Starch-based carbohydrates display the bifidogenic and butyrogenic properties in pH-controlled faecal fermentation

Modulation of Gut Microbiota by the Complex of Caffeic Acid and Corn Starch

To understand the impact of different types of polyphenol-starch complexes on digestibility and gut microbiota, caffeic acid (CA) and corn starch (CS) complexes were prepared by coheating and high-pressure homogenization. The resistant starch content in CS coheated with CA (HCS-CA) and HCS-CA after high-pressure homogenization (HCS-CA-HPH) was 47.75 and 56.65%, respectively. Fourier transform infrared spectroscopy and X-ray diffraction analysis revealed hydrogen bonding in coheated samples and enhanced V-complex formation with high-pressure homogenization. The in vitro-digested complexes were of the B + V type, with higher relative crystallinity and short-range ordering of HCS-CA-HPH. Fermentation of the digested complex with human feces increased the yield of acetate, butyrate, and total short-chain fatty acids (SCFAs), which was more pronounced for HCS-CA-HPH. HCS-CA increased torques-Ruminococcaceae abundance, while HCS-CA-HPH boosted Prevotella, Roseburia, Lachnospiraceae, and Lachnospiraceae-NK4A136. Overall, CA and CS complexes enhanced beneficial bacteria and increased SCFA production.

Recent developments in enzymatic preparation, physicochemical properties, bioactivity, and application of resistant starch type III from staple food grains

Resistant starch (RS) was classified into five types and referred to the starch that cannot be digested and absorbed by the small intestine of healthy human beings. Among them, RS3 has received a lot of attention from researchers because of its good functional properties and greater application prospects. Meanwhile, the enzymatic method is widely used in the preparation of RS3 because of its high efficiency and environmental protection. α-Amylase and pullulanase as the main enzymes can effectively improve the yield of RS3. The physical properties of RS3 have an excellent potential for application in improving food crispness, texture and producing low glycemic index (GI) foods. It is more valuable because it has biological activities such as inducing apoptosis in tumor cells, lowering intestinal pH, and regulating blood glucose, etc. This paper summarized the current research progress of RS3 from different staple food grains, including current applications of enzymes commonly used in the preparation of RS3, physical properties and biological activities of RS3, and the application of RS3 in different areas to provide a theoretical basis for future research on RS3 as well as further development and applications based on the market requirement.

Structural changes and degradation mechanism of type 3 resistant starch during in vitro fecal fermentation

The colonic fermentation metabolites of resistant starch (RS) are recognized to have various health benefits. However, the relationship between the structural variation of RS and the colonic fermentation properties, remains inadequately studied, especially for type 3 resistant starch. The in vitro fecal fermentation properties with multi-structure evolution of A- and B-type polymorphic resistant starch spherulites (RSS) were investigated. Both polymorphic types of RSS showed similar fermentation rate and total short-chain fatty acid profiles, while the butyrate concentration of the A-type RSS subjected to 24 h of fermentation was significantly higher compared to B-type RSS. In the case of recrystallized starch spherulites, irrespective of the polymorphic type, gut bacteria preferentially degraded the intermediate chains and crystalline regions, as the local molecule-ordered area potentially serves as suitable attachment sites or surfaces for microbial enzymes.

Preparation of type 3 rice resistant starch using high-pressure homogenous coenzyme treatment and investigating its potential therapeutic effects on blood glucose and intestinal flora in db/db mice

Resistant starch from rice was prepared using high-pressure homogenization and branched chain amylase treatment. The yield, starch external structure, thermal properties, and crystal structure of rice-resistant starch prepared in different ways were investigated. The results showed that the optimum homogenizing pressure was 90 MPa, the optimum digestion time was 4 h, the optimum concentration of branched-chain amylase was 50 U/g and the yield of resistant starch was 38.58 %. Scanning electron microscopy results showed a rougher surface and more complete debranching of the homogenized coenzyme rice-resistant starch granules. FT-IR and X-ray diffraction results showed that the homogenization treatment exhibited a spiral downward trend on rice starch relative crystallinity and a spiral upward trend on starch debranching and recrystallization. The 4-week dietary intervention in db/db type 2 diabetic mice showed that homogeneous coenzyme rice-resistant starch had a better glycemic modulating effect than normal debranched starch and had a tendency to interfere with the index of liver damage in T2DM mice. Additionally, homogeneous coenzyme rice-resistant starch proved more effective in improving intestinal flora disorders and enhancing the abundance of probiotics in T2DM mice.

