Minimization of Water and Energy Consumption During Non-isothermal Fermentation for High-quality Red Wines

ABALLAY, PABLO M; VALLEJO, M. D.; SCAGLIA, G. J. E; MENGUAL, C. A; SERRANO, M. E.; ORTIZ, O. A.

Mar del Plata

Congreso; 1er Congreso Internacional de Ciencia y Tecnología Ambiental y y 1er Congreso Nacional de la Sociedad Argentina de Ciencia y Tecnología Ambiental – AA2012; 2012

In last decades, it has been observed the use of controlled non-isothermal procedures in the production of high-quality red wines. Such techniques are specially designed to enhance the extraction from grape and the production, during the fermentation, of components responsible for some important quality characteristics of wines such as, colour and aroma. Also, avoiding sluggish and stuck fermentations by manipulating fermentation temperature is a frequent practice. It is obvious that efficient cooling and automatic temperature control systems must be used. The objective of this work is to minimize the water and energy consumption during the fermentation stage of the wine production, by means an optimal temperature profile maintaining ethanol production at the desired level, and preserving the wine quality. The optimal temperature profile is obtained by means of a dynamic optimization algorithm. States and control actions are discretized and the optimization problem is transformed into a nonlinear programming problem. Water and energy consumption at the fermentation stage may be controlled as a function of a desired evolution - represented by a carbon dioxide released, density or cell concentration profile - of this process. Also, constraints, that intend to maintain the wine quality, are generally temperature and time requirements. In this work, an improved non-isothermal model for a batch alcoholic fermentation, combining mass and energy balances is used. This model is appropriate to be used in optimization and control of alcoholic fermentations for high-quality red wines. The parameters of the model were adjusted taking into consideration winemaking processes that use cold pre-fermentation. This practice makes that the fermentation step begins at 5 - 10 ºC, following then usual profiles that not exceed 30ºC. Computer simulations using the mentioned model were carried out. Water and energy consumptions were calculated and compared with data from literature. The results suggest that, by means of optimization techniques, important improvements in water and energy savings can be obtained, whereas the quality of wine is maintained.