Phenomenological Modelling for Non-Isothermal Wine Fermentation

ABALLAY PABLO; VALLEJO, M. D.; SCAGLIA, G.; SERRANO, M. E.; ROMOLI SANTIAGO; ORTIZ, O. A.

Montevideo

Congreso; V Encuentro Regional y el XXVI Congreso Interamericano de Ingeniería Química – AIQU CIIQ 2012; 2012

During winemaking, yeast, product, and substrate kinetics are temperaturedependent. Also, the quality, quantity and rate of aroma compounds may be “finetuned” by manipulating temperature. Then, winemakers use variable temperature trajectories throughout the fermentation, to obtain high-quality wines. The nonisothermal fermentation must be carefully controlled to prevent sluggish or stuck fermentations and favour the appearance of the desired sensory characteristics, acidity, alcoholic graduation, and sugar depletion. The objective of this work is to extend a phenomenological model able to predict yeasts, during alcoholic fermentation, to ethanol prediction during the non-isothermal fermentation. The proposed model couples mass and energy balances predicting viable cells, fermentable sugars and ethanol concentrations, CO2 released, and the bioreactor temperature. The model considers a new expression for the maximum growth rate, the death rate depending on temperature, and the parameter CO2 released at 85- 95% of its maximum value. The model was validated by own lab-scale fermentations and by data from literature. The accuracy of the model is acceptable. Simulations at constant temperature and for variable temperature trajectories, between 10 - 40ºC, were performed. Since results are satisfactory, this model can be used to track complex temperature profiles for high quality wines, as well as, in another control and optimization strategies.