Postharvest research is relatively young and has been rapidly increasing since the 1980s.Its main objective is to reduce postharvest losses by enlarging insight in the underlying physiological process to understand the responsible mechanisms.Given the complex nature of the biochemistry and physiology driving the metabolism of living produce during postharvest,it is,however,not always evident how to interpret the experimental results.The main purpose of modelling in postharvest is often not the model itself,but the process of modelling in which the researcher is forced to line up concepts to bring order in the experimental chaos.This contribution will highlight the importance of kinetic modelling as a scientific tool in testing different concepts on their fitness to explain the data using ethylene biosynthesis during tomato fruit ripening as an example.A mathematical mechanistic model was developed describing the tomato ethylene biosynthesis pathway covering metabolite,protein and transcript measurements during fruit development,climacteric ripening and postharvest storage.The model consists of a set of differential equations based upon the underlying biochemical pathways and their known stoichiometry.Data from individual tomato fruit was rescaled in correspondence to their exact biological age.Gene expression data was used as independent model input,while all ethylene biosynthesis intermediate metabolites(ethylene,ACC,MACC)and protein levels(ACO and ACS)were treated as dependent model outputs.The model was successfully calibrated on the experimental data.Using the model,hypothesis testing will be demonstrated.