Author : Pepito, Maria Fe B.

Summary : Saba bananas exhibited the green soft disorder (GSD) when subjected to modified atmosphere (MA) by seeling in 0.03mm thick polyethylene bags (PEB) for longer than 6 days at 25 degree C. The O (subscript 2) levels in the bag were depleted to as low as 1-3 percent. Concomitant with the decline in O (subscript 2) was the accumulation of Carbon Dioxide (CO2) to as high as 23 percent. Ethylene production in bananas under these conditions led to a build up of this volatile to a level of 28 ppm. Anaerobiosis was indicated by the presence of ethanol (EtOH) and acetaldehyde (AA) in the bags. GS fruits had fermented odor and flavor with pulp and peel discoloration. Anaerobiosis stimulated 1-aminocyclopropane-1-carboxylic acid (ACC) synthesis in GS fruits but the low O (subscript 2) levels in the bags depressed the ethylene forming enzyme (EFE) activity. Despite the high levels of ACC, sustained ethylene production, which requires O (subscript 2), was inhibited. Low O (subscript 2) was subsequently found to inhibit ethylene-induced peel color development but not pulp softening. Similarly, 20 percent EtOH and 10 percent CO (subscript 2) were shown to inhibit peel color development without the concomitant inhibition of pulp softening. In contrast, AA could enhance pulp softening without significantly retarding peel color development. Under N (subscript 2), which leads to very low O (subscript 2) levels, both ethylene-induced pulp softening and peel color development were arrested. The result of this series of studies are consistent with the hypothesis that the GSD arises from the combined effects of low O (subscript 2) (5 percent) and threshold levels of ethylene which lead to anaerobiosis. Elevated CO (subscript 2), EtCH, and AA in the fruits, which arise from anaerobic metabolism, inhibit peel color development but not softening.