Short-chain fatty acid content and pH in caecum of rats fed various sources of starch

Caecal pH and contents of short-chain fatty acids (SCFA) were registered in rats fed three potential sources of resistant starch (RS); raw pea starch, raw potato starch, and an RS-enriched preparation obtained from wheat starch by autoclaving and enzymatic incubation. Small intestinal digestibility and delivery of RS to the hind-gut in the case of raw starches were determined by analysis of faecal starch in animals treated with antibiotics to prevent hind-gut fermentation. RS content in the RS-enriched preparation was determined as total starch remaining in an enzymatic gravimetric dietary fibre residue. The fermentability of RS was estimated from the faecal recovery of starch in normal animals with intact hind-gut microflora. Approximately 35 g per 100 g and 32 g per 100 g were RS in the case of raw potato starch and the RS-enriched preparation, respectively, versus only 1 g per 100 g in the case of raw pea starch. The caecal pH decreased with all test diets, being most significant with raw potato starch. SCFA production and faecal bulking were negligible with raw pea starch, whereas both raw potato starch and the RS-enriched preparation significantly increased these parameters. The fermentability of RS in raw potato starch and the RS-enriched preparation was similar, or about 60–70%. If calculated on basis of fermented amount, RS in raw potato starch was more potent in generating SCFA (49 μmol g^?1) than in the RS-enriched preparation (19 μmol g^?1). RS in raw potato starch also displayed the highest faecal bulking capacity. In fact, the faecal dry weight increased more than expected merely from delivery of RS. The relative proportion in caecal contents of acetic-, propionic- and butyric acid was 70, 17 and 8%, respectively, with no significant differences between the three sources of RS.     

Resistant starch prepared from high-amylose maize starch with citric acid hydrolysis and its simulated fermentation in vitro

Resistant starch (RS) was prepared from high-amylose maize starch through two autoclaving–cooling cycles and then acid hydrolysis of retrograded starch. Experimental results showed that hydrolysis of retrograded high-amylose maize starch with 0.1 mol L⁻¹ citric acid at room temperature for 12 h would increase RS yield to 39%. At simulated conditions of large intestine (anaerobic and 37 °C), the prepared RS product was fermented in culture by fresh feces extract from healthy adult or healthy infant to produce short chain fatty acids. Formic, acetic, propionic and butyric acid produced in culture were analyzed by GC with capillary column. The GC analysis results showed that as the increase of fermentation time and the addition level of RS in culture, the production of short chain fatty acids was increased. However, the production of short chain fatty acids (especially butyric acid) in culture fermented by healthy infant feces extract was much higher than that fermented by healthy adult feces extract. It suggested that the production of short chain fatty acids from RS in simulated intestinal conditions might be affected by the intestinal microflora.     

Resistant Starch and Health — Himalaya 292, a Novel Barley Cultivar to Deliver Benefits to Consumers

Dietary and lifestyle change is a recognised strategy for the management and prevention of socio‐economically important non‐infectious diseases. Dietary fibre is composed largely of non‐starch polysaccharides (NSP), and greater consumption of NSP‐rich foods relieves simple constipation very effectively. Starch (as resistant starch, RS) is also receiving attention for its potential role in promoting colonic function. Resistant starch is that fraction of starch which escapes human small intestinal digestion and enters the large bowel where (together with a variable fraction of NSP) it is fermented by the resident microflora. The resulting short chain fatty acids (SCFA) are taken up by the large bowel and metabolised. SCFA mediate many of the health benefits ascribed to NSP and RS. Starch consumption is low in affluent westernised countries, despite recommendations by health agencies. In Australia, foods enriched in RS as a high amylose maize starch have gained consumer acceptance. However, scope remains for additional products and ingredients and a company, Ascentia Pty Ltd, has been established to develop a novel barley cultivar (Hordeum vulgare var. himalaya 292) for this purpose. This cultivar has a specific gene alteration leading to a loss of starch synthetase lla activity resulting in a grain which is low in starch but disproportionately higher in amylose and also NSP. Animal and human studies have shown that Himalaya 292 is high in RS relative to existing products and has a low glycaemic index and the cultivar offers promise as a vehicle to deliver health benefits to consumers.     

