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 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 non- polar 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 (over- fining) Nothing replaces fining trials!

Fining Can Be Used For Chemical Instability Macromolecular Instability

Chemical Instabilities 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 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 Protein Particles Agglutination Stabilization Polysaccharides

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 Proteins Earths Colloids Synthetic polymers Silica suspensions Activated carbon Yeast-derived components Yeast cell walls (ghosts) Lees fining

The Protein Fining Agents Casein Gelatin Albumin Isinglass Plant proteins

The Earths: Bentonite Silicate (SiO 2 ) 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 NaNaNaNaNaNaNa 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 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