Presence of digestible starch impacts in vitro fermentation of resistant starch

Starch is an important energy source for humans. Starch escaping digestion in the small intestine will transit to the colon to be fermented by gut microbes. Many gut microbes express α-amylases that can degrade soluble starch, but only a few are able to degrade intrinsic resistant starch (RS), which is insoluble and highly resistant to digestion (≥80% RS). We studied the in vitro fermentability of eight retrograded starches (RS-3 preparations) differing in rapidly digestible starch content (≥70%, 35-50%, ≤15%) by a pooled adult faecal inoculum and found that fermentability depends on the digestible starch fraction. Digestible starch was readily fermented yielding acetate and lactate, whereas resistant starch was fermented much slower generating acetate and butyrate. Primarily Bifidobacterium increased in relative abundance upon digestible starch fermentation, whereas resistant starch fermentation also increased relative abundance of Ruminococcus and Lachnospiraceae. The presence of small fractions of total digestible starch (±25%) within RS-3 preparations influenced the fermentation rate and microbiota composition, after which the resistant starch fraction was hardly fermented. By short-chain fatty acid quantification, we observed that six individual faecal inocula obtained from infants and adults were able to ferment digestible starch, whereas only one adult faecal inoculum was fermenting intrinsic RS-3. This suggests that, in contrast to digestible starch, intrinsic RS-3 is only fermentable when specific microbes are present. Our data illustrates that awareness is required for the presence of digestible starch during in vitro fermentation of resistant starch, since such digestible fraction might influence and overrule the evalution of the prebiotic potential of resistant starches.

Type of intrinsic resistant starch type 3 determines in vitro fermentation by pooled adult faecal inoculum

Resistant starch (RS) results in relatively high health-beneficial butyrate levels upon fermentation by gut microbiota. We studied how physico-chemical characteristics of RS-3 influenced butyrate production during fermentation. Six highly resistant RS-3 substrates (intrinsic RS-3, 80-95 % RS) differing in chain length (DPn 16-76), Mw distribution (PI) and crystal type (A/B) were fermented in vitro by pooled adult faecal inoculum. All intrinsic RS-3 substrates were fermented to relatively high butyrate levels (acetate/butyrate ≤ 2.5), and especially fermentation of A-type RS-3 prepared from polydisperse α-1,4 glucans resulted in the highest relative butyrate amount produced (acetate/butyrate: 1). Analysis of the microbiota composition after fermentation revealed that intrinsic RS-3 stimulated primarily Lachnospiraceae, Bifidobacterium and Ruminococcus, but the relative abundances of these taxa differed slightly depending on the RS-3 physico-chemical characteristics. Especially intrinsic RS-3 of narrow disperse Mw distribution stimulated relatively more Ruminococcus. Selected RS fractions (polydisperse Mw distribution) obtained after pre-digestion were fermented to acetate and butyrate (ratio ≤ 1.8) and stimulated Lachnospiraceae and Bifidobacterium. This study indicates that especially the α-1,4 glucan Mw distribution dependent microstructure of RS-3 influences butyrate production and microbiota composition during RS-3 fermentation.

Production of a Series of Long-Chain Isomaltooligosaccharides from Maltose by Bacillus subtilis AP-1 and Associated Prebiotic Properties

Bacillus subtilis strain AP-1, which produces α-glucosidase with transglucosidase activity, was used to produce a series of long-chain isomaltooligosaccharides (IMOs) with degree of polymerization (DP) ranging from 2 to 14 by direct fermentation of maltose. A total IMOs yield of 36.33 g/L without contabacillusmination from glucose and maltose was achieved at 36 h of cultivation using 50 g/L of maltose, with a yield of 72.7%. IMOs were purified by size exclusion chromatography with a Superdex 30 Increase column. The molecular mass and DP of IMOs were analyzed by matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF/MS). Subsequently, linkages in produced oligosaccharides were verified by enzymatic hydrolysis with α-amylase and oligo-α-1,6-glucosidase. These IMOs showed prebiotic properties, namely tolerance to acidic conditions and digestive enzymes of the gastrointestinal tract, stimulation of probiotic bacteria growth to produce short-chain fatty acids and no stimulating effect on pathogenic bacteria growth. Moreover, these IMOs were not toxic to mammalian cells at up to 5 mg/mL, indicating their biocompatibility. Therefore, this research demonstrated a simple and economical method for producing IMOs with DP2–14 without additional operations; moreover, the excellent prebiotic properties of the IMOs offer great prospects for their application in functional foods.

