title: Impact of a pectic polysaccharide on oenin copigmentation mechanism.
abstract: Copigmentation plays an important role in the colors provided by anthocyanins. However, little attention has been paid to the interaction between anthocyanins and cell wall compounds (e.g. polysaccharides) and the impact of this interaction on anthocyanins color, a fundamental issue to be considered in industrial applications of these pigments as food colorants. The copigmentation binding constants (KCP) for the interaction between malvidin-3-O-glucoside and (+)-catechin in the presence of low methoxylated pectic polysaccharide were determined. The values obtained showed that in the presence of pectic polysaccharide the copigmentation binding constants decreased. These results probably suggest the occurrence of competition equilibrium in which the presence of pectin limited the association between catechin and oenin. (1)H NMR studies revealed that the dissociation constant determined for these complexes was very similar in absence and presence of 1.5g/L pectin with this polysaccharide apparently not affecting the strength of anthocyanin-catechin binding.
authors.affiliation: REQUIMTE⧹LAQV, Departamento de Química e Bioquímica, Faculdade de Ciências, Universidade do Porto, Rua do Campo Alegre, s/n, 4169-007 Porto, Portugal. Electronic address: ana.fernandes@fc.up.pt.
authors.forename: Ana
authors.initials: A
authors.lastname: Fernandes
authors.affiliation: REQUIMTE⧹UCIBIO, Departamento de Química e Bioquímica, Faculdade de Ciências, Universidade do Porto, Rua do Campo Alegre, s/n, 4169-007 Porto, Portugal.
authors.forename: Natércia F
authors.initials: NF
authors.lastname: Brás
authors.affiliation: REQUIMTE⧹LAQV, Departamento de Química e Bioquímica, Faculdade de Ciências, Universidade do Porto, Rua do Campo Alegre, s/n, 4169-007 Porto, Portugal.
authors.forename: Joana
authors.initials: J
authors.lastname: Oliveira
authors.affiliation: REQUIMTE⧹LAQV, Departamento de Química e Bioquímica, Faculdade de Ciências, Universidade do Porto, Rua do Campo Alegre, s/n, 4169-007 Porto, Portugal.
authors.forename: Nuno
authors.initials: N
authors.lastname: Mateus
authors.affiliation: REQUIMTE⧹LAQV, Departamento de Química e Bioquímica, Faculdade de Ciências, Universidade do Porto, Rua do Campo Alegre, s/n, 4169-007 Porto, Portugal.
authors.forename: Victor
authors.initials: V
authors.lastname: de Freitas
mesh_terms: D000872:Anthocyanins / Q000737:chemistry / Q000378:metabolism*; D002392:Catechin / Q000737:chemistry / Q000378:metabolism*; D003116:Color; D005960:Glucosides / Q000737:chemistry / Q000378:metabolism*; D010368:Pectins / Q000737:chemistry / Q000378:metabolism*; D010858:Pigmentation; D010860:Pigments, Biological / Q000737:chemistry / Q000378:metabolism*
chemical_list: D000872:Anthocyanins; D005960:Glucosides; D010860:Pigments, Biological; C458419:malvidin-3-glucoside; D010368:Pectins; D002392:Catechin
keywords: Anthocyanins; Copigmentation; Dissociation constants (K(d)); Pectic polysaccharides