A comparative evaluation of new prebiotic candidates. Part 1: Chemical and structural characterization,...

Despite growing interest in new oligosaccharides from agro-industrial wastes as sustainable alternatives to commercial prebiotics, comparative studies linking their structure to the fermentation behaviour and microbiota modulation remain limited. This study evaluated the prebiotic potential of three structurally distinct oligosaccharide mixtures derived from agro-industrial residues: sugar beet pectooligosaccharides (SBPOS), pine wood glucogalactomanooligosaccharides (GGMOS), and lemon pectooligosaccharides (LPOS). Substrates were chemically characterized, subjected to INFOGEST in vitro digestion, and fermented in vitro using pooled faecal microbiota from healthy donors. Substrate consumption, short-chain fatty acid (SCFA) production, gas generation, and microbiota modulation were analyzed for comparisons. All substrates showed high digestive stability, and fermentation behaviour was closely associated with structural characteristics. SBPOS, composed mainly of low-molecular-weight arabinooligosaccharides, was rapidly fermented and showed advantages over the oligofructose control, including lower gas production, an acetate-oriented profile, and preservation of microbial diversity maintaining key genera such as Faecalibacterium while promoting beneficial genera such as Bifidobacterium. In contrast, the more structurally complex GGMOS and LPOS exhibited slower fermentation kinetics and distinct metabolic profiles, although both produced higher SCFAs yields than oligofructose after 48 h. LPOS, enriched in oligogalacturonides, promoted butyrate production through lactate-based cross-feeding, whereas GGMOS favoured propionate generation. Overall, the results demonstrate that fermentation performance strongly depends on substrate structure and composition and support these agro-industrial mixtures as promising next-generation functional ingredients, with SBPOS emerging as an efficient low-gas alternative to commercial oligofructose.