This study was conducted to determine which index can be used to estimate the pericarp color development and fruit firmness change of mature green tomatoes (cv. Momotaro) during ripening, to determine the optimum harvest stage of mature green tomatoes. The time courses of the changes in CO2 output rate, cumulative CO2 output, ethylene production rate, cumulative ethylene production, pericarp color and firmness of individual tomatoes harvested at the mature green stage were determined during storage at 25℃. Time course analysis revealed a particular pattern of change in each monitored parameter during the investigation period. Moreover, without the effect of individual sample variations, the changes in the pericarp color and fruit firmness of tomatoes correlated well with cumulative ethylene production. Additionally, the pericarp color development of tomatoes obviously coincided with the period of high ethylene production. On the other hand, fruit firmness with decreasing low ethylene production. Thus, the overall results suggest that the ripening of tomatoes can be predicted based on ethylene production.
