Phenolics Distribution in Rice and Their Macromolecular Interactions: A Matrix-Centric Perspective

Rice is a globally indispensable staple food and a major dietary source of phenolic compounds, whose nutritional and functional properties are influenced by their interactions within the rice matrix. This review provides a comprehensive synthesis of current knowledge on rice phenolics distribution and their macromolecule interactions, integrating evidence from binary, and ternary systems, to whole-matrix perspectives and examines their structural, functional, and nutritional consequences. Across rice genotypes, 76 polyphenols have been identified and quantified, encompassing phenolic acids, flavonoids, proanthocyanidins, and anthocyanins. Their abundance, chemical structure, and localization significantly dictated by grain anatomy, pigmentation, and processing. Mechanistically, phenolic binding is dominated by non-covalent interactions, including hydrogen bonding, hydrophobic interactions, electrostatic forces, CH-π interactions, and π-π stacking, facilitating multiscale structural reorganizations through amylose inclusion complexation, protein conformational rearrangements, lipid-assisted V-type crystallization, and dietary fiber binding. In ternary systems, competitive and synergistic interactions further modulate binding strength and structural organization. Functionally, these matrix-mediated interactions regulate stability and bioaccessibility of phenolic, macronutrient digestibility, glycemic response, and key technofunctional properties. By integrating compositional, mechanistic, and functional evidence, this review establishes a robust framework for understanding rice matrix-phenolic interactions and supports the rational design of phenolic-enriched, low-glycemic rice products with targeted nutritional benefits.