Red wine fermentations are performed in the presence of grape skins and seeds to ensure extraction of color and other phenolics. The presence of these solids results in two distinct phases in the fermentor, as the solids float to the top to form a âcap.â Modeling of red wine fermentations is, therefore, complex and must consider spatial heterogeneity to predict fermentation kinetics. We have developed a reactor engineering model for red wine fermentations that includes the fundamentals of fermentation kinetics, heat transfer, diffusion, and compressible fluid flow via Finite Element Analysis in COMSOL. A kinetic model for the extraction of phenolics from grapes as a function of temperature and ethanol concentration was derived, incorporating the release of phenolics from grape cells, the adsorption equilibria of phenolics onto grape cell wall material, and the reaction of phenolics in solution. This extraction model was then combined with the spatial-temporal fermentation reactor engineering model, enabling prediction of phenolic extraction as a function of fermentation progression and winemaking conditions.
Research Interests: Dr. Miller's research interests include bioprocess engineering (both fermentation and downstream processing), food process engineering, process intensification, and separations processes.
Teaching Interests: Dr. Miller's teaching interests center around process engineering, such as separations, reaction kinetics, unit operations laboratories, process design, and biochemical engineering.