Drying temperature affects essential oil yield and composition of black cardamom (Amomum tsao-ko)

Black cardamom is the dried ripe fruit of Amomum tsao-ko Crevost et Lemaire, which is both a materia medica and an important spice widely appreciated in eastern and southeastern Asia. Metabolomics methods were applied here to study the composition and content of essential oils of black cardamom dried under various temperatures, 25 °C, 40 °C, 55 °C, 70 °C, 85 °C and 100 °C. Samples dried under 55 °C shared the highest oil yield, and treatment with higher temperatures (85 °C and 100 °C) resulted in low oil yielded. Multivariate analyses indicated that the content of compounds varied with different drying temperatures. High drying temperatures (85 °C and 100 °C) produced dried samples richer in monoterpene hydrocarbons, whereas lower temperatures yielded (E)-2 unsaturated aldehydes. Eucalyptol, the main constituent of this extract accumulated highly in 100 °C dried samples. The current study would aid researchers to set specific drying temperatures targeted to abtain pre-selected natural products.