Agriculture Reference
In-Depth Information
Table 16.18
Continued
Agent
Origin and nature
Uses
1
Comments
Egg white
Animal, from fresh
eggs or in powdered
form
Red wine, at rate of
3-8 egg whites/225 l
or 100-150 mg/ 225 l
(powder)
Active agent is albumen.
Needs high polyphenol
content to work well.
Traditional fi ning agent.
GRAS
Gelatin
Animal: bones and
hide. Degradation
product of collagen
Beer and wine, also
removes tannins.
Rate: 1.5-15 g/hl
(white wine);
3-10 g/hl (red wine)
Not as effi cient as isinglass.
Popular with some US
brewers. In winemaking,
usually used in conjunction
with silica gel (sometimes
tannic acid). GRAS
Isinglass
Animal, dried swim
bladder of
subtropical fi sh (e.g.
catfi sh and drumfi sh
species), often as
1% aqueous
suspension
Beer, cider, wine.
Removes yeast cells
and some proteins.
Rate: 1-2.5 g/hl
(white wine);
0.4-1.0 l/hl (1-2%
suspension) (beer)
A very effi cient clarifi er.
Collagen is main active
agent. Gelatin is also present.
Minor components
(parvalbumins) are allergenic
proteins. Works well only at
low temperatures (<15°C).
GRAS
Skimmed
milk
Animal: as native
form, from cow's
milk, or in powdered
form
White wine, cider.
Rate (skimmed milk):
2-4 ml/l or 10-25 g/hl
(caseinate)
Whole milk not allowed in
EU. Casein is major active
agent. Often used as
potassium caseinate, in
powder form. GRAS
Notes:
Dried blood was a once common fi ning agent that was used at the rate of 5-10 g/hl for white wine
and 10-20 g/hl for red wine. Although effective and with organoleptic benefi ts, it is now banned in
most countries.
1
Rates are typical values. A brewery or winery will determine the optimum rate of addition for a
particular beverage by small-scale trial.
The mechanisms of clarifi cation using fi nings are complex, but electrostatic
(ionic) interactions are important - the neutralization of opposite charges, resulting
in the coalescence of particles. For example, isinglass, although amphoteric,
carries a net positive charge at beer, cider or wine pH, so it is effective in the
precipitation of yeast cells, whose surfaces are overall negatively charged.
Hydrogen bonding interactions are also important in certain fi nings systems, such
as silica gel, whose particles are covered with silanol groups that are able to form
hydrogen bonds with certain proteins and polyphenols. Silica gel particles also
carry net negative charges at beer, cider or wine pH.
Isinglass is a very effective clarifying agent
per se
and is widely used in the
alcoholic drinks industry. In beer production it is employed either early in the
process to aid fi ltration (or centrifugation), or at the same time as or just before
packaging, as in the production of cask-conditioned beer. It selectively removes
unwanted haze-active proteins, without having much infl uence on desirable foam-
active proteins; indeed, foam stability (see Section 16.3.3) is improved by the use
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