Construction and characterization of antioxidative ferulic acid-grafted carboxylic curdlan conjugates and their contributions on 8-carotene storage stability

Grafting copolymerization of phenolic acids onto polysaccharides is an important strategy to improve their biological activities. In this study, ferulic acid (FA)-grafted carboxylic curdlan conjugates, namely, Cur-8 -g-FA, Cur-24 -g-FA, and Cur-48 -g-FA, were synthesized by free radical-induced grafting. Results showed that FA was covalently grafted onto carboxylic curdlans via ester bonds. The grafting ratios of Cur-8 -g-FA, Cur-24 -g-FA, and Cur-48 -g-FA were 223.03 +/- 12.63, 115.63 +/- 5.96, and 152.30 +/- 4.57 mg FA/g, respectively, which were related with the carboxylate contents, molecular weights, and chain conformations of carboxylic curdlans. Compared with carboxylic curdlans, the FA-grafted carboxylic curdlan conjugates had lower thermal stability, molecular weight, and rheological property and looser surface morphology but had more prominent antioxidant benefits in vitro, which were proportional to their grafting ratios. Moreover, good storage stability against chemical degradation was exhibited by the 8-carotene in Pickering emulsions stabilized by Cur-8 -g-FA with a high grafting ratio and molecular weight.

Automated summary

In this study, ferulic acid-grafted carboxylic curdlan conjugates were successfully synthesized via free radical-induced grafting, showing more prominent antioxidant benefits in vitro proportional to their grafting ratios. Compared with carboxylic curdlans, the grafted conjugates had lower thermal stability, molecular weight, and rheological property, as well as looser surface morphology.