Improvement of emulsifying behavior of pea proteins as plant-based emulsifiers via Maillard-induced glycation in electrospun pea protein-maltodextrin fibers.

Abstract

Heat-treated electrospun pea protein isolate (PPI)-maltodextrin fibers containing glycated PPI were analyzed for their interfacial tension and emulsifying properties compared to unheated electrospun PPI-maltodextrin fibers. Interfacial tension at the oil-water-interface of the heated fibers was higher (19.2 ± 0.1 mN m-1) compared to the unheated fibers (16.3 ± 1.4 mN m-1) due to the covalently bound hydrophilic maltodextrin in the glycoconjugates. Applied in oil-in-water emulsions (10% w/w oil, 0.7% protein, 103.4 MPa, 3 passes), unheated PPI-maltodextrin fibers