Medium-chain inulin as well as preparation method and application thereof

Abstract

The invention discloses medium-chain inulin as well as a preparation method and application thereof, and belongs to the technical field of plant extraction. The unique inulin structure and chain length disclosed by the invention remodel intestinal microbiome and metabolome, and particularly selectively regulates key microorganisms such as faecalis bacillus, bifidobacterium, parabacterium, Clostridium sensuricto1, Akkermansia and the like, and metabolites such as nicotinamide, taurocholic acid, aldosterone, corticosterone, 2-(1H-indole-3-yl) acetic acid, 5-hydroxy-L-tryptophan, 5 alpha-DHT, maltose and the like, so that the inulin can be used for preparing the food-grade functional food. The improvement of the obesity and the overall health condition of the host is promoted. The core microorganisms and metabolites identified by the technical scheme represent potential therapeutic targets for preventing or treating obesity and related metabolic symptoms. These findings support the development of inulin-based nutritional strategies that effectively manage body weight by modulating specific microbiota and metabolome.

Description

Technical Field

[0001] The invention relates to the technical field of plant extraction, and in particular to medium-chain inulin and a preparation method and application thereof. Background Art

[0002] Obesity is a global health problem that affects 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 are overweight, of which more than 890 million are classified as obese. In addition, obesity is always accompanied by a variety of metabolic diseases, including diabetes, hypertension, cardiovascular disease (CVD), and musculoskeletal diseases. The main cause of obesity is the imbalance between energy intake and expenditure, which leads to excessive fat storage in white adipose tissue. High-fat diet (HFD) is common in both developed and developing countries and is a major factor in the global obesity epidemic. HFD usually lacks sufficient dietary fiber, which can disrupt the intestinal microbiome, affect physiological processes and lead to obesity, hyperlipidemia and other metabolic problems. Therefore, in contemporary society, the prevention of obesity and its complications caused by high-fat diet and insufficient dietary fiber has attracted 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 the special glycosidic bond, inulin is not easily digested by amylase in the proximal gastrointestinal tract. However, almost 90% of inulin can reach the colon and be fermented by beneficial bacteria to produce a variety of metabolites, including short-chain fatty acids (SCFAs), amino acids and vitamins, which is considered to be the main way for inulin to exert its biological activity. However, inulins of different chain lengths (different DP values) specifically regulate different microbial flora, thereby producing different metabolites and showing different biological effects. The biological activity of inulin is closely related to its DP value. Current research in this field believes that medium-chain inulin with a chain length between 10 and 20 has a wide range of biological effects. However, the exploration of the biological effects of medium-chain inulin in the targeted extraction of medium-chain inulin is still blank. Exploring the targeted extraction technology of medium-chain inulin and its biological effects, especially for the treatment of obesity and metabolic syndrome, is of great significance for the development of natural functional foods and biomedicines. Summary of the invention

[0004] The purpose of the present invention is to provide a medium-chain inulin and a preparation method and application thereof, so as to solve the problems existing in the above-mentioned prior art.

[0005] To achieve the above object, the present invention provides the following solutions:

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

[0007] (1) grinding Jerusalem artichoke to obtain slurry, adding water to extract, and then filtering, concentrating, removing protein, and precipitating with alcohol to obtain crude polysaccharide;

[0008] (2) dialyzing the crude polysaccharide with a semipermeable membrane, concentrating, and freeze-drying to obtain the medium-chain inulin.

[0009] The second technical solution of the present invention is that the medium-chain inulin prepared by the above preparation method is composed of fructose connected 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 use of the medium-chain inulin in the preparation of products for preventing and treating obesity.

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

[0012] A fifth technical solution of the present invention is the use of the medium-chain inulin in the preparation of products for regulating intestinal flora.

[0013] A sixth technical solution of the present invention is the use of the medium-chain inulin in the preparation of products that upregulate Faecalibaculum, Bifidobacterium, Parasutterella, Muribaculum, Clostridium_sensu_stricto_1 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 the present invention reshape the intestinal microbiome and metabolome, and in particular selectively regulate key microorganisms such as Faecalibacterium, Bifidobacterium, Parabacterium, Clostridium_sensu_stricto_1 and Akkermansia, as well as 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 improvement of obesity and overall health. In addition, 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 regulating specific microbiota and metabolomes to effectively manage weight. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0017] Figure 1 are the structural characteristics of medium-chain inulin. Wherein, A is the ion chromatogram (IC) of medium-chain inulin. B is the trend of multi-angle laser scattering (LS), refractive index (RI) and fitted molar mass signals of medium-chain inulin. The red line represents the trend of LS 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 of the polysaccharide molecules contained in the test samples and their relative proportions. The blue line is the trend of the molar mass fitted by the LS and RI signals of inulin with retention time. C is the Fourier transform infrared (FT-IR) spectrum of medium-chain inulin. D is the proposed chemical and structural formula of medium-chain inulin. E is a scanning electron microscope (SEM) image of inulin. E.1 is the overall appearance of inulin scanned by electron microscope; E.2 is the composition of inulin balls observed by scanning electron microscope at a magnification of 200 times; E.3 is the inulin observed by scanning electron microscope at a magnification of 1000 times. F is the three-dimensional spatial structure of the inulin image fitted with the determined structural parameters. F.1 is spherical inulin; F.2 is the three-dimensional structure of inulin molecule 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 inulins of different chain lengths at a magnification of 70,000 times; G.2 is a network woven by long-chain inulins at a magnification of 30,000 times; G.3 is a single long chain of inulin at a magnification of 30,000 times.

