Quality Control of Sweeteners: Production, Handling, and Storage - Sweeteners: Nutritional Aspects, Applications, and Production Technology - page 290

Theacesulfamecompactsdemonstratedarelativelylow H 0 ,andtheaspartamecompactsdem-
onstratedarelativelyhigh H 0 .Thisindicatesacesulfamecompacts(whichwereinthelower20%
of the excipient population) deformed rather easily, suggesting interparticulate bonding surfaces
formedrelativelyeasily.
Onewouldtypicallyprefertoselectmaterialswithmoderate H 0 ,forexample,withintheinter-
quartile range ( H 0 ≈ 100-250 MPa), such as sucrose and saccharin, whose particles deform well
underrapidcompression.
Thequasistaticindentationhardness( H 10 )ofacompactisdeinedasthepressurerequiredto
plasticallydeformacompactduringextremelyslowindentation.
Thetwoindentationhardnessmeasurementsforeachmaterialfollowedasimilartrend:aspar-
tame > saccharin ~ =sucrose > acesulfame.
Theelasticmoduliofthesweetenersweredeterminedbythemeasurementofthedentrecovery
duringquasistaticindentationhardnesstesting.Thesematerialsareconsideredtodemonstratemod-
erateelasticity.Theexperimentalresultsshowedthatmostofthetensilestrengthsofthesweetener
compactswerenotablydifferent(aspartame>saccharin > sucrose ~ =acesulfame).Becausetensile
strengthisproportionaltothetabletcrushingstrength,thishasasigniicanteffectonmeasurable
tabletpropertyperformance.Theaspartamecompactswereapproximately5timesstrongerthanthe
sucrosecompacts,7timesstrongerthantheacesulfamecompacts,and2.5timesstrongerthanthe
saccharincompacts(Mullarneyetal.2003).
9.24 pUrIFICatION teChNIQUeS
Fortheapplicationofsweetenersasadietarysupplementoradrug,safeandsustainablepurii-
cationtechniquesareneeded.
The use of solvents should be avoided as much as possible. Although the sweeteners can
be extracted with water, current puriication techniques still make use of methanol or ethanol
(Carakostasetal.2008).Kutowy,Zhang,andKumar(1999)weretheirsttoproposeamembrane-
basedpuriicationprocess.Aftertheextractioncolumn,theirprocessconsistsofamicroiltration
and an ultrailtration membrane stage to remove impurities with a higher molecular weight than
rebaudioside A and, inally, a nanoiltration membrane stage to remove impurities with a lower
molecularweightthanstevioside.Zhang,Kumar,andKutowy(2000)presentedsomeinteresting
lab-scaleresultsconcerningthisprocessconiguration;however,productpurityandyieldwerenot
mentioned.Althoughthepuritycanbemeasuredeasilybasedonthesweetenercontentandtotaldry
weightofasample,itisveryimpracticaltomeasureforlab-scalemembraneprocesses,especially
whenmanydifferentmembranesandconditionsaretestedtooptimizetheprocessbecauseofthe
presenceofalargeamountofpermeate,soanaccuratereadingofthedryweightonastandardbal-
anceistaken.
Reisetal.(2009)studieddifferentmicroiltrationmembranesandconditionsandproposedto
usetheUVabsorptionat420nmand670nmasspeciicindicatorsfortheimpuritycontentasthe
sweetenersonlyabsorbat210nm.
Vannesteetal.(2011)preparedpolyethersulfonemembranesusingthediffusion-inducedphase
inversiontechnique(Boussuetal.2006).Inthisprocess,athinlayerofthepolymerdissolvedinan
appropriatesolventiscastonasupport,andphaseseparationisinducedbyanonsolvent.Themost
eficientwayofinducingthephaseinversionisbyimmersingthepolymersolutionilminanonsol-
ventbath.Bychangingthepreparationfactors,anoptimizedmembraneforaspeciicpurposecan
beobtained.Threeparameterswerevariedtostudytheeffectonpermeabilityandselectivity:the
polymerconcentration,compositionofthenonsolventbath(water-isopropanol,IPA,mixture),and
amixtureofsolvents—dimethylformamide(DMF)orN-methylpyrrolidone(NMP).