Wine Chemistry and Biochemistry

154 R. Marchal and P. Jeandet

It has been demonstrated that a model wine solution supplemented with a

thermally-extracted mannoprotein fraction, that is, by heating 2 g of yeast cell walls

at 80–85◦C under stirring, shows better foaming properties than does the one sup-

plemented with an enzymatically-extracted mannoprotein fraction, that is, 2 g of

cell walls treated with Glucanex 200G (Mart ́ınez-Rodr ́ıguez et al. 2007; Nunez

et al. 2006), the behavior of the last being very similar to that of the control model

wine solution (Fig. 5.8). After supplementation of the model wine solution with

varying, but low, concentrations of the thermally-extracted mannoproteins (0.05–

0.4 mg/L), a positive correlation was observed between the quantity of mannopro-

teins added and the foaming parameters analyzed (Hpeak, Hplato and Sd300, that

is, respectively, the maximum height reached by the foam after air injection through

a glass frit, the foam height stability during air injection and the standard devia-

tion of foam measurements in the last 300 points) (Nunez et al. 2006). Within the

extracts, it was shown that the protein concentration is practically three times higher

in the thermal extract than in the enzymatic one, confirming the prominent role

played by proteins or glycoproteins in the foaming properties of champagnes and

sparkling wines, which has previously been suggested by others (Brissonnet and

Maujean 1993; Cilindre et al. 2008; Dambrouck et al. 2005; Marchal et al. 2002a;

Moreno-Arribas et al. 2000).

Within the extracts (thermal or enzymatic), besides polysaccharides, manno-

proteins were proven to be the main components, the molecular characterization

of which has been carried out using SEC and SDS-PAGE (Mart ́ınez-Rodr ́ıguez

et al. 2007; Nunez et al. 2006). Results showed in both cell wall extracts a protein
band corresponding to a relative molecular mass of 30 kDa (Fig. 5.9). Moreover,

three bands, which were absent from the extract obtained enzymatically, with rela-

tive molecular masses between 10 kDa and 21.5 kDa were observed in the thermal

extract. Only glycoproteins withMrbetween 10 kDa and 21.5 kDa, were proven to

be foam-active though the protein at 30 kDa (also present in the enzymatic extract)

was found to be inactive.

0

100

200

300

400

500

Mv

Hpeak Hplato Sd300

Fig. 5.8Effect of two soluble yeast extracts (0.25 g/L) on the foaming properties of a model wine.
Data presented are the mean of three different experiments. Model wine (control) (left); model
wine supplemented with the enzymatic extract (middle) and model wine supplemented with the
thermal extract (right) (reprinted with permission from Mart ́ınez-Rodr ́ıguez et al. 2007)