[0018] Figure 2 Supplementation of medium-chain inulin for 12 weeks prevents HFD-induced obesity and improves lipid deposition in C57BL / 6 mice. A and B are the experimental design and obese phenotype of mice fed HFD or HFD+; C is the weekly weight change and body weight of mice fed HFD or HFD+inulin at the end of the experiment; D is the tissue weight change of liver, white adipose tissue (burrow epididymal fat pad), and brown adipose tissue (bat) fed HFD or HFD+inulin during the experiment; E is the serum lipid level; F is the fasting blood glucose (FBG) and serum urea level; G is the oil red stained section showing the degree of liver fat accumulation and distribution. H represents the percentage (%) of the oil red stained positive area of ​​the liver in the corresponding section (G); I is the liver lipid profile. Asterisks indicate significant differences, *P<0.05, **P<0.01, ***P<0.001.

[0019] Figure 3Medium-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. Summary of total fatty acids (TFA), short-chain fatty acids (SCFAs), and branched-chain fatty acids (BCFAs) in feces. DF. Morphology and quantitative analysis of the ileum. After hematoxylin and eosin (H&E) staining, the villus height, crypt depth, and the ratio of villus height / crypt depth (V / C) of the ileum were observed under a ×100 magnification light microscope. GI: ​​Quantitative determination of colon morphology and related parameters, crypt depth, intestinal wall thickness, intestinal contents, pH value, and representative images of colon sections in mice in the five experimental groups. *P<0.05, **P<0.01.

[0020] Figure 4 This is the overview of the intestinal microbiome and differential microbial screening after adding inulin. Among them, A is the Shannon index, which represents the diversity index of the intestinal microbiome, B is the Beta diversity of the intestinal microbiome, C is the abundance ratio of the main intestinal bacteria Firmucute and Bacteroidota, D is the differential microorganisms at the phylum level, E is the differential microorganisms at the genus level, F is the differential microbial column chart obtained by the LEfse analysis method, and G is the evolutionary branch diagram of the intestinal microbiome obtained by the LEfse analysis method.

[0021] Figure 5 Metabolome profiles and differential metabolites between experimental groups. A. Heat map shows the effects of HFD feeding and inulin addition on intestinal metabolites in mice. B. Orthogonal projection of latent structure discriminant analysis (OPLS-DA) shows the distribution of intestinal metabolites in different groups. C. S-chart of OPLS-DA shows the distribution of differential metabolites. Red dots represent metabolites with VIP≥1, and blue dots represent metabolites with VIP<1. D~H. Volcano plots show the differences in metabolites between HFD, ND and inulin supplementation groups. I. Classification of differential metabolites in the inulin-added group and the HFD-fed group were upregulated and downregulated.

[0022] Figure 6Correlations between health parameters, microbes, and metabolites altered by inulin addition. In Figures A, B, and C, red fonts indicate that microbes or metabolites were significantly upregulated after inulin addition. A. Correlations between health parameters and different gut microbes. B. Correlations between health parameters and differentially abundant metabolites. C. Correlations between different gut microbes and metabolites. D. Analysis of metabolic pathways regulated by HFD feeding and / or inulin addition, compared between the ND group and 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 interconversion of pentoses and gluconates, 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 niacin / 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 Figure 3. ...

[0024] Figure 8 Figure 2. Co-occurrence network of gut microbes and metabolites with body weight (BW) and SCFAs. Light blue dotted line linkage indicates that two nodes are negatively correlated (mutually exclusive, mu-), and light pink solid line linkage indicates that two nodes are positively correlated (co-). A. Correlation between microbes, body weight and short-chain fatty acids (SCFAs). B. Correlation between metabolites, body weight and SCFAs. DETAILED DESCRIPTION

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

[0026] It should be understood that the terms described in the present invention are only for describing special embodiments and are not intended to limit the present invention. In addition, for the numerical range in the present invention, it should be understood that each intermediate value between the upper and lower limits of the scope is also specifically disclosed. Each smaller range between the intermediate value in any stated value or stated range and any other stated value or intermediate value in the described range is also included in the present invention. The upper and lower limits of these smaller ranges can be independently included or excluded in the scope.

[0027] Unless otherwise indicated, all technical and scientific terms used herein have the same meanings as those generally understood by those skilled in the art. Although the present invention describes only preferred methods and materials, any methods and materials similar or equivalent to those described herein may also be used in the implementation or testing of the present invention. All documents mentioned in this specification are incorporated by reference to disclose and describe the methods and / or materials associated with the documents. In the event of a conflict with any incorporated document, the content of this specification shall prevail.

[0028] It will be apparent to those skilled in the art that various modifications and variations may be made to the specific embodiments of the present invention description without departing from the scope or spirit of the present invention. Other embodiments derived from the present invention description will be apparent to those skilled in the art. The present application description and examples are exemplary only.

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

[0030] The technical solutions described in the present invention, unless otherwise specified, are all conventional solutions in the art, and the reagents or raw materials used, unless otherwise specified, are purchased from commercial channels or have been disclosed.

