Controlled-atmosphere storage of tomato fruit: low oxygen or elevated carbon dioxide levels alter galactosidase activity and inhibit exogenous ethylene action

Abstract

The effects of 3% O2 and 20% CO2, both alone and together with 100 µg g−1 C2H4, on ethylene production, chlorophyll degradation, carotenoid biosynthesis and α- and β-galactosidase activity in breaker tomato (Lycopersicon esculentum Mill) fruit were investigated. The low O2 and high CO2 atmospheres prevented the rise in ethylene production, total carotenoid and lycopene biosynthesis and α- and β-galactosidase activity and slowed down chlorophyll degradation and loss of firmness (P < 0.05). These suppressive effects were not reversed, or only in part – in the case of chlorophyll breakdown – by addition of 100 µg g−1 C2H4 to said controlled atmospheres. After transfer from the various atmospheres to air, flesh firmness decreased and ethylene production, total carotenoids, lycopene and β-galactosidase II activity increased but these parameters were, in all cases, still significantly different from those of fruit held in air. Keeping tomatoes in controlled atmospheres, even in the presence of ethylene, had marked residual effects. Results suggest an antagonism between elevated CO2/low O2 and exogenous ethylene which could determine most of the ripening parameter behaviour under controlled-atmosphere storage, though a direct regulatory mechanism by O2 and/or CO2 should not be discarded. © 1999 Society of Chemical Industry