Controlled freeze-thawing test to determine the degree of deionization required for tartaric stabilization of wines by electrodialysis

Abstract

A controlled freeze-thawing test for wines is proposed to predict the deionization degree required for tartaric stabilization by electrodialysis. In this test, wine samples are frozen and then thawed in controlled conditions. The required deionization degree is estimated based on the difference of specific conductivity of the wines before and after the freeze-thawing cycle. The effect of freezing holding time and thawing time on the predicted deionization degree was investigated, using different types of red, rose and white table wines. For the recommended operating conditions, the freeze-thawing test gives reproducible results, which are between 5 and 9% higher than the corresponding values obtained by the mini-contact test at -4 °C during 4 h. The passive version of freeze-thawing test seems to be an expedite and reliable method that can yield in 24 h an estimate of the deionization degree of wines for tartaric stabilization by electrodialysis.

Keywords: Conductivity; Electrodialysis; Freeze-thawing test; Mini-contact test; Tartaric stabilization; Wine.