[0031] The embodiment of the present invention provides a method for preparing medium-chain inulin, comprising the following steps:

[0032] (1) grinding Jerusalem artichoke to obtain slurry, adding water to extract, and then filtering, concentrating, removing protein, and precipitating with alcohol to obtain crude polysaccharide;

[0033] (2) dialyzing the crude polysaccharide with a semipermeable membrane, concentrating, and freeze-drying to obtain the medium-chain inulin.

[0034] In some specific embodiments, 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 h;

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

[0036] The protein removal method comprises: adding an equal volume of a trichloroacetic acid solution with a mass concentration of 5%, standing for 60 minutes, centrifuging at 8000 rpm and 20° C. for 10 minutes to remove the precipitate;

[0037] The alcohol precipitation method is as follows: adding 4 times the volume of anhydrous ethanol, standing for 8 to 12 hours, centrifuging at 6000 rpm and 20° C. for 10 minutes, and discarding the supernatant.

[0038] In some specific embodiments, in step (2), the dialysis condition is: membrane pore diameter D = 3500 Daltons.

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

[0040] The embodiment of the present invention also provides the use of the medium-chain inulin in preparing products for preventing and treating obesity.

[0041] An embodiment of the present invention further provides a product for preventing and treating obesity, comprising the medium-chain inulin.

[0042] The embodiment of the present invention also provides the use of the medium-chain inulin in preparing a product for regulating intestinal flora.

[0043] The embodiment of the present invention also provides the use of the medium-chain inulin in preparing a product that upregulates Faecalibaculum, Bifidobacterium, Parasutterella, Muribaculum, Clostridium_sensu_stricto_1 and Akkermansia.

[0044] The present invention extracts inulin from Jerusalem artichoke and dialyzes it through a semipermeable membrane (molar mass>3,000D) to eliminate small molecules, including monosaccharides or some oligosaccharides with a DP value of less than 10. Structural feature analysis shows that the extraction process produces medium-chain inulin (DP=12). The present invention proposes the following hypotheses: (1) Inulin with a DP ranging from 10 to 20 can selectively promote beneficial intestinal microorganisms and affect the metabolome / metabolic pathways, and (2) Inulin can alleviate obesity and its related complications in HFD-fed mice. The purpose of the present invention is to explore the effects of supplementation with medium-chain inulin on obesity and its mechanism, particularly by regulating the intestinal microbiome and metabolome of diet-induced obese (DIO) mice.

[0045] Inulin is a natural dietary fiber with multiple biological activities. However, few studies have focused on the effects of medium-chain inulin (DP = 12) on high-fat diet (HFD)-induced obesity in mice. The present invention verifies whether medium-chain inulin intake (1%, 3%, and 5% in the diet) can counteract obesity in HFD-fed mice by regulating the intestinal microbiota and metabolome. The structural characteristics and spatial conformation of inulin were investigated by determining the structural parameters of inulin. Forty 3-week-old C57BL / 6 male mice were selected and randomly divided into 5 groups (n = 8 / group) and fed with standard feed or HFD supplemented with 1%, 3%, and 5% inulin for 12 consecutive weeks. Obesity and health status were detected by examining body weight, serum biochemical and physiological indicators, as well as the microbiota and metabolome of intestinal contents to interpret the underlying mechanisms. Medium-chain inulin is mainly composed of fructose linked by 2,1 glycosidic bonds, with an average DP of 12. Inulin supplementation (3% or 5%) prevents diet-induced obesity (DIO) and metabolic disorders in mice. In addition, dietary inulin supplementation reshaped the intestinal flora and increased the abundance of Bacteroidetes, Faecalibacterium, Bifidobacterium, Parabacteria, Lactobacillaceae, Bacteroidetes, Clostridium, and Akkermansia. At the same time, dietary inulin supplementation selectively increased the concentrations of 11 key metabolites in the intestinal contents of HFD-fed mice, which were directly related to energy utilization pathways. Overall, medium-chain inulin alleviated DIO by specifically reshaping key intestinal microorganisms and metabolites and regulating metabolic pathways related to energy utilization. Therefore, medium-chain inulin can be used as a potential functional food or therapeutic agent to prevent or treat host DIO.

[0046] Example 1

[0047] 1. Inulin extraction and structural characteristics determination

[0048] The medium-chain inulin used in this experiment was extracted from Jerusalem artichoke and dialyzed through a semipermeable membrane (molar mass > 3,000D) to remove free monosaccharides or some oligosaccharides with a DP value less than 10. The monosaccharide composition, 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 an appropriate temperature: grind the dried Jerusalem artichoke slices or fresh Jerusalem artichokes, add distilled water (volume ratio of material to water 1:30) in a stainless steel pot, extract at 80°C for 3h, filter twice with a polyester fiber mesh (mesh <1cm) after cooling, remove the residue, and mix the filtrate. (2) Concentration: Use a vacuum low-temperature concentration tank to concentrate the filtrate to 30% of the original extract volume at 60-80°C. (3) Protein removal: After the concentrate is cooled, add an equal volume of trichloroacetic acid solution with a mass concentration of 5% and let it stand for 60 minutes. Centrifuge at 8000 rpm and 20°C for 10 minutes to remove the precipitate. The supernatant is a polysaccharide solution without protein. (4) Alcohol precipitation of polysaccharides: Based on the characteristics that polysaccharides are insoluble in ethanol solutions, the deproteinized polysaccharide solution is transferred to a 5000ml beaker and anhydrous ethanol 4 times the volume of the polysaccharide solution is added. 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 as crude polysaccharide. (5) Dialysis: Dissolve the extracted crude polysaccharide solution in deionized water at a dosage of 1:1.5, put the crude polysaccharide solution into a treated dialysis bag (membrane pore diameter D = 3500 Daltons, molecular weight interception> 3500D), rinse the surface of the dialysis bag, clamp one end of the dialysis bag with a special clamp for the dialysis bag, add 70% volume of crude polysaccharide solution to the dialysis bag, and then clamp the other end with a large clamp, place the sealed dialysis bag in deionized water for dialysis, replace the deionized water at 3, 9, and 18 hours, and collect the solution in the dialysis bag after 40 hours. (6) Freeze drying: After the dialysis is completed, collect the liquid in the dialysis bag, concentrate it to one-tenth of the volume, and freeze dry it to obtain medium-chain inulin with a degree of polymerization greater than 10.

