Inhibition of respiration, ethylene synthesis and cell wall softening enzyme activity in tomato fruit during ripening by ethanol.

The exposure of mature-green tomato fruits (Lycopersicon esculentum Mill. cv. Bombay) to ethanol vapour at 0, 2.5, 5, 10, 20 or 25 ml/2.5 kg fruit/5 liter volume of jar delayed the ripening of fruits. The delay was found to be concentration dependent. The most effective concentration of ethanol was found to be 20 ml/2.5 kg fruit in delaying ripening. Ethanol reduced respiration rate, ethylene production and delayed the climacteric peak. The regulation of tomato fruit ripening was attributed to delay in fruit softening caused by reduced activities of enzymes like polygalacturonase (PG) and pectin methyl esterase (PME). The possible role of PG and PME activity in delaying ripening and maintaining fruit softness is also discussed.