Changes in polygalacturonase, cellulase and pectin methylesterase activities and sugars during fruit ripening in banana varieties Ney Poovan and Robusta in response to ethylene treatment

The activity profiles of the cell wall hydrolytic enzymes polygalacturonase, cellulase and pectin methylesterase under both control and ethylene treated conditions indicated considerable variation in two varieties of banana viz., Ney Poovan and Robusta. Induction of polygalacturonase and cellulase activity upon ethylene treatment was observed in both the varieties although the induction of PG in Ney Poovan was 4x greater than that of Robusta, while cellulase activity started declining towards the final stages of ripening in Ney Poovan samples unlike in Robusta where it continued rising up to a stage before final sampling. For pectin methylesterase, induction was observed only during the initial stages of ripening in Robusta but was observed initially and during final stages of ripening for Ney Poovan samples. Total soluble (TSS) increased with increase in ripening in induced and uninduced samples of both the varieties while the reducing sugar content also showed similar trend except for the induced samples of Ney Poovan, which maintained constant reducing sugar content two days after harvest. In terms of sugar content, Ney Poovan recorded higher TSS and reducing sugar contents as compared to Robusta.