Determination of odour detection thresholds for acetic acid and ethyl acetate in ice wine

Abstract

Collectively acetic acid and ethyl acetate are responsible for ‘volatile acidity’ (VA) in wine. The detection limit or threshold for these compounds is well documented in table wine but not for ice wine. Knowledge of the ice wine thresholds is important for understanding perception limits and setting legal standards, particularly for a product with high intrinsic concentrations. Thresholds were determined for each compound using seventeen subjects and an ascending series of paired comparison tests, consisting of five concentrations. The detection threshold, the concentration at which there is 75% correct detection, was determined using least-squares linear regression. The correlation coefficients for the linear regressions for acetic acid and ethyl acetate were r = 0.996 (p < 0.001) and r = 0.972 (p < 0.001), respectively. The thresholds for acetic acid and ethyl acetate were 3.185 and 0.198 g/l, respectively. The threshold for acetic acid was approximately three times that found in table wines, but was relatively unchanged for ethyl acetate. This work supports the need for the legal limit for VA to be higher in ice wine, but also suggests that the legal requirements for the two compounds should be specified independently, not together.

Acknowledgments

Many thanks to the OEVI students at Brock University who participated in this study and to Gail Higenell for her technical assistance. The National Science and Engineering Research Council of Canada, is gratefully acknowledged for its financial support. Thanks also to the following CCOVI individuals for their input and assistance with the chemical analyses: Dr Canan Nurgel, Amanda Bartel, Lynda van Zuiden, and James Lin. Finally; thank you to Dr Andy Reynolds for providing the ice wine for this trial.