Plant-derived galacto-oligosaccharides produced from potato galactan by endo-β(1,4)-galactanase (AtGH53) exhibit prebiotic selectivity and antioxidant properties.

Galacto-oligosaccharides derived from plant polysaccharides are emerging as multifunctional bioactive ingredients with potential applications in gut health and oxidative stress management. In this study, galacto-oligosaccharides (GaOS) were enzymatically produced from potato galactan using Acetivibrio thermocellus endo-β-1,4-galactanase (AtGH53) and evaluated for gastrointestinal stability, prebiotic functionality and antioxidant activity. The isolated GaOS solution (DP2-DP5) exhibited high resistance to α-amylase digestion (80%), simulated gastric conditions (93%) and bile salts (85%), indicating their ability to reach the colon largely intact. Fermentation studies demonstrated that GaOS supported the growth of selected probiotic Bifidobacterium and Lactobacillus strains while showing limited utilization by the non-probiotic strains tested. Moreover, fermentation also generated beneficial short-chain fatty acids, including acetate, propionate and butyrate, accompanied by moderate pH decrease. In addition, GaOS displayed concentration-dependent antioxidant activity, showing maximum DPPH scavenging (66%), hydroxyl radical scavenging (35%), inhibition of ascorbate auto-oxidation (20%) and reducing power (9%) at 20 mg mL-1. Collectively, these findings demonstrated that plant-derived GaOS possess favourable gastrointestinal stability, fermentability and antioxidant properties, highlighting their potential as functional food and nutraceutical ingredients. Further studies comparing GaOS with commercial galacto-oligosaccharides and evaluating their efficacy in vivo are warranted.