Berry polyphenol-macronutrient interactions reduce starch digestibility and modulate glycemic potential in bread and...

This study evaluates how polyphenol-rich raspberry and boysenberry powders interact with starch and gluten matrices in bread and pasta products, and how these interactions influence starch digestibility.

Through model systems and enriched products, we demonstrate that polyphenols bind to starch and gluten in both raw and heat-processed systems, reducing their bioaccessibility and enzyme inhibitory capacity. In vitro digestion assays revealed that polyphenol-matrix interactions, particularly with starch, hinder enzymatic starch breakdown via both direct enzyme inhibition and physical entrapment mechanisms. Raspberry polyphenols exhibited greater binding capacity and inhibitory potency than boysenberry counterparts, despite their lower total polyphenol content. The incorporation method significantly impacted functional performance: co-ingestion of berries with cereal products was more effective at reducing starch hydrolysis than enrichment. Thermal processing altered anthocyanin profiles but retained bioactivity.

These findings support the design of functional foods that modulate postprandial glycemic response by leveraging polyphenol-macronutrient interactions. Furthermore, this study emphasizes the importance of food matrix structure, processing conditions, and polyphenol stability in achieving effective glycemic modulation. © 2026 Society of Chemical Industry.