Hydrodistillation alters the compositional originality in black turmeric (Curcuma caesia Roxb.) essential oil

Hydrodistillation in a Clevenger-type apparatus is a widely used technique for the extraction of essential oil from the aromatic plants. Many times, aroma chemicals have been reported to be thermolabile and hydrodistillation may possibly influence their half-life. In the current study, thermolability of furanodienone (a furanosesquiterpenoid with 1,5-diene system) was demonstrated during the hydrodistillation of black turmeric (Curcuma caesia Roxb.) rhizome. The formation of curzerenone through [3,3]- sigmatropic rearrangement of furanodienone was observed. 1H Nuclear Magnetic Resonance spectroscopy-based profiling revealed a higher curzerenone versus furanodienone ratio in the essential oil in comparison to oil-enriched solvent extract. The ratio increased upon heating (40–80°C) the solvent-extract in an aqueous medium. Purified furanodienone also converted partially to curzerenone while incubating at 80°C in water. The rearrangement was found to be exclusively temperature-dependent which followed the first-order kinetics. This study confirmed curzerenone to be the major artefact in the essential oil of black turmeric.