Chemistry Reference
In-Depth Information
8.8 FreeZING FrUIt
Fruitstobefrozenbeneitfromeitheradrysugarpackorfreezinginsugarsyrup.Foradrysugar
pack,thefruitisgentlymixedwithsugarinagivenproportionsothateachpieceiscoated.Thechoice
ofdryorsyruppackgenerallydependsontheusetowhichthefrozenfruitistobeput.Fruitspackedin
syrupareusuallychosenfordessert,andfruitspackedindrysugararepreferredforcookingpurposes.
Somefruits,suchasblueberries,cranberries,raspberries,andrhubarb,maybefrozeninadry
packwithoutsugar;however,theseandallotherfruitsbeneitgreatlyfromasugarpackregardless
ofthetypeused(dryorsyrup).
Sugarhelpsprotectthesurfacesoffrozenfreshfruitfromcontactwithair,whichproducesenzy-
maticbrowningdiscolorationresultingfromoxidation.Insomefruits,suchaspeaches,nectarines,and
apricotsfrozeninasyruppack,ascorbicacidisalsoaddedtopreventdarkening.Thepresenceofsugar
alsolessenslavorchangebyretardingpossiblefermentation.Inaddition,texture,freshfruitaroma,and
normalsizeareretaineduponthawingwhensugarisusedinfreezingfruit(Pintauro1990).
1. Checkthevarietyoffruittogivethehighestqualitywhenfrozen.
2. Makeandchillsyrup.Ifascorbicacidoranyotherantibrowningagentisused,thisshouldbeadded
tothesyrupbeforeuse(onlywhenfreezinglight-coloredfruitsindrysugartoavoidbrowning).A
mediumsyrup(40%)ispreferredformostfruits.
3. Usefullyripebutnotoverripefruitsofinelavorandcolor.Washtheminicecoldwater,thendrain,
hull,andpitorpeel.Fruitsshouldbehandledgentlytoavoidbruising.
4. Freezefruitsinsyruporsugar,dependingonthefruitbeingfrozenandtheintendeduse.Mostfruits
havebettercolor,texture,andlavorwhenfrozeninsyrupandareusuallybestfordessert.
5. Packfruitswhileleavinganappropriateamountofheadspace.
6. Place containers into the freezer as soon as they are packed. Freezer should be at −18°C during
freezingandstoring.
8.9 SUGarS aND SWeeteNerS IN BaKerY prODUCtS
Cakes, cookies, breads, and croissants require sugar for lavor, color, texture, improved shelf
life,yeastfermentation,andmoistureretention.
Whatarethefunctionalrolessugarplaysinbakedproducts?
8.9.1 Gluten Development
Duringdoughmixing,lourproteinsarehydrated,formingglutenstrands.Glutenformsthou-
sandsofsmall,balloon-likepocketsthattrapgasesproducedduringleavening.Theseglutenstrands
arehighlyelasticandallowthedoughtostretchundergasexpansion.However,iftoomuchgluten
develops,thedoughbecomesrigidandtough(Gates1981;Ponte1990).Glutenresultsfromthemix-
ingofthewheatproteinsgliadinandglutenininthepresenceofwater.
Sugarcompeteswiththesegluten-formingproteinsforwaterinthedoughandpreventsthefull
hydrationoftheproteinsduringmixing.Ifsugarisaddedcorrectlyintherecipe,glutenmaintains
optimumelasticity,allowingforgasestobeheldwithinthedough.Sugarpreventsglutendevelop-
mentandgivestheinalbakedproductgoodtextureandvolume(Beranbaum1985;Ponte1990).
8.9.2 Leavening
Under moisture and growth, sugar is broken down by yeast cells, and carbon dioxide gas is
releasedatafasterrate.Sugarincreasestheeffectivenessofyeast.Theleaveningprocessishastened
anddoughrisesatafasterrate(Knecht1990).
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