(254a) Chemical Synthesis of Potential Prebiotic Oligosaccharides from Simple Sugars and Lignocellulosic Biomass in Concentrated Acids
AIChE Annual Meeting
2022
2022 Annual Meeting
Forest and Plant Bioproducts Division
Biochemical Conversion Processes in Forest/Plant Biomass Biorefineries
Tuesday, November 15, 2022 - 8:00am to 8:15am
Prebiotics are non-digestible compounds that modulate the composition and/or activity of the gut microbiota through their selective fermentation by microorganisms in the gut, thus conferring health benefits to the host. Non-digestible oligosaccharides like fructo-oligosaccharides (FOS), galacto-oligosaccharides (GOS), isomalto-oligosaccharides (IMO), xylo-oligosaccharides (XOS), and manno-oligosaccharides (MOS) have been recognized as prebiotics, and they have been commercially produced for application in functional food/drinks and dietary supplements. It is highly attractive to develop efficient processes for large-scale production of prebiotic oligosaccharides from inexpensive and abundant substrates. For this purpose, we developed chemical methods for the synthesis of potential prebiotic oligosaccharides from biomass-derived simple sugars (bottom-up process) or directly from lignocellulosic biomass (top-down process) in concentrated acid systems. In the bottom-up synthesis strategy, gluco-oligosaccharides (GlcOS) were synthesized from glucose via dehydration condensation (acid-catalyzed glycosylation) in concentrated sulfuric acid (SA, 60â92%) with a high single-pass yield of GlcOS (83%) at 70 °C for 20 min. The synthesized GlcOS were a mixture of disaccharides (44%), trisaccharides (22%), tetrasaccharides (13%), and higher oligosaccharides (DP 5-9). The glucose residues in GlcOS were linked by predominantly α- and β-(1â6) linkages and other linkages including (1â4), (1â3), (1â2), and (1â1). The in vitro fermentation of GlcOS by probiotic bacteria Bifidobacterium bifidum, Bifidobacterium animalis, and Limosilactobacillus reuteri suggested that GlcOS could be utilized as a carbon source for bacterial growth, and their promotion effect was comparable to the commercial prebiotic IMO. It was found that concentrated phosphoric acid (PA, 70-85%) was as efficient as concentrated SA for GlcOS synthesis. Different oligosaccharides were also successfully synthesized from other mono- and di-saccharides (e.g., galactose, xylose, arabinose, lactose, maltose, and cellobiose) in the concentrated acid systems. In the top-down synthesis strategy, GlcOS and XOS/MOS were synthesized from cellulose and hemicelluloses (xylan or mannan) in lignocellulosic biomass (corn stover) via simultaneous hydrolysis and glycosylation in concentrated SA/PA.