STARWINE

Nowadays, a multiplicity of wines is proposed on the international market. The main characteristic that enables to discriminate these wines is their sensorial profile. In recent years, the “international” taste of wine consumers is rather focused on the fruity aromas. As a consequence, to maintain its competitiveness and to conquer new markets in the intensive international competition, the French winemaking industry is constantly requesting solutions to enhance the aromatic quality of its wines. To address this question, the overall objective of the STARWINE research project is to control the fruity flavour of wine through the development of innovative real-time control strategies of the winemaking fermentation process, using a predictive mathematical model. This aim will be reached through a multidisciplinary approach based on the following scientific competences: bioprocess management, yeast metabolism, experimental design, bioprocess modelling, control theory and implementation of sensors. Nitrogen and temperature have been recently identified as the main parameters impacting on aroma synthesis. Nevertheless, winemakers lack methods to monitor and adjust these parameters because their relative contributions and interactions have never been evaluated. Therefore, in the first part of the project, done on a laboratory scale, we will assess the impact on aroma production of a combined management of: (1) nitrogen addition during the fermentation process and (2) anisothermal profile of temperature. The obtained data will be used both to better understand the yeast physiology and to build a mechanistic mathematical model (representative of the main reactions of yeast metabolism). Then, a real-time control strategy based on this model will be proposed and validated on a laboratory scale using an online GC (gas chromatography) laboratory equipment. In parallel to this first part, we will assess the performances of a physical sensor based on photoacoustic spectroscopy to evaluate the industrial feasibility of an online monitoring of key aroma compounds. Finally, we will combine the results obtained on a laboratory scale and the calibrated physical sensor to test the control strategy in industrial conditions. The project STARWINE will contribute to the wine industry renewal through the optimization of the production process and the adaptation to consumer demands. The objective is not to maximize the final aroma content of the wine but to reach a predefined aroma profile through a constant adjustment of the control parameters of the fermentation process. Such a management of the fermentation will be very innovative because, using the real-time control law that will be developed in STARWINE, it will be possible for a winemaker to define his unique wine “style” and to adapt to consumer demands. As a consequence, the project STARWINE can be considered as a proof of concept of both the implementation of new online devices and breakthrough strategies for a better management of aromas in wineries and the real-time control of fermentation processes using microorganisms. The concepts and methods developed in the project will be generic enough to be applied, after adaptation, to other bioprocesses.