Relative density control in winemaking

The control of fermentation is very important in order to ensure a sustained level of wine quality year after year. Usually wine fermentation is carried out at a constant temperature. This fact is due mainly to traditional reasons. Nevertheless the results year after year and from region to region may be very different due to large variations in must characteristics. A more complex control is needed to overcome these fluctuations. Recent works have introduced some innovation but still have some empirical characteristics and cannot control the duration of fermentation. In order to predict the behaviour of the fermentation, a reasonably accurate mathematical model is required. Unfortunately mathematical models for wine fermentation are scarce, particularly for wine batch fermentation. In this work, the authors develop a mathematical fermentation model and an industrial tank thermal model. A new control strategy is proposed: relative density control instead of temperature control. A reference model is developed and the authors try to tune a PID controller to the process. The need of more complex controllers such as predictive controllers is also addressed