138 R. Marchal and P. Jeandet
bentonites tested. However, the best results were obtained with 1 g/hL fish glues
(particularly when in combination with tannins) and with 10 and 20 g/hL (Fig. 5.1).
5.1.3.2 Combination of Gluten with Other Fining Agents for Chardonnay
Wine Clarification
Clarifications obtained with the combination gluten 4-tannin 2 were always better
than with gluten 4, only (Fig. 5.1). For example, the turbidity obtained with gluten
4 at 20 g/hL and tannin 2 at 4 g/hL was 60% lower than with gluten 4, only. One can
also observe that flocculation/clarifyingappeared when tannins were added in the
wine without proteins (−56% for T 2 at 6 g/hL, compared tothe control wine). In
this experiment, there was a synergy between hydrolyzed gluten proteins and tan-
nins. However, when the dose of gluten 4 increased (40 g/hL), the synergy between
wheat proteins and tannins was less marked. The combination of gluten 3 or gluten
6 with tannins gave better results only for the dose of 5 g/hL, but the increase repre-
sented only 20% or 25% when compared to the untreated wine. With higher doses,
the clarification was better with gluten 3 and 6 alone than with the combinations
of gluten-tannins (except for gluten 6 at 10 g/hL and tannin 2 at 2 g/hL, but this
treatment gave poor turbidity decrease and cannot be applied in the wine industry).
The combination of gluten-casein generates negative interactions. When com-
pared to the untreated wine, gluten 3 alone or casein alone, both at 10 g/hL, led
respectively to a decrease of 24 and 44 NTU (Fig. 5.1). But the combination of
both in the same conditions made the turbidity fall by only 41 NTU. Therefore, the
combination of the two is not advisable, nor is the combination caseins+bentonite.
To sum up, these results show that gluten is really an efficient fining agent for clari-
fying white wines after alcoholic fermentation. Differences between the efficiencies
at 28 and 48 h were quite small or even non-existent for numerous treatments. In
conclusion, it seems that wine fining efficiency varies little during clarification. This
makes it possible to accomplish small-scale fining tests with short reaction times.
The influence of the fining type on lees volume has also to be considered as taken
into account for the fining agent choice because it is related to the loss of wine.
All the glutens generate volumes of lees that are similar to the values observed
for casein, tannin-gelatin and fish glue. However, these volumes are smaller than
those obtained with bentonite-casein or with bentonites at 30 g/hL. Globally, glutens
generate volumes of lees comparable to those obtained with animal proteins used as
fining agents.
5.1.4 Must Clarification Using the Flotation Technique
Some sparkling wines such as “Clairette deDie” (France), “Asti spumante” (Italy)
and many others throughout the world (Spain, Portugal, Greece, Brazil for example)
are sparkling wines with approximately 6–8% alcohol and 35–50 g/L residual sug-
ars. Pectinolytic enzymes are often added to Muscat grapes in the crusher to increase
the extraction of aroma compounds. The consequence of this treatment is that the