Effect of soybean protein isolate-Aronia melanocarpa extract interaction on the bioaccessibility of anthocyanins after low-pressure cold plasma treatment

This study evaluated the impact of cold plasma (CP) treatment on the structural and digestive properties of soybean protein isolate (SPI)–Aronia melanocarpa extract (AME) complexes. CP treatment significantly modified the secondary structure of SPI–AME complexes, while AME addition enhanced protein stability by increasing α-helix content. FTIR and UHPLC-PDA analyses suggested pronounced structural changes and substantial phenolic changes, particularly for chlorogenic acids and cyanidin derivatives, throughout the digestive process. Anthocyanin levels increased in the gastric phase due to flavylium cation stabilization but declined significantly at intestinal pH 7.0. CP-treated complexes showed 84-89% anthocyanin retention compared to free AME, which showed a decline to 2-3%. Molecular docking further supported these findings, revealing strong binding affinities between cyanidin derivatives and glycinin (1FXZ), explaining the enhanced complex stability. These results indicate that CP-mediated protein-polyphenol interactions successfully protect sensitive bioactives during digestion, offering a promising approach for developing stable functional food systems.