DOI: https://doi.org/10.36347/sajp.2026.v15i11.001

Pages: 278-282

Liupao tea is a post-fermented dark tea produced only in Wuzhou, Guangxi. Substantial quantities of tea residue are generated during its processing and consumption, and this residue is rich in flavonoids, making it a potential source of natural antioxidants. This review summarises recent progress in the extraction and antioxidant evaluation of total flavonoids from Liupao tea residue. Organic solvent extraction, deep eutectic solvent (DES) extraction, ultrasound- and microwave-assisted extraction, and enzyme-assisted extraction are compared in terms of their operating principles and practical suitability. The viscosity and polarity of DES emerge as the decisive factors governing extraction efficiency, and the combination of ternary DES with ultrasound is shown to raise flavonoid yield markedly while shortening processing time. The merits and limitations of DPPH·, ABTS⁺· and hydroxyl radical scavenging assays, together with those of cellular models, are then assessed, and the structural features that determine activity the number and position of phenolic hydroxyl groups, the o-dihydroxy group on the B ring, the C2 C3 double bond of the C ring, and glycosylation are discussed. Finally, taking account of the oxidative polymerisation of catechins during pile fermentation, standardisation of raw materials, scale-up of the process and comprehensive characterisation of components are proposed as the main directions for future research.