Comparative Effects of Acetylated and Unmodified High‐amylose Maize Starch in Rats

Acetylated, propionylated or butyrylated starches raise the large bowel pools of these short chain fatty acids (SCFA) in rats but their resistant starch (RS) content in vivo is unknown. This content was determined for acetylated starch (Starch A, DS = 0.18) in colectomised rats and compared to a standard maize (control) or high‐amylose (HAMS) maize starch. Digestibilities were 99.8% (control), 47.5% (Starch A) and 58% (HAMS). The effects of Starch A and HAMS were compared also in intact rats, that were fed a fibre‐free diet in which either 200 g/kg of HAMS or 100, 200 or 300 g of Starch A/kg was substituted for the standard maize starch. Caecal SCFA pools were larger in rats fed either RS with the greatest increase being in acetate in rats fed Starch A. Other acids (succinate and formate) appeared with increasing incorporation of RS. However, when the experiment was performed with a commercial diet, feeding Starch A or HAMS did not lead to any great increase in these other acids but SCFA pools expanded. The greatest increase in acetate was in rats fed Starch A. This suggests that other factors were necessary for optimal RS fermentation but not for release of acetate from Starch A. Comparison of the effects of Starch A and HAMS on SCFA suggests that the former was at least 100% more effective than HAMS at equivalent dietary intakes, despite similarities in RS content. Incubation of Starch A with caecal bacterial enzymes confirmed that release of acetate was relatively slow, indicating a capacity of this modified starch for sustained SCFA delivery in vivo.     

Integration of ileum cannulated pigs and in vitro fermentation to quantify the effect of diet composition on the amount of short‐chain fatty acids available from fermentation in the large intestine

Using cannulated pigs and a standardised in vitro fermentation system the effect of diet and non‐starch polysaccharides (NSP) on the amount of energy available from microbial fermentation in the large intestine could be predicted. The available energy was calculated from the amounts of short‐chain fatty acids (SCFA) produced. Three diets were investigated: a low fibre diet based essentially on wheat flour (56 g NSP kg⁻¹ feed) and two high fibre diets with added oat bran (93 g NSP kg⁻¹ feed) or wheat bran (102 g NSP kg⁻¹ feed). Colonic fermentation was estimated by in vitro fermentation of freeze‐dried ileal effluent collected from cannulated pigs. The in vitro fermentation method was optimised to use 10 g ileum content litre⁻¹ incubated at pH 6.0 in a fermentor containing faecal slurry consisting of anaerobic mineral salts medium and 50 g litre ⁻¹ faeces from pigs fed the same diets as the cannulated pigs. The results demonstrate that it is very important to compensate for the faecal SCFA contribution when calculating the amount of SCFA produced from ileal digesta during in vitro fermentation. The amount of NSP digested in vitro was compared with data obtained from in vivo studies and there was a good agreement between in vivo and in vitro data. We concluded that the integrated in vivo–in vitro method is a valuable technique to estimate the effect of diet and NSP on the amount of SCFA produced in the large intestine and when fed the three diets the microbial fermentation in the large intestine provided between 2.4–6.4% of the total available energy. © 1999 Society of Chemical Industry     

Acid-treated high-amylose corn starch suppresses high-fat diet-induced steatosis

Resistant starch (RS) has been reported to improve steatosis as well as obesity. Type 4 resistant starch (RS4), a chemically modified starch, is particularly hard to digest and suggesting higher efficacy. However, because the effects of RS4 on steatosis are not yet fully understood, the effects of RS4 on steatosis were examined using a murine high-fat diet model. Seven-week-old male mice were divided into three groups and fed a normal diet, a high-fat diet (HFD), or a high-fat diet with added RS (HFD + RS). Amylofiber SH^® produced from acid-treated corn starch was used as the dietary RS. At 22 weeks old, hepatic steatosis and short chain fatty acid (SCFA) content and gut microbiota in cecum stool samples were analyzed. The ratio of body weight to 7 weeks was significantly suppressed in the HFD + RS group compared to the HFD group (132.2 ± 1.4% vs. 167.2 ± 3.9%, p = 0.0076). Macroscopic and microscopic steatosis was also suppressed in the HFD + RS group. Analysis of cecum stool samples revealed elevated SCFA levels in the HFD + RS group compared with the HFD group. Metagenome analysis revealed that Bifidobacterium (17.9 ± 1.9% vs. 3.6 ± 0.7%, p = 0.0019) and Lactobacillus (14.8 ± 3.4% vs. 0.72 ± 0.23%, p = 0.0045), which degrade RS to SCFA, were more prevalent in the HFD + RS group than the HFD group. In conclusion, RS4 suppressed steatosis, and increased Bifidobacterium and Lactobacillus, and SCFAs. RS4 may prevent steatosis by modulating the intestinal environment.     

