Effect of maturity on some chemical constituents of turmeric ( Curcuma longa L.)

Abstract

The effect of maturity on rhizome yield, essential oil content and com- position, and curcumin I. XI and 111 of the main Sri Lankan cultivar of Curcuma longa L. is reported. The optimum time of harvest for maximum rhizome yield, was found to be 9 months. The oil content in bulbs was higher than that of finger rhizomes. The optimum time for harvest for maximum yield of tunTIeric oil was found to be 7.5 - 8.0 months. Essential oil composition varied with maturity, sew quiterpenes (ar-turmerone and turmerone) increased while monoterpenes (1.8 cineole and a-phellandrene) declined in both bulbs and finger rhizomes. Monoterpene content was lower in the mother sets during the early stages of growth. Curcumin (curcumin, demethoxysurcumin, bis-demethoxycurcumin also termed curcumin I, 11 and 111 respectively) content was monitored using t.l.cuv spectrophotometry and a technique based on t.1.c.u~ densitometry which was developed during this study. Curcumin I content was highest, however curcumin 111 content was more than curcumin 11. Maturity did not affect the ratio of curcumins to any great extent. Advanced marurity resulted in a decline in total curcumin content. Maximum curcumin per bush was attained about 9 months after planting. 1.