INHIBITION OF TOMATO RIPENING BY ACETALDEHYDE VAPOR OR ANAEROBIC CONDITIONS PRIOR TO STORAGE

Exposure of tomatoe fruits (Lycopersicon esculentum Mill.) to 0.2 - 0.4 % acetaldehyde (AA) vapours for 24 h prior to storage caused inhibition of fruit ripening as expressed by less colour development. The endogenous levels of AA and ethanol found in the juice were positively correlated with the AA concentration applied. Application of 0.6 % AA vapours for durations of 6 to 24 h also caused significant delay in colour development. Colour inhibition occurred with fruits harvested either at the breaker or turning-pink stage. Application of a N2 atmosphere or CO2 at different concentrations (50 - 90 %) for 48 h resulted in production of endogenous AA and ethanol. Inhibition of ripening was the highest after treatment with 98 % N2 or 90 % CO2, which also led to the highest levels of AA and ethanol. Polygalacturonase (PG) activity was inhibited by AA as well as by CO2 or N2 pretreatments.