In vitro batch fecal fermentation comparison of gas and short-chain fatty acid production using "slowly fermentable" dietary fibers

Abstract: Sustained colonic fermentation supplies beneficial fermentative by‐products to the distal colon, which is particularly prone to intestinal ailments. Blunted/delayed initial fermentation may also lead to less bloating. Previously, we reported that starch‐entrapped alginate‐based microspheres act as a slowly fermenting dietary fiber. This material was used in the present study to provide a benchmark to compare to other “slowly fermentable” fibers. Dietary fibers with previous reports of slow fermentation, namely, long‐chain inulin, psyllium, alkali‐soluble corn bran arabinoxylan, and long‐chain β‐glucan, as well as starch‐entrapped microspheres were subjected to in vitro upper gastrointestinal digestion and human fecal fermentation and measured over 48 h for pH, gas, and short‐chain fatty acids (SCFA). The resistant fraction of cooked and cooled potato starch was used as another form of fermentable starch and fructooligosaccharides (FOS) served as a fast fermenting control. Corn bran arabinoxylan and long‐chain β‐glucan initially appeared slower fermenting with comparatively low gas and SCFA production, but later fermented rapidly with little remaining in the final half of the fermentation period. Long‐chain inulin and psyllium had slow and moderate, but incomplete, fermentation. The resistant fraction of cooked and cooled potato starch fermented rapidly and appeared similar to FOS. In conclusion, compared to the benchmark slowly fermentable starch‐entrapped microspheres, a number of the purported slowly fermentable fibers fermented fairly rapidly overall and, of this group, only the starch‐entrapped microspheres appreciably fermented in the second half of the fermentation period. Practical Application: Consumption of dietary fibers, particularly commercial prebiotics, leads to uncomfortable feelings of bloating and flatulence due to their rapid degradation in our large intestine. This article employs claimed potential slowly fermenting fibers and compares their fermentation rates with a benchmark slow fermenting fiber that we fabricated in an in vitro simulation of the human digestive system. Results show a variety of fermentation profiles only some of which have slow and extended rate of fermentation.     

Different concentrations of grape seed extract affect in vitro starch fermentation by porcine small and large intestinal inocula

BACKGROUND: Grape seed extract (GSE) phenolics have potential health‐promoting properties, either from compounds present within the extract, or metabolites resulting from gastrointestinal tract (GIT) fermentation of these compounds. This study describes how GSE affected the kinetics and end‐products of starch fermentation in vitro using pig intestinal and fecal inocula. Six GSE concentrations (0, 60, 125, 250, 500, and 750 µg ml^?1 were fermented in vitro by porcine ileal and fecal microbiota using starch as the energy source. Cumulative gas production, and end‐point short chain fatty acids and ammonia were measured. RESULTS: GSE phenolics altered the pattern (gas kinetics, and end‐products such as SCFA and NH ) of starch fermentation by both inocula, at concentrations above 250 µg ml^?1. Below this level, neither inoculum showed any significant (P > 0.05) effect of the GSE. CONCLUSION: The results show that GSE phenolics at a concentration over 250 µg ml^?1 can have measurable effects on microbial activity in an in vitro fermentation system, as evidenced by the changes in kinetics and end‐products from starch fermentation. This suggests that fermentation patterns could be conceivably shifted in the actual GIT, though further evidence will be required from in vivo studies. Copyright © 2012 Society of Chemical Industry     

Physicochemical properties, α-amylase and α-glucosidase inhibitory effects of the polysaccharide from leaves of Morus alba L. under simulated gastro-intestinal digestion and its fermentation capability in vitro by human gut microbiota

The investigation aimed at determining the impact of sequential simulated digestion on the physicochemical properties and digestive enzymes inhibitory effects of the polysaccharides fraction (MLP-2) of Morus alba L. leaves as well as its in vitro fermentation behaviours. After artificial salivary, gastric and intestinal digestions, the chemical components and microstructure of MLP-2 were altered with significantly (P < 0.05) decreased molecular weight. The α-amylase and α-glucosidase inhibitory activities of MLP-2 were significantly (P < 0.05) improved throughout simulated digestion. MLP-2I, the intestinal digested fraction of MLP-2, could significantly (P < 0.05) decrease the pH value of fermented culture and increase the short-chain fatty acids (SCFA) concentrations, especially acetic, propionic and butyric acids. In conclusion, MLP-2 could be gradually degraded under simulated digestion with altered physicochemical properties and enhanced α-amylase and α-glucosidase inhibitory effects, and further utilised by human gut microbiota to decrease pH value and promote SCFA production.     

