Question

abstract on how to isolate a spice essence and what techniques used to characterize it

Answer 1

Among the natural products, obtained from plant, many of the neutral materials (terpenes and some of the acetogenins) are commonly, extracted by steam distillation of the appropriate plant parts. All volatile, water-insoluble oils known as essential oils get separated.

The steam containing the essential oil is passed through a cooling condenser system to condense the steam, which forms a liquid. Later, oil and water is then separated. Steam distillation produces high quality essential oil which is extracted from other components using separatory funnel.The steam is produced at a much greater pressure than the atmospheric, so that it boils at above 100 degrees Celsius. This facilitates the removal of the essential oil from the plant parts by force of the steam at a faster rate .Such a process allows for easy extraction of essential oil without dissociating its molecules..

Soxhlet extraction method is also used to extract essential oils. Soxhlet extraction produces essential oil in crude form , when solvent is evaporated to yield pure solid component of plant using rotary evaporator. Typically, Soxhlet extraction process is used when the desired essential oil has a limited solubility in a given solvent while the impurity is completely insoluble in that solvent. In the process recycling of solvent is done to dissolve a larger amount of crude component.

For example,the percentage of cinnamaldehyde in essential oil from Cinnamon obtained from steam distillation was about 90% and 62-73% from Soxhlet extraction.

For characterization of essential oil,appropriate separation and analytical techniques are used- fractional distillation, thin-layer chromatography, column chromatography and gas chromatography. Such methods are used to separate pure samples from crude extracts.

Once a pure sample is extracted ,techniques like FTIR, NMR and mass spectroscopy of the sample is obtained to decifer the probable molecular weight and nature of the functional group(s) present in the sample.