Date of Award


Degree Name

MS in Agriculture - Food Science and Nutrition


Marianne Wolf


Background and Aims: Volatile loss of carbon dioxide, ethanol, esters and other compounds occurs during wine fermentation. When collected nondestructively, valuable ethanol and aroma compounds can be preserved for various uses while mitigating production restrictions and regulations regarding volatile organic compound (VOC) loss from wine production. Knowledge of the volume of volatiles lost during wine fermentation contributes to a better understanding of the magnitude of possibilities for resource recovery/aroma recovery, the implications of volatile loss on wine composition as well as a more clear understanding of the possible effect of alcoholic fermentation on air quality. The aim of this study was to contribute to a better understanding of how the loss of volatiles from wine fermentation varies with temperature.

Methods and Results: Temperature controlled microscale fermenters were developed and infrared detection technology was adapted to study the effect of temperature on volatile loss. Results are presented for the rates and volumes of volatile loss from the fermentation of California Syrah at constant temperatures (17, 23, 27, 33˚C) in 1.9L containers. Observed volatile losses are compared to theoretical losses based on kinetic and stoichiometric principals. Each ferment started with 1200g of fruit and was adjusted to 23.5˚B. Following Brix adjustment, final volumes ranged from 1129.16mL to 1160.10mL.

Conclusion: The loss of VOC from fermentation increases exponentially with temperature. Total VOC and CO2 loss appears to be slightly less than theory predicts.

Significance of the Study: A significant loss of compounds occurs during wine fermentation. Commercial and environmental benefits may be achieved if efforts are made to recover and make use of these otherwise wasted compounds. Funding provided by the Agricultural Research Initiative, California State University.