Sydney Fritsch, Kevin Bargetto, Federico Casassa, and Miguel Pedroza*
*California Polytechnic State University, 1 Grand Avenue, San Luis Obispo, CA, 93407 (miguelp@calpoly.edu)

Bentonite is commonly used in production of white wines to clarify must before alcoholic fermentation and to remove unstable proteins responsible for turbidity. However, it can also remove nitrogen compounds that affect fermentation kinetics and the development of wine aromas. We investigated how sodium-based and sodium-calcium-based bentonite dosage rates affect fermentation kinetics, yeast assimilable nitrogen (YAN), and standard chemical composition in Chardonnay wines from the Edna Valley AVA. Bentonite dosage rates of 0, 0.24, 0.48, and 0.72 g/L were applied to 60 gallons of must with four replicates per treatment at a commercial winery. Our initial findings show that regardless of dosage or bentonite type, wines treated with bentonite experienced a longer lag phase and took approximately one additional day to reach 0 Brix compared to the control wine. In sodium-based bentonite treatments, the 0.72g/L dosage significantly decreased YAN levels by 15 mg/L compared to the control, while with calcium-based bentonite, there were no significant differences observed in YAN concentrations across dosage rates. Future analysis, including gas chromatography-mass spectrometry, color, and phenolic compounds, will provide additional insights into the effects of bentonite treatment on Chardonnay wine quality.

Funding Support: Center of Effort Winery