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1、PROBLEMS WITH FERMENTSYeastIssuesandReferencesusedforlectureWineScience-JacksonChapter7WineMicrobiology-FugelsangChapter3MakingGoodWineRankineChapter6PacificRimOenologyHarvest2010ProductlistProducingaHealthyFermentationBruceZoecklein,VirginiaTechhttp:/www.fst.vt.edu/extension/enology/EN/105.htmlSwie
2、gers,J.etal,(2005).Yeastandbacterialmodulationofwinearomaandflavour.AustralianJournalofGrapeandWineResearch,11,2,Pages139-173http:/ 07/15/2007http:/ diagrammatic representation of the microbial modulation of the profile of volatile compounds in wine (based upon Swiegers and Pretorius 2005). Wine yea
3、sts and malolactic bacteria can produce desirable sensory results -by helping to extract compounds from the solids in grape must, -by modifying grape-derived molecules and -by producing flavour-active metabolites.Thefullpicture.Formation of flavour-active compounds from sugar, amino acids and sulphu
4、r metabolism by wine yeast.Swiegers, J. et al, (2005). Yeast and bacterial modulation of wine aroma and flavour. Australian Journal of Grape and Wine Research, 11, 2, Pages 139-173 Whatsomeoftheoutputscontribute:Seetable1Sweigersetal,2005Esters-fromfermentinfluencesfruityflavours.Scerevisiaestrainsp
5、roduceavariableamount.E.g.isoamylacetate,ethylhexanoate,hexylacetateMixedculturesofS.cer,Pichiasp.&HanseniasporaspincreasesacetateestersHigherAlcoholsalsocalledFuselExcessivelevelspungent400mg/le.gsharsh,spiritlikeoptimalfruityComplexity300mg/lProductsoffermentandalcoholbreakdown-alcohol,acetaldehyd
6、e,aceticacid.DiacetylalsoMLFGlycerolMajorproductofferment.Polyol-colourless,viscous,noodour.CaneffectapparentsweetnessofwineFallacynorelationshiptotears.Onlyatveryhighconc(abovenormal)doesitaffectviscosityWhatsomeoftheoutputscontribute:MonoterpenesFormedduringfermentsbyyeastorbacteriaenzymaticallyre
7、leasetheseboundupnon-volatileprecursorsGewrztraminer,Muscat,RieslinghighlevelsofmonoterpenesFaultsThiolspotentgrpofaromacompoundsextraSomealmostnon-existentingrapejuiceresultoffermente.g.Combination.FurfurythiolIDedinredBordeauxandtoastedoakstavesAlsoroastedcoffee,meat.Presenceinwinefromyeasttransfo
8、rmationoffurfuralinoakNon-volatileinjuicee.g.inSauvignonblancboundtoaminoacid(cysteine)Yeastreleases4MMP-boxwood,3MH,3MHAExpressionseehandoutYeastchoicenewoptions(yesterdayshandout)Newinoculatedwildyeaststrains1.Torulasporadelbrueckii(Prelude)pitchedinwithSaccharomycessp.Redsenhancedredfruitandflora
9、lmedchainfattyestersWhitesSBLenhanced3MH(3-mercaptohexanol)IncreasedpalateweightforallwinesmoreandfullermouthfeelYeastchoicenewoptionsNewinoculatedwildyeaststrains2.PichiakluyveriagaincofermentedwithSaccharomycessp.IsolatedinNZ.EnhancementofSBLcharacteristicsIncreasesallthiolsbutesp3MHAAlsoelevatesl
10、evelsofmidchainfattyacidestersMidchainmorestablethanshortermoleculesClaimedeffectsonwine:(VinifloraFrootzen)IncreasedfruitflavourintensityenhancedtropicalfruitandcitrusLargerspectrumoffruitflavours,givingwinesadditionalcomplexityLowervolatileacidityRoundermouth-feelDesiredCharacteristicsforayeast1.L
11、owfoamingwhy?2.Lowproductionofundesirablese.g?3. Abilitytofermenttodryness-vigorouse.g.Premiercurvee(1118).4. Abilitytobestoppedifrequired-lessvigorouse.g.Epernay(Cotedeblanc)5. Neutralfruit-deponstyle-Sparklinge.gDV10,1118DesiredCharacteristics6. Enhancedcharacters-coloure.g.W46,Bordeauxred-flavour
12、&aroma(D47,RC212)7. Abilitytoflocculaterapidly-Sparklingandrapidturnaroundwinese.g.Lalvin0168.EfficientconversiontoAlcohol.(NottoomuchenergyconsumedbyYeast)9.Toleratelowtemps-whitese.gM110. TolerateSO2-competition,controlbacteriaandwildyeastDesiredCharacteristics11. Evenfermentshortlagphase,evenspee
13、d12.Toleratehighalcohol-restarts&hialcoholUV43,L222613.Cantoleratehighfructose.TodealwithhiFstuckferments(e.g.Fermichamp)14. Hascompetitivefactors(killerproperties)What does “competitive factor” mean?KILLER!Wineyeastmaycontainproteinswhichallowthemtopreventotheryeastsfromcompetingduringthefermentati
14、on.Enablesonestraintocompetesuccessfullyanddominateaferment.ProteinsarecalledKillertoxins,(K1/K2)Wineyeastscanbekillerpositive(containthetoxin),killersensitive(notoxinandarekilledbythetoxin)orkillerneutral(notoxinandarenotkilledbythetoxin).What does “competitive factor” mean?Thesekillercompetitivefa
15、ctorsaretinyproteinsproducedinthemitochondriaofoneyeasttheymovethroughthecellwalloftheotheryeastandupsetMgmetabolismsothecelldies.AllthosefactorsinmindWhichyeastisrightfortheferment?Howcanawinemakergoaboutselectingacertainyeast?Firstly:Theycanrelyonpastexperience.Usuallythebestguide.Butjustbecauseye
16、astperformedwellorinadesirablewayforthewinemakeroneyear,itwillnotmeanthatitwillperforminasimilarmanneryearafteryear.Why?Secondly:Seekadvicefromanotherwinemaker.Oneinthesamearea,potentiallysimilarvineyardsRemembertoo.Theirstyleaimsmaybedifferent.Sharinginfo.Howcanawinemakergoaboutselectingacertainyeast?Thirdly:Seekinformation/advicefromtheyeastmanufacturerorsuppliersthemselves.However,canawinemakerbelievewhatiswrittenonthepacketorFact sheet?And.Sometimesawinemakerhasopposingneedsandnostrainisidea