In vitro fermentation of different types of α-amylase resistant corn starches

α -amylase resistant corn starches were in vitro fermented (72 h) using cecal content of rat as inoculum. Resistant starches were prepared from native (NCS), retrograded (RS_A ), and retrograded and boiled (RS_B ) corn starch by treatment with α-amylase to remove digestible starch. Short-chain fatty acid (SCFA) production, molar ratios (acetate: propionate: butyrate), fermentability with respect to lactulose and dry matter disappearance were measured. SCFA production was significantly correlated with non-fermented residue (P <0.001). The three starches showed a similar fermentability, although the rate of SCFA production and disappearance of substrate were slower for retrograded starches. NCS was fermented early while RS_A and RS_B prolonged their degradation to 72 h. There were slight differences in the molar ratios of acetate, propionate and butyrate. Structural changes in the materials were observed by scanning electron microscopy (SEM). In summary, commonly utilised domestic cooking and technological treatments modified the in vitro fermentative characteristics of resistant corn starches probably due to structural changes. Received: 15 November 1999 / Revised version: 27 January 2000     

Dietary starch level and rumen-protected methionine,lysine, and histidine: Effects on milk yield,nitrogen, and energy utilization in dairy cows fed diets low in metabolizable protein

Our objective was to investigate the interactions between starch level and rumen-protected Met, Lys, His (RP-MLH) on milk yield, plasma AA concentration, and nutrient utilization in dairy cows fed low metabolizable protein diets (mean = −119 g/d of metabolizable protein balance). Sixteen multiparous Holstein cows (138 ± 46 d in milk, 46 ± 6 kg/d in milk) were used in a replicated 4 × 4 Latin square with a 2 × 2 factorial arrangement of treatments. Each period lasted 21 d with 14 d for diet adaptation and 7 d for data and sample collection. Dietary starch level varied by replacing (dry matter basis) pelleted beet pulp and soyhulls with ground corn resulting in the following treatments: (1) 20% pelleted beet pulp and 10% soyhulls (reduced starch = RS), (2) RS plus RP-MLH (RS+AA), (3) 30% ground corn (high starch = HS), and (4) HS plus RP-MLH (HS+AA). Dietary starch concentrations averaged 12.3 and 34.4% for RS and HS basal diets, respectively. Diets were supplemented with RP-MLH products to supply digestible Met, Lys, and His. Compared with RS and RS+AA diets, HS and HS+AA diets increased yields of milk (37.9 vs. 40.1 kg/d) and milk protein (1.07 vs. 1.16 kg/d) and decreased dry matter intake (25.9 vs. 25.2 kg/d), milk urea N (12.6 vs. 11.0 mg/dL), and plasma urea N (13.3 vs. 11.6 mg/dL). Milk N efficiency was greater in cows fed the HS and HS+AA than RS and RS+AA diets (28.9 vs. 25%), and RP-MLH supplementation improved milk true protein concentration. Starch level × RP-MLH interactions were observed for plasma concentrations of Arg and Lys, with RP-MLH being more effective to increase plasma Arg (+16%) and Lys (+23%) when supplemented to the RS than the HS basal diet. Replacing pelleted beet pulp and soyhulls with ground corn lowered the plasma concentrations of all essential AA except Met and Thr. In addition, the plasma concentrations of His and Met increased with RP-MLH. The apparent total-tract digestibilities of neutral and acid detergent fiber were lower, and those of starch and ether extract greater in cows offered the HS and HS+AA diets than RS and RS+AA diets. Urinary excretion of urea N decreased by replacing pelleted beet pulp and soyhulls with ground corn. Enteric CH₄ production, CH₄ yield, and CH₄ intensity all decreased in the HS and HS+AA versus RS and RS+AA diets. Diets did not affect the intakes of gross energy, metabolizable energy, and net energy of lactation. In contrast, digestible energy intake increased with feeding the RS and RS+AA diets, whereas CH₄ energy decreased in cows fed the HS and HS+AA diets. Supplementation with RP-MLH had no effect on energy utilization variables. Overall, the lack of interactions between dietary starch level and RP-MLH supplementation on most variables measured herein showed that the effects of starch intake and RP-MLH were independent or additive.     

