THE ENDOGENOUS PARTICLES OF A SPARKLING WINE AND THEIR INFLUENCE ON THE FOAMING BEHAVIOR

The endogenous particles of a champagne were identified by means of sc anning electron microscopy coupled to energy dispersive X-ray spectros copy. The influence of bentonites and yeasts on the wine foaming prope rties was investigated at a local scale on a bubble attached at a free surface, and at a global scale by a sparging method. Yeasts, unlike b entonites, can remain attached to the bubble surface, and they accumul ate in the Plateau borders of the foam influencing the drainage rates for steric reasons. No influence is observed on the maximal expansion whatever the particles, whereas the foam lifetime increases toward a p lateau with the yeasts concentration, and it presents a minimum when t he bentonite concentration increases. The latter effect results from t wo opposite phenomena, namely protein adsorption on bentonites that de creases the foam films stability, and the increase of the wine dynamic viscosity that lowers the foam drainage rate. (C) 1998 Published by E lsevier Science Ltd. All rights reserved.