Articles
TOMATO FRUIT DEVELOPMENT AND THE CONTROL OF RIPENING
The pericarp cells eventually become very large and thin-walled.
Nucleic acid and protein turnover, low at the mature-green stage, increases sharply during the climacteric respiration rise, resulting in new protein synthesis within a constant ceiling.
High metabolic activity at incipient ripening results in a parallel series of texture and pigment changes.
Starch, which is built up in green fruit, is progressively replaced by reducing sugars as development continues.
Early in ripening, sugars reach their maximum concentration and at about the same time as the peak in the organic acids.
Against this background of a sequence of well-ordered changes in composition, the initiation of ripening is largely under genetic control.
From then on, the ripening rate can be influenced by low temperature, ethylene removal or modified atmospheres.
With careful control, once these constraints to ripening are removed, the quality of the ripe product is unimpaired.
The best flavour is given when tomatoes are left to ripen on the plant, but this is often unacceptable commercially.
Alternatively, the fruit should be harvested when partially-coloured, and then transported under modified-atmospheres to postpone overripeness and deterioration.
Genetic techniques are being explored so that the storage-life of tomatoes can be extended.
As advances are made concerning the key steps in ripening, selection criteria whereby good quality fruit can be developed that soften, dehydrate and deteriorate at a slow rate are being established.