Enhancement of the oxidative stability of linseed oil in Pickering emulsions stabilized by polydopamine-modified cellulose nanocrystals

Abstract

Virgin linseed oil-in-water emulsions stabilized by unmodified or polydopamine-modified cellulose nanocrystals (CNCs) were prepared in the presence of NaCl. The production of primary oxidation products (i.e. conjugated dienes, or CD) was evaluated over time for both types of emulsions and compared with that of a control emulsion stabilized by a surfactant (sodium dodecyl sulfate or SDS). The evolution of CD over time was found to depend on the droplet interfacial area and concentration of introduced prooxidants (Fe(+II) ions). While unmodified CNCs retarded oil oxidation compared with SDS, their protective properties could be further improved by coating the nanoparticles with polydopamine, using a simple and environmentally-friendly protocol; a negligible oxidation of the oil was indeed measured after 57 days, despite the presence of a high concentration of Fe(+II) ions.