[0050] 2 Design of experimental verification of biological function of medium-chain inulin

[0051] A total of 40 male C57BL / 6 mice (3 weeks old, 11-13 g; SPF grade) were purchased from Jinan Pengyue Experimental Animal Breeding Co., Ltd. (Jinan, China). All experiments were approved by the Animal Use Ethics Committee of Shandong Agricultural University (protocol number 20200526). Mice were housed in an environmentally controlled shed at the Animal Center of Shandong Agricultural University (temperature 22±2℃, relative humidity 55–60%, 12 / 12 h light / dark cycle). During the experiment, they were given free access to water and food. They were weighed once a week to check body weight changes, and their food intake was measured every day. All experiments were approved by the Animal Use Ethics Committee of Shandong Agricultural University (protocol number 20200526).

[0052] Forty male C57BL / 6 mice (3 weeks old, 11-13 g; SPF grade) were purchased from Jinan Pengyue Experimental Animal Breeding Co., Ltd. (Jinan, China). All experiments were approved by the Animal Use Ethics Committee of Shandong Agricultural University (protocol number: 20200526). Mice were housed in an environmentally controlled room (temperature, 22 ± 2 °C; relative humidity 55-60%; regular 12 / 12 h light / dark cycle at the Animal Center of Shandong Agricultural University) and had free access to water and food (normal diet) during the experiment.

[0053] After the purchased mice were adapted to the mouse house environment and feed for 1 week, they were randomly divided into 5 groups (n=8, 4 mice / cage) and fed with normal diet (normal group), high-fat diet (HFD), and HFD supplemented with 1%, 3%, and 5% inulin for 12 consecutive weeks. The mice were allowed to eat and drink freely, were weighed once a week, and food intake was monitored daily.

[0054] 3. Sample collection and determination

[0055] On the last three days of the experiment, fresh feces were collected and the levels of short-chain fatty acids (SCFAs) were determined by high-performance gas chromatography (HPGC97, Zhejiang R&F). At the end of the experiment, fasting blood glucose (FBG) was measured from the tail vein using a rapid glucometer before sacrifice. Blood samples were collected from the eyeball of each mouse to determine serum biochemical parameters, and the mice were then killed by cervical dislocation. After opening the abdominal cavity, the hindgut contents (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. The 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. 3 cm intestinal segments were cut from the colon and mid-ileum with surgical scissors to make histological sections. The collected intestinal samples were rinsed with saline (9 g / L, w / v) and fixed in formaldehyde-phosphate buffer (100 g / L, w / v) for no less than 24 hours, and then paraffin sectioned. For each intestinal sample, 5-10 observation samples (5 μm thick sections) were cut continuously using a microtome and stained with hematoxylin and eosin (H&E). Intestinal morphology was evaluated 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). The measurement was repeated 10 times for each sample.

[0056] 4 Determination of cecal microbiota using 16S rDNA amplicon sequencing

[0057] Determination of the microbiota was performed using the IonS5TMXL sequencing platform (Novogene, Beijing, China). DNA was extracted from cecal digesta samples using the QIAamp DNA stool mini kit (Qiagen Inc., Hilden, Germany); then, the V3-V4 hypervariable region of the 16S rRNA gene was amplified. Amplicon libraries were sequenced on the IonS5TMXL sequencing platform (Novogene, Beijing, China) with single-end reads of 400 and 600 bp (SE400 and SE600). The detailed procedures are listed in the Supplementary Materials.

[0058] 5. Determination of the metabolome of cecal digesta

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

[0060] 6 Statistical analysis

[0061] Statistical analysis was performed using one-way analysis of variance (ANOVA) according to Dunn's multiple comparisons using IBM SPSS Statistics 23. Histograms were generated using GraphPad Prism 8.0 to present the analysis results. Linear discriminant analysis (LDA) effect size analysis of intestinal flora changes was performed using the BIC online program (http: / / www.ehbio.com / Cloud_Platform / front / # / ), and the differences were considered statistically significant when P < 0.05. MetaboAnalyst4.0 online software and the KEGG pathway database (https: / / www.metaboanalyst.ca / ) were used to perform enrichment of metabolic pathways and analysis of differential metabolic pathways. The correlations between differentiated microorganisms, metabolites, and health parameters were analyzed using Spearman analysis and presented in the form of heatmaps using the heatmap illustrator program (version 1.0.3.7).

