Development of Khlu (Pluchea indica (L.) Less.) leaves drying technology for Khlu leaves tea production in the Palian River Basin Community, Trang Province

Abstract

This research aims to investigate the optimal temperature conditions for drying Khlu (Pluchea indica (L.) Less.) leaves (KLs) in a laboratory, develop KLs drying technology, and transfer the technology to the Palian River Basin Community in Trang Province. The results showed that after drying KLs at different temperatures for 7 hours, the optimal choice was 45°C, which resulted in a moisture content of 10.95 ± 0.54%, a lightness (L) value of 48.87 ± 1.58, and the lowest effective concentration (EC₅₀) of 0.200 ± 0.024 mg/mL. Drying at 55°C produced results similar to drying at 45°C, with a moisture content of 10.16 ± 1.27%, a lightness (L) value of 35.33 ± 1.75, and an EC₅₀ of 0.370 ± 0.003 mg/mL. Drying at 65°C wasn't as effective. At the same time, the KLs had a low moisture content of 9.40 ± 1.24%, they turned out very dark (L value = 34.33 ± 0.38), and they also had the highest EC₅₀ of 0.730 ± 0.007 mg/mL, indicating the weakest antioxidant ability. The KLs drying technology can utilize sunlight and heat from biomass to reduce the moisture content to just 5.80 ± 0.61% and 7.02 ± 1.97%, respectively, and has an EC₅₀ of 0.240 ± 0.011 mg/mL and 0.290 ± 0.010 mg/mL, respectively. Finally, the researchers transferred the KLs drying technology to the community for drying KLs to produce Khlu leaves tea. This technology can dry about 10 kg of fresh KLs per period. Upon drying, the technology is expected to yield approximately 2 kg of dried KLs for the production of Khlu leaves tea.