Protein and Starch Digestibility and Flatulence Potential of Germinated Cowpeas (Vigna unguiculata)

In vivo and in vitro methods with experimental rats and commercial digestive enzymes, respectively, were used in assessing the protein and starch digestibility and flatulence potential of germinated cow-peas. Germination (24 hr at 25° or 30°C) reduced the flatulence potential of seeds (52 to 77%). In vivo digestibility of starch and protein was also significantly increase by germination. Germination did not affect in vitro protein digestibility, but reduced in vitro digestibility of freeze-dried and 70°C-dried starch. Cooking in boiling water significantly increased in vitro protein and starch digestibility of both ungerminated and germinated seed.     

Effect of bioprocessing of wheat bran in wholemeal wheat breads on the colonic SCFA production in vitro and postprandial plasma concentrations in men

The health benefits of whole grain consumption can be partly attributed to the inclusion of the bran or outer-layers of the grain rich in dietary fibre. Fibre is fermented in the colon, leading to the production of beneficial metabolites, such as short-chain fatty acids (SCFA). The effect of five different types of bread on the SCFA production was studied in an in vitro model of human colon. Additionally, the postprandial effects of two selected breads on the SCFA plasma concentrations were investigated in men. A higher in vitro production of butyrate was induced by wholemeal wheat bread with bioprocessed bran than by native bran. The increase in butyrate seemed to be in exchange for propionate, whilst the total SCFA production remained similar. However, differences between the two breads in the postprandial butyrate concentrations could not be detected in peripheral blood of men, probably due to an effective utilisation by colonocytes.     

Comparative digestibility of groundnut and soyabean meal in vitro and in chicks

In vitro experiments showed that there is less trypsin-inhibiting activity in raw groundnut meal (RG) than in raw soyabean meal (RS). Some of the typical effects which were observed in chicks fed RS were seen also in chicks fed RG, but to a different extent, i.e. growth retardation, pancreas hypertrophy, and a high percentage of intestinal nitrogen precipitated by trichloracetic acid. These effects were not obtained in chicks fed toasted groundnut meal or in those fed toasted soyabean meal. Some relationships between in vitro experiments and growth retardation, pancreas hypertrophy and the undigestible nitrogen fraction in the intestine of chicks fed RG and RS are discussed.     

Short-chain fatty acid content and pH in caecum of rats given various sources of carbohydrates

The caecal content of short-chain fatty acids (SCFA; acetic, propionic and butyric acid), caecal pH, fermentability and dry matter digestibility (DMD) were examined through balance experiments in rats fed 11 various indigestible carbohydrates. The following carbohydrate sources were incorporated into test diets: cellulose, oat husk, wheat bran, oat bran, pea fibre, linseed fibre, low methoxylated (LM)-pectin, guargum, β-glucans, neosugar and raffinose. The indigestible carbohydrates, except for those in wheat bran, oat husk and cellulose, were highly fermented, ie > 90%. Caecal pH varied between 5·6 and 7·8, with neosugar and raffinose causing the lowest pH and the fibre-free diet and the diet with oat husk the highest. The caecal pool sizes of SCFA were highest with raffinose, β-glucans, LM-pectin, guargum and linseed fibre (335-400 μmol) while pea fibre, wheat bran, oat bran and neosugar gave intermediate levels (137–227 μmol). The pool size with oat husk and cellulose was similar as with the basal diet (45–64 μmol). A high proportion of propionic acid was obtained with guargum and linseed fibre, whereas acetic acid was the predominant product in case of LM-pectin. On the other hand, linseed fibre gave a remarkably low proportion of butyric acid. The quantity fermented and caecal pH correlated well to the amount of SCFA with most materials (r = 0·96 and r = ?0·87, respectively), an exception was neosugar and in case of fermentability also oat bran. DMD values with most of the easily fermented carbohydrates were high (>96%). Exceptions were diets with β-glucans and oat bran which caused low DMD values, about 93%. It is concluded that indigestible carbohydrates may differ in ability to lower caecal pH and to form SCFA during fermentation.     

