Plant polyphenols are ubiquitous secondary metabolites in plants whose antioxidant, anti-inflammatory, antimicrobial, and cardioprotective activities have been systematically elucidated. They exert their physiological functions by scavenging intracellular reactive oxygen species, precisely regulating inflammatory mediators, and inhibiting pathogenic proliferation, exhibiting tremendous application potential in functional foods, biomedicine, and natural cosmetics. However, the inherent chemical instability of polyphenols leads to severe structur...al degradation and bioactivity loss during extraction, processing, and storage. This manifests not only as detectable content reduction but also as significant "hidden bioactivity loss" without apparent content changes, which has emerged as the core bottleneck restricting their industrial translation. Most existing reviews are limited to single-stage optimizations, and a systematic regulatory framework spanning the entire process of biosynthesis, extraction, and processing has not yet been established. In this narrative critical review, we construct an integrated system for polyphenol content enhancement and stability regulation across the entire value chain from biosynthesis to extraction and processing. We critically elaborate on stress-mediated biosynthetic mechanisms, extraction loss control strategies, and processing stabilization technologies, with the ultimate goal of improving their resource utilization efficiency and advancing the industrial innovation and application of plant polyphenols.Read more