The Fundamentals of Fining
Linda F. Bisson
Department of Viticulture and
Enology, UCD
Introduction to Fining
DEFINITION: Fining refers to the removal of
components from a juice or wine that are
currently soluble or in small aggregates that will
associate with the insoluble fining agent thereby
being pulled out of the wine
Introduction to Fining
• Fining agents may be used alone or in
combination with other agents
• Natural settling may be sufficient to remove
fining agent and its associated components
• Centrifugation or filtration may be needed to
remove fining agent
Types of Fining Agent Interactions
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Charge-based
Disulfide bridging
Hydrophobic interactions
Affinity interactions
Charge-Based Interactions
• Hydrogen bonding
• Salt bonding
Hydrogen Bonding
Salt Bonding
Disulfide Bridging
Can Get a Mixture of Types of Bonding
Hydrophobic Interactions
• Takes advantage of regions of molecules that
“abhor” water and will associate with other nonpolar components
• Many macromolecules have both hydrophobic
and hydrophilic regions
• Hydrophobic regions associate with each other in
juice but as protein denatures regions may be
exposed to water and then will associated with
the hydrophobic region of another molecule
Hydrophobic Interactions
Denatured protein
Soluble protein
Hydrophobic Complex Formation
Both Hydrophobic and Charge
Interactions May Occur
Affinity Interactions
• Affinity interactions refer to a more complex
recognition of a component by another
component
• These reactions often require a step of
recognition
• These reactions are more specific in terms of
partners being able to participate than charge or
hydrophobic interactions
• Usually multiple points of contact
• Generally used to remove specific wine
components like phenolic compounds
Affinity Interactions
Protein
Target Compound
Choice of Fining Strategy
• What are you trying to remove?
• Will you remove positive characters along
with the negative character?
• Will the fining agent leave and impact (overfining)
• Nothing replaces fining trials!
Fining Can Be Used For
• Chemical Instability
• Macromolecular Instability
Chemical Instabilities
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Metal ions
Tartrate
Polymerized phenols
Oxidation products
Metal Ions
• Fe and Cu can form a precipitate “casse”
• Caused by use of iron or copper
containing materials in winery or from
pesticides
Tartrate
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At low temperature, tartrate will crystallize
Mistaken for ground glass by consumers
Unstable in presence of Ca++
Solubility depends upon pH, K+, tartrate
concentrations
• Can get co-crystallization with other organic
acids
Polymerized Phenols
• Can precipitate during aging
• Maybe undesired in bottle
Oxidation Products
• Off-colors
– Brown
– Pink
– Orange
• Off-characters
– S- volatile compounds
• Prevented by using antioxidants
• Prevented by removal of off-color potential
Macromolecular Stability
• Protein
• Polysaccharide
Protein Instability
• Proteins involved are from grape
• Denature over time causing visible haze
– Hydrophobic regions interact
– Agglutination complexes formed
– Complex becomes visible
• Accelerated by treatment of wine at high
temperature (HTST)
• Can be prevented by fining to strip protein
HTST
• “High Temperature Short Time”
• Used on juices with high oxidase levels
– Polyphenol oxidase from plant
– Laccase from Botrytis
• Used on wines
– Pasteurization (Kosher wines)
– Inactivation of added enzymatic activity
Alternatives to Removing Protein
• Stabilizing protein via protective colloid
formation
• Use of yeast polysaccharides to “coat” protein
and hold it in soluble conformation
Stabilization of Particles
Agglutination
Protein Particles
Polysaccharides
Stabilization
Polysaccharide Instability
• Polysaccharides come from either plant or
microbial activity
• Insoluble at high ethanol causing visible
haze
• Insoluble at low temperatures
• More difficult to prevent/remove
Mechanism of Fining
• Take advantage of either hydrophobic or
hydrophilic interactions to remove
offending component
• Wine will initially be cloudy, but particles
will eventually become large and sink
• Clarify by racking or filtration
Mechanism of Fining
• Add a charged component that will interact
with oppositely charged components
followed by precipitation of the neutral
complex
• Add a denaturing component that will
expose hydrophobic surfaces that will then
interact allowing a hydrophobic complex to
form
The Fining Agents
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Proteins
Earths
Colloids
Synthetic polymers
Silica suspensions
Activated carbon
Yeast-derived components
Yeast cell walls (ghosts)
Lees fining
The Protein Fining Agents
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Casein
Gelatin
Albumin
Isinglass
Plant proteins
The Earths: Bentonite
• Silicate (SiO2)
• Large surface area: occurs in sheets
• Net negative charge at wine pH: ideal for
interaction with wine proteins that
generally have a net positive charge
• Different forms occur differing in salts
associated with silicate: Na+, K+, Ca++
Bentonite
• Functions by exchange of associated cation for
wine components having a higher affinity
Na+
NaNaNaNaNaNaNa
NaNaNaNaNaNaNa
NaNaNaNaNaNaNa
NaNaNaNaNaNaNa
Na+
Na+
Na+
Na+
Na+
Na+
Na+
Na+
Bentonite Levels
• Typically 1 – 4 lbs/1000 gal (0.12 –0.48
g/L) is ample to remove wine protein
• If 10 lbs/1000 gal (1.0 g/L) is needed,
haze problem might not be due to protein!
Bentonite: The Problems
• Must swell properly in water or water/wine
mixture before use
• High lees volume
• Addition of ions that may encourage
tartrate instability
Colloidal Fining Agents
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Natural polysaccharides
Agar
Gum Arabic
Sparkolloid: alginate based
Ferrocyanide colloidal preparations
Colloidal Fining Agents
• Naturally dispersed or “protective” colloids
can hold proteins, tartaric acid crystals,
other colloidal materials in suspension
• Colloidal fining agents neutralize surface
charges on naturally dispersed colloids
thereby allowing them to dissolve or
coagulate
Synthetic Polymers
• Polyglycine
• Polyamide
• Polyvinylpolypyrrolidine (PVPP)
Have carbonyl oxygen atoms on surface
that act as adsorption sites.
Synthetic Polymers
• Absorb monomeric phenolic compounds
– Pinking potential
– Browning potential
– Bitter catechins
• Narrow spectrum
Silica Suspensions
• The “sols”
• Used primarily with gelatin
Activated Carbon
• High and broad affinity
• Removes color, wide range of phenolics
• Strips wine: used only as a last resort to
salvage a wine for blending
Today’s Program
• Pending potential labeling regulations for fining
agent use: Mari Kirrane, TTB
• Supplier Panel: Innovative agents and proper use
of agents
• Design and Evaluation of Fining Trials: Anita
Oberholster
• Winemaker Panel: Strategies for use of fining
agents
• Fining for Defects Removal: A case study: Chik
Brenneman
Importance of Diagnosis of Problem
• To avoid over-fining
• To avoid positive character removal
• To consider alternatives when appropriate
– Patience
– Oxygen treatments
– Lees treatments
• To make sure problem is truly addressed