Antioxidant Dietary Fibre: A Structure-Function Journey

Background: Non-extractable polyphenols (NEP) are polyphenols that are bound to dietary fibre (DF) and have important health benefits to humans. Past studies have used hydrolysis methods to extract NEP, studying NEP and DF separately. However, hydrolysis may affect their structures and functional properties. In fact, DF is a carrier of NEP in foods, and they physically and/or chemically interact with each other and exist as a complex, known as "antioxidant dietary fibre (ADF)". Therefore, the review focuses on the natural structure: ADF. The food matrix is a complex system with multiple components, and it is very important to explore approaches to obtain ADF and the effect of its structure on functional properties.Scope and approach: This review summarizes methods for isolating ADF from samples or forming it in vitro, as well as structural characterization, and discusses the functional implications arising from ADF.Key findings and conclusions: The ADF structure, especially the interactions between NEP and DF, has been characterized. Covalent interactions have been identified in the isolated ADF, and non-covalent interactions are the primary driving force in formed ADF. ADF is bioaccessible and bioavailable, has prebiotic, antioxidant, and anti-inflammatory properties. The structures of ADF, such as the structures and compositions of NEP and DF and their interactions, have a significant role in its functional properties. This review highlights the importance of ADF and provides structure-function information, which will contribute to future studies on its health benefits and the development of functional foods.