[0062] 7 Experimental results

[0063] 7.1 Structural characteristics of medium-chain inulin

[0064] The molecular structure characteristics of inulin are as follows Figure 1 Ion chromatography (IC) analysis showed that inulin molecules are composed of two monosaccharides, fructose (Fru) and glucose (Glc), with a molar ratio of 82.61%:17.39% ( Figure 1A in Table 1). The average molecular weight (Mw), number average molecular weight (Mn) and Z average molecular weight (Mz) of inulin are 1.30×10 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 that the molar mass distribution range was relatively narrow. In addition, 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. Using the molar mass change trend curve ( Figure 1 B) The molecular weight characteristics of inulin were examined, and the results showed that the laser scattering (LS) curve (red line) decreased rapidly and the refractive index (RI) curve (green line) increased gradually. As the retention time increased, the molar mass line (blue line) decreased at 10 3 ~10 4 Fourier transform infrared spectroscopy (FT-IR) showed that there were hydroxyl (-OH) groups (3,600-3,200 cm -1 ). 3,490cm -1 The peak at clearly indicates the OH stretching vibration, further confirming the presence of polysaccharides. According to the GC-MS analysis results, the inulin molecule is composed of 12 monosaccharide residues connected by three different types of glycosidic bonds, involving t-Fruf and t-Glcp at the non-reducing end (the molar ratios are 16.44% and 16.33%, respectively), and intrachain residues of 2,1-Fruf and 1,6-Fruf (the molar ratios are 66.68% and 0.55%, respectively) (Table 2). This shows that the ratio of Fru to Glc residues is 83.68%:16.33%, which is consistent with the composition analysis. After NMR spectral analysis, the structural formula of the inulin molecule is a medium-chain PS with 12 monosaccharide residues ( Figure 1 D). Combining all structural parameters, the potential spatial conformation of inulin molecules was further fitted. The three-dimensional molecular structure showed that inulin molecules were spherical, with few branches and contained a small amount of rod-shaped macromolecules ( Figure 1 In addition, the images obtained from the scanning electron microscope (SEM) showed that the inulin molecules were spherical and had a smooth surface ( Figure 1 In addition, transmission electron microscopy (TEM) images show that inulin samples contain both long-chain molecules and short-chain molecules, and inulin molecules of different chain lengths form spherical or interconnected network spatial conformations through folding and curling ( Figure 1 (G.1~G.3).

[0065] Table 1 Monosaccharide composition and molecular weight parameters

[0066]

[0067]

[0068] Table 2 Glycosidic bond residue structure and molar ratio

[0069]

[0070] 7.2 Effects of medium-chain inulin supplementation on diet-induced obesity (DIO) in mice

[0071] like Figure 2 As shown in Figure A, C57BL / 6 mice were fed a normal diet (ND), HFD, or HFD plus different concentrations (w / w: 1%, 3%, and 5%) of medium-chain inulin. After 12 weeks of the experimental period, the body weight (BW) of mice fed with HFD increased significantly compared with that of mice fed with ND (P<0.05), while inulin supplementation significantly inhibited the HFD-induced BW increase in a dose-dependent manner ( Figure 2 (B, C). Figure 2 As shown in D, liver weight (ratio of liver weight to body weight, w / w) of HFD-fed mice was significantly increased compared with ND-fed mice, while inulin supplementation inhibited the increase in liver weight of HFD-fed mice (P<0.05). Similarly, HFD feeding led to an increase in the weight of white adipose tissue (WAT) and epididymal fat pads, but a decrease in the weight of brown adipose tissue (BAT), while inulin supplementation reduced the proportion of WAT in the body and increased the proportion of BAT.

[0072] In addition, changes in lipid profile, glucose and urea levels such as Figure 2 As shown in Figures E and F; the levels of triglyceride (TG), total cholesterol (TCHO), and urea in the inulin supplementation group were significantly lower than those in the HFD group. In addition, inulin supplementation can increase serum high-density lipoprotein (HDL) levels and reduce serum low-density lipoprotein (LDL) levels, thereby improving the HDL / LDL ratio. Figure 2 As shown in G, liver sections were stained with modified Oil Red O to observe the accumulation of lipids in the liver ( Figure 2 In G, the red-stained area indicates lipid droplets). The hepatic lipid accumulation in the HFD group was significantly higher than that in the ND group (P<0.01), while inulin supplementation significantly reduced hepatic 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 with the ND group (P<0.05) ( Figure 2Finally, the liver lipid profile was evaluated and it was found that inulin supplementation reduced triglyceride (TG), total cholesterol (TCHO) and low-density lipoprotein (LDL) concentrations (P<0.05), while increasing high-density lipoprotein (HDL) levels and HDL / LDL ratio in a dose-dependent manner ( Figure 2 Middle I).

[0073] 7.3 Effects of medium-chain inulin on intestinal development and short-chain fatty acid (SCFA) production

[0074] like Figure 3 As shown in Figures A to C, feeding mice with a HFD reduced (P<0.05) the intestinal SCFAs content compared with the normal group (ND), while inulin supplementation restored the content of acetate, propionate, and butyrate in a dose-dependent manner. In contrast, HFD feeding significantly increased (P<0.05) the levels of branched-chain fatty acids (BCFAs), such as isobutyrate and isovaleric acid (P<0.05). However, dietary inulin supplementation reduced the production of BCFAs in a dose-dependent manner (P<0.05).

