Oligomalt, a New Slowly Digestible Carbohydrate, Is Well Tolerated in Healthy Young Men and Women at Intakes Up to 180 Gram per Day: A Randomized, Double-Blind, Crossover Trial.

In this randomized, double-blind triple-crossover study (NCT05142137), the digestive tolerance and safety of a novel, slowly digestible carbohydrate (SDC), oligomalt, an α-1,3/α-1,6-glucan α-glucose-based polymer, was assessed in healthy adults over three separate 7-day periods, comparing a high dose of oligomalt (180 g/day) or a moderate dose of oligomalt (80 g/day in combination with 100 g maltodextrin/day) with maltodextrin (180 g/day), provided as four daily servings in 300 mL of water with a meal. Each period was followed by a one-week washout. A total of 24 subjects (15 females, age 34 years, BMI 22.2 kg/m2, fasting blood glucose 4.9 mmol/L) were recruited, of whom 22 completed the course. The effects on the primary endpoint (the Gastrointestinal Symptom Rating Score (GSRS)) showed a statistically significant dose dependency, albeit of limited clinical relevance, between a high dose of oligomalt and maltodextrin (mean (95% CI) 2.29 [2.04, 2.54] vs. 1.59 [1.34, 1.83], respectively; difference: [-1.01, -0.4], p < 0.0001), driven by the GSRS-subdomains "Indigestion" and "Abdominal pain". The GSRS difference ameliorated with product exposure, and the GSRS in those who received high-dose oligomalt as their third intervention period was similar to pre-intervention (mean ± standard deviation: 1.6 ± 0.4 and 1.4 ± 0.3, respectively). Oligomalt did not have a clinically meaningful impact on the Bristol Stool Scale, and it did not cause serious adverse events. These results support the use of oligomalt across various doses as an SDC in healthy, normal weight, young adults.

Exploring novel non-Leloir ß-glucosyltransferases from proteobacteria for modifying linear (ß1->3)-linked gluco-oligosaccharide chains.

Over the years several ß-glucan transferases from yeast and fungi have been reported, but enzymes with such an activity from bacteria have not been characterized so far. In this work, we describe the cloning and expression of genes encoding ß-glucosyltransferase domains of glycosyl hydrolase family GH17 from three species of proteobacteria: Pseudomonas aeruginosa PAO1, P. putida KT2440 and Azotobacter vinelandii ATCC BAA-1303. The encoded enzymes of these GH17 domains turned out to have a non-Leloir trans-ß-glucosylation activity, as they do not use activated nucleotide sugar as donor, but transfer a glycosyl group from a ß-glucan donor to a ß-glucan acceptor. More particularly, the activity of the three recombinant enzymes on linear (ß1 â†’ 3)-linked gluco-oligosaccharides (Lam-Glc(4-9)) and their corresponding alditols (Lam-Glc(4-9)-ol) was studied. Detailed structural analysis, based on thin-layer chromatography, matrix-assisted laser desorption ionization time-of-flight mass spectrometry, electrospray ionization mass spectrometry, and 1D/2D (1)H and (13)C nuclear magnetic resonance data, revealed diverse product spectra. Depending on the enzyme used, besides (ß1 â†’ 3)-elongation activity, (ß1 â†’ 4)- or (ß1 â†’ 6)-elongation, or (ß1 â†’ 6)-branching activities were also detected.

Physicochemical properties and starch digestibility of whole grain sorghums, millet, quinoa and amaranth flours, as affected by starch and non-starch constituents.

Minor grains such as sorghum, millet, quinoa and amaranth can be alternatives to wheat and corn as ingredients for whole grain and gluten-free products. In this study, influences of starch structures and other grain constituents on physicochemical properties and starch digestibility of whole flours made from these grains were investigated. Starches were classified into two groups according to their amylopectin branch chain-length: (i) quinoa, amaranth, wheat (shorter chains); and (ii) sorghum, millet, corn (longer chains). Such amylopectin features and amylose content contributed to the differences in thermal and pasting properties as well as starch digestibility of the flours. Non-starch constituents had additional impacts; proteins delayed starch gelatinization and pasting, especially in sorghum flours, and high levels of soluble fibre retarded starch retrogradation in wheat, quinoa and amaranth flours. Enzymatic hydrolysis of starch was restricted by the presence of associated protein matrix and enzyme inhibitors, but accelerated by endogenous amylolytic enzymes.

