the phylogenetic distribution of the differentially expressed bacteria in the different experimental groups (G in Figure 4).

[0078] 7.5 Intestinal metabolomics analysis and differential metabolites

[0079] LC-MS analysis of the gut contents metabolome identified 1,503 metabolites: 946 positive and 557 negative ions. Overall correlation analysis of all metabolites showed that the HFD+1% inulin and HFD groups clustered together, while the HFD+3% inulin and HFD+5% inulin groups formed a separate cluster (Figure 5A). Further analysis using orthogonal projective latent structure discriminant analysis (OPLS-DA) showed complete separation between all five treatment groups (Figure 5B). These findings indicate that gut metabolites are significantly altered by HFD feeding and / or dietary inulin supplementation. The contribution of each metabolite to inter-group differentiation was assessed using the importance of projected variables (VIP) values. The S-plot from the OPLS-DA analysis identified 505 metabolites that showed significant effects in this trial (P<0.05, VIP≥1) (Figure 5C). The differentially expressed metabolites among the ND, HFD, and inulin supplementation groups are presented in volcano plot form (Figure 5DH). Compared with the ND group, the HFD group had 265 differentially expressed metabolites, of which 245 were upregulated and 19 were downregulated.

[0080] Similarly, compared with the HFD group, the 1%, 3%, and 5% inulin groups showed 40, 44, and 71 differentially expressed metabolites, respectively (P<0.05) (FH in Figure 5). Among them, inulin supplementation led to the upregulation of 18, 22, and 30 metabolites in the 1%, 3%, and 5% groups, respectively (P<0.05). Regardless of inulin dosage, the metabolites regulated in the inulin supplementation groups primarily included indoles / derivatives (5-hydroxytryptophan, 2-(1H-indole-3-yl)acetic acid), steroids / derivatives (taurocholic acid, corticosterone, aldosterone, 5α-dihydrotestosterone (5α-DHT)), organic oxygen compounds (maltopentose and maltose), fatty acids (arachidonic acid, prostaglandin D2, docosapentaenoic acid, all-cis-4,7,10,13,16-docosapentaenoic acid, ethyl laurate, propionyl-L-carnitine, and docosahexaenoic acid), and pyridine / derivatives (nicotinamide) (Figure 5, I). Furthermore, similar metabolites and regulatory effects were observed in all three inulin supplementation groups.

[0081] 7.6 Correlation between physiological parameters, differentially expressed microorganisms, metabolites, and metabolic pathways regulated by inulin supplementation

[0082] Spearman rank correlation and metabolic pathway analyses were performed to assess the potential correlations between mouse physiological parameters, gut microbiota, metabolites, and altered metabolic pathways. Inulin selectively promoted microbes including Bacteroides, Faecalibacterium, Lactobacillus, Bifidobacterium, Akkermansia, Bacteroides, Clostridium sensu stricto 1, and Parasutterella, which were positively correlated with mouse fatty acid (acetic acid, propionic acid, butyric acid, SCFAs, and TFAs) concentrations, ileal villus height, HDL, and the HDL / LDL ratio in liver and serum (P<0.05), while negatively correlated with mouse body weight, liver and serum TG, TCHO, and LDL levels, and the degree of fat accumulation in the liver (P<0.05) (Figure 6A). Similarly, the metabolites improved by inulin supplementation mainly included nicotinamide, taurine, 5α-DHT, aldosterone, corticosterone, 5-hydroxy-L-tryptophan, 2-(1H-indol-3-yl)acetic acid, propionyl-L-carnitine, MN-18N-(5-hydroxypentyl) metabolites, maltose, and maltose. These metabolites were positively correlated with fatty acids, ileal villus height, HDL content, and HDL / LDL ratio in mouse liver and serum (P<0.01), but negatively correlated with mouse body weight, TG, TCHO, and LDL content in liver and serum, and the degree of hepatic fat accumulation (P<0.05) (Figure 6, B). Furthermore, the microbial increases resulting from inulin supplementation were positively correlated with specific metabolites increased by inulin supplementation (Figure 6, A), but negatively correlated with HFD-derived metabolites, including arachidonic acid, ethyl laurate, docosahexaenoic acid, and retinoic acid (P<0.05, Figure 6, C).

