Inhibition of chlorophyll degradation in stay-green langra mango (Mangifera Indica L.) fruits

Langra mangoes (Mangifera indica L.) ripened at tropical temperature (25–30ºC) appear green due to incomplete degradation of chlorophyll even though the fruits are table ripe. About 30% of total chlorophyll was retained and two fold increase in total carotenoids was observed during ripening. Ripening at lower temperature resulted in more loss of chlorophyll and reduced levels of carotenoids. RP-HPLC of the pigments extracted from various stages of ripening indicated accumulation of an unknown Chl derivative (retention time 7.32 min) and pheophytin a (retention time 20.4 min). Soluble protein fraction from peel catalyzed faster degradation of Chl a as compared to Chl b. Screening of the intermediates of enzymatic Chl a degradation by RP-HPLC indicated operation of chlorophyllase pathway. Accumulation of the unknown intermediate was observed when Chl b was used as a substrate with respect to incubation time up to 60 min. However, other polar intermediates were formed and disappeared after 30 min. The results indicated that upon ripening possibly a derivative of Chl b and pheophytin a accumulate giving the fruit a ‘stay-green’ character.