难消化淀粉的功能及其食品中的应用

难消化淀粉是指难以被小肠吸收消化的淀粉,它能被结肠微生物发酵产生许多独特的生理作用;如抑制膳后血糖升高、防治肠胃疾病、降低血清胆固醇含量、促进益生菌的繁殖等。与膳食纤维相比,其发酵率更高,产生的丁酸更多。难消化淀粉的物性与普通淀粉相似,添加到食品后不会改变食品的颜色和质地。在国外,难消化淀粉已应用到许多食品中。     

Effect of Germination and Fermentation on in vitro Starch and Protein Digestibility of Pearl Millet

Germination of pearl millet grain for 24 hr significantly improved its in vitro starch and protein digestibility. Fermentation of pearl millet sprouts by mixed culture combinations of yeasts and bacteria (Saccharomyces diastaticus and Lactobacillus brevis; Saccharomyces diastaticus and Lactobacillus fermentum; Saccharomyces cerevisiae and Lactobacillus brevis; and Saccharomyces cerevisiae and Lactobacillus fermentum) resulted in a significant increase in protein and starch digestibility. The pearl millet sprouts fermented with mixed culture containing S. diastaticus and L. brevis had the highest in vitro starch digestibility, while the sprouts fermented with the culture containing 5. cerevisiae and L. fermentum had the highest in vitro protein digestibility.     

Faecal fermentation of partially hydrolyzed guar gum

Partially hydrolyzed guar gum (PHGG) remains undigested in the upper gastrointestinal tract, but is fermented by bacteria in the large intestine to stimulate short-chain fatty acids, particularly butyric acid. In this study, the bacterial composition in the in vitro faecal fermentation of PHGG was analyzed by real-time PCR to identify the bacteria contributing to the stimulation of butyric acid production. The production of short-chain fatty acids in a PHGG culture was compared with that in inulin and blank (no substrate) cultures. After the fermentation of the substrates by fresh human faeces, PHGG clearly promoted the production of butyric acid. The butyryl-CoA CoA-transferase gene copy number and the 16S rRNA gene copy number of the Roseburia/Eubacterium rectale group in the PHGG culture were significantly higher than those in the blank culture. These results indicated that Roseburia/E. rectale group bacteria would play an important role in the butyric acid production in vitro fermentation of PHGG.     

Non-Starch Polysaccharides and in Vitro Starch Digestibility of Raw and Cooked Chick Peas

The effects of domestic and industrial cooking methods on the non-starch polysaccharides (NSP) content and in vitro starch digestibility of chick pea (variety “blanco lechoso”) have been studied. Total and soluble NSP increased, as did the slowly digestible starch (SDS), whereas the resistant starch (RS) fraction decreased after cooking, showing higher content in domestic than industrially cooked chick peas. The in vitro starch digestible rate index (SDRI) was similar in the cooked chick peas, as was the rapidly available glucose (RAG). Due to the low values of RAG, chick peas would give a slow post-prandial glycaemic response. Domestic cooked chick peas consumption would increase the intakes of RS in human diet, whereas the industrially cooked chick peas with lower content of RS would result in less flatulence problems.     

Effects of different types of potato resistant starches on intestinal microbiota and short-chain fatty acids under in vitro fermentation

The prebiotic effects of potato resistant starches RS1, RS2, RS3a, RS3b and RS4 were studied using simulated gut fermentation in vitro. The intestinal microbial composition was significantly changed by resistant starch (RS) after 24-h fermentation. All RSs (P < 0.05) decreased the ratio of Firmicutes/Bacteroidetes (F/B), and RS2 exhibited the lowest value of 0.95 ± 0.07. The relative abundance of Bifidobacterium was significantly increased by RS4, whereas Megamonas and Prevotella were promoted by RS2. Further, RS4 produced the highest levels of acetate (138.34 µM), whereas RS2 produced the highest levels of propionate (41.45 µM) and butyrate (21.65 µM). However, Bifidobacterium did not promote the production of propionate or butyrate, even though it was proficient in fermenting RS. Megamonas and Prevotella were positively associated with the higher production of propionate and butyrate. Here, different RSs played key roles in promoting intestinal health, and RS2 especially showed more abundant probiotic functions.