Drying Temperature Modulates Phytochemical Integrity and Antioxidant Potential of Sungkai (Peronema canescens Jack)...

Sungkai (Peronema canescens Jack) leaves are traditionally used in Southeast Asian medicine and are enriched in bioactive compounds having antioxidant activity, which may help mitigate oxidative stress-related disorders. Preservation of such compounds during post-harvest processing is essential to maintain their functional potential for disease prevention. However, the influence of drying temperature on the quality of Sungkai leaf simplicia－dried plant material used for medicinal purposes－has not been systematically evaluated. This study investigated the effects of various drying temperatures: ambient, 40°C, 50°C, 60°C, and 70°C－on the physicochemical properties, phytochemical content, antioxidant capacity, color stability, microstructure, and metabolite profile. Drying at 40°C effectively preserved total flavonoid and phenolic contents, antioxidant activity, chlorophyll retention, and metabolite diversity while significantly reducing duration compared with ambient drying. In contrast, temperatures ≥50°C accelerated demoisturization and caused a substantial degradation of phytochemicals, enhanced browning, structural collapse, and reduced antioxidant capacity. Multivariate analysis confirmed drying temperature as the primary determinant of Sungkai leaf quality. These findings demonstrate that moderate temperatures optimize the processing efficiency-bioactive preservation balance, providing scientific guidance for standardizing the processing of Sungkai leaves as a functional herbal ingredient for preventive nutrition applications.