Chemistry Reference
In-Depth Information
thesurfacetensionandpHofitssolutionsshouldnotleadtoexcessivefoaming,forexample,in
carbonatedsoftdrinks.Inaqueoussolution,thestabilityofNTMvariesstronglywiththepHand
the temperature. Like APM, NTM is relatively stable at pH from 3 to 5.5. The optimal pH for
NTMstabilityis4.5.ThedegradationofNTMfollowsapseudo-irst-orderkinetics.AtpH4.5,
thehalf-lifeofNTMis30weeksat25°C,45daysat40°C,and40hat80°Cin0.1Mphosphate
buffers.AtpH3,thehalf-lifeofNTMis11weeksat25°C,22daysat40°C,and24hat80°C.
ThestabilityofNTMat80°CinpHrangeof3-5.5impliesthathigh-temperatureshort-timepro-
cessingispossiblewithfoodproductssweetenedwithNTM;forexample,after30minat80°C,
NTMpercentageremaininginapH3solutionis98.6%,whichindicatesthatthereispractically
nolossofNTMwithin30minat80°C.AtpH7,thehalf-lifeofNTMis2weeksat25°C,3days
at40°C,and4hat80°C.
4.10 SaCCharIN
Saccharin(SAC)ischaracterizedasanartiicialhigh-intensitysweetener.Itisalsocallednon-
nutritivesweetener,andtodayiscommonlyusedinthefoodindustry.However,inthepast,saccha-
rinwasusedinavarietyofapplicationsapartfromitsmajorknownusetodayasasweetener.Itwas
irstusedasanantisepticandpreservativetoretardfermentationinfood.Lateron,saccharinwas
usedintheplasticindustryasanantistaticagentandasamodiier.Saccharinhasbeenevenusedas
abrightenerinnickel-platedautomobilebumpers(Arnoldetal.1983).Saccharinistheoldesthigh-
intensitysweetener.Itiscommerciallyavailableinthreeforms:acidsaccharin,sodiumsaccharin
(Figure4.8),andcalciumsaccharin.Sodiumsaccharinisthemostcommonlyusedformbecauseof
itshighsolubilityandstability.Saccharinanditssaltsintheirsolidformshowgoodstabilityunder
conditionspresentinsoftdrinks.However,atlowpH,theycanslowlyhydrolyzeto2-sulfobenzoic
acidand2-sulfamoylbenzoicacid.Nowadays,itisexclusivelyusedforlow-caloriefoodintakethat
helpsconsumerstomaintaintheirweight.Itisalsomedicallysuggestedtodiabeticstoconsume
foodscontainingsaccharininsteadofsugar.
Saccharin (1,2-benzisothiazol-3(2H)-on-1,1-dioxide) is the oldest sweetener on the market. It
wasdiscoveredaccidentallyin1879byConstantinFahlberg,agraduatestudentatJohnsHopkins
University.Hewasworkingonthesynthesisoftoluenederivatives.Oneday,whilehavinghislunch,
hetastedsomethingsweetinhisbread(SardesaiandWaldshan1991).Thissweettastewasattrib-
utedtoacompoundknowntodayassaccharin.
Itisawhitecrystallinepowderwithanintenselysweettasteandisavailableinthreeforms(acid
saccharin, sodium saccharin, and calcium saccharin). Aqueous solutions of saccharin are slightly
acidic.Calciumandsodiumsaltsofsaccharinareneutralandslightlybasic.Themeltingpointofacid
saccharinis228.8°C-229.7°C,whereasthesaltsdecomposeabove300°C.Saccharinischaracter-
izedbyitshighsolubility,stability,andbittermetallicaftertaste.Saccharinisabout300-500times
sweeterthansugar.Theexcellentstabilityofsaccharinunderfoodprocessingmakesitideallysuited
inmanydifferentproducts.Itisusedinawiderangeofcaseswhereheatprocessingisrequired(e.g.,
jams, canned products). However, at low pH (2.5), it can slowly hydrolyze to 2-sulfobenzoic acid
and2-sulfoamylobenzoicacid(Pearson1991).Saccharinisusedinawidevarietyoffoodproducts
O
N
-
Na
+
SO
2
Figure 4.8
Chemical structure of saccharin (sodium salt).
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