[0083] Furthermore, by matching differentially expressed metabolites from the mouse KEGG pathway database (HFD vs. ND; 1%, 3%, and 5% inulin vs. HFD), we further identified metabolic pathways significantly modulated by HFD feeding and / or dietary inulin supplementation (Figure 6, D). The results showed that HFD feeding upregulated physiological processes related to inflammation and energy metabolism, including steroid hormone biosynthesis, lysine degradation, tryptophan, arachidonic acid, tyrosine, and starch / sucrose metabolism, and downregulated biotin metabolism (effect >0.02, Figure 6, D).

[0084] However, all inulin-supplemented groups showed downregulation of the arachidonic acid metabolic pathway (Figure 6, D). The intrinsic correlation of metabolic pathways regulated by inulin supplementation (Figure 7) further indicates that inulin supplementation significantly upregulated the metabolism of tryptophan, niacin, nicotinamide, starch, sucrose, taurine / linotaurine, primary bile acids, and steroid hormone biosynthesis, while downregulating the biosynthesis of unsaturated fatty acids and arachidonic acid metabolism. Eight metabolites were observed to be involved in the upregulation of metabolic pathways: nicotinamide, taurcholic acid, aldosterone, corticosterone, 5-hydroxy-L-tryptophan, 2-(1H-indole-3-yl)acetic acid, 5α-DHT, and maltose. Therefore, dietary inulin supplementation can downregulate inflammation-related metabolic pathways while improving glucose and lipid metabolism, which may be a potential mechanism by which inulin affects physiological health and alleviates obesity symptoms.

[0085] 7.7 Identification of inulin-mediated core microbes and metabolites directly associated with body weight (BW) in HFD-fed mice

[0086] Using body weight gain (BW) and SCFAs as environmental factors, a co-occurrence network was constructed to further identify core microorganisms and metabolites associated with BW in mice. As shown in Figure 8A, SCFAs inhibited HFD-induced weight gain. *Faecalibaculum*, *Bifidobacterium*, *Prevotellaceae_UCG-001*, *Parasutterella*, *Ruminococcus*, *Muribaculum*, *Lachnospiraceae_UCG_006*, *Clostridium_sensu_stricto_1*, *Akkermansia*, and *Bacteroides* were also negatively correlated with body weight. Among these microorganisms, *Faecalibaculum*, *Bifidobacterium*, *Parasutterella*, *Muribaculum*, *Clostridium_sensu_stricto_1*, and *Akkermansia* had relatively high abundance (>0.5%), and were significantly upregulated by dietary inulin supplementation. Therefore, these microorganisms may be potential core bacteria in inulin intake-mediated inhibition of HFD-induced obesity.

[0087] Similarly, inulin supplementation modulates metabolites that are directly or indirectly related to body weight. As shown in Figure 8B, arachidonic acid, lysergic acid diacetamide D3 (LSD-d3), ethyl laurate, 16-hydroxyhexadecanoic acid, all-cis-4,7,10,13,16-docosapentaenoic acid, and docosapentaenoic acid are directly and positively correlated with body weight, and all of these metabolites are reduced in the inulin supplementation group. Therefore, these metabolites represent a subset of metabolites that promote body weight gain in HFD-fed mice (Figure 8B, light purple nodes). Conversely, the inulin supplementation group showed increased levels of nicotinamide, taurine, aldosterone, corticosterone, 2-(1H-indol-3-yl)acetic acid, MN-18N-(5-hydroxypentyl) metabolite, 5α-DHT, maltopentose, 5-hydroxytryptophan, propionyl-L-carnitine, and maltose, and these metabolites showed a mutually exclusive relationship with those in the subgroup that promotes body weight gain. Furthermore, short-chain fatty acids are directly related to body weight and exhibit mutually exclusive relationships. However, tocopherol quinoline (TQH), 2-oxoindole, and 2-(1H-indole-3-yl)acetic acid are positively correlated with the production of short-chain fatty acids. Therefore, these metabolites may interfere with weight gain by affecting the production of short-chain fatty acids. Considering the differences and pathway enrichment, eight key metabolites—nicotinamide, taurocholic acid, aldosterone, corticosterone, 2-(1H-indole-3-yl)acetic acid, 5-hydroxy-L-tryptophan, 5α-DHT, and maltose—formed the BW inhibitory metabolite subset (B in Figure 8, light pink node).