Preparation of synbiotic milk powder and its effect on calcium absorption and the bone microstructure in calcium deficient mice

Calcium deficiency can lead to osteoporosis. Adequate calcium intake can improve calcium deficiency and prevent osteoporosis. Milk powder is the best source of dietary calcium supplements. Probiotics and prebiotics are considered to be beneficial substances for promoting calcium absorption. In this study, synbiotic milk powder (SMP) was prepared by combining the three, and its calcium supplementation effect and osteogenic activity were evaluated in calcium deficient mice. Through prebiotic screening experiments in vitro, after adding 1.2% iso-malto-oligosaccharide, the number of viable bacteria and the calcium enrichment of Lactobacillus plantarum JJBYG12 increased by 8.15% and 94.53% compared with those of the control group. Long-term calcium deficiency led to a significant reduction in calcium absorption and bone calcium content in mice, accompanied by structural deterioration of bone trabeculae. SMP significantly improved apparent calcium absorption, increased serum calcium and phosphorus levels, and decreased ALP activity and CTX-1 levels. In the meantime, the bone mineral density increased significantly, and the number of bone trabeculae and the proliferation and differentiation of osteoblasts also increased. SMP has good dietary calcium supplementation capacity and bone remodeling ability without significant side effects on major organs. These findings provide insights into using SMP as a dietary calcium source to improve bone health.

New insights suggest isomaltooligosaccharides are slowly digestible carbohydrates, rather than dietary fibers, at constitutive mammalian α-glucosidase levels

Isomaltooligosaccharides (IMOs) have been characterized as dietary fibers that resist digestion in the small intestine; however, previous studies suggested that various α-glycosidic linkages in IMOs were hydrolyzed by mammalian α-glucosidases. This study investigated the hydrolysis of IMOs by small intestinal α-glucosidases from rat and human recombinant sucrase-isomaltase complex compared to commonly used fungal amyloglucosidase (AMG) in vitro. Interestingly, mammalian α-glucosidases fully hydrolyzed various IMOs to glucose at a slow rate compared with linear maltooligosaccharides, whereas AMG could not fully hydrolyze IMOs because of its very low hydrolytic activity on α-1,6 linkages. This suggests that IMOs have been misjudged as prebiotic ingredients that bypass the small intestine due to the nature of the assay used. Instead, IMOs can be applied in the food industry as slowly digestible materials to regulate the glycemic response and energy delivery in the mammalian digestive system, rather than as dietary fibers.

New definition of resistant starch types from the gut microbiota perspectives - a review

Current definition of resistant starch (RS) types is largely based on their interactions with digestive enzymes from human upper gastrointestinal tract. However, this is frequently inadequate to reflect their effects on the gut microbiota, which is an important mechanism for RS to fulfill its function to improve human health. Distinct shifts of gut microbiota compositions and alterations of fermented metabolites could be resulted by the consumption of RS from the same type. This review summarized these defects from the current definitions of RS types, while more importantly proposed pioneering concepts for new definitions of RS types from the gut microbiota perspectives. New RS types considered the aspects of RS fermentation rate, fermentation end products, specificity toward gut microbiota and shifts of gut microbiota caused by the consumption of RS. These definitions were depending on the known outcomes from RS-gut microbiota interactions. The application of new RS types in understanding the complex RS-gut microbiota interactions and promoting human health should be focused in the future.

Gut Health Function of Instant Dehydrated Rice Sticks Substituted with Resistant Starch Types 2 and 4

The purpose of this study was to analyze the effects of instant dehydrated rice sticks (IDRS) which were substituted with resistant starch (RS) types 2 and 4 whose gut health function targets gut microbiota. IDRS are a type of rice noodles that were developed by two formulations. The first formulation had substitution of rice flour with 20% RS type 2 and 0.15% carboxymethyl cellulose (CMC) (RSc-2), and the second formulation had 25% RS type 4 and 0.15% CMC (RSc-4). RSc-2 and RSc-4 were investigated for gut health function by human fecal fermentation in a pH-controlled batch culture. The results of gut microbiota enumeration by fluorescent in situ hybridization confirmed that significantly (P < 0.05) higher numbers of bifidobacteria were obtained with RSc-2 (10.06 ± 0.09 log cells/mL) and RSc-4 (10.00 ± 0.06 log cells/mL) compared to the control (100% rice flour formula) at 24 h fermentation. Additionally, the prebiotic indexes of RSc-2 and RSc-4 were 3.8 and 2.8 -fold higher than that of the control at 24 h fermentation. The short-chained fatty acids, acetic, propionic and butyric acid were analyzed by gas chromatography-flame ionization detector. The butyric acids were significantly (P < 0.05) higher with RSc-2 (43.56 ± 0.01 mM) and RSc-4 (43.63 ± 0.07 mM) compared to the control at 24 h. Thus, RSc-2 and RSc-4 showed butyrogenic, bifidogenic and prebiotic potential to support gut health and could aid in prevention of colon cancer.

