Effects of colloidal delivery systems for curcumin-Brassica rapa L. polysaccharide mixture encapsulation on...

The therapeutic potential of curcumin is severely constrained by its poor physicochemical stability and low oral bioavailability. Co-formulation with Brassica rapa L. polysaccharide offers a promising strategy to enhance its functionality; however, the impact of different colloidal delivery systems on the encapsulation performance and subsequent biological fate of this mixture remains unclear. In this study, we systematically compared three spray-dried delivery platforms, including liposomes (LP-CP), sodium caseinate nanoparticles (SC-CP), and β-cyclodextrin inclusion complexes (CYC-CP), for encapsulating CP. Our results demonstrated that the carrier system critically determined encapsulation performance, with SC-CP exhibiting superior curcumin loading capacity (7.24%), curcumin thermal stability (82.87% retention at 95 °C), and favorable hygroscopicity profiles. Notably, SC-CP facilitated enhanced colonic accumulation in vivo, achieving a peak accumulation of 53.45% at 8 h post-gavage, representing a 15-fold increase compared to curcumin from unencapsulated CP. By integrating in vitro fermentation models with in vivo animal experiments and employing 16S rRNA sequencing alongside short-chain fatty acid (SCFA) analysis, we systematically elucidated the carrier-specific modulatory effects on the gut microbiota. In the in vitro fermentation system, SC-CP significantly promoted the production of acetate, propionate, and butyrate, while enriching butyrate-producing genera such as Lachnospiraceae_NK4A136_group. In the in vivo animal model, SC-CP intervention resulted in a 1.6-fold increase in cecal butyrate levels and a marked increase in the abundance of beneficial genera, including Akkermansia, demonstrating superior modulation of microbial community structure and metabolic function. Collectively, these findings establish that the selection of a colloidal carrier not only dictates the physicochemical stability of the curcumin-polysaccharide mixture but also governs its spatiotemporal distribution within the gastrointestinal tract and its prebiotic capacity to remodel the gut microecology. This study provides a theoretical foundation for the rational selection of delivery systems to maximize the functional efficacy of bioactive ingredients in functional food applications.