Rapid microwave-assisted synthesis of polydextrose and identification of structure and function

Gluco-oligosaccharides as potential prebiotics: Synthesis, purification, structural characterization, and evaluation of prebiotic effect

Prebiotics have long been used to modulate the gut microbiota and improve host health. Most established prebiotics are nondigestible carbohydrates, especially short-chain oligosaccharides. Recently, gluco-oligosaccharides (GlcOS) with 2-10 glucose residues and one or more O-glycosidic linkage(s) have been found to exert prebiotic potentials (not fully established prebiotics) because of their selective fermentation by beneficial gut bacteria. However, the prebiotic effects (non-digestibility, selective fermentability, and potential health effects) of GlcOS are highly variable due to their complex structure originating from different synthesis processes. The relationship between GlcOS structure and their potential prebiotic effects has not been fully understood. To date, a comprehensive summary of the knowledge of GlcOS is still missing. Therefore, this review provides an overview of GlcOS as potential prebiotics, covering their synthesis, purification, structural characterization, and prebiotic effect evaluation. First, GlcOS with different structures are introduced. Then, the enzymatic and chemical processes for GlcOS synthesis are critically reviewed, including reaction mechanisms, substrates, catalysts, the structures of resultant GlcOS, and the synthetic performance (yield and selectivity). Industrial separation techniques for GlcOS purification and structural characterization methods are discussed in detail. Finally, in vitro and in vivo studies to evaluate the non-digestibility, selective fermentability, and associated health effects of different GlcOS are extensively reviewed with a special focus on the GlcOS structure-function relationship.

Effects of partially hydrolyzed guar gums of different molecular weights on a human intestinal in vitro fermentation model

Partially hydrolyzed guar gums (PHGGs) are prebiotic soluble dietary fibers. High molecular-weight PHGGs have rapid fermentation and high short-chain fatty acid (SCFA) productivity rates, compared to low molecular-weight PHGGs. Therefore, low molecular-weight PHGGs may have less pronounced prebiotic effects than high molecular-weight PHGGs. However, the effects of PHGGs of different molecular weights on the human intestinal microbiota, as well as their fermentation ability and prebiotic effects, have not been investigated. The aim of this study was to evaluate the effects of two PHGGs of different molecular weights, Sunfiber-R (SF-R; 20 kDa) and Sunfiber-V (SF-V; 5 kDa), on human colonic microbiota and SCFA production. A human intestinal in vitro fermentation model was operated by fecal samples with and without the PHGGs. The addition of 0.2% SF-R or SF-V increased the relative abundance of Bacteroides spp., especially that of Bacteroides uniformis. This increase corresponded to a significant (p = 0.030) and non-significant (p = 0.073) increase in propionate production in response to SF-R and SF-V addition, respectively. Both fibers increased the relative abundance of Faecalibacterium and stimulated an increase in the abundance of unclassified Lachnospiraceae and Bifidobacterium. In conclusion, the low molecular-weight PHGG exerted prebiotic effects on human colonic microbiota to increase SCFA production and bacteria that are beneficial to human health in a manner similar to that of the high molecular-weight forms of PHGG.

Glycosidic Linkage Structures Influence Dietary Fiber Fermentability and Propionate Production by Human Colonic Microbiota In Vitro

Some dietary fibers can be produced by starch modification; however, information regarding the relationships between glycosidic linkages and dietary fiber fermentability or the production of short-chain fatty acids is limited. Thus, these relationships are investigated using an in vitro model of human colonic microbiota, which approximates the bacterial species richness and diversity in inoculated fecal samples. Six dietary fibers with various glycosidic linkage contents are prepared. Each dietary fiber (final concentration: 1.0 wt%) is administered in vitro to human microbiota models 18 h after fecal samples are inoculated. The contents of (1 → 2) plus (1 → 3) linkages and β-linkages in the six dietary fibers negatively correlate with the fermentation speed and fermentation ratio of the indigestible parts of the dietary fibers (R² = 0.8126 or 0.8306 and R² = 0.9106 or 0.9673, respectively) 24 h after administering each dietary fiber. Further, the concentrations of propionate produced in vitro by human microbiota positively correlate with the fermentation speed and fermentation ratio (R² = 0.9149 and 0.9581, respectively). The in vitro assay reveals that (1 → 2) plus (1 → 3) linkages and β-linkages in dietary fiber affect resistance to fermentation and propionate production by the human colonic microbiota.

