In order to develop a pericarp color prediction model applicable to different varieties of mature green tomatoes, the CO2 output rate, C2H4 production rate, and pericarp color (a* value) of four tomato varieties (Momotaro, PK331, PK353 and KGM011) were investigated during the storage of tomato at 25°C. Momotaro and PK331 are normal lines, PK353 is a rin (ripening inhibitor) mutant line, and KGM011 is an F 1 hybrid line between PK331 and PK353. Time course analysis revealed the significant effect of the different varieties and individual tomato samples on the monitored parameters. However, changes in the pericarp color of the different varieties of tomato, except PK353, correlated well with the cumulative ethylene production. Consequently, a mathematical model for predicting the pericarp color of each individual sample on the basis of its cumulative ethylene production was developed as a sigmoid-type function. Calculation results obtained by using the model and by considering all the data of three varieties －all the varieties other than PK353－showed a high correlation coefficient (R2＝0.97). Therefore, there appear to be a possibility of developing a method involving the use of the model with cumulative ethylene production as a variable for predicting changes in the pericarp color of tomato fruits of all varieties.
