Curcumin is the pigment that lends the bright stunning yellow colour to turmeric. Curcumin crystals of 95% or more purity are today preferred in the food industry because of the brilliant golden colour. It is the main biologically active phytochemical compound present in turmeric. The compound is extracted for research purposes and has proven disease preventing medicinal properties.
Known by the molecular formula: C21H20O6, curcumin has the following molecular representation:
The percentage of curcumin in different varieties of turmeric is given below and listed country wise according to the ASTA method:
- Salem finger, Tamil Nadu, India: 3.5%
- Alleppey finger, Kerala, India: 5-6%
- Rajapuri finger, India: 3 - 3.5%
- Kadappa finger, Andhra Pradesh, India: 2-3%
- Burma finger, Burma: 2.5 3%
- South Vietnam finger, Vietnam: 5 5.5%
- North Vietnam finger, Vietnam: 2.5 3%
- Indonesia finger, Indonesia: 4.2 5%
- Ethiopia finger: 2.5 3%
- Nigeria sliced finger: 2.5 3%
Traditionally, oleoresin is most popularly used in the food industry over ground turmeric. The oleoresin is obtained by solvent extraction of ground, dry rhizomes and is orange red in colour. It consists of an upper oily layer and a lower crystalline layer, when not homogenised.
In the recent years, crystallised curcumin of 95% purity has rapidly gained an important place as a valuable food ingredient, replacing oleoresin. The yields of oleoresin and 95% curcumin crystals are 7-14% and 2-4% in dry turmeric respectively.