STUDIES OF THE TOMATO IN RELATION TO ITS STORAGE: II. THE EFFECTS OF ALTERED INTERNAL ATMOSPHERE UPON THE RESPIRATORY AND RIPENING BEHAVIOUR OF TOMATO FRUITS STORED AT 12.5 °C.

Abstract

When a mature green tomato fruit is stored at 12.5 °C. either with or without its stem, the expected respiratory climacteric accompanies the colour change associated with ripening. When the stem is removed and the stem scar area is covered carefully with hot paraffin wax, the fruit thereafter ripens slowly with a low, relatively constant rate of carbon dioxide output. These characteristics are ascribed to "auto-gas" storage resulting from restricted diffusion at the stem scar. The effect of waxing is reversible within limits since removal of the artificial seal after one month has resulted in a return to normal ripening and respiratory behaviour.When yellowing, yellow orange, and full red fruits are stored either with or without their stems, they complete in storage those phases of the respiratory climacteric that had not been completed before detachment from the plant. The careful waxing of fruits picked at these stages of maturity inhibits further coloration and reduces the rate of carbon dioxide output to the same extent as in fruits waxed at the mature green stage. The respiratory drift of fruits picked and stored unwaxed at the early "growing green" stage is characterized by two distinct peaks. Such fruits eventually ripen and the second peak is associated with the colour change that accompanies ripening. Similar fruits stored with stem scars waxed fail to ripen before their pathological "death" and their respiration rate is reduced by the waxing treatment.When yellowing and yellow-orange fruits are waxed, they become soft and highly susceptible to fungal attack before their ripening coloration has been completed. To inhibit the softening process in stored tomatoes, it thus appears to be necessary to apply wax before ripening has commenced. Unwaxed fruits become highly susceptible to fungal wastage only after attaining full ripeness. Waxed fruits on the other hand are subject to fungal wastage when green or partially coloured as well as when fully ripened. This is attributed to the progress of softening in the absence of the usual colour change associated with ripening. Waxing of the stem scars does not act as a deterrent to storage moulds at the waxed area. The waxed tomato has been found to be subject to several physiological disorders the symptoms of which are described.