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Availableonlineat AssociationoftheChemicalEngineers AChE www.ache.org.rs/CICEQ ChemicalIndustry&ChemicalEngineeringQuarterly17(1)59 −66(2011) CI&CEQ 59 BADHERDINE 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,andthe eff ect ofthe additi onof nat ural ant ioxida nts. The app roachwas based ona uice- like liqui d mediu m (10.1 ° Bx, pH 3.48), whi ch was used as the mod el matrixtotesttheeffectoftheadditionofnaturalantioxidants( L-cysteine,as- corbi c acid, catech in and querce tin)on the degra dabil ity of antho cyanin pigments,extractedfromgrapepomace.Itwasfoundthattreatmentofthemodel sol uti ons at 80 ° C induce d ant hocyanin decomp osi tio n, whi ch obeyed fir st orderkinetics.Additionofincreasingamountsofantioxidants,including L-cysteine,ascorbicacid,catechinandquercetin,didnotprovokeaproportionalim- pact,eith erpositiv eornegative,with regardtoanthocya ninstabil ity.Thebest stabi lisin geffectwasseenafteraddi tionofascorb icacidandcatechi natcon- centrationsof4and2mgL -1 , respec tivel y (P < 0.001) . Quercetin,however, wasdemons trated a veryeffic ientco-p igmen t,induci nganincrease inA 520 by 63%,atpH5.6andacopigment-to-pigmentratioof10. Key words: ant hocyanin; co- pig mentat ion ; model systems; natural ant ioxi- dants;thermaldegradation. Thefoodindustry,followingscientificandtech- nologicaldevelopmentsandbeingclosetomarketde- mands, takes into accoun t the consumers’ concer ns and prefer ence for naturally coloure d food, adopting new,moreprotectivetechnologiestoobtainfoodco- lorants[1].Ithasbeenrecognisedformanyyearsthat anthocyanins mak e a significant con trib ution to the colour,andhenceacceptability,ofmanyfruits,some vegetablesandassociatedproducts,includingbeve- rages. The re is worldwide interest in additional use of anthocyaninsasaconsequenceofperceivedconsu- mer preferenc es as well as legislativ e act ion, which hascontinuedthedelistingofapprovedartificialdyes. Ant hoc yan in-r ich ext rac ts thu s migh t have pot ent ial as food additives, and in this view a number of resi- dualsourceshavebeenproposedforanthocyaninre- cov ery , including grapes [2–4]. However, one of the majorlimitingfactorsintheutilisationofanthocyanins Correspondeningauthor:D.P.Makris,DepartmentofFoodSci- ence and Nutrition, Uni ver sit y of the Aeg ean , 2, Mitr. Ioakim, 81400,Lemnos,Greece. E-mail:[email protected] Paperreceived:01July,2010 Paperrevised:13August,2010 Paperaccepted:02October,2010 asfoodcolorant sistheirstabilityasprimar yextracts , especiallyinaqueousenvironments,commonlyfound inmostfoodmatrices. Anthoc yanins are unstab le,particularlyoncere- movedfromtheirnativeenvironmentandtheprotec- tionaffordedbycopigmentation[5].Asaconsequen- ce,varioustransformationsoccurduringtheproces- sing or domest ic coo king of foo ds contai ning antho- cya nins, pro duc ing yel lowish or bro wnis h pigmen ts whicharelargelyuncharacterised.Further,theampli- tudeofvariationsinthepotentialofanthocyaninsas pig ment s was reported to be dependent on certain basicco-actingfactors,includingpH,temperature,the natureoftheanthocyanicchromophoreandthepre- senceofco-pigments[6]. In spite of the quite a few data on the antho- cyanincomp osition ofgrapeby-product s[4,7-10] ,the sta bility of the anthocyanin ext racts is ill cha rac ter i- sed.Forthisreason,thisstudywasundertakenwith thescopetoexamineanypossibleeffectofselected natural antio xi dants on the st ability of anthocyanin pigmentsextractedfromgrapepomace.Forthisrea- son,ajuice- likemodelmatrixwasemployedtoinv es- tigatethestabilityofanthocyaninsinresponsetothe additionofvaryingamountsofascorbicacid, L-cyste-

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