Encapsulation of betacyanins and polyphenols extracted from leaves and stems of beetroot in Ca(II)-alginate beads: A structural study

The aim of this work was to use the recovery of antioxidant compounds (betacyanin and polyphenols) derived from beetroot industrial wastes (stems and leaves), and their subsequent encapsulation in Ca(II)-alginate beads containing sugars, providing a detailed structural characterization of these systems determined by SAXS from the molecular (arrange of Ca(II)-alginate dimers) to the supramolecular (interconnection of the rods composing the hydrogel microstructure). Water extract contained significant quantities of betacyanin and polyphenol, which were retained in Ca(II)-alginate beads between 15 and 60%, depending on the formulation, retaining also the antioxidant activity. Both the inclusion of sugars as synthesis additives and beetroot extracts induced main structural changes, which can have counteracting effects. We revealed that, though being overlooked in most alginate encapsulation research, the presence of natural extracts prompts important structural changes in the alginate network, affecting key parameters which define the encapsulation performance in most of industrial and environmental applications.