AvailableonlineatAssociationoftheChemicalEngineersAChE www.ache.org.rs/CICEQChemicalIndustry&ChemicalEngineeringQuarterly17(1)59 −66(2011)CI&CEQ 59BADHERDINE SIDANI 1 DIMITRIS P. MAKRIS 2 1 Food Quality and Chemistry of Natural Products Programme, Mediterranean Agronomic Institute of Chania (M.A.I.Ch.), Chania, Greece 2 Department of Food Science and Nutrition, University of the Aegean, Lemnos, Greece SCIENTIFIC PAPER UDC 547.973:58:66.094 DOI 10.2298/CICEQ100701055S INTERACTIONS OF NATURAL ANTIOXIDANTS WITH RED GRAPE POMACE ANTHOCYANINS IN A LIQUID MODEL MATRIX: STABILITY AND COPIGMENTATION EFFECTS Thepurposeofthisstudywasanexaminationofthestabilityandcolouren-hancementofredgrapepomaceanthocyaninsinajuicemodelmatrix,andtheeff ect oftheadditi onofnat ural ant ioxida nts.Theapp roachwasbasedonauice- likeliqui dmediu m(10.1 °Bx, pH3.48), whi chwasusedasthemod el matrixtotesttheeffectoftheadditionofnaturalantioxidants(L-cysteine,as-corbi cacid, catech inandquerce tin)onthedegra dabil ityofantho cyanin pig-ments,extractedfromgrapepomace.Itwasfoundthattreatmentofthemodelsol uti onsat80°Cinduce dant hocyanindecomp osi tio n,whi chobeyedfir storderkinetics.Additionofincreasingamountsofantioxidants,includingL-cys-teine,ascorbicacid,catechinandquercetin,didnotprovokeaproportionalim-pact,eith erpositiv eornegative,with regardtoanthocya ninstabil ity.Thebeststabi lisin geffectwasseenafteraddi tionofascorb icacidandcatechi natcon-centrationsof4and2mgL -1,respec tivel y(P<0.001) .Quercetin,however,wasdemons trated averyeffic ientco-p igmen t,induci nganincrease inA 520by63%,atpH5.6andacopigment-to-pigmentratioof10.Keywords: ant hocyanin; co- pig mentat ion ;model systems;natural ant ioxi-dants;thermaldegradation.Thefoodindustry,followingscientificandtech- nologicaldevelopmentsandbeingclosetomarketde- mands, takesintoaccoun ttheconsumers’concer nsandprefer encefornaturallycoloure dfood,adoptingnew,moreprotectivetechnologiestoobtainfoodco- lorants[1].Ithasbeenrecognisedformanyyearsthatanthocyaninsmak easignificant con trib utiontothe colour,andhenceacceptability,ofmanyfruits,somevegetablesandassociatedproducts,includingbeve- rages.The reisworldwideinterest inadditional useof anthocyaninsasaconsequenceofperceivedconsu- mer preferenc esaswell aslegislativ eact ion, whichhascontinuedthedelistingofapprovedartificialdyes.Ant hoc yan in-r ich ext rac tsthu smigh t havepot ent ial asfoodadditives, andinthisviewanumberof resi- dualsourceshavebeenproposedforanthocyaninre- cov ery , includinggrapes [2–4]. However, one of the majorlimitingfactorsintheutilisationofanthocyaninsCorrespondeningauthor:D.P.Makris,DepartmentofFoodSci- enceand Nutrition, Uni ver sit yof the Aeg ean , 2, Mitr. Ioakim, 81400,Lemnos,Greece.E-mail:[email protected]Paperreceived:01July,2010Paperrevised:13August,2010Paperaccepted:02October,2010asfoodcolorant sistheirstabilityasprimar yextracts ,especiallyinaqueousenvironments,commonlyfound inmostfoodmatrices.Anthoc yanins areunstab le,particularlyoncere- movedfromtheirnativeenvironmentandtheprotec- tionaffordedbycopigmentation[5].Asaconsequen- ce,varioustransformationsoccurduringtheproces- sing ordomest iccoo king of foo dscontai ning antho- cya nins, pro duc ingyel lowishorbro wnis hpigmen tswhicharelargelyuncharacterised.Further,theampli- tudeofvariationsinthepotentialofanthocyaninsaspig ment swasreportedtobedependent oncertain basicco-actingfactors,includingpH,temperature,thenatureoftheanthocyanicchromophoreandthepre- senceofco-pigments[6].Inspite of thequite afewdataon theantho- cyanincomp osition ofgrapeby-product s[4,7-10] ,thesta bilityof the anthocyaninext ractsisill cha rac ter i- sed.Forthisreason,thisstudywasundertakenwiththescopetoexamineanypossibleeffectofselectednatural antio xi dantsonthest abilityof anthocyaninpigmentsextractedfromgrapepomace.Forthisrea- son,ajuice- likemodelmatrixwasemployedtoinv es- tigatethestabilityofanthocyaninsinresponsetotheadditionofvaryingamountsofascorbicacid,L-cyste-