This paper presents a performance analysis of a typical fermentation batch process by applying the method of Decoupled Dynamic Simulations to integrate the models that describe the behavior of the stages with the overall plant design and optimization. The kind of analysis allows the determination of the optimal value for some decision variables which have an important economic impact on the performance of the process. By implementing a complete case study, typical trade-off variables are illustrated A better insight on the trade-off involved and on how the process variables affect different components of the performance index is obtained as a result of the analysis. The simulation of whole batch processes is a formidable task but the Decoupled Dynamic Simulations methodology greatly simplifies the computational burden and makes it affordable.