Chemistry Reference
In-Depth Information
Aspartame is one of the irst artiicial sweeteners that was approved by the FDA in 1988 to
useinyogurt-typeproducts(VanderVen1988;Kelleretal.1991).Thesweetnesscharacteristics
ofaspartameshowsimilaritiestothatofsucrose(Kelleretal.1991;NutraSweet1996).According
toFarooqandHaque(1992),thereplacementofsucrosebyaspartameinyogurtmakingresultsin
some50%reductioninthecaloriespercup.Thesweeteningpowerofaspartameisgenerallygreater
atlowconcentrationsandinproductsstoredatroomtemperature.
Thestabilityofsweeteningagentsduringprocessingorcoldstorageofyogurtisadecisivefac-
torfortheirincorporationintothemanufacturingprocess.Lotz,Klug,andKreuder(1992)found
thataspartamewasdegradedduringfermentation,butacesulfameKformedastablesweetening.
AnoppositeindingwasreportedbyFellows,Chang,andKeller(1991)whodemonstratedthatthe
recoveryofaspartamewas95%and90%insundae-styleyogurtsproducedusinga6-hincubation
at 43.3°C and 13 h at 32.2°C, respectively. The stability of aspartame in three fruit preparations
storedfor6monthsatthreedifferenttemperatures(i.e.,32.2°C,21.1°C,and4.4°C)wasassessedby
Fellows,Chang,andShazer(1991).Theauthorsshowedthat~60%oforiginalaspartameremained
stableafter6monthsat21.2°C.ThejointeffectofpH,time,andstoragetemperaturewasfound
tobedeterminativeonthestabilityofaspartameinfruitpreparations.Therateofdegradationof
aspartameinyogurtiscloselyrelatedwiththegrowthandmetabolicactivitiesofthestarterbacteria
(Kelleretal.1991).Ingeneral,thelowerthemetabolicactivityofthestarterbacteria,thelowerthe
degradationofaspartameduringprocessingand/orstorage.Inreverse,thepresenceofaspartame
didnotaffecttheviabilityofhuman-derivedprobioticbacteria(
Lb.acidophilus
,
Lb.agilis
,and
Lb.
rhamnosus
)inicecream(Basyigit,Kuleasan,andKarahan2006).
Aspartamecanwithstandawiderangeofheattreatments(Table8.5).Thisisparticularlyimpor-
tantforlavoredmilksandyogurtstowhichaspartameisaddedpriortofermentation.
Themilkcomponentsmayaffectthesweetnessperceptioninyogurtssweetenedbyartiicial
sweeteners.Althoughmilkfatcontributestothesweetnessperceptioninyogurt,theeffectofaspar-
tameonthischaracteristicismuchgreater(King,Lawler,andAdams2000).Withtheincreasein
thelevelofaspartame(i.e.,400or600ppm),thefruitylavor,metallicnotes,andsweetnesswere
stronger.Onthecontrary,thiseffectwasnotfoundinyogurtcontaininglowlevelsofaspartame
(i.e.,200ppm)(King,Lawler,andAdams2000).Replacementofmilkfatbymicroencapsulated
whey proteins as a fat substitute (e.g., Dairy Lo™) affected the perception of acid taste in fruit
yogurtsweetenedwithaspartame(Brandão,Silva,andReis1995).Therefore,thelevelofaspartame
maybereducedwhenDairyLo™isusedatrelativelyhigheramounts(e.g.,>2%-3%).
Yogurtgelisprimarilybasedontheprotein-proteininteractions,andthisassociationisinlu-
encedbyamphipathicpeptides,suchasaspartame(MozaffarandHaque1992;Haque1993).This,
inturn,mayaffectthevoidspacesofthecaseinnetwork,whichalsoinluencesthelevelofsyn-
eresis of yogurt. Haque and Aryana (2002) compared the effects of sugar and aspartame on the
microstructureoflavoredyogurt.Theauthorsconcludedthatwhenaspartamewasused,thecasein
micelles formed double longitudinal polymers. In contrast, sugar caused casein micelles to form
clusters. In the yogurt containing no sweetener, the gel network was formed predominantly by
casein micelles arranged in longitudinal polymers. Aspartame stimulated the polymerization of
caseinmicelles.Kumar(2000)incorporatedaspartame(atalevelof0.08%)intheproductionof
table 8.5
Stability of aspartame toward Various heat treatments
heat treatment
ph
Loss in aspartame (%)
UHT (121°C-135°C for 15 s)
2.5-3.5
0.5%-1.5%
Pasteurization (VAT system 80°C for 15 min)
2.6-4.2
2.0%-4.0%
HTST (72°C for 15 s)
3.5
<1.0%
Hot illing (88°C)
3.5
3.0%-6.0%
High-heat treatment (90°C for 20 min)
3.8
<5.0%
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