5Types of filtration Depth filtration Wine moves through tortuous path Filtration occurs on surface AND interior matrixRated with nominal or normal porositySome % (70-98%) of particles of that size will be retainedUse specified flow ratesEx: DE, plate and frame filters, disc filtersGusmer Inc.
6Disadvantages of Depth filtration Media migrationIncreases with surge vs uniform flowMicrobial growth within filter matrixContamination of filtrateSome product can remain in filter matrix“Sterile” pads?; cannot validate porosity
7Types of filtration Absolute filtration Membrane filtration Filtration occurs at the surfaceStandard sized pores;99%+ reliabilityTrap all particles larger than pore sizeClog easily0.45 micron, “sterile”; sequential depth plus absolute filtrationGusmer Inc.
8Disadvantages of Absolute filtration Low “dirt handling”capacityUse only with “clean”wines to remove microorganismsNot all particles with diameters less than pore size flow throughMay be retained in pore passage, blocking flowDo not wait >48 hours after prefilter
9Deformable vs. Non-deformable particles Non-deformable: retain shapeDiatoms or diatomaceous earth: various gradesRigid nature: act as filtration mediumTartrate crystalsShape will not change with applied pressureDeformable-majority of wine/juice particlesYeast, bacteria, colloids (including fining agents ex: gelatin), protein/phenol/polysaccharide complexesElastic nature-spread over surface area; block filtrationsProactive: rack, fine, enzymes
10Deformable vs Non-deformable Gusmer Enterprises, Inc.<0.2 microns-1000 microns
11Colloids Protein fractions: mw 20-40 Kda Polysaccharide fractions: mw KdaGrapesYeastBotrytis cinereaMarginally soluble fractionsForm fine dispersed aggregates in solutionDeposits on surfacesMembrane filter fouling
12Botrytis Beta-glucan insoluble in 30% ethanol (v/v) Filament like precipitateSpecific detection for this polysaccharidePrevents natural sedimentation of particles (like pectin)Alcohol acts as aggregation factor; polymerizationMost severe at end of fermentationBeta-glucanaseStemstore.tumblr.com
14AgglomerationImage by Kathryn ErbeMany suspended particles will adhere to similar particlesResult in single larger particleLarger particles may precipitate naturally or by finingEasier to remove by filtration
15Polysaccharides Includes pectins and glucans Deformable particles May be colloidal in juice and wineImpede filtrationIn alcoholic solution, both are unstableForm gelatinous aggregates
16PolysaccharidesPolysaccharides may derive from the plant or from microbial activity
17Pectins Structural component of plant cell walls Can impede clarificationTest : add pectolytic enzyme and perform precipitation testProactive enzymatic treatment of must/juice recommendedPectins and glucans high in concentrates
18Glucans Result of Botrytis growth on grapes Result of spoilage LAB Gel formation with acidified ethanol(Zoecklein et al., 2005)Laffort.com
19Starch Can cause haze in apple juice and cider Affects clarity and filtrationTest for starch haze (Zoecklein et al. 2005)
20Sterile filtration Integrity Testing Membrane filters must be preceded by 99.9% filtrationMust be bubble tested before, during, and after runIf fails, product between that time is suspect
21Bubble pointGas pressure where surface tension of water in filter pores is overcomeGas passes through poresDependent on pore sizeAre leaks present anywhere?Means of checking integrityof system
23Pressure Hold Integrity Test Monitor upstream pressure decay as gas diffuses through wetted membranePressurize housing to 80% bubble pointTurn off gasMonitor how quickly upstream pressure drops (<2 psig in 5 min)Precise pressure gauges
24Filter sheets Ruptured sheets: major source back-pressure shock Rapid valve closing, shutting off/pulsation of pumpWinesand vines.com
25Does filtration change sensory character? Soluble flavor and aroma compounds are well below 0.45 micronsSensory impact hard to quantifysubjective nature of sensory analysisSoluble species are probably not removed by macro and micropore filtrationMaybe colloidal macromolecules that impact mouthfeel
26Colloidal macromolecules May be present as large aggregates of polysaccharides, mannoprotein or protein-phenolic complexes (500+kd)May play role in wine’s texture/structureInteraction between macromolecules and and low mw volatile compounds may account for aromatic changes after sterile filtration
27Mouthfeel Colloids-viscosity May have tannins and anthocyanins attachedDoes filtration (0.45 micron) remove significant amount of colloids?No conclusive evidencePossible?
28Aging Phenols bind together and polymerize Molecular weight and size increasesFiltration can remove theseOlder red wines have more polymerized phenolsGreater negative effect from filtrationColor reductionEzramagazine.com
29Sorbate? Can replace with filtration to 1 micron Removing yeast, not bacteriaSensory changes due to ethyl sorbateSorbate and ethanolCandied fruit, Juicy fruitGeranium taintmicrobial
30Conclusions No filtration?-can lead to instabilities Sanitation Follow manufacturers operating directionsFlow rate, pressure differentialTest wines for filterabilityWines with similar turbidity can have different filterability indices (Cattaruzza et al. 1987)Keep good records
31ReferencesZoecklein, B. Filtration. Wine/Enology and grape Chemistry Group, Virginia TechMansfield, A.K. Cellar Dweller. Cornell Extension Enology Lab, February Accessed Feb 29.Bisson, L. Post Fermentation Processing. Accessed FebButzke, C. Winemkaing Problems Solved. Woodhead Publishing, OxfordReynolds, A. Managing Wine Quality. Woodhead Publishing, OxfordAlarcon-Mendez and R. Boulton Automated measurement and interpretation of wine filterability. Am. J. Enol. Vitic. 52:3.Villettaz, J.C. et al The use of a beta glucanase as an enzyme in wine clarification and filtration. Am. J. Enol. Vitic. 35:4.Patterson, T. If filtration strips wine, what’s getting stripped?. Wines and Vines. Oct 2008.