Enhanced stability of berry pomace polyphenols delivered in protein-polyphenol aggregate particles to an in vitro gastrointestinal digestion model

•Berry pomace polyphenols were complexed with protein to form protein-polyphenol aggregate particles.•The particles were evaluated in an in vitro gastrointestinal model against unmodified samples (pomace extracts)•Complexed particles were more stable than unmodified samples post digestion.•Complexed particles delivered higher polyphenol concentrations in their digest.•Complexed particles retained higher antioxidant/anti-inflammatory activities. Stability of protein-polyphenol aggregate particles, created by complexing polyphenols from blueberry and muscadine grape pomaces with a rice-pea protein isolate blend, was evaluated in an in vitro gastrointestinal model. Recovery index (RI; % total phenolics present post-digestion) was 69% and 62% from blueberry and muscadine grape protein-polyphenol particles, compared to 23% and 31% for the respective pomace extracts. Anthocyanins RI was 52% and 42% from particles (6% and 13% from pomace extracts), and proanthocyanidins RI was 77% and 73% from particles (25% and 14% from pomace extracts), from blueberry and grape, respectively. Protein-polyphenol particle digests retained 1.5 to 2-fold higher antioxidant capacity and suppressed the expression of pro-inflammatory cytokines, iNOS, IL6, and IL1β, compared to unmodified extract digests, which only suppressed IL6. Protein-polyphenol particles as a delivery vehicle in foods may confer better stability during gastrointestinal transit, allow protected polyphenols to reach the gut microbiota, and preserve polyphenol bioactivity.