Gut-targeted curcumin delivery with controlled release via sustainable emulsions co-stabilized by yeast protein isolate and citrus peel pectin

Microbial and plant-derived biopolymers have gained increasing attention as sustainable emulsifiers for food-grade delivery systems; however, individual materials often suffer from intrinsic limitations in stability or functionality. This study aimed to develop a gut-targeted emulsion system using yeast protein isolate (YPI), a fermentation-derived microbial protein, and citrus peel pectin (CPP), a fruit-processing byproduct, as complementary co-emulsifiers for curcumin delivery. Oil-in-water emulsions with varying YPI:CPP ratios were prepared and evaluated for their physicochemical stability and gastrointestinal digestion behavior. YPI provided strong interfacial activity but exhibited limited stability near its isoelectric point, whereas CPP contributed electrostatic and steric stabilization but showed weak interfacial adsorption. Co-stabilized emulsions with balanced YPI:CPP ratios (2:2 and 1:3) exhibited excellent colloidal stability across a pH range of 3-9 and resisted droplet disruption under gastric conditions. During small intestinal digestion, CPP delayed lipolysis, resulting in controlled curcumin release kinetics. Importantly, during the colonic phase, microbial degradation of CPP enabled sustained curcumin release. Overall, YPI-CPP co-stabilized emulsions integrate protein-driven interfacial stabilization with polysaccharide-mediated digestion responsiveness, offering a sustainable and effective platform for the gut-targeted delivery of hydrophobic bioactives. This strategy highlights the potential of microbial proteins and agri-food by-product valorization to advance both human health (UN Sustainable Development Goal [SDG] 3) and sustainable resource utilization (SDG 12).