Beerisapopulardrink.Manypeopleenjoyit.Theprocessofmakingbeerisinteresting.Fermentationisakeypart.Thistexttalksaboutbeerfermentation.Itusessimplewords.Itexplainsthescienceinabasicway.

Beerneedsfourmainthings.Thesearewater,malt,hops,andyeast.Yeastisveryimportantforfermentation.Yeastisatinylivingthing.Iteatssugar.Thesugarcomesfromthemalt.Theyeastturnssugarintoalcoholandgas.Thegasiscarbondioxide.Thismakesbeerfizzy.

First,brewerspreparethemalt.Maltusuallycomesfrombarley.Theysoakthebarleyinwater.Theyletitgrowalittle.Thisiscalledgermination.Thentheydryitwithhotair.Thisprocessmakesenzymes.Enzymeshelpchangestarchesintosugars.Thedriedgrainiscrushed.Itmixeswithhotwater.Thisismashing.Themashsitsinabigtank.Theenzymeswork.Theybreakdownthestarches.Thewaterbecomessweet.Thissweetliquidiscalledwort.

Thewortisseparatedfromthegrain.Itgoesintoalargekettle.Brewersaddhops.Hopsareflowers.Theygivebeerabittertaste.Theyalsoaddnicesmells.Thewortboilsforawhile.Boilingkillsgerms.Itstopstheenzymework.Itmakesthewortsafeforyeast.Theboilingalsotakesawaysomebadtastes.Afterboiling,thewortiscooleddownquickly.Itmustreachtherighttemperatureforyeast.

Nowfermentationstarts.Thecoolwortgoesintoafermentationtank.Brewersaddyeast.Therearetwomaintypesofyeastforbeer.Oneisaleyeast.Theotherislageryeast.Aleyeastworksatwarmertemperatures.Around15to24degreesCelsiusisgood.Thisyeastrisestothetopofthetank.Beersmadethiswayarecalledales.Theyoftenhavemorefruit-liketastes.Lageryeastworksatcoldertemperatures.Around7to13degreesCelsiusisgood.Thisyeastsinkstothebottom.Beersmadethiswayarecalledlagers.Theyoftenhaveacleaner,crispertaste.

Theyeasteatsthesugarsinthewort.Itmakestwomainthings.Oneisalcohol.Theotheriscarbondioxide.Thisisthecoreoffermentation.Theprocesstakestime.Forales,itmaytakeaweekortwo.Forlagers,ittakeslonger.Sometimesseveralweeks.Thetankisoftensealed.Atubeletsthegasescape.Butaircannotgetin.Thiskeepsthebeersafefrombadmicrobes.

Theyeastalsomakesothercompounds.Thesearecalledestersandphenols.Theyareverysmallinamount.Buttheychangethetastealot.Esterscangivetasteslikeapple,banana,orrose.Phenolscangivespicyorclove-likenotes.Thetemperaturechangestheseflavors.Warmerfermentationmakesmoreesters.Coolerfermentationmakesfewer.Brewerscontrolthetemperaturecarefully.Theywanttherightflavorsfortheirbeer.

Afterthemainfermentation,thereisanotherstep.Thisisconditioning.Thebeerisstoredformoretime.Theyeastkeepsworkingslowly.Iteatssomeleftoversugars.Italsocleansupsomebyproducts.Thesebyproductscangivebadflavors.Anexampleisdiacetyl.Ittasteslikebutterorbutterscotch.Yeastcanabsorbit.Conditioningmakesthebeertastesmoother.Forlagers,thisstepisverylongandcold.Itiscalledlagering.Itcantakemonths.Itmakesthebeerveryclearandcrisp.

Finally,thebeerisready.Theyeastisremoved.Somebeerskeepalittleyeastinthebottle.Thisiscalledbottleconditioning.Theyeastmakesalittlemoregasinthebottle.Thismakesthebeernaturalandfizzy.Mostbigbrewerybeersfiltertheyeastoutcompletely.Thentheyaddcarbondioxidelaterforthefizz.

Thetypeofyeastchangeseverything.Aleyeastandlageryeastaredifferentfamilies.Scientistsstudytheirgenes.Theyfindnewyeasttypesallthetime.Someyeastsareforspecialbeers.Forexample,Belgianbeersusespecialyeaststrains.Theymakeuniquespicyandfruityflavors.Wildyeastsexistintheair.Somebeersusethem.Thesearesourbeers.Thefermentationisspontaneous.Itislesscontrolled.Thetasteissourandcomplex.

Brewersmustkeepeverythingclean.Bacteriaandwildyeastcanspoilthebeer.Theycanmakeittastelikevinegarorspoiledfood.Cleaningtanksandpipesisabigjob.Itisveryimportantforgoodbeer.

Fermentationisanaturalprocess.Peoplehaveuseditforthousandsofyears.Theydidnotknowaboutyeastlongago.Nowweunderstanditbetter.Weknowyeastarelivingcells.Theytakesugar.Theygiveusalcoholandcarbondioxide.Thisisthemagicofbeer.

Thesciencehelpsmakebetterbeer.Brewerscanchooseyeastfortheflavortheywant.Theycancontroltemperaturefordifferentresults.Theycanmakeconsistentproducts.Homebrewersalsousethisknowledge.Theymakebeerintheirkitchens.Thebasicideasarethesame.

Beerfermentationissimpleinidea.Yeasteatssugar.Itmakesalcoholandgas.Butthedetailsmatteralot.Thetypeofmaltchangesthesugar.Thetypeofhopschangesthebitterness.Thetypeofyeastchangesthealcoholandflavors.Thetemperaturechangesthespeedandthetastes.Thetimechangesthesmoothness.Allthesefactorsworktogether.Theycreatethewideworldofbeer.Fromlightlagerstodarkstouts.Fromsweetalestosourlambics.Fermentationistheheartofitall.