Chemistry and Functional Properties of Carbohydrates and Sugars (Monosaccharides, Disaccharides, and Polysaccharides) - Sweeteners: Nutritional Aspects, Applications, and Production Technology - page 38

Seaweed extracts : The algae gums are a group of hydrocolloids that are received by algae
through extraction and puriication and are widely used in food industry. The most important of
thesearealginateoralginatesalts,carrageenan,andagar.
Alginate : Alginate is a linear polysaccharide consisting of mannuronic acid and l-guluronic
acidindifferentproportions.Alginatesalts,whichareobtainedbyreplacingalginatecationswith
sodiumorpotassium,arecommonlyused.Thealginateshavetheabilitytoformgelsthatarestable
athightemperatures.Invariousfoodapplications,thegelformationwithcalciumionsisofgreat
interest.Thealginatesmayalsoactasstabilizersinoilinwateremulsions,likeicecream,sauces,
andfruitpulp,inhibitingaggregationandphaseseparation.
Carrageenan :Carrageenanisnearlyalinearmoleculeconsistingofapolysaccharidemixture
(galactanderivatives)mainlyofsulfateordisulfategalactoseesters.Therearevarioustypesofcar-
rageenancharacterizedbytheGreeklettersκ,λ,μ,andι,whichdifferwithrespecttothemolecule
sizeandtheextentandlocationofesteriicationwithsulfuricacid,thushavingdifferentgellingand
thickeningpropertiesthatindapplicationsinfoods(Coultate2002).
Allcarrageenansaresolubleinhotwater,whereasλ-carrageenanandsodiumsaltsofκ-and
ι-carrageenanaresolubleincoldwater.λ-Carrageenangivesviscoussolutions,whichareusedas
thickenersespeciallyindairyproductsinordertoofferacreamytexture.Hotsolutionofκ-and
ι-carrageenancanformarangeofdifferenttexturegelswhencooledtotemperaturesbetween40°C
and 60°C, depending on the existing cations. Carrageenan presents synergistic interaction with
proteinsandotherstabilizers.
Agar :Agarconsistsofpartiallyesteriiedgalactanswithsulfuricacidandcanbedividedinto
twofractions:theneutralagaroseandtheacidagaropectin.Agar,asacarrageenan,issolubleinhot
waterand,eveninsmallconcentrations,cangiveconsistentgels(Lee1975).
Otherpolysaccharidesusedasthickenersorgellingagentsinfoodsareasfollows.
Xanthan :Xanthanistheirstofanewgenerationofpolysaccharidesproducedbiotechnologi-
cally.Thestructureofxanthanconsistsofaβ-1,4linkedd-glucosecentralchainsupportingatrisac-
charidechain(3,1,-α-d-mannopyranose-2,1-β-d-mannopyranose)atalternatingglycoseunits.
Somecharacteristicsofxanthanthatareimportantforindustrialapplicationsincludeitshigh
stabilitywithrespecttopH,heat,andreactiontoenzymes.Thexanthangelsmaintaintheirviscos-
ityatacertaintemperatureandarenotgreatlyaffectedbypH.Xanthanisapermittedthickening
agentinmanyfoods.Itfunctionsasastabilizerandimpartssmoothtextureandcreamyconsistency.
Itisaddedtopourabledressings,dairyproducts(suchasmilkshakesandicecream),whippeddes-
serts,sauces,gravies,anddrymixes.Owingtoitslowdigestibility,xanthanfunctionsasadietary
iber(Owusu-Apenten2005).
2.6 FUNCtIONaL prOpertIeS OF CarBOhYDrateS
Carbohydratespossessfunctionalpropertiesduetowhichtheyindusefulapplicationsinfood.
Themaineffectsonfoodsconcernthefollowingcharacteristics(Tomasik2002).
Taste :Carbohydratesareassociatedwithsweettaste,althoughsomeofthemdonotpossessthis
feature.Commonlyusedcarbohydratesassweetenersareglucose,fructose,lactose,sucrose,malt-
ose,andamylosyrup.Asmalldegreeofsugarcaramelizationcontributestothelavorandaromaof
thermallyprocessedfoods.
Color : Carbohydrates help in producing a dark brown color when sugar caramelization and
dextrinizationoccur,whicharefavoredathightemperaturesandinthepresenceofvariousaddi-
tives(Coultate2002).
Flavor :Duringheatingofcarbohydrates,substancesthatcontributetofoodlavorareproduced
(carbohydratederivativessuchasfuro-2-aldehyde).