Micropropagation of Bixa orellana L. and regulation of annatto dye synthesis.

Color is a physical property or phenomena possessed by certain class of chemical
compounds that are capable of absorbing and reflecting the electromagnetic waves in the
visible region (400-700nm) as perceived through vision (Masland, 1996) by those
biological organisms possessing cone cells. Such chemical compounds are called as
pigments and the part of the pigment that absorbs or reflects the light are called as
chromophores. Of the different types of plant pigments, carotenoids possess a special
concern and attention due to its diverse structural and functional properties that are well
known. Till date, more than 650 types of carotenoids were identified and reported (Otles
and Cagindi, 2008). Plant pigments with special reference to food colorants were four
types viz., carotenoids (annatto), anthocyanins, betalains (beetroot pigment) and curcumin
(Davies, 2004). These four pigments along with cochineal, account for over 90% of the
market (quantitatively) for natural food colorants (Hendry, 1996).
Annatto pigment is produced on the aril portion of the seeds of Bixa orellana
(Fam: Bixaceae) – a tree native to Brazil – that is responsible for the reddish orange color
appearance. Bixin – a unique apocarotenoid (monomethyl ester) – is the major
constituent of annatto pigment (Aparnathi and Sharma, 1991). Annatto pigment is well
known for its usage in dairy industry for cheese and butter (50 percent), fish processing
(20 percent), confectionaries (10 percent), cosmetics and other major food grade coloring
industries (20 percent). In general, oil-soluble extracts and oil suspensions are
commercialized at 0.2-0.3% and 4% pigment content respectively; whereas, watersoluble
extracts and spray dried products are at 5% and 14% respectively (Francis, 1999).
Maximum levels of annatto pigment that can be used in various food formulations were
specified by the expert committee of FAO/WHO (JECFA, 2001). Annatto pigment was
extracted mostly by using chloroform. There are various processes available for annatto
pigment extraction including the one from CFTRI Resource Center, Hyderabad
(730/DEL/2000)
On analyzing the requirements for advancement of science in annatto towards the
better utility of the crop for better prospects and better understanding, the present study
was formulated and framed with six objectives viz., i) standardization of tissue culture
PhD synopsis of Parimalan, R.
2
protocol for efficient mass multiplication; ii) studies on the levels of annatto color during
developmental stages of fruits and elicitor mediated enhancement of annatto color under
in vitro and in vivo; iii) down stream processing of annatto pigment; iv) molecular
characterization of germplasm by RAPD; v) regulation of the lycopene cleavage
dioxygenase gene using anti-sense approach for production of lycopene; and vi)
developing an efficient transformation protocol for Bixa orellana for in vitro production
of annatto pigment.