[0075] In addition, intestinal morphology studies showed that HFD feeding increased crypt depth while decreasing villus height and V / C ratio compared with ND-fed mice (P<0.05)( Figure 3 D-F). Dietary inulin supplementation prevented this damage and instead promoted ileal growth and development, as indicated by increased ileal villus height and V / C ratio (P<0.05) and decreased crypt depth (P<0.05). Similarly, HFD feeding 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 Medium G~I).

[0076] 7.4 Characteristics of intestinal microbial communities and differential microorganisms among groups

[0077] Gut microbial community analysis showed that the intestinal microorganisms of each group were dominated by Firmicutes and Bacteroidetes at the phylum level. However, HFD feeding reshaped the differential intestinal microbiota, with a decrease in α diversity (P<0.05), while the richness of Firmicutes and F / B ratio increased (P<0.05) ( Figure 4 In contrast, dietary inulin supplementation enhanced (P < 0.05) microbial diversity, especially the richness of Bacteroidetes and the F / B ratio ( Figure 4 In addition, principal coordinate analysis (PCoA) and group clustering showed that the ND group was completely separated from the 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 (middle B).

[0078] In addition, inulin supplementation suppressed the increase in abundance of Lachnospiraceae_NK4A136_group, Alistipes, Dubosiella, and Colidextribacter caused 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 Figures F and G) show that feeding HFD increased the relative abundance of Fibrobacter, Fibrobacteres, Desulfobacterota, and unidentified bacteria (LDA score > 4), while inulin supplementation increased the richness of Verrucomicrobiota, Muribaculaceae, Lactobacillaceae, and Bifidobacteriaceae (LDA score > 4.0) in the HFD-fed group, but not in the HFD-fed group. Finally, the cladogram shows the phylogenetic distribution of differentially expressed bacteria in different experimental groups ( Figure 4 Middle G).

[0079] 7.5 Intestinal metabolome analysis and differential metabolites

[0080] The intestinal content metabolome was analyzed by LC-MS, and 1,503 metabolites were found: 946 positive ions and 557 negative ions. The overall correlation analysis of all metabolites showed that the HFD+1% inulin and HFD groups clustered into one group, while the HFD+3% inulin and HFD+5% inulin groups formed a separate cluster ( Figure 5 Further analysis using orthogonal projection latent structure discriminant analysis (OPLS-DA) showed that all five treatment groups were completely separated ( Figure 5 These findings suggest that gut metabolites were significantly altered by HFD feeding and / or dietary inulin supplementation. The contribution of each metabolite to the discrimination between the groups was assessed using the projected variable importance (VIP) value. The S-plot of the OPLS-DA analysis identified 505 metabolites that showed significant effects in this experiment (P < 0.05, VIP ≥ 1) ( Figure 5 The differential metabolites between ND, HFD and inulin supplementation groups were presented in the form of volcano plots ( Figure 5 There were 265 differential metabolites in the HFD group compared with the ND group, of which 245 were up-regulated and 19 were down-regulated.

[0081] Similarly, compared with the HFD group, the 1%, 3%, and 5% inulin groups showed 40, 44, and 71 differential metabolites, respectively (P < 0.05) ( 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 the inulin dose, the regulated metabolites in the inulin supplementation group mainly included indoles / derivatives (5-hydroxytryptophan, 2-(1H-indol-3-yl)acetic acid), steroids / derivatives (taurocholic acid, corticosterone, aldosterone, 5α-dihydrotestosterone (5α-DHT)), organic oxygen compounds (maltopentaose 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 In addition, similar metabolites and regulatory effects were present in the three inulin-supplemented groups.

[0082] 7.6 Correlations among physiological parameters, differential microorganisms, metabolites, and metabolic pathways modulated by inulin supplementation

[0083] Spearman rank correlation and metabolic pathway analysis were performed to evaluate the potential correlations between physiological parameters, intestinal microbiota, metabolites, and altered metabolic pathways in mice. The microorganisms selectively promoted by inulin included Bacteroidetes, Faecalibacterium, Lactobacillus, Bifidobacterium, Akkermansia, Bacteroidetes, Clostridium_sensu_stricto_1, and Parasutterella, which were positively correlated with the concentrations of fatty acids (acetate, propionate, butyrate, SCFAs, and TFAs), ileal villus height, HDL, and HDL / LDL ratio in liver and serum of mice (P<0.05), while negatively correlated with the body weight, TG, TCHO, and LDL content in liver and serum, and the degree of fat accumulation in liver of mice (P<0.05) ( Figure 6 Similarly, the metabolites improved by inulin supplementation mainly included nicotinamide, taurocholic acid, 5α-DHT, aldosterone, corticosterone, 5-hydroxy-L-tryptophan, 2-(1H-indol-3-yl)acetic acid, propionyl-L-carnitine, MN-18N-(5-hydroxypentyl) metabolite, maltopentose, and maltose, which were positively correlated with fatty acids in liver and serum, ileal villus height, HDL content, and HDL / LDL ratio in mice (P<0.01), but negatively correlated with mouse body weight, TG, TCHO, and LDL content in liver and serum, and the degree of liver fat accumulation (P<0.05) ( Figure 6 Furthermore, those microbes that were increased by inulin supplementation were positively correlated with specific metabolites that were increased by inulin supplementation ( Figure 6 A), while negatively correlated with HFD-fed derived metabolites, including arachidonic acid, ethyl laurate, docosahexaenoic acid, and retinoic acid (P < 0.05, Figure 6 Middle C).