Effect of roasting on degradation and structural features of polysaccharides in Arabica coffee beans.

The degree and nature of polysaccharide degradation at different roasting levels was determined for three Arabica (Coffea arabica) bean varieties. Between 12 and 40% of the bean polysaccharides were degraded depending on the roasting conditions. The thermal stability of the arabinogalactans, (galacto)mannans and cellulose was markedly different. The arabinogalactans and mannans were degraded up to 60 and 36%, respectively, after a dark roast, while cellulose showed negligible evidence of degradation. Roasting led to increased solubility of both the arabinogalactans and (galacto)mannans from the bean but the structural modifications, which accompanied this change in solubility, were different for each polysaccharide. Despite the moderate degradation of the (galacto)mannans, those remaining in the bean after roasting showed no evidence of change to their molecular weight even after a dark roast. In contrast, arabinogalactans were depolymerised after a light roast both by fission of the galactan backbone and loss of arabinose from the sidechains. The recently discovered covalent link between the coffee bean arabinogalactans and protein survived roasting. The glucuronic acid component of the AG was degraded markedly after a dark roast, but approximately 30% of the original content remained as part of the AG polymer. The results show that polysaccharide degradation during roasting is more marked than previously documented, and points to roasting induced changes to the polysaccharides as major factors in the changing physicochemical profile of the coffee bean during processing.

Coffee bean arabinogalactans: acidic polymers covalently linked to protein.

The arabinogalactan content of green coffee beans (Coffea arabica var. Yellow Caturra) was released by a combination of chemical extraction and enzymatic hydrolysis of the mannan-cellulose component of the wall. Several arabinogalactan fractions were isolated, purified by gel-permeation and ion-exchange chromatography and characterised by compositional and linkage analysis. The AG fractions contained between 6 and 8% glucuronic acid, and gave a positive test for the beta-glucosyl-Yariv reagent, a stain specific for arabinogalactan-proteins. The protein component accounted for between 0.5 and 2.0% of the AGPs and contained between 7 and 12% hydroxyproline. The AG moieties displayed considerable heterogeneity with regard to their degree of arabinosylation and the extent and composition of their side-chains. They possessed a MW average of 650 kDa which ranged between 150 and 2000 kDa. An investigation of the structural features of the major AG fraction, released following enzymatic hydrolysis of the mannan-cellulose polymers, allowed a partial structure of coffee arabinogalactan to be proposed.

Changes to the galactose/mannose ratio in galactomannans during coffee bean ( Coffea arabica L.) development: implications for in vivo modification of galactomannan synthesis.

Endosperm was isolated from Arabica Caturra coffee beans 11, 15, 21, 26, 31 and 37 weeks after flowering, and the chemical composition and relative solubility of its component polysaccharides determined at each growth stage. Chemical analysis of the total mannan content of the cell wall material was done after solubilisation of galactomannans by alkaline extraction of the cell wall material followed by enzymatic digestion of the alkali-insoluble residue with a mixture of endo-mannanse and endo-glucanase. Eleven weeks after flowering, galactomannans accounted for approximately 10% of the polysaccharides but were highly substituted, with galactose/mannose ratios between 1:2 and 1:7. As the bean matured, galactomannan became the predominant polysaccharide, until 31 weeks after flowering it accounted for approximately 50% of the polysaccharides. However, it was less substituted, possessing galactose/mannose ratios between 1:7 and 1:40. Early in bean growth, up to 50% of the cell wall polysaccharides were extractable but as the galactomannan content of the bean increased there was a reduction in the extractability of all polysaccharides. The decrease in the galactose/mannose ratio of the galactomannans commenced between 21 and 26 weeks after flowering and was in synchrony with a rise in the concentration of free galactose in the beans. The results indicated that the degree of substitution of the galactomannans in coffee beans is developmentally regulated and may result, in part, from the modification of a primary synthetic product by the action of an alpha-galactosidase.