Indonesian bay leaves (Syzygium polyanthum) hold significant value in both culinary and traditional medicine. However, its perishable nature limits its shelf life and product quality. Conventional and modern drying methods often reduce the content of bioactive compounds and affect the visual appearance of the leaves. This study investigates the effect of cold plasma exposure time (0, 20, 40, 60, 80 seconds) as a non-thermal pre-treatment on the physical and chemical properties, as well as the drying rate of bay leaves. The research aims to analyze physical properties, such as colour, chemical properties, including antioxidant activity (DPPH, ABTS, FRAP), total phenolic and flavonoid content, and tannin content, as well as evaluate process parameters, including changes in moisture content and drying rate during the drying process. The cold plasma treatment was performed using the dielectric barrier discharge (DBD) method, followed by a drying process using a cabinet dryer at 50 °C. The results showed that physically, longer plasma exposure times helped preserve the colour of the leaves by inhibiting enzymatic browning. Moreover, antioxidant activity, phenolic content, and flavonoid content increased significantly, while tannin content decreased. Longer cold plasma exposure also increased drying efficiency, reducing the drying time by up to one hour. The drying process immediately entered a falling rate period, which indicates that moisture diffusion from within the tissue increased due to microstructural changes caused by plasma exposure. In conclusion, cold plasma pre-treatment has been proven effective in maintaining the quality and accelerating the drying process of bay leaves. This method has the potential to be a promising energy-efficient technology for post-harvest processing of herbal plants.
