Anthocyanin stabilization by chitosan-chondroitin sulfate polyelectrolyte complexation integrating catechin co-pigmentation

The thermochemical instability of anthocyanins (ATC) presents a challenge to their utilization as natural colorants in many food systems. This is addressed herein with the development of polysaccharide based carriers formed by combined encapsulation and copigmentation approaches which utilize polyelectrolyte complexation between chitosan and chondroitin sulfate (CS). At pH 3, a 1.5 mg/mL and 1: 1 wt ratio mix of both polysaccharides produced hydrophilic and positively charged polyelectrolyte complexes (PECs) with which a maximum ATC encapsulation efficiency of 88% could be achieved using a 1: 6 elderberry extract as the ATC source. ATC coupled with EGCG co-pigmentation achieved the highest encapsulation efficiencies. Storage studies showed the combination of polysaccharide encapsulation and EGCG copigmentation improved ATC stability against elevated temperature and ascorbic acid. Copigmented PECs were shown to retain ATC color at a rate more than 3-fold greater than of non-encapsulated ATC, and, furthermore, were shown to improve and preserve ATC anti-oxidant activity and stability during storage.