From Agri-Food Byproducts to High-Value Bioactive Compounds: A Critical Review Linking Green Recovery and Chemical Profiling to Circular Valorization

Agri-food byproducts are increasingly recognized as sustainable feedstocks for high-value bioactive compounds; but their practical valorization requires integrated evidence on recovery conditions; chemical composition; bioactivity; and application readiness. This review critically examines green recovery strategies and chemical profiling platforms for bioactive compounds recovered from peels; pomace; seed residues; hulls; vegetation waters; and pruning waste. Emphasis is placed on how extraction variables shape chemical profiles; extract quality; and reported biological activities. Ultrasound- and microwave-assisted extraction; enzyme- and fermentation-assisted recovery; supercritical fluid extraction; pressurized liquid extraction; pulsed electric field-assisted pretreatment; and green solvent-based extraction are discussed in terms of target-compound selectivity; solvent and energy demand; process safety; scalability; and sustainability-related evidence. Chromatographic; mass-spectrometric; spectroscopic; and metabolomics-based profiling approaches are evaluated for identification; annotation; quantification; fingerprinting; quality-marker selection; and standardization; with confidence levels distinguished according to authentic-standard matching; tandem mass spectrometry evidence; spectral libraries; or fingerprint-level evidence. Circular valorization pathways in food; nutraceutical; cosmetic; pharmaceutical, and biopesticide-related applications are further considered with attention to feedstock heterogeneity; process standardization; stability; safety; regulatory feasibility; scalability; and techno-economic feasibility. Overall; this review provides a linkage-oriented framework for developing standardized; application-readiness-oriented bioactive candidates from agri-food byproducts.