Developing the typical ripening pattern curve model for tomato harvested at mature green stage based on the pericarp color using the CIE a* value

This study aims to develop a model predicting the red color development for tomatoes that were harvested at the mature green stage of development as a function of the storage period. The model predicting change in CIE a* value based on the storage period was developed by modifying the original sigmoid-type function model with cumulative ethylene production as a free variable based on a previous study. The modification was conducted by changing the free variable from cumulative ethylene production to storage period. However, the modified sigmoid-type function model was only able to describe the change in red color development in the range where CIE a* value is greater than zero. Therefore, data were divided into two parts based on the CIE a* value, below zero (P1) and greater than zero (P2). For P1, it is possible to know the time lag. This is the time taken for mature green tomatoes to reach the onset of the red color development. For P2, it is possible to apply the modified sigmoid-type function model for the change in CIE a* value in time. The typical ripening pattern curve of tomato was obtained by combining all the parameters for P1 and P2. Findings showed that this model can predict the ripening process of tomato clearly compared to our previous model. The previous model developed was based on cumulative ethylene production. Therefore, this typical ripening pattern curve will enable us to predict the ripening process of tomato harvested at the mature green stage based on the storage period.