[0088] In summary, this invention investigated the effects of Jerusalem artichoke medium-chain inulin (DP=12) on HFD-induced obesity and related metabolic disorders in mice. The unique cross-linked network and / or spherical spatial conformation of inulin may contribute to its observed bioactivity. Inulin supplementation effectively reversed the negative effects of HFD, leading to a dose-dependent decrease in BW and WAT mass. Simultaneously, it increased the BAT index. Furthermore, HFD feeding resulted in elevated serum TG, TCHO, LDL, FBG, and urea levels, while inulin supplementation restored these physiological indicators to normal levels. Inulin supplementation led to increased production of SCFAs, primarily acetate, propionate, and butyrate. These SCFAs are important energy sources for intestinal cells and play a crucial role in activating the host immune system. Conversely, HFD feeding resulted in elevated levels of branched-chain fatty acids (BCFAs), potentially leading to insulin resistance. Moreover, SCFAs bind to receptors and improve the production of glucagon-like peptide-1 (GLP-1) and peptide tyrosine, thereby affecting the host's energy balance and lipid metabolism. Therefore, in this invention, the increased production of SCFAs by inulin supplementation is fundamental to improving obesity-related metabolic complications. The observed improvements in metabolic parameters in this invention are associated with changes in the gut microbiota and metabolome. HFD feeding significantly reduced gut microbiota diversity and increased the F / B ratio, indicating dysbiosis. Conversely, inulin supplementation significantly increased microbiota diversity, reduced the F / B ratio, and enriched beneficial bacteria, including Bacteroides, Akkermansiaceae, Bacteroidetes, Lactobacillus, Faecalibacterium, Clostridium sensustricto, Bifidobacterium, and Parasutterella. Furthermore, this invention found a positive correlation between inulin-promoted microbiota and key metabolites that drive the regulation of metabolic pathways involving fatty acid, amino acid, and energy metabolism. In addition, gut microbiota structure (diversity and composition) has a significant impact on host energy uptake, storage, and consumption.

[0089] Metabolomics analysis revealed that, compared to the HFD-fed group, medium-chain inulin supplementation specifically reduced the concentrations of arachidonic acid, LSD-d3, ethyl laurate, 16-hydroxyhexadecanoic acid, all-cis-4,7,10,13,16-docosapentaenoic acid, and docosapentaenoic acid in the intestinal contents. These metabolites were negatively correlated with improved health parameters (HDL, BAT, and SCFAs) and positively correlated with weight gain. Therefore, these metabolites constitute a functional subgroup of core metabolites that promote weight gain. Conversely, inulin supplementation in HFD-fed mice increased the levels of nicotinamide, taurine, aldosterone, corticosterone, 2-(1H-indol-3-yl)acetic acid, MN-18N-(5-hydroxypentyl) metabolite, 5α-DHT, maltolose, 5-hydroxytryptophan, propionyl-L-carnitine, maltose, and 4-hydroxyretinoic acid, while these metabolites inhibited weight gain in HFD-fed mice. Therefore, these metabolites constitute a subpopulation of metabolites that inhibit weight gain, playing a crucial role in preventing weight gain in HFD-fed mice. Furthermore, these inulin-altered metabolites modulate key metabolic pathways, including downregulating arachidonic acid metabolism and upregulating niacin / nicotinamide metabolism, primary bile acid biosynthesis, and tryptophan metabolism. These metabolic pathways are closely related to inflammation, lipid, and energy metabolism, providing insights into the mechanisms by which inulin exerts its beneficial effects. In this invention, co-occurrence network analysis revealed that specific microbial taxa (Faecalibaculum, Bifidobacterium, Parasutterella, Clostridium sensustricto 1, and Akkermansia) directly inhibit weight gain, highlighting their potential role in weight management. Thus, these microbes form a functional subpopulation capable of fermenting poorly digestible inulin into key metabolites, including SCFAs, and exerting an inhibitory effect on weight gain through the “diet-microbiota-metabolite-phenotype” axis. Regarding different metabolites, SCFAs, as the primary microbial-derived metabolite, likely play a key role in combating weight gain. Furthermore, 2-(1H-indole-3-yl)acetic acid, an essential intermediate produced during tryptophan metabolism, is positively correlated with SCFA but negatively correlated with body weight. Additionally, 2-(1H-indole-3-yl)acetic acid is positively correlated with Bacteroides, Faecalibacterium, Bifidobacterium, Parabacterium, Clostridium sensustricto-1, and Akkermansia, while negatively correlated with TG, TCHO, and LDL levels in mouse liver and serum. This finding suggests that 2-(1H-indole-3-yl)acetic acid may be a core metabolite in the physiological process by which inulin influences overall health through the "diet (inulin)-gut microbiota / metabolite-phenotype" axis.

