Wine Chemistry and Biochemistry

5 Use of Enological Additives for Colloid and Tartrate Salt Stabilization 153

Ta b l e 5. 3 Protein stabilization obtained following addition of different invertase hydrolysates
(redrawn with permission from Moine-Ledoux and Dubourdieu 2007)

Turbidity (NTU) Bentonite (g/hL)

Control wine 16 60

Wine+25 g/hL EEM 10 30

Wine+25 g/hL IPA 2 0

Wine+25 g/hL IG 2 0

Ta b l e 5. 4MP32 content of EEM and of different invertase hydrolysates (redrawn with permission
from Moine-Ledoux and Dubourdieu 2007)

Percentage of MP32

Mannoproteins extracted by enzymes 18

Invertase hydrolysate by Glucanex 60

Invertase hydrolysate by protease A 65

yeast cell wall by the joint action of the parietalβglucanase and the vacuolar pro-

tease A from yeast. In vitro MP32 can be obtained by invertase hydrolysis using

Glucanex. Hydrolysates obtained after hydrolysis of a commercial invertase prepa-

ration by the vacuolar protease A from yeast (IPA) and Glucanex (IG) were added

to a given wine at a dose of 25 g/h. Their possible effects on protein stability and the

bentonite dosage required to stabilize the wine were compared to that of yeast cell

wall enzyme (Glucanex©R)-extracted mannoproteins (EEM) (Table 5.3).

The invertase hydrolysate obtained by protease A (IPA) shows a remarkable heat

stabilizing activity. The turbidity of the heated wine decreases from 16 to 2 NTU,

an efficaciousness comparable to that ofthe invertase hydrolysate obtained with

Glucanex©R (IG) (Moine-Ledoux and Dubourdieu 1999, 2007). Likewise, analy-

sis of the different invertase hydrolysates by capillary electrophoresis (Table 5.4)
indicates that they all contain MP32 as do EEM. The hydrolysate obtained by pro-

tease A is slightly richer in MP32 than the hydrolysate obtained by Glucanex©R.An

extraction procedure for MP32 has been developed at an industrial scale, involv-

ing use of the same enzyme activities (glucanase and protease) (Dubourdieu and

Moine 1994, 1996).

5.4 Use of Mannoprotein Fractions to Improve the Foaming

Properties of Sparkling Wines

Mannoproteins have previously been shown to improve the quality of foam prop-

erties in sparkling wines (Nunez et al. 2005). We have seen that mannoproteins are

currently obtained either by enzymatic or thermal procedures, or by a combination

of them. The method chosen for protein extraction may greatly influence character-

istics of the mannoprotein fraction obtained (Dupin et al. 2000).