Undesirable changes in color from green to yellow (abnormal coloring) on part of the surface of tomato 'Momotaro' are often observed after harvest. In this study, the effects of harvest maturity of the fruits and postharvest ripening temperature on their abnormal yellowing were investigated. Tomatoes 'Momotaro' of five kinds of maturities (indices are as follows : 5=mature green, 4=pinkish-white, 3=pink, 2=red, 1=fully ripe) were incubated at various temperature in the range of 10-degrees-35-degrees-C.
1. Abnormal coloring occurred when fruits with maturity index greater than 3 were ripened at the temperatures above 25-degrees-C and below 15-degrees-C.
2. Flesh firmness and total soluble solids contents (TSS) of ripe fruit were not influenced by the stage of maturity at harvest or the ripening temperature.
3. There were no significant changes in sugar contents of tomato harvested at any maturity index, whereas the citric acid content tended to show a decrease; malic acid content remained nearly constant.
Our limited data indicate that the 'Momotaro' tomato under our current distribution systems should be harvested at a maturity index of 3 (pink stage) and kept at 20-degrees-C to ripen normally.