Creation and validation of a reactor engineering model for multiphase red wine fermentations

Area of Science:

• Enology and Viticulture
• Chemical Engineering
• Biochemical Engineering

Background:

• Red wine fermentation involves grape solids (skins and seeds) forming a "cap," creating spatial heterogeneity.
• Accurate modeling of red wine fermentation requires consideration of fermentation kinetics, heat transfer, diffusion, and fluid flow.
• Existing models often simplify the complex, multiphase nature of red wine fermentations.

Purpose of the Study:

• To develop and validate a comprehensive reactor-engineering model for red wine fermentation.
• To incorporate fundamental principles of fermentation kinetics, heat transfer, diffusion, and fluid flow into the model.
• To investigate the impact of key parameters, such as nitrogen availability, on fermentation outcomes.

Main Methods:

• Experimental determination of grape heat transfer properties throughout fermentation.
• Development of a multiphase reactor model using COMSOL software.
• Utilization of finite element analysis to solve model components simultaneously.
• Validation of model predictions against experimental data.

Main Results:

• The developed model demonstrated excellent agreement with experimental data.
• The model successfully predicted spatial profiles of active yeast cell concentration and ethanol productivity.
• Predicted liquid velocity profiles within the fermentor were obtained.
• The model was used to simulate the effects of varying initial bioavailable nitrogen concentrations.

Conclusions:

• The reactor-engineering model provides a robust framework for understanding and predicting red wine fermentation dynamics.
• The model's ability to capture spatial heterogeneity is crucial for accurate kinetic predictions.
• This tool can aid in optimizing fermentation conditions, particularly in nitrogen-limited environments, to improve wine quality.