Impact of the source of fermentable carbohydrate on SCFA production by human gut microbiota in vitro - a systematic scoping review and secondary analysis

Short chain fatty acids (SCFA) are produced by bacterial fermentation of non-digestible carbohydrates (NDC) and have many potential tissue and SCFA specific actions, from providing fuel for colonic cells to appetite regulation. Many studies have described the fermentation of different carbohydrates, often using in vitro batch culture. As evidence-based critical evaluation of substrates selectively promoting production of individual SCFA is lacking, we performed a systematic scoping literature review. Databases were searched to identify relevant papers published between 1900 and 12/06/2016. Search terms included In vitro batch fermentation and In vitro short chain fatty acid production. Articles were considered for essential criteria allowing equivalent comparison of SCFA between NDC. Seventy seven articles were included in the final analysis examining 29 different carbohydrates. After 24-hour fermentation, galacto-oligosaccharide ranked highest for butyrate and total SCFA production and second for acetate production. Rhamnose ranked highest for propionate production. The lowest SCFA production was observed for kiwi fiber, polydextrose, and cellulose. This review demonstrates that choosing a substrate to selectively enhance a specific SCFA is difficult, and the molar proportion of each SCFA produced by individual substrates may be misleading. Instead the rate and ratio of SCFA production should be evaluated in parallel.

Infant food applications of complex carbohydrates: Structure, synthesis, and function

Professional health bodies such as the World Health Organization (WHO), the American Academy of Pediatrics (AAP), and the U.S. Department of Health and Human Services (HHS) recommend breast milk as the sole source of food during the first year of life. This position recognizes human milk as being uniquely suited for infant nutrition. Nonetheless, most neonates in the West are fed alternatives by 6 months of age. Although inferior to human milk in most aspects, infant formulas are able to promote effective growth and development. However, while breast-fed infants feature a microbiota dominated by bifidobacteria, the bacterial flora of formula-fed infants is usually heterogeneous with comparatively lower levels of bifidobacteria. Thus, the objective of any infant food manufacturer is to prepare a product that results in a formula-fed infant developing a breast-fed infant-like microbiota. The goal of this focused review is to discuss the structure, synthesis, and function of carbohydrate additives that play a role in governing the composition of the infant microbiome and have other health benefits.

Assessing the effects of different prebiotic dietary oligosaccharides in sheep milk ice cream

The objective of this study was to assess the effects of different prebiotic dietary oligosaccharides (inulin, fructo-oligosaccharide, galacto-oligossacaride, short-chain fructo-oligosaccharide, resistant starch, corn dietary oligosaccharide and polydextrose) in non-fat sheep milk ice cream processing through physical parameters, water mobility and thermal analysis. Overall, the fat replacement by dietary prebiotic oligosaccharides significantly decreased the melting time, melting temperature and the fraction and relaxation time for fat and bound water (T₂₂) while increased the white intensity and glass transition temperature. The replacement of sheep milk fat by prebiotics in sheep milk ice cream constitutes an interesting option to enhance nutritional aspects and develop a functional food.

Glycosylation improves the functional characteristics of chlorogenic acid–lactoferrin conjugate

Chlorogenic acid (CA)–lactoferrin (LF) conjugate prepared via alkali treatment was glycoslated with glucose (Glc) or polydextrose (PD) by the Maillard reaction, and the modification improved the functional properties of the conjugate.