Assessment of Post-Harvest Handling Practices and Their Impact on Phytochemical Quality of Medicinal Plants in Onitsha Market, Anambra State

Post-harvest handling conditions including drying method, storage duration, and packaging significantly influence the phytochemical stability and therapeutic potency of medicinal plant materials. In Onitsha, Anambra State, South East Nigeria, medicinal plants are traded under diverse and often suboptimal handling conditions. This study assesses post-harvest handling practices among medicinal plant vendors in Onitsha Main Market and evaluates their impact on the phytochemical quality of five high-volume traded species. A structured questionnaire survey was administered to 80 plant vendors, and fresh versus aged samples of Azadirachta indica leaves, Morinda lucida bark, Garcinia kola seeds, Carica papaya leaves, and Vernonia amygdalina leaves were analysed for total phenolic content, total flavonoid content, and antioxidant activity using DPPH assay. HPTLC marker profiling was conducted on fresh versus stored samples. Results showed that 63% of vendors sun-dried plant materials on bare concrete surfaces, 44% used polythene bags for storage, and the average time from harvest to sale was 23 days. Significant reductions in total phenolic content (22-41%) and antioxidant activity were documented in samples stored under vendor conditions for 30 days compared to fresh controls. HPTLC profiles revealed degradation or loss of key marker compounds in aged samples. These findings recommend standardised post-harvest protocols as a priority intervention for improving herbal product quality in South East Nigerian markets. Keywords: post-harvest handling, phytochemical quality, Onitsha, herbal market, storage