Remedios Yáñez

Pectic oligosacharides from lemon peel wastes: production, purification, and chemical characterization.

Lemon peel wastes were extracted with water to remove free sugars and other soluble compounds, and the insoluble solid was employed as a substrate for the manufacture of pectin-derived oligosaccharides by processing with hot, compressed water. When water-extracted lemon peel wastes were treated with water at 160 °C, the oligomer concentration reached the maximum value (31 g/L). Autohydrolysis liquors were subjected to two membrane filtration stages (diafiltration followed by concentration), yielding a refined product containing about 98 wt % of oligomers at a global yield of 14 kg/100 kg oven-dry lemon peel. The concentrate contained oligogalacturonides (with DP in the range of 2-18) and arabinooligosaccharides (with DP in the range of 2-8).

Direct enzymatic production of oligosaccharide mixtures from sugar beet pulp: experimental evaluation and mathematical modeling.

The potential of sugar beet pulp as raw material for neutral and acidic oligosaccharide production by direct enzymatic treatment was evaluated. The effect of the polygalacturonase to solid ratio (PGaseSR), cellulase activity to polygalacturonase activity ratio (CPGaseR), and reaction time (t) on several dependent variables (selected to quantify the mass of recovered liquors, the conversion of each polysaccharide into monosaccharides, and the conversion of each polysaccharide into oligomers) was studied. Mathematical models suitable for reproducing and predicting the experimental results were also developed. Operational conditions leading to a maximum oligomer production were calculated from models being PGaseSR = 10 U/g, CPGaseR = 0.725 filter paper units/U, and t = 12.82 h. Under these conditions, the models predicted that 906 kg of liquors containing 26.7 kg of oligosaccharides can be obtained from 100 kg of SBP, the distribution being as follows: 5.9 kg of glucooligosaccharides, 2.4 kg of galactooligosaccharides, 9.7 kg of arabinooligosaccharides, and 8.7 kg of oligogalacturonides. Therefore, this study demonstrated that pectic oligomers (for which prebiotic properties have been reported) can be obtained from SBP at high yield by direct enzymatic hydrolysis using mixtures of cellulases and pectinases.

Assessment of the prebiotic effect of quinoa and amaranth in the human intestinal ecosystem.

Quinoa and amaranth belong to the group of the so called superfoods and have a nutritional composition that confers multiple benefits. In this work, we explored the possibility of these foods exhibiting a prebiotic effect. These pseudocereals were subjected to an in vitro digestion and used as carbon sources in batch cultures with faecal human inocula. The effects on the microbiota composition and their metabolic products were determined by assessment of variations in pH, short-chain fatty acid (SCFA) production and changes in the dynamic bacterial populations by fluorescence in situ hybridization (FISH). After 48 h of incubation, the total SCFAs were 106.5 mM for quinoa and 108.83 mM for amaranth, in line with the decrease in pH. Considerable differences (p < 0.05) were found in certain microbial groups, including Bifidobacterium spp., Lactobacillus-Enterococcus, Atopobium, Bacteroides-Prevotella, Clostridium coccoides-Eubacterium rectale, Faecalibacterium prausnitzii and Roseburia intestinalis. Our research suggests that these pseudocereals can have the prebiotic potential and that their intake may improve dysbiosis or maintain the gastrointestinal health through a balanced intestinal microbiota, although additional studies are necessary.

A biorefinery approach based on fractionation with a cheap industrial by-product for getting value from an invasive woody species.

Acacia dealbata wood (an invasive species) was subjected to fractionation with glycerol (a cheap industrial by-product), and the resulting solid phase was used as a substrate for enzymatic hydrolysis. Glycerol fractionation allowed an extensive delignification while preserving cellulose in solid phase. The solids from the fractionation stage showed high susceptibility to enzymatic hydrolysis. Solids obtained under selected fractionation conditions (glycerol content of media, 80 wt%; duration, 1h; liquid to solid ratio, 6 g/g; alkaline and neutral washing stages) were subjected to enzymatic saccharification to achieve glucose concentrations up to 85.40 g/L, with almost complete cellulose conversion into glucose. The results confirmed the potential of glycerol as a fractionation agent for biorefineries.

Valorization of peanut shells: manufacture of bioactive oligosaccharides

Peanut shells were subjected to non-isothermal aqueous treatments to cause the partial breakdown of hemicelluloses into soluble oligosaccharides and lignin-derived compounds with high antioxidant activity. The effects of temperature on the chemical composition of the substrate and soluble reaction products were assessed. Under selected conditions (210°C, severity=4.09), the overall amount of poly- and oligo- saccharides present in the liquid phase reached 9.8g/L. This solution was refined by consecutive stages of discontinuous diafiltration, yielding a refined product containing about 72.4wt% of oligomers at a global yield of 8.5kg/100kg oven-dry PS. The purified products were characterized by HPLC, MALDI-TOF-MS and FTIR, confirming the major reaction products were saccharides made up of xylose with degrees of polymerization up to 17, substituted with acetyl and methylglucuronosyl groups, for which a number of pharmaceutical and food applications have been proposed. Solubilization of hemicelluloses in the treatments resulted in the production of solids enriched in cellulose and lignin suitable for further applications.

Manufacture and Properties of Glucomannans and Glucomannooligosaccharides Derived from Konjac and Other Sources

Glucomannans (GM) are polymers that can be found in natural resources, such as tubers, bulbs, roots, and both hard- and softwoods. In fact, mannan-based polysaccharides represent the largest hemicellulose fraction in softwoods. In addition to their structural functions and their role as energy reserve, they have been assessed for their healthy applications, including their role as new source of prebiotics. This paper summarizes the scientific literature regarding the manufacture and functional properties of GM and their hydrolysis products with a special focus on their prebiotic activity.

Extraction of Oligosaccharides With Prebiotic Properties From Agro-Industrial Wastes

Abstract A prebiotic is a selectively fermented ingredient that results in specific changes in the composition and/or activity of the gut microbiota, thus conferring benefit(s) upon host health. Nowadays, there is a growing list of inexpensive and abundant potential prebiotics for which the scientific evidence, especially in humans, is not well established as for other commercial ones such as fructooligosaccharides (FOS), and therefore more research studies are needed. Among the most widely water-extracted oligosaccharides, from wood and agro-industrial wastes, with prebiotic activity are xylooligosaccharides (XOS), glucomannooligosaccharides (GMOS), and pectin-derived oligosaccharides (POS). This chapter includes scientific literature regarding the production, the manufacture, and the evaluation of the possible health benefits of this group of emerging prebiotics obtained from renewable sources.