Cooking and sensorial quality, nutritional composition and functional properties of cold-extruded rice/white bean gluten-free fettuccine fortified with whole carob fruit flour

A different rice/white bean-based gluten-free fettuccine (rice 0-100%, bean 0-100%) fortified with 10% carob fruit has been developed. The proximate composition, total and resistant starch, and total, soluble and insoluble dietary fibre content as well as the cooking and sensorial quality of uncooked and cooked pasta were determined. All the novel gluten-free fettuccine forms showed good cooking quality (cooking loss < 10%) highlighting that those containing the carob fruit had better nutritional and healthy profiles than the commercial gluten-free rice pasta; they were low in fat (10-fold) and high in protein (on average 3.6-fold) with resistant starch (16%) and dietary fibres (2.4-fold). The cooking process increased (p < 0.05) the protein and total dietary fibre content but reduced the total and resistant starch. The addition of carob fruit increased the total dietary fibre content, thus improving the functional value of fettuccine. Considering the sensorial analysis, fettuccine produced with 40% bean and 10% carob could be well accepted by consumers and can be advised as a functional food.

A postbiotic consisting of heat-treated lactobacilli has a bifidogenic effect in pure culture and in human fermented faecal communities

The gut microbiota has a significant impact on host health. Dietary interventions using probiotics, prebiotics and postbiotics have the potential to alter microbiota composition and function. Other therapeutic interventions such as antibiotics and faecal microbiota transplantation have also been shown to significantly alter the microbiota and its metabolites. Supplementation of a faecal fermentation model of the human gut with a postbiotic product Lactobacillus LB led to changes in microbiome composition (i.e. increase in beneficial bifidobacteria) and associated metabolic changes (i.e. increased acid production). Lactobacillus LB is a heat-treated preparation of cellular biomass and a fermentate generated by Limosilactobacillus fermentum CNCM MA65/4E-1b (formerly known as Lactobacillus fermentum CNCM MA65/4E-1b) and Lactobacillus delbrueckii ssp. delbrueckii CNCM MA65/4E-2z, medically relevant strains used to produce antidiarrheal preparations. In pure culture, Lactobacillus LB also stimulates the growth of a range of bifidobacterial species and strains. Lactobacillus LB-like preparations generated using other Lactobacillaceae, including commercially available probiotic bacteria, did not have the same impact on a model strain (Bifidobacterium longum subsp. infantis ATCC 15697). This bifidogenic activity is heat- and enzyme-stable and cannot be attributed to lactose, which is a major constituent of Lactobacillus LB. L fermentum CNCM MA65/4E-1b is largely responsible for the observed activity and there is a clear role for compounds smaller than 1 kDa.Importance In general, disruptions to the gut microbiota are associated with multiple disorders in humans. The presence of high levels of Bifidobacterium spp. in the human gut is commonly considered to be beneficial. Bifidobacteria can be supplemented in the diet (as probiotics) or those bifidobacteria already present in the gut can be stimulated by the consumption of prebiotics such as inulin. We demonstrate that Lactobacillus LB (a product consisting of two heat-killed lactic acid bacteria and their metabolites) can stimulate the growth of bifidobacteria in human fermented faecal communities and in pure culture. Given the heat-treatment applied during the production process, there is no risk of the lactic acid bacteria colonising (or causing bacteraemia) in vulnerable consumers (infants, immunocompromised, etc). Lactobacillus LB has the potential to affect human health by selectively promoting the growth of beneficial bacteria.

Prebiotics in vitro digestion by gut microbes, products' chemistry, and clinical relevance

Several investigations have elucidated the chemistry of prebiotics based on their fermentation by the colonic microbes, which release metabolites that are often implicated in host's gut and whole body health. The present study aims at providing a preview of prebiotics and their interactions with the colonic microbiota for a slow fermentation in vitro. The metabolites produced, mainly short chain fatty acids (SCFA), their chemistry, interactions with prebiotic structural mechanisms, and beneficial impacts on the host were also reported. The present review further considers the clinical relevance of the SCFAs produced. It was deduced that the physicochemical properties of prebiotics would influence their colonic fermentation rate, microbial choice, and growth as well as SCFA type and ratios. This will in turn be of utmost clinical significance. KEY POINTS: • Prebiotics affect the composition of gut microorganisms. • The chemistry of short chain fatty acids are described. • Microbial and clinical applications of SCFAs were provided.

