abstract
Grape pectic polysaccharides-malvidin 3-O-beta-D-glucoside binding was studied, aiming to unveil the impact of structural diversity of polysaccharides on anthocyanins-polysaccharides interactions. Polysaccharides were extracted with solutions of imidazole (ISP) and carbonate at 4 degrees C (CSP-4 degrees C) and room temperature (CSP-RT) and also recovered from the dialysis supernatant of the remaining cellulosic residue after the aqueous NAOH extraction of hemicellulosic polysaccharides (Sn-CR). Polysaccharides richer in homogalacturonan domains, like those present in the CSP-4 degrees C fraction had approximately 50-fold higher binding affinity to malvidin-3-O- beta-D-glucoside, than polysaccharides with side chains (as ISP and CSP-RT extractable polysaccharides). CSP-4 degrees C polysaccharides showed a positive effect on malvidin-3-O beta-D-glucoside colour fading. Hydration equilibrium constant of malvidin-3-O- beta-D-glucoside in the presence of CSP-4 degrees C polysaccharides was higher, showing the preferential stabilization of the flavylium cation. The results showed that anthocyanins colour stabilization can be promoted by pectic polysaccharide structures such as those extracted by cold carbonate.
keywords
BERRY CELL-WALLS; STRUCTURAL-CHARACTERIZATION; KINETIC-PROPERTIES; L.; POLYPHENOLS; BINDING; POMACE; STABILITY; POLYMERS; SULFATE
subject category
Chemistry, Applied; Chemistry, Organic; Polymer Science
authors
Fernandes, A; Raposo, F; Evtuguin, DV; Fonseca, F; Ferreira-da-Silva, F; Mateus, N; Coimbra, MA; de Freitas, V
our authors
acknowledgements
This research was financially supported by FCT/MCTES through national funds and co-financed by FEDER, under the Partnership Agreement PT2020 (UIDB/50006/2020 and QOPNA Research Unit, UID/QUI/00062/2019). Ana Fernandes gratefully acknowledges the FCT for the Research Contract (CEECIND/00029/2018). Frederico Ferreira-da-Silva was financed by FEDER - Fundo Europeu de Desenvolvimento Regional funds through the COMPETE 2020 - Operational Programme for Competitiveness and Internationalization (POCI), Portugal 2020, and by Portuguese funds through FCT - Fundacao para a Ciencia e a Tecnologia/Ministerio da Ciencia, Tecnologia e Ensino Superior in the framework of the project Institute for Research and Innovation in Health Sciences (POCI-01-0145-FEDER-007274). Fatima Fonseca financed by the project Norte-01-0145-FEDER-000008 -Porto Neurosciences and Neurologic Disease Research Initiative at I3S, supported by Norte Portugal Regional Operational Programme (NORTE 2020), under the PORTUGAL 2020 Partnership Agreement, through the European Regional Development Fund (FEDER).