C A T A L O G U E e n o l o g i c a l p r o d u c t s
160721085328
160721085328
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Fining Agents<br />
...About fining<br />
Fining agents are materials that help remove undesirable<br />
elements from wine. Fining is not just used as a clarification<br />
technique to prepare wines for bottling, but can also be used<br />
to modify several wine attributes that will lead to organoleptic<br />
improvements and wine balance. Generally speaking, there are<br />
more benefits from early fining rather than later in the life of a<br />
wine. Early fining allows the wine to age properly, while limiting<br />
further more aggressive treatments prior to bottling.<br />
The purposes of fining:<br />
• Clarification<br />
• Stabilization against future haze and sediment formation<br />
• Improving organoleptic properties<br />
• Reducing astringency<br />
• Reducing bitternes<br />
• Removal of off-aromas<br />
• Color improvement<br />
44<br />
HOW DOES FINING WORK?<br />
The mechanisms of action in fining are diverse and depend on<br />
the nature of the fining agent. These interactions can be based<br />
on charge, formation of chemical bonds, and/or absorption or<br />
adsorption of compounds. When added to wine, fining agents<br />
usually form a colloidal dispersion. Depending on the electrical<br />
charge of the fining agent molecules when dispersed in wine,<br />
the colloids may be classified as being either electropositive<br />
(e.g. protein fining agents such as gelatins) or electronegative<br />
(e.g. tannin, bentonite, silica sol). These interactions lead to the<br />
formation of two important processes that need to happen in<br />
sequence: first, flocculation (the aggregation of two or more<br />
macromolecules) then sedimentation (when the flocculated<br />
materials settle to the bottom of the tank).<br />
Research on interactions between tannin and gelatin have shown<br />
that other factors are important in flocculation and sedimentation.<br />
FLOCCULATION AIDS (CO-FINING)<br />
When fining white and rosé wines, some protein-based fining<br />
agents (particularly gelatin and isinglass), which form colloids<br />
with a positive electric charge, require the addition of negativelycharged<br />
colloids in order to ensure complete flocculation and,<br />
eventually, precipitation. Such negatively-charged flocculation aids<br />
include: tannin, silica sol and bentonite. Bentonite can be used as<br />
a co-fining agent for all protein fining agents. When fining with<br />
gelatins or isinglass the best co-fining agents are silica sol or<br />
tannins. (Tannins need to be added a day before fining)<br />
EVALUATING THE PERFORMANCE OF FINING AGENTS<br />
Trials are essential for evaluating the efficacy of a treatment. Fining<br />
agents, as well as the concentration ranges used for a trial, should<br />
be selected on the basis of the change that is desired in the wine.<br />
It is important to test several rates and select the lowest dosage<br />
needed to achieve the desired effect to avoid over-fining.<br />
When particles with opposite electrical charges are attracted to<br />
each other by electrostatic interaction, a dehydration phenomenon<br />
takes place on the outer surface of the aggregated particles (or<br />
micelles). The presence of Na + , K + , Ca 2+ , Mg 2+ and specially Fe 3+<br />
cations is indispensable for this phenomenon to occur. This will<br />
lead to hydrophobic interaction between the aggregated particles<br />
which then leads to their precipitation.<br />
Origin and charge<br />
Proteins (+)<br />
Earths (-)<br />
Tannins (-)<br />
Synthetic<br />
compounds (-)<br />
Table 1 Nature of fining agents<br />
Material<br />
Gelatin, casein, albumin, isinglass<br />
Bentonite, silica sol<br />
Ellagic tannins<br />
PVPP, PVI-PVP<br />
For fining trials intended to modify organoleptic properties<br />
of wine, the most important test of all is a properly conducted<br />
sensory evaluation of fined samples against an untreated control.<br />
Additionally, there are several tests that winemakers can use to<br />
cross reference with their sensory evaluation (see table 2).<br />
Clarity<br />
Color<br />
Polyphenols<br />
Filterability<br />
Protein stability<br />
Color stability<br />
Overfining<br />
Volume of lees<br />
Turbidimeter or naked eye<br />
Abs. 420,520, 620 nm<br />
(color intensity, hue)<br />
Abs. 280 nm<br />
Fouling index and/or Vmax<br />
Heat test<br />
24 hrs at 0°C (32°F)<br />
microscopic examination of sediment<br />
Addition of tannin<br />
Cone or cylinder<br />
PREPARING FINING TRIALS<br />
• Decant wine samples to desired volume, leaving space for<br />
fining material to be added.<br />
• Label each with sample identification and material addition<br />
level. It is best to make additions as soon as possible after<br />
decanting.<br />
• Keep one bottle as a control.<br />
• Use Table 3 for volume of material to add per 100 mL of<br />
wine. IMPORTANT: Make the addition to wine sample and<br />
mix immediately.<br />
• Top off each bottle with wine, mix again. Make sure Control<br />
bottle is topped off.<br />
• Store at about 15°C (59°F) for settling, usually 1-2 days, until<br />
samples are ready to be evaluated.<br />
• Remove and let come to room temperature before evaluating.<br />
g/hL 1% 3% 5% 10%<br />
1 0.1 0.03 0.02 0.01<br />
5 0.5 0.17 0.1 0.05<br />
10 1 0.33 0.2 0.1<br />
15 1.5 0.5 0.3 0.15<br />
20 2 0.67 0.40 0.2<br />
30 3 1.0 0.6 0.3<br />
40 4 1.33 0.8 0.4<br />
Table 3 Millilters of a fining agent (%) solution to add to 100 ml of wine