Postharvest Quality Deterioration Mechanisms and Preservation Technologies of Tea (Camellia sinensis): A Review

Tea, a globally important cash crop with abundant bioactive constituents, suffers widespread postharvest quality deterioration that causes substantial economic losses. This review compares the divergence of deterioration pathways between postharvest fresh tea leaves and six major processed tea categories, distinguishes undesired deterioration from desirable maturation in aging-oriented categories such as Pu-erh and aged oolong, and integrates universal core mechanisms with category-specific regulatory characteristics. It identifies ascorbic acid and chlorophyll as reliable freshness indicators for green tea, evaluates mainstream preservation technologies across industrial-adaptability dimensions including cost, scalability, and technical maturity, and analyzes the coupled regulatory effects of moisture, oxygen, temperature, and light. A three-tier whole-chain staged precise preservation framework is proposed, covering source-end fresh-leaf cold-chain transportation, processed-tea storage, and terminal open-state distribution, an integration not explicitly structured in prior tea-storage reviews. The review further discusses industrial challenges and outlines directions for green, precise, composite, intelligent, and standardized preservation, offering systematic references for whole-chain tea quality regulation and supporting the industrial translation of low-carbon technologies.