The oral lubrication performance of plant-derived polymers: A review focusing on microstructure, functionality, and polymer-saliva interactions

Oral tribology offers unique insights into how plant-derived biopolymers shape texture and mouthfeel in plant-based foods. This review examines the current literature on saliva composition, oral perception, and tribological principles to understand how molecular and microstructural characteristics such as polysaccharide branching, protein secondary structure, particle morphology, and aggregation state govern lubrication behaviour. Furthermore, it explores how extraction and processing modify these features. Polymer–saliva interactions, particularly with mucins, remain underexplored, with unclear roles in boundary lubrication, shear disruption, and sensory attributes such as creaminess and astringency. Although new processing strategies can reduce oral friction and improve mouthfeel, links between in vitro measurements and in vivo perception remain inconsistent. Future progress relies on mechanistic frameworks linking molecular and micro-scale structures to sensory outcomes, supported by biomimetic oral models and physiologically relevant tribological testing. This approach can enable the rational design of novel plant-based formulations with improved lubrication, smoothness, and consumer acceptability. • Plant biopolymer microstructure influences functionality and saliva-mediated lubrication. • Processing pathways and delubrication mechanisms link to creaminess and astringency. • Mucin-protein aggregation knowledge gaps limit oral friction prediction. • Biomimetic oral models and saliva characterisation are key to advancing oral tribology.