Extraction characteristics and hydrolysis of flavoring compounds of cinnamon (Cinnamomum zeylanicum) under subcritical-water conditions.

Subcritical water extraction (SWE) of four flavoring compounds from cinnamon was performed at various temperatures and for various extraction times. The extraction temperature (°C) and time (min) corresponding to the maximum content of flavoring compounds were 190 °C and 5 min for cinnamyl alcohol, 200 °C and 20 min for cinnamic acid, 130 °C and 10 min for cinnamaldehyde, and 170 °C and 20 min for coumarin, respectively. Cinnamaldehyde underwent structural conversion to benzaldehyde via hydrolysis at high temperatures, and the rate of conversion rapidly increased above 150 °C. The extraction efficiency using subcritical water was slightly higher or comparable to that using conventional extractants. SWE is a potential and highly selectivity technology for extracting flavoring compounds from cinnamon.