Delayed ripening of bananas through minimization of ethylene

Mature green Williams and Lady's Finger bananas grown on the east coast of Australia were obtained at about 6-weekly intervals over a 12-month period. Individual fingers were held at 20 degrees C in air containing ethylene at 0.001, 0.01, 0.1, and 1 mu L L-1 and green life was assessed as the time t aken to reach the respiratory climacteric as determined by carbon dioxide e volution. The green life of both cultivars was extended as ethylene was red uced over the whole range of concentrations examined with the rate of incre ase in the logarithm of green life quadratically related to a logarithmic d ecrease in ethylene concentration. For Williams bananas, the green life was about 27-33 days at 0.001 mu L L-1 and 11-12 days at 0.1 mu L L-1 and for Lady's Finger it was about 44 and 11 days, respectively. A survey was condu cted over 12 months of the concentration of ethylene in cartons of Williams bananas in commercial shipments on arrival at the Sydney wholesale markets . Of the 363 cartons analysed, the mean ethylene concentration was 0.06 mu L L-1 and ranged from 0.28 to <0.002 mu L L-1 with 15% of cartons containin g ethylene at greater than or equal to 0.1 mu L L-1. It was concluded that the accumulation of ethylene that currently occurs in commercial road shipm ents of bananas was significantly reducing green life and that any interven tion that reduced ethylene levels should extend the marketing period.