Intermolecular binding of blueberry anthocyanins with water-soluble polysaccharides: Enhancing their thermostability and antioxidant abilities

This study investigated the protective effect of β-glucan (BG), konjac glucomannan (KGM) and xanthan gum (XG) on thermo-stability and antioxidant capacities of blueberry anthocyanins (ACN) and their interaction mechanisms. Twenty-six glycosylated and acylated ACN were identified, and malvidin-3- O -galactose was predominant (36.78 %) in ACN extracts. Three polysaccharides retained colour and stability and antioxidant capabilities of ACN under thermal-treatments (XG > KGM > BG). Rheological properties (shear stress, apparent viscosity) of three polysaccharides were enhanced in presence of ACN. UV–visible spectra, SEM and DLS results indicated that co-aggregation between ACN and specific zones of these polysaccharides was formed. TGA and DSC studies confirmed that introduction   of three polysaccharides, especially XG could improve thermostability of ACN. FTIR, and molecular dynamics simulations revealed that thermo-stabilization of polysaccharides-ACN conjugates might be attributed   to their intermolecular interactions mainly via hydrogen bindings. The protection by water-soluble polysaccharides foresees novel anthocyanins in food products with increased heat-resistant stability.