FOAM MEASUREMENTS IN WINES - COMPARISON OF PARAMETERS OBTAINED BY GASSPARGING METHOD

Two procedures for foam determination, based on the method of gas spar ging, were applied in samples with different foam capacities. The foam ing parameters measured by Maujean et al. (1990) [maximum height (HM), stability height (HS), and stability time (TS)] and Robillard et al. (1993) [foam expansion (E), foam stability (L-F), and Bikerman coeffic ient (Sigma)] were compared. HM, E, and L-F were positively correlated (r > 0.9), so E and L-F do not provide additional information on wine foamability. Furthermore, measurement off in samples with low foamabi lity is unreliable, and in samples with high foamability E is less abl e to discriminate foaming properties than HM. TS did not have any pred ictive relationship with the other parameters, so it could be used as a parameter of another aspect of foam. Sigma is preferable to HS, beca use it is independent of determination conditions. The precisions of H M and TS were low (80%) in some wines, but the coefficients of variati on were related with the mean values. The most appropriate parameters to characterize the foam capacity of several wines were HM, Sigma, and TS.