Wine Chemistry and Biochemistry

5 Use of Enological Additives for Colloid and Tartrate Salt Stabilization 137

Different experimental procedures were established to compare gluten efficacious-

ness with usual fining agents (Lefebvre et al. 2000; Marchal et al. 2002b, c).

5.1.3.1 Comparison of Wheat Gluten and Other Fining Agents for White Wine

The results presented here concern a Chardonnay base wine from the Champagne

wine-growing area (Marchal et al. 2002c). As for bentonites or gelatins, preliminary

laboratory tests showed some glutens were not able to clarify white wines. This is

certainly related to the low dispersion of the viscoelastic particles, leading to a small

contact surface. Also, glutens composedof prolamins with a low molecular weight

cannot lead to the formation of floculates with wine particles. For all of the glutens

tested, an addition of 5 g/hL led to an increase in the wine turbidity (Fig. 5.1). Yet,

the clarifying effect (from 10 g/hL) increased proportionally to the gluten quantity

added to the wine. Also, differences between glutens were observed. Gluten 3 at

20 g/hL (see Fig. 5.1) was nearly as efficient as gluten 4 at 40 g/hL. These variations

can be explained by the different treatments applied to vital gluten, and to the protein

composition which depends on the wheat species. As for classical fining treatments

(bentonite, gelatin, casein....), the enology literature does not provide precise infor-

mation (molecular mechanisms) able to explain the differences observed.

Turbidities obtained with gluten at 20 and 40 g/hL were between the minimal

and maximal values obtained with the different associations of tannins-gelatins. The

clarifying effect obtained with bentonites was greater with 60 g/hL than with 30 g/hl
but the increase was quite small (Fig. 5.1). Wine fining with glutens (especially

gluten 3 and gluten 4 at 40 g/hL) resulted in better clarification than with the two

0

15

30

45

60

Control wine

Gluten4 + T2 5,1Gluten4 + T2 10,2Gluten4 + T2 20,4Gluten4 + T2 40,8Gluten6 + T2 5,1Gluten6 + T2 10,2Gluten6 + T2 20,4Gluten6 + T2 40,8Gluten3 + T2 5.1Gluten3 + T2 10.2Gluten3 + T2 20.4Gluten3 + T2 40,8

Gluten4 5Gluten4 10Gluten4 20Gluten4 40Gluten5 5Gluten5 10Gluten5 20Gluten5 40Gluten6 5Gluten6 10Gluten6 20Gluten6 40Gluten3 5Gluten3 10Gluten3 20Gluten3 40

T2 2T2 6CP1 1CP1 3

CP1 T2 1,2CP1 T2 3,6

CP2 1CP2 3

CP2 T2 1,2CP2 T2 3,6

Ca 5Ca 10Ca 20

Ca 5 + Gluten3 5Ca 10 + Gluten3 10Ca 20 + Gluten3 20

Ca10 B1 10G1T1 5.5G1T1 5.2,5G1T2 5.5G1T2 5.2,5G2T1 5.5G2T1 5.2,5G2T2 5.5G2T2 5.2,5

B1 15B1 30B1 60B2 15B2 30B2 60

NTU

Fig. 5.1Effect of different fining procedures on the turbidity of a Chardonnay wine. Measurements
were made 28 h after treatments