loadinganytraceofmercaptanordisulfide.Ahealthyfermentshouldbethefirstpriority.
Whenitcomestobottling,freesulfurdioxidelevelsthatarealittlelowerthanthoseusedwithotherclosuresareadvisable,asisaknowledgeofthevariationinoxygenpick-uponthebottlinglineused.Itshouldbeemphasizedthatallowingmoreoxygenpick-uporleavingalargerheadspaceofairdoesnotcounterpost-bottlingreduction,butratherresultsinoxidation.
Copperfiningcanhelpinsomecircumstances:Thiscertainlygetsridofmercaptans,butitdoesn'teliminatedisulfideswhich,aswehaveseen,canrevertinalowredoxenvironmenttomercaptans.Besides,copperfiningwillalsoremovethedesirablesulfideswhichareimportantforvarietalcharacterinSauvignonBlancandothergrapes.
DoConsumersNotice?
Theextentofscrewcapreductioniscurrentlyunclear.Theonlylargesurveytolookforit,thefaultsclinicoftheUK-basedInternationalWineChallenge(IWC),reportedthat2.2%ofscrewcappedwinessufferedfrom
mercaptanproblemsin2006,andin2007provisionalresultswereslightlyup,at2.7%.Thissoundsalarming,butitshouldbeborneinmindthatcorktaintirredeemablyruinsbottlesitaffects,whileveryfewconsumerswillhaveaproblemwithlow-levelmercaptansintheirwines.
Idoubtthatmostofthewinetradewouldspotthisasaprobleminallbutthemostextremecases,soitisunfairtoequateitwiththeverywellrecognizedproblemofcorktaint.Havingsaidthis,though,screwcap-sealedwinesaffectedbymercaptansshouldbeamajorconcernforwinemakers,becausetheclosureismodifyingtheflavorofthewine,whichisemphaticallynotreachingtheconsumer\waythewinemakerintended.\
Itwouldbedangerouslycomplacentfortheindustrytotaketheviewthatiftheconsumerdoesn'tnoticeit,thenitdoesn'tmatter.Howdoyouspotlow-levelmercaptans?\impactfromanorganolepticperspectivetowardstheendofthepalate,\Limmersays,\a'mineral'orbitter/hard/astringentaspect.Thishasthe
appearanceofshorteningorclosingupthepalate,sothewinedoesnotdisplayafine,fresh,longfinish,butendsabruptly,andsomewhatharshly.\
Thepictureemergingisacomplexone,butasimplified\taintwine\messagewouldbedangerousifitcausedproducerstobackawayfromadoptingalternativeclosuresolutions,whichwouldthenhavethesecondaryeffectofremovinganyincentivefromthecorkindustrytoputitshouseinorderanddoallitcantoreducetaintlevels.However,complicationslikethisreductionissueshouldputpressureonwinemakerstobemorecuriousabouttheclosurestheyareusing,andpaymoreattentiontothepotentiallossofqualitythatcanoccurduringthebottlingprocess.