Dietary fiber-phenolic interactions: Recent advances in formed conjugates and complexes and interaction-driven functional property changes

Background: Dietary fiber and phenolics are promising functional ingredients, with their health benefits and processing properties widely reported. However, studies commonly overlook the existence of their bound states in natural food matrices, processing, and dietary intake. Although an increasing number of studies have focused on the preparation and properties of dietary fiber-phenolic conjugates/complexes (DF-PCs), a systematic understanding of how these interactions affect their properties remains limited. Scope and approach: This paper summarizes the existing natural and artificial DF-PCs and their characteristics, including preparation, composition, and types of interactions between components, through a comprehensive literature search. We further analyzed how the interactions change DF-PCs’ functional properties. Key findings and conclusions: Compositional differences in phenolics naturally bound to dietary fiber (predominantly phenolic acids) exist depending on the source, solubility and preparation parameters of conjugates and phenolic release methods. The interactions within artificially prepared complexes vary based on the preparation methods and specific components, involving both covalent and non-covalent bonds. Due to the phenolic binding, DP-PCs generally have enhanced multiple health benefits and processing properties, such as stability and packaging performance, compared to fibers. Compared to phenolics, DP-PCs may strengthen health regulation of colonic and related tissue, despite their chemical antioxidant and digestive enzyme inhibitory activities diminishing. Fibers' binding also ameliorates poor solubility or astringency in phenolic application. Interactions between components mostly enhance specific functional properties of DP-PCs, benefiting their application as ingredients in the food industry. Understanding and leveraging the effects of interactions require more in vivo studies and stricter comparative models.