[0084] In addition, by matching the differential metabolites in the Mus musculus KEGG pathway database (HFD vs. ND; 1%, 3%, and 5% inulin vs. HFD), we further identified metabolic pathways that were significantly regulated by HFD feeding and / or dietary inulin supplementation ( Figure 6 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 (middle D).

[0085] However, all inulin-supplemented groups downregulated the arachidonic acid metabolic pathway ( Figure 6 Middle D). Intrinsic relevance of metabolic pathways modulated by inulin supplementation ( Figure 7 ) further showed that inulin supplementation significantly upregulated the metabolism of tryptophan, niacin, nicotinamide, starch, sucrose, taurine / hypotaurine, primary bile acids, and steroid hormone biosynthesis, while downregulated the biosynthesis of unsaturated fatty acids and arachidonic acid metabolism. Eight metabolites, nicotinamide, taurocholic acid, aldosterone, corticosterone, 5-hydroxy-L-tryptophan, 2-(1H-indol-3-yl)acetic acid, 5α-DHT, and maltose, were observed to be involved in the upregulation of metabolic pathways. Therefore, dietary inulin supplementation can downregulate inflammation-related metabolic pathways while improving glucose and lipid metabolism, which may be the potential mechanism by which inulin affects physiological health and alleviates obesity symptoms.

[0086] 7.7 Identification of inulin-mediated core microbiota and metabolites directly associated with body weight (BW) in HFD-fed mice

[0087] Using BW and SCFAs as environmental factors, a co-occurrence network was constructed to further identify core microorganisms and metabolites associated with mouse BW. Figure 8As shown in Figure 1A, SCFAs have an inhibitory effect on 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, the abundance of Faecalibaculum, Bifidobacterium, Parasutterella, Muribaculum, Clostridium_sensu_stricto_1, and Akkermansia were relatively high (>0.5%) and were significantly upregulated by dietary inulin supplementation. Therefore, these microorganisms may be potential core bacteria for the inhibition of HFD-induced obesity mediated by inulin intake.

[0088] Likewise, metabolites regulated by inulin supplementation were also directly or indirectly related to body weight. Figure 8 As shown in Figure B, arachidonic acid, lysergic acid diethylamide D3 (LSD-d3), ethyl laurate, 16-hydroxyhexadecanoic acid, all-cis-4,7,10,13,16-docosapentaenoic acid, and docosapentaenoic acid were directly positively correlated with body weight, and all of these metabolites were reduced in the inulin-supplemented group. Therefore, these metabolites represent a subset of metabolites that promote weight gain in HFD-fed mice ( Figure 8 B, light purple nodes). In contrast, nicotinamide, taurocholic acid, aldosterone, corticosterone, 2-(1H-indol-3-yl)acetic acid, MN-18N-(5-hydroxypentyl) metabolite, 5α-DHT, maltopentaose, 5-hydroxytryptophan, propionyl-L-carnitine, and maltose increased in the inulin-supplemented group and showed mutually exclusive relationships with these metabolites in the subgroup that promoted weight gain. In addition, short-chain fatty acids were directly related to body weight and had mutually exclusive relationships. However, tocopherol quinoline (TQH), 2-oxindole, and 2-(1H-indol-3-yl)acetic acid were 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 including nicotinamide, taurocholic acid, aldosterone, corticosterone, 2-(1H-indol-3-yl)acetic acid, 5-hydroxy-L-tryptophan, 5α-DHT and maltose formed the BW-inhibited metabolite subgroup ( Figure 8 middle B, light pink nodes).

[0089] In summary, the present 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 mesh and / or spherical spatial conformation of inulin may contribute to its observed biological activity. Inulin supplementation effectively reversed the negative effects of HFD, resulting in a dose-dependent decrease in BW and WAT mass. At the same time, it increased the BAT index. Secondly, HFD feeding resulted in higher levels of TG, TCHO, LDL, FBG and urea in serum, while inulin supplementation restored these physiological indicators to normal levels. Inulin supplementation led to increased production of SCFA, mainly acetate, propionate and butyrate. These SCFAs are important energy sources for intestinal cells and play a key role in activating the host immune system. In contrast, HFD feeding leads to increased levels of branched-chain fatty acids (BCFA), which may lead to insulin resistance. In addition, SCFA binds to receptors and improves the production of glucagon-like peptide-1 (GLP-1) and peptide tyrosine, thereby affecting the host's energy balance and lipid metabolism. Therefore, in the present invention, inulin supplementation increases the production of SCFA and is the basis for improving obesity-related metabolic complications. In the present invention, the observed improvements in metabolic parameters are related to changes in intestinal microbiota and metabolome. HFD feeding significantly reduces the diversity of intestinal microbiota and increases the F / B ratio, indicating the presence of dysbacteriosis. On the contrary, inulin supplementation significantly increases the diversity of microbiota, reduces the F / B ratio, and enriches beneficial bacteria, including Bacteroidetes, Akkermansiaceae, Bacteroidetes, Lactobacillaceae, Faecalibacterium, Clostridium_sensu_stricto_1, Bifidobacterium and Parasutterella. In addition, the present invention also finds that the microorganisms promoted by inulin are positively correlated with key metabolites, which drive the regulation of metabolic pathways involving fatty acids, amino acids and energy metabolism. In addition, the intestinal microbial structure (diversity and composition) has a significant impact on the host's energy absorption, storage and consumption.

