Author : Chumphon Suckaseam

Summary : Detached mature green bitter gourd (Momordica charantia L.) fruits of the "Jade Star X" variety, were held at 25 deg Celsius and 35 deg Celsius to re-examine the carotenoid distribution in bitter gourd fruits at different maturities and also to study the effect of high temperature on carotenoid composition in the pericarp and the aril during the ripening process. Zero, two, four, six, and eight days after harvest, the pericarp and aril of bitter gourd fruits were separately analyzed for carotenoid composition. Carotenoids content of bitter gourd fruits obviously changed with maturity. At the mature green stage, only six carotenoids were isolated in the pericarp. They are alpha carotene, beta carotene, alpha cryptoxanthin, lutein, isolutein and antheraxanthin. As soon as fruits turned yellow, the principal pigments of mature green stage, lutein and isolutein, disappeared, and beta cryptoxanthin, zeaxanthin and violaxanthin accumulated rapidly. At the same time, alpha carotene and alpha cryptoxanthin concentrations decreased while beta carotene content slightly increased without significant difference. The total carotenoid content of the pericarp at fully ripen stage was almost double that content at mature green stage. Effect of high temperature on carotenoid composition of bitter gourd pericarp was observed in the acceleration of color development in the pericarp of fruits held at 35 deg Celsius as a result of earlier accumulation of beta cryptoxanthin and zeaxanthin accompanying the earlier degradation of lutein and isolutein. Lycopene was not detected in the pericarp at any time during ripening. It was proposed thatc arotenoids in the pericarp and aril of bitter gourd fruits are synthesized by two alternative pathways in which beta carotene is not formed from the lycopene.