Fermentation of prebiotics by human colonic microbiota in vitro and short-chain fatty acids production: a critical review

Prebiotics are known for their health benefits to man, including reducing cardiovascular disease and improving gut health. This review takes a critical assessment of the impact of dietary fibres and prebiotics on the gastrointestinal microbiota in vitro. The roles of colonic organisms, slow fermentation of prebiotics, production of high butyric and propionic acids and positive modulation of the host health were taken into cognizance. Also, the short-chain fatty acids (SCFAs) molecular signalling mechanisms associated with their prebiotic substrate structural conformations and the phenotypic responses related to the gut microbes composition were discussed. Furthermore, common dietary fibres such as resistant starch, pectin, hemicelluloses, β-glucan and fructan in context of their prebiotic potentials for human health were also explained. Finally, the in vitro human colonic fermentation depends on prebiotic type and its physicochemical characteristics, which will then affect the rate of fermentation, selectivity of micro-organisms to multiply, and SCFAs concentrations and compositions.

In vitro fermentation of Gracilaria lemaneiformis sulfated polysaccharides and its agaro-oligosaccharides by human fecal inocula and its impact on microbiota

The fermentation behaviour of sulfated polysaccharides (GLP) and their agaro-oligosaccharides (GLO) derived from Gracilaria lemaneiformis were examined. During in vitro fermentation, GLP and GLO increased the concentrations of short chain fatty acids (SCFAs) and modulated the composition and diversity of gut microorganisms compared with control groups. GLP increased the abundance of Bacteroidetes and decreased the abundance of Firmicutes, while GLO increased the abundance of Firmicutes and Actinobacteria. Moreover, the abundances of potential pathogenic bacteria were reduced. Molecular weight and intrinsic viscosity of GLP decreased significantly from 2.15 × 10⁵ to 1.22 × 10⁵ Da, 374.45-113.91 mL/g, respectively. Furthermore, GLP was degraded into smaller degree of polymerization of oligosaccharides, with no significant change observed in GLO. Overall, this study revealed GLP and GLO could be beneficial for gastrointestinal tract by producing SCFAs and modulating intestinal microbes, indicating GLP and GLO are potentially sources of prebiotics in functional foods.

Enteral Nutrition as a Growth Medium for Cultivable Commensal Bacteria and Its Effect on Their Quantity in the Stool of Children with Crohn's Disease

Current studies indicate a link between the intake of exclusive enteral nutrition (EEN) and the induction of complex changes in the intestinal microbiota, as well as the clinical improvement of Crohn's disease (CD). The first aim of this study was to test the ability of various commensal bacterial strains (n = 19) such as bifidobacteria, lactobacilli, and Escherichia coli to grow on three different polymeric EN in vitro. Tested EN formulas were found to be suitable growth media for tested commensals. Furthermore, the counts of these bacteria and total counts of anaerobic bacteria in the fecal samples of children with CD (n = 15) before and after 6 weeks of EEN diet administration were determined using cultivation on selective media. The counts of cultivable commensal bacteria in the fecal samples of CD children were not significantly affected by EEN. However, tested bacteria showed some individual shifts in counts before and after EEN therapy. Moreover, cultured bifidobacteria were found to be in reduced counts in CD children. Therefore, the application of bifidogenic prebiotic compounds to EN for CD patients might be considered.

Prebiotic compounds from agro-industrial by-products

Prebiotics are nondigestible food components that have an impact on gut microbiota composition and activity, which in turn results in the improvement of health conditions. Nowadays, the production of prebiotics from agro-industrial by-products is under investigation. In this regard, polysaccharides are usually found in these sources and their potential use as prebiotics has been studied recently since these compounds act as substrates for the human gut microbiota, and they have the potential to modulate its composition through many mechanisms. Additionally, the use of agricultural by-products is advantageous because it is a cheap and abundantly available material. This review focuses on the recent scientific literature regarding the prebiotic properties of polysaccharides from agro-industrial by-products. PRACTICAL APPLICATIONS: Currently, the maintenance of gut homeostasis is a target for the improvement of human health. This review can broaden the perspective on the utilization of agro-industrial by-products that can compete in the market with the commercial ones or act as a source for new food ingredients.