[0090] Inulin alleviates HFD-induced obesity and metabolic disorders by modulating the "diet (inulin)-gut microbiota / metabolite-phenotype" axis. Specifically, inulin promotes the abundance of key microbes (Faecalibaculum, Bifidobacteria, Parasutterella, Clostridium sensustricto-1, and Akkermansia) and promotes the production of specific metabolites, particularly 2-(1H-indole-3-yl)acetic acid, which collectively contribute to improving metabolic health in DIO mice.

[0091] In summary, this invention provides compelling evidence for the beneficial effects of medium-chain inulin (DP=12) in alleviating obesity and metabolic disorders caused by HFD. The unique inulin structure and specific chain length remodel the gut microbiome and metabolome, particularly selectively modulating key microorganisms such as *Femtobacterium faecium*, *Bifidobacterium*, *Pseudomonas*, *Clostridium sensustricto*, and *Akkermansia*, as well as metabolites such as nicotinamide, taurine, aldosterone, corticosterone, 2-(1H-indole-3-yl)acetic acid, 5-hydroxy-L-tryptophan, 5α-DHT, and maltose, thereby promoting improvements in obesity and overall health. Furthermore, the identified key microorganisms and metabolites represent promising therapeutic targets for the prevention or treatment of obesity. These findings support the development of inulin-based nutritional strategies designed to modulate specific microbiomes and metabolomes for effective weight management.

[0092] Obviously, the above embodiments of the present invention are merely examples for clearly illustrating the present invention, and are not intended to limit the implementation of the present invention. For those skilled in the art, other variations or modifications can be made based on the above description. It is neither necessary nor possible to exhaustively describe all embodiments here. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of the present invention should be included within the scope of protection of the claims of the present invention.

Claims

1. A method for preparing medium-chain inulin, characterized in that, Includes the following steps: (1) Jerusalem artichoke was ground into a pulp, and water was added for extraction. Then, crude polysaccharide was obtained by filtration, concentration, protein removal, and alcohol precipitation. (2) The crude polysaccharide was dialyzed and concentrated using a semi-permeable membrane, and then freeze-dried to obtain the medium-chain inulin.

2. The preparation method according to claim 1, characterized in that, In step (1), the conditions for water extraction are: the volume ratio of the slurry to water is 1:30, the extraction temperature is 80℃, and the time is 3h; The concentration specifically refers to concentrating to 30% of the original volume; The method for removing protein is as follows: add an equal volume of 5% trichloroacetic acid solution, let stand for 60 minutes, centrifuge at 8000 rpm and 20°C for 10 minutes to remove the precipitate; The method for alcohol precipitation is as follows: add 4 times the volume of anhydrous ethanol, let stand for 8-12 hours, centrifuge at 6000 rpm and 20°C for 10 minutes, and discard the supernatant.

3. The preparation method according to claim 1, characterized in that, In step (2), the dialysis conditions are: membrane pore diameter D = 3500 Daltons.

4. The medium-chain inulin prepared by the preparation method according to any one of claims 1-3, characterized in that, The medium-chain inulin is composed of fructose linked by 2,1 glycosidic bonds, with an average degree of polymerization of 12.

5. The use of medium-chain inulin as described in claim 4 in the preparation of products for preventing and treating obesity.

6. A product for preventing and treating obesity, characterized in that, Includes the medium-chain inulin as described in claim 4.

7. The use of medium-chain inulin as described in claim 4 in the preparation of products that regulate intestinal flora.

8. The use of the medium-chain inulin as described in claim 4 in the preparation of products that upregulate Faecalibaculum, Bifidobacterium, Parasutterella, Muribauculum, Clostridium sensu stricto, and Akkermansia.

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