Protein Aggregation in White Wines: Influence of the Temperature on Aggregation Kinetics and Mechanisms

High temperatures (typically 80 degrees C) are widely used to assess wine stability with regard to protein haze or to study mechanisms involved in their formation. Dynamic light scattering experiments were performed to follow aggregation kinetics and aggregate characteristics in white wines at different temperatures (30-70 degrees C). Aggregation was followed during heating and cooling to 25 degrees C. Results were coupled with the study of the time temperature dependence of heat-induced protein aggregation. At low temperature (40 degrees C), aggregation developed during heating. Colloidal equilibria were such that attractive interactions between species led to the rapid formation of micrometer-sized aggregates. At higher temperatures (60 and 70 degrees C), enhanced protein precipitation was expected and observed. However, high temperatures prevented aggregation, which mainly developed during cooling. Depending on the wine, cooling induced the formation of sub-micronic metastable aggregates stabilized by electrostatic repulsions, or the rapid formation of micrometer-sized aggregates, prone to sedimentation.