[0090] Metabolomic analysis showed that 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 compared with the HFD-fed group. 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 subset of core metabolites that promote weight gain. In contrast, inulin supplementation of HFD-fed mice increased the contents of nicotinamide, taurocholic acid, aldosterone, corticosterone, 2-(1H-indol-3-yl)acetic acid, MN-18N-(5-hydroxypentyl) metabolite, 5α-DHT, maltopentose, 5-hydroxytryptophan, propionyl-L-carnitine, maltose, and 4-hydroxyretinoic acid, which inhibited weight gain in HFD-fed mice. Therefore, these metabolites constitute a subgroup of metabolites that inhibit weight gain and play an important role in preventing weight gain in HFD-fed mice. In addition, these metabolites altered by inulin supplementation regulate key metabolic pathways, including downregulation of arachidonic acid metabolism and upregulation of 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 the present invention, co-occurrence network analysis showed that specific microbial taxa (Faecalibaculum, Bifidobacterium, Parasutterella, Clostridium_sensu_stricto_1, and Akkermansia) directly inhibited weight gain, highlighting their potential role in weight management. Therefore, these microorganisms form a functional subgroup that can ferment indigestible inulin into key metabolites including SCFAs and exert an inhibitory effect on weight gain through the "diet-microbiota-metabolite-phenotype" axis. Regarding different metabolites, SCFAs, as the main microbial-derived metabolites, may play a key role in resisting weight gain. In addition, 2-(1H-indol-3-yl)acetic acid, an essential intermediate produced during tryptophan metabolism, was positively correlated with SCFA but negatively correlated with body weight. In addition, 2-(1H-indol-3-yl)acetic acid was also positively correlated with Bacteroidetes, Faecalibacterium, Bifidobacterium, Parabacterium, Clostridium_sensu_stricto_1, and Akkermansia, but negatively correlated with TG, TCHO, and LDL levels in mouse liver and serum. This finding means that 2-(1H-indol-3-yl)acetic acid may be a core metabolite in the physiological process by which inulin affects systemic health through the "diet (inulin)-gut microbes / metabolites-phenotype" axis.

[0091] Inulin alleviated HFD-induced obesity and metabolic disorders by modulating the "diet (inulin)-gut microbiota / metabolites-phenotype" axis. Specifically, inulin promoted the abundance of key microorganisms (Faecalibaculum, Bifidobacterium, Parasutterella, Clostridium_sensu_stricto_1, and Akkermansia) and promoted the production of specific metabolites, especially 2-(1H-indol-3-yl)acetic acid, which together contributed to the improved metabolic health of DIO mice.

[0092] In summary, the present invention provides convincing evidence for the beneficial effects of medium-chain inulin (DP=12) in alleviating HFD-induced obesity and metabolic disorders. The unique inulin structure and specific chain length reshape the intestinal microbiome and metabolome, especially selectively regulating key microorganisms such as Faecalibacterium, Bifidobacterium, Parabacterium, Clostridium_sensu_stricto_1 and Akkermansia, as well as 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 improvement of obesity and overall health. In addition, 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 regulating specific microbiota and metabolomes to effectively manage weight.

[0093] 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 methods of the present invention. For ordinary technical users in the relevant field, other different forms of changes or modifications can be made on the basis of the above description. It is not necessary and impossible to list all the implementation methods here. Any modifications, equivalent substitutions and improvements made within the spirit and principles of the present invention should be included in the protection scope of the claims of the present invention.

Claims

1. A method for preparing medium-chain inulin, characterized in that: The following steps are involved: (1) grinding Jerusalem artichoke to obtain slurry, adding water to extract, and then filtering, concentrating, removing protein, and precipitating with alcohol to obtain crude polysaccharide; (2) dialyzing the crude polysaccharide with a semipermeable membrane, concentrating, and freeze-drying 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° C., and the extraction time is 3 h; The concentration specifically refers to concentration to 30% of the original volume; The protein removal method comprises: adding an equal volume of a trichloroacetic acid solution with a mass concentration of 5%, standing for 60 minutes, centrifuging at 8000 rpm and 20° C. for 10 minutes to remove the precipitate; The alcohol precipitation method is as follows: adding 4 times the volume of anhydrous ethanol, standing for 8 to 12 hours, centrifuging at 6000 rpm and 20° C. for 10 minutes, and discarding the supernatant.

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

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

5. Use of the medium-chain inulin as claimed in claim 4 in the preparation of products for preventing and treating obesity.

6. A product for preventing and treating obesity, characterized in that: The invention comprises the medium-chain inulin as claimed in claim 4.

7. Use of the medium-chain inulin as claimed in claim 4 in the preparation of a product for regulating intestinal flora.

8. Use of the medium-chain inulin as claimed in claim 4 in the preparation of a product that upregulates Faecalibaculum, Bifidobacterium, Parasutterella, Muribaculum, Clostridium_sensu_stricto_1 and Akkermansia.

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