66 A.J. Mart ́ınez-Rodr ́ıguez and E. Pueyo
One, almost unanimous, criterion is that wine proteins are the chemical
compounds with the greatest positive influence on the foam quality of wines
(Molan et al. 1982; Brissonnet et al. 1991, 1993; Malvy et al. 1994; Andr ́es-
Lacueva et al. 1996a; L ́opez-Barajas et al. 1997; Pueyo et al. 1995; Moreno-Arribas
et al. 2000; Vanrell et al. 2002). However, other compounds have also been described
in wines that can improve their foaming qualities, such as polysaccharides (Bris-
sonnet et al. 1991; Moreno-Arribas et al. 2000), although Girbau-S `ola et al. (2002b)
found the opposite effect. Glucose has also been attributed beneficial effects on the
foaming qualities of wines (Pueyo et al. 1995; L ́opez-Barajas et al. 1997).
It has been shown recently that mannoproteins from yeast cell walls make a sig-
nificant contribution to improving foaming properties (Nunez et al. 2006). These
authors also demonstrated the importance of the method of mannoprotein extraction
from the yeast cell wall, since not all mannoproteins have the same effect on the
foam of sparkling wines.
The compounds with negative effects on foaming qualities include the lipids. The
first work to explain this effect was carried out on beer (Roberts et al. 1978), where
it was shown that the harmful effect can bereduced with time, owing to the micellar
configuration of the lipids. Therefore, this effect will depend more on the physical
state of the lipids than on their concentration. This was later verified by Dussaud
et al. (1994) in work carried out in wines. This group also reported that this effect
would depend on the concentration of ethanol. At low ethanol concentrations they
will have negative effects but at high concentrations their effects will be negligible
relative to the negative effects that the ethanol has on the foam.
Gallart et al. (2002) have demonstrated that the fatty acids C 8 ,C 10 and C 12 ,do
indeed damage the foaming qualities of the wines, but some fatty acid esters actually
cause an improvement. Pueyo et al. (1995) have reported previously that linolenic
acid when not present in the free state (forming part of another type of lipid) is
positively correlated with foam quality.
Several authors also agree that sulphur dioxide can negatively affect the foaming
qualities of wines (maujean 1990; Pueyo et al. 1995; L ́opez-Barajas et al. 1997;
Girbau-S `ola et al. 2002b), as can ethanol, as mentioned above (Molan et al. 1982;
Dussaud et al. 1994; Girbau-S `ola et al. 2002b).
There is some controversy about the effect of total acidity on foaming qual-
ity, since some authors consider it to have beneficial effects (Andr ́es-Lacueva
et al. 1996a; Girbau-S `ola et al. 2002b) while others assign it negative effects (Bris-
sonnet et al. 1993; L ́opez-Barajas et al. 1997).
Studies carried out to establish the effects of different technological variables
on wine foaming qualities include those on the effects of stabilization treatments,
either using clarifiers or filtrations(Brissonnet et al. 1991; Robillard et al. 1993;
Viaux et al. 1994; Andr ́es-Lacueva et al. 1996a; L ́opez-Barajas et al. 1998; Lao
et al. 1999; Puig-Deu et al. 1999; Marchal et al. 2002; Vanrell et al. 2002, 2007;
Mart ́ınez-Rodr ́ıguez and Polo 2003; Dambrouck et al. 2005). In all cases, the foams
are negatively affected by these treatments, and this is directly correlated with the
reduced protein concentration they produce.