Chemistry Reference
In-Depth Information
employedinthemanufactureofdieteticyogurts.Maplesugar;brownsugar;andsyrupmadefrom
rice,oats,andothergrainshavethepotentialtobeusedinthemanufactureoflavoredyogurt,but
atpresent,theircommercialapplicationsarefairlylimited.Thesesweetenersaregenerallyincor-
poratedintoyogurtafterfermentation.
Honey, which is a natural sweetener, consists of inverted sugar (74.5%), moisture (17.5%),
sucrose(2%),dextrin(2%),andmiscellaneous(4%)(MarshallandArbuckle2000).Theincorpora-
tionofhoneyintheproductionofsweeteneddairyproductsisnotcommon.However,successful
attempts were made to substitute sucrose with bee-honey to produce a naturally sweetened ice
cream(Groschner1998).Themajordrawbackofincorporatinghoneyinicecreamprocessingisthat
thehoneylavorpoorlyblendswithotherlavors.RizaiandZiar(2008)investigatedtheeffectof
naturalhoneyonthegrowthcharacteristicsof
Str.thermophilus
and
Lb.delbrueckii
subsp.
bulgari-
cus
employedinyogurtmakingassingleormixedcultures.Thegrowthandacidiicationcapacity
ofthe
Str.thermophilus
monoculturewasincreasedinthepresenceof10%honey.However,the
growth of the
Lb. delbrueckii
subsp.
bulgaricus
monoculture waslimited under the same condi-
tions.Thecountsandmetabolicactivitiesofmixedyogurtcultureswereaffectedadversely,result-
inginanincreasedcurdlingtimebyabout1h.Varga(2006)showedtheadditionofacaciahoney
tolavoredyogurtatlevelsvaryingfrom1%to5%didnotinluencethecountsofyogurtstarter
bacteria.Regardingthesensoryqualityoftheinalproduct,theadditionofacaciahoneyatarate
of3%wasrecommended.
Inanovelapproach,extrudedblendsofwheyproteinconcentrate35(WPC35),cornstarch,and
sugarcanebagassewith0%,25%,and50%substitutedyogurtformulaweredeveloped(Verdalet-
Guzmanetal.2011).Yogurtsubstitutedwithextrudedblendsshowedhigherviscosityandlower
syneresisvaluesthanthatwithoutblends.Additionally,yogurtswithextrudedblendsatdifferent
levelshadsensoryattributesoftaste,acidity,andtexturescoressimilartothoseobservedforyogurt
withnoextrudedblends.
In another approach, Jaros et al. (2003) investigated the possibility of replacing sucrose with
whey-basedpowdersinthemanufactureoflavoredyogurt.Theauthorsdemonstratedthatwhen
incorporatingpowdersfromwheyultrailtratepermeatesintothefruitpreparation,upto25%of
sucrosewasreplacedbyaniso-sweetamountbeforesensorydifferencesweredetected.Whenusing
dried,nanoilteredwheyultrailtratepermeate,thisamountcouldbeincreasedto30%.According
tothesameauthors,theconcentrationofmonovalentionswasthelimitingfactorforthereplace-
mentofsucrosebyaniso-sweetamountofwheypermeatepowder.
For safety reasons, the sweeteners are usually incorporated into the yogurt mix prior to
heattreatment.Theadvantagesofthisapplicationaretheeliminationofosmophilicyeastsand
moldsthatmightbepresentinthesugaringredients,preventingpostpasteurizationcontamina-
tionandbettertexturalqualityintheinalproduct.Insomecases,incorporationofsugarinto
fermented milk after incubation is required. In this situation, sugar should be added as pas-
teurizedliquidsugarorlavoredsweetenedsyrups,andextracaremustbetakentoavoidany
contamination.Usingliquidsugarismorewidelypreferredbyyogurtmanufacturersbecause
oftheeficiencyofitshandling.Fromatechnologicalpointofview,theuseofsugarseemsto
bemoreadvantageoustomanufacturers.However,productionofliquidsugarfromdrysugar
requires additional installations, such as storage tanks, pumps, heaters, strainers, etc., which
bringaboutadditionaloperationalcosts.Inordertoavoidmicrobialcontaminationtothepas-
teurizedliquidsugars,thestoragetanksareattachedwithaUVlightsource.Additionally,the
moisturecondensation,whicheasesthegrowthofmicroorganisms,shouldbepreventedbya
properventilationsystem(Özer2010).Theoptimumstoragetemperatureoftheliquidsugaris
around 30°C-32°C (Chandan and O'Rell 2006). Other speciications of liquid sugar are pre-
sentedinTable8.4.
Sucroseisthemainsweetenerusedinicecreammaking.Thedesiredsweetnessoficecream,
basedonequivalencetosucrose,rangesfrom13%-16%(MarshallandArbuckle2000).Sweeteners
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