Predicting the Impact of Red Winemaking Practices Using a Reactor Engineering Model

Abstract

Red wine fermentations have long eluded accurate simulation due to their inhomogeneous nature. In this work, a three-dimensional time dependent reactor engineering model for jacketed red wine fermentations was utilized to explore the impact of fermentor volume (500 L, 50,000 L, and 500,000 L), aspect ratio (H:D of 1:1 and 3:1), temperature set point (15C, 25C, and 35C), and initial Yeast Assimilable Nitrogen (YAN) concentration (100 MG/L, 225 MG/L, and 350 MG/L) on fermentation dynamics. The model simulated nitrogen limited, ethanol inhibited, temperature dependent Monod fermentation kinetics, mass transfer of sugar, yeast, nitrogen, and ethanol, evaporative, convective, and conductive heat transfer, and the motion of the bulk fluid beneath the cap. Fermentor surface area to volume ratio, temperature set point, and initial YAN were all found to significantly affect fermentation performance in simulated fermentations. Heat transfer by conduction into the cap was nondimensionalized and analyzed. Finally, the formation of temperature gradients in the cap between cap management cycles was visualized from simulations using the model.