Optimizing the Cash Still Procedure for Determination of Volatile Acidity Wine
Faculty Mentor Information
Warren Schutz, Coeur d'Alene Cellars
Presentation Date
7-16-2026
Abstract
Accurate measurement of volatile acidity is important for evaluating both wine quality and potential health concerns, since spoilage conditions may produce irritating or harmful compounds that make wine unsuitable for consumption. Determination of volatile acids is often done by the Cash still method. However, this method can be affected by sources of error such as inconsistent distillation rate, distillate loss, sample entrainment, endpoint determination variance, and sulfur dioxide interference. This project serves to optimize the standard operating procedure for measuring volatile acidity in wine using a Cash still. The revised procedure focuses on controlled distillation duration and distillate amount. To quantify effectiveness, a quality control sample was created with a known concentration of acetic acid. Additionally, samples of wine were used for intermethod comparison using automated sequential enzymatic analysis to accurately determine volatile acid concentrations. The changes resulted in an increase of percent recovery from 79.59% to 91.84% while reducing the relative standard deviation of measurements from 13.53% to 0.90%. Improving the Cash still standard operation procedure provides a more reliable method for detecting elevated acetic acid in wine and supports better indication of production and storage conditions that may affect consumer safety and product quality.
Optimizing the Cash Still Procedure for Determination of Volatile Acidity Wine
Accurate measurement of volatile acidity is important for evaluating both wine quality and potential health concerns, since spoilage conditions may produce irritating or harmful compounds that make wine unsuitable for consumption. Determination of volatile acids is often done by the Cash still method. However, this method can be affected by sources of error such as inconsistent distillation rate, distillate loss, sample entrainment, endpoint determination variance, and sulfur dioxide interference. This project serves to optimize the standard operating procedure for measuring volatile acidity in wine using a Cash still. The revised procedure focuses on controlled distillation duration and distillate amount. To quantify effectiveness, a quality control sample was created with a known concentration of acetic acid. Additionally, samples of wine were used for intermethod comparison using automated sequential enzymatic analysis to accurately determine volatile acid concentrations. The changes resulted in an increase of percent recovery from 79.59% to 91.84% while reducing the relative standard deviation of measurements from 13.53% to 0.90%. Improving the Cash still standard operation procedure provides a more reliable method for detecting elevated acetic acid in wine and supports better indication of production and storage conditions that may affect consumer safety and product quality.