Chemistry Reference
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8%-24%isreinedtoaparticlesize<30mm,normallyusingacombinationoftwo-andive-roll
reiners(Beckett2000).Finalparticlesizecriticallyinluencestherheologicalandsensoryproper-
ties.Aive-rollreinerconsistsofaverticalarrayoffourhollowcylinders,temperaturecontrolled
byinternalwaterlow,heldtogetherbyhydraulicpressure.Athinilmofchocolateisattractedto
increasinglyfasterrollers.Rollershearingfragmentssolidparticles,coatingnewsurfaceswithlipid,
so these become active, absorbing volatile lavor compounds from cocoa components (Afoakwa,
Paterson,andFowler2007).
Textureinmilkchocolateappearsimprovedbyabimodaldistributionofparticleswithasmall
proportionhavingsizesupto65mm.Optimumparticlesizefordarkchocolateislowerat<35mm
althoughvaluesareinluencedbyproductandcomposition(Awua2002).Reiners,insummary,not
onlyaffectparticlesizereductionandagglomeratebreakdownbutalsodistributeparticlesthrough
thecontinuousphase,coatingeachwithlipid.
Reined mixtures then move into conching (slow mixing of heated chocolate paste to reduce
particlesizeandincreasethickness),aprocessthatcontributestodevelopmentofviscosityandinal
textureandlavor(Figure8.5).Thisistheendpointformanufactureofbulkchocolate.
Fine crystalline sucrose, the main sweetener in chocolate products, compound coatings, and
cocoadrinks,isutilizedatupto50%oftheformulaonaweightbasisinchocolateconfectionery
(Kruger1999).Ithasalowhygroscopicityandiseasytoblend.Sucrosemustbedrytoeliminate
cakingandshouldnotcontaininvertedsugarbecausethiswoulddecreaseviscosity.
Lactose,inmilksolids,ispresentatlowerlevelsinanamorphousform,andinitsglassystate,it
holdsaproportionofmilkfat(Beckett2000),inluencingchocolatelavorandlowproperties,and
ispresentinmilkchocolate.LactoseenhancesthebrowningbyparticipatinginMaillardreactions
(Bolenz,Amtsberg,andSchape2006;Kruger1999).Monosaccharides,glucoseandfructose,are
rarelyusedinchocolateastheyaredificulttodry.Consequently,theadditionalmoisturepresent
in chocolate increases interactions between sugar particles and increases viscosity. Dextrose and
lactosecansuccessfullyreplacesucroseinmilkchocolate(Bolenz,Amtsberg,andSchape2006;
Muller2003).
Recently,sucrose-freechocolateshavebecomepopularamongconsumersandmanufacturers
because of reduced caloriic values and being noncariogenic and suitable for diabetics (Olinger
1994;OlingerandPepper2001;SokmenandGunes2006;ZumbeandGrosso1993).
Sugar alcohols, including xylitol, sorbitol, mannitol, and lactitol are used for the manufac-
tureoflower-calorieorsugar-freeproducts.However,replacementofsucrosewithsugaralcohols
affects rheological properties and, hence, processing conditions and chocolate quality (Sokmen
and Gunes 2006; Wijers and Strater 2001; Zumbe and Grosso 1993). Moreover, Sokmen and
Gunes(2006)reportedthatmaltitolresultsinsimilarrheologicalpropertiesofchocolatetosucrose
and,thus,mayberecommendedasagoodalternativetosucroseinchocolateformulations.These
authorsalsoobservedthatchocolatewithisomaltresultedinhigherplasticviscosity,andxylitol
causes a higher low behavior index. Polydextrose may be added as an edible carbohydrate and
intensesweetener.TheEUlimitsconsumptionofsugaralcoholsto20g/daybecauseoflaxative
effects(Kruger1999).
Sugarbloomisadefectinchocolateproducts,appearingaswhiteorgreylecksonthechocolate
surface.Therearetwotypesofbloom:fatbloom,whentheincorrectcrystallineformofthefatis
presentintheinalproduct,andsugarbloomcausedbymoisturemigrationratherthanbycrystal-
lizationchanges.Sugarbloomiscausedbydampstorage;dampcoolerair;impure,hygroscopic,or
brownsugars;orimproperpackaging,resultingwhenchocolateiscoatedontoacenterwithhigher
ERHthanthechocolate(Alexander1998).
Sugaralcoholsareusedinchocolatemanufacture. Theseincludemaltitol,sorbitol,mannitol,
lactitol,isomalt,andxylitol.
Sorbitolprovidesaslightcoolingeffect.Itisverysolubleandisusuallyaddedduringmixing.
Theγcrystallineformshouldbeusedinainegrade(Grenby,Parker,andLindley1983).
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