Ripening period influences fruit softening and antioxidative system of 'Samar Bahisht Chaunsa' mango

Increased respiration rate and textural softening in mango during fruit ripening limit its postharvest shelf life with poor quality. Changes in ethylene production, respiration rate, activities of fruit softening [exo-polygalacturonase (exo-PG), endo-polygalacturonase (endo-PG), pectin esterase (PE) and endo-1,4-beta-D-glucanase (EGase)], and antioxidative [peroxidase (POX), catalase (CAT) and superoxide dismutase (SOD)] enzymes were studied in mango cv. 'Samar Bahisht Chaunsa' during ripening at ambient conditions (25 +/- 1 degrees C; 60-65% RH). Ethylene production (0.01-0.34 mu mol kg(-1) h(-1)) and respiration rate (1.14-2.70 mmol CO2 kg(-1) h(-1)) showed quadratic and cubic increase respectively up to day-5 of fruit ripening and later on reduced as the fruit reached to fully ripe stage (day-9). Fruit showed a linear decreasing trend for fruit firmness (160.6-4.1 N) during the entire ripening period. Fruit exhibited significant linear increase in the activities of endo-PG (4.11-8.15 viscosity changes mg(-1) protein h(-1)), cubic increase for exo-PG (18.95-60.3 mu g gal acid mg(-1) protein h(-1)) and EGase (3.96-9.52 viscosity changes mg(-1) protein h(-1)) and cubic decrease in PE (0.93-0.19 mM NaOH mg(-1) protein h(-1)) enzymes during the entire ripening period. Linear decreasing trend for SOD (50.71-26.75 U mg(-1) protein) and cubic increasing trend for CAT (37.63-78.45 U mg(-1) protein) and PDX (17.11-82.35 U mg(-1) protein) enzymes were observed during fruit ripening in 'Samar Bahisht Chaunsa' mango. Fruit showed linear increase in total antioxidant scavenging activities (766.87-478.41 IC50 value) up to day-7 and later on it decreased. Conclusively, along with the ethylene production and respiration rate, fruit ripening period was well associated with the activities of fruit softening and antioxidative enzymes of Samar Bahisht Chaunsa' mango fruit. As the ripening stage advanced, except PE and SOD, activities of fruit softening and antioxidative enzymes significantly increased in Samar Bahisht Chaunsa' mango fruit. (C) 2013 Elsevier B.V. All rights reserved.