Impact of grape pectic polysaccharides on anthocyanins thermostability

• Autor(a) principal: Fernandes, Ana
• Data de Publicação: 2020
• Outros Autores: Brandão, Elsa, Raposo, Filomena, Maricato, Élia, Oliveira, Joana, Mateus, Nuno, Coimbra, Manuel A, de Freitas, Victor
• Tipo de documento: Artigo
• Idioma: eng
• Título da fonte: Repositório Científico de Acesso Aberto de Portugal (Repositórios Cientìficos)
• Texto Completo: http://hdl.handle.net/10773/37278
• topic: Anthocyanins; Grape skins; HPLC-DAD; NMR; Pectic polysaccharides; Thermostability

The impact of grape pectic polysaccharides on malvidin-3-O-β-d-glucoside thermostability was evaluated in model solutions. Pectic polysaccharides richer in homogalacturonan domains, with less neutral sidechains (chelator fraction) showed higher binding with malvidin-3-O-β-d-glucoside, by 1H NMR (Ka=505 M-1). Binding affinity with water soluble extract was estimated to be 10-fold lower, possibly due to the presence of neutral branched regions and more compacted structure, hampering the binding. Hydrophobic domains, such as rhamnogalacturonans-I domains in acid soluble polysaccharides, may participate in the formation of complexes with malvidin-3-O-β-d-glucoside. The thermostability of anthocyanin-polysaccharides complexes was evaluated at different temperatures, assessing anthocyanins degradation by HPLC-DAD. Polysaccharides showed to improve anthocyanin thermostability, with chelator and acid extract having the highest impact at lowest temperatures. Electrostatic interactions, additionally stabilized by hydrophobic effect contribute to the anthocyanin-polysaccharides binding and to the consequent thermostabilization. The protection provided by grape pectic polysaccharides foresees innovative anthocyanin food products with improved thermostability and colour features.