Khiam (Cotylelobium lanceolatum) as a bittering and preservative wood in Nipa (Nypa fruticans) sugar and alcohol production in Southern Thailand

Background: Although khiam (Cotylelobium lanceolatum) is locally recognized as a preservative in palm sap processing, its deliberate use as a bittering material has received little attention. This note documents its dual role in nipa sugar making and community alcohol production in Pak Phanang, southern Thailand. Methods: Ethnobotanical fieldwork was conducted in 2025 in nipa-producing communities of the Pak Phanang River Basin. Data were gathered through semi-structured interviews with local sugar producers and distillers (n = 6) and through direct observation of tapping, boiling, fermentation, and distillation practices. Results: Producers used small amounts of khiam during nipa sugar processing to help maintain sap quality and to impart a slight bitter-astringent note that contributes to a balanced “three-taste” profile. In alcohol production, substantially larger amounts were added during fermentation to prevent souring and to produce a stronger, bitter taste with a more pronounced character. Producers deliberately adjusted the quantity of khiam according to the intended product, showing a clear empirical understanding of dose-dependent effects on both fermentation outcome and flavor. Conclusions: This study highlights a previously undocumented or little-documented dimension of khiam use: its deliberate management as a bittering and fermentation-modifying material, not merely a preservative. Keywords: Ethnobotany; Asteraceae, Indigenous communities; Human diseases, Herbal medicine