Controlled irradiation-engineered low-molecular-weight pectin exhibits high digestive stability and retains prebiotic activity in vivo

Dietary fibers are valued for colon delivery and prebiotic activity, yet the high molecular weight of natural pectins can hinder processability and reduce bioavailability. This study utilized electron beam irradiation (EBI) to engineer lemon pectin (LP) into a precise MW gradient: HMW LP (1180.65 kDa), MMW ELP25 (83.49 kDa), and LMW ELP200 (11.39 kDa). Physicochemical analysis revealed a clear MW-dependent stability trend during simulated digestion. Notably, LMW ELP200 exhibited superior digestive stability with a cumulative digestibility of only 15.47%, significantly lower than that of HMW LP (21.81%) and MMW ELP25 (18.92%), thereby facilitating the efficient delivery of intact bioactive domains to the colon. In vitro and in vivo evaluations confirmed that ELP200 not only retained the gut-modulating efficacy of native LP but also demonstrated an enhanced safety profile. Specifically, ELP200 maintained overall microbial alpha-diversity and significantly promoted the growth of beneficial taxa (e.g., Faecalibaculum ) while suppressing pathogens such as Campylobacterota . Crucially, unlike HMW LP, ELP200 avoided the enrichment of specific pathobionts (e.g., Rodentibacter ), thereby fostering a safer gut microecology. These results suggest that EBI effectively optimizes the physical stability and delivery efficiency of lemon pectin while preserving its essential gut-modulating functions, positioning ELP200 as a stable next-generation prebiotic product candidate.