Wine Chemistry and Biochemistry

5 Use of Enological Additives for Colloid and Tartrate Salt Stabilization 143

the number indicates the dosage in g/hL) (Fig. 5.5) (Marchal et al. 2003). The indus-

trial experiment was made twice and the musts obtained with the same treatment

were blended. So, 1000 hL of must clarified by flotation with gluten as protein

fining agent were obtained, and also 1000 hL of must clarified by flotation using

fish gelatin as protein fining agent.

Measurements were made just after flotation (between the flotation tank and

the temporary storage tank). Turbidities decreased by 95.9% and 96.7% when the

fining treatments were B 20 +Si 10 +gluten 20 and B 20 +Si10+FG 10 , respectively

(Fig. 5.6a–c) when compared with the control must without flotation (1446 NTU).

The turbidity of the must flotated with gluten as a fining protein was 20% higher

than that of the must flotated with FG as a fining protein (Fig. 5.6a–cb). The same

treatments were experimented with the laboratory flotator, with the same must.

Results (Fig. 5.6a–ca) confirmed the good efficaciousness of gluten (− 95 .4% of

the initial NTU) compared to that of FG (− 97 .5% of the initial NTU). If we now

observe the residual turbidities, the must flotated with FG 10 has a turbidity lower

by 44% than that of the must flotated with gluten. Differences in turbidity were

twice higher on a laboratory scale than at an industrial scale. Turbidities were also

measured in temporary storage tanks (500-hL), 14 h after the industrial clarification

by flotation. The turbidity of the must flotated with gluten was 14% lower than that

of the must flotated with FG 10 (Fig. 5.6a–cc). During these 14 h, a static settling

occurred in the tank. Then, results of static settling (when the must was fined and

clarified by sedimentation of flocculates) indicated a higher efficacy for fining with

gluten, even if the kinetics was longer. One can hypothesize that small flocculates,
present in the must after gluten fining, have higher density than flocculates formed

with fish gelatin. According to this hypothesis: (1) during the flotation, the higher

0

10

20

30

40

50

60

70

80

B 20 + Si 10

+ FG 10

B 20 + Si 10

+ Gluten 20

B 20 + Si 10

+ FG 10

B 20 + Si 10

+ Gluten 20

B 20 + Si 10

+ FG 10

B 20 + Si 10

+ Gluten 20

Turbidity (NTU)

B

Industrial scale

Measurements during flotation

C

Industrial scale

Measurements 14 hrs

after flotation

A

Mini-flotator

experiments

Fig. 5.6a–cClarification of a Muscat must using the flotation technique. Comparison between
industrial trials and laboratory experiments (three measurements), during and 14 h after flotation
(average of three sampling). For industrial trials, measurements are the average of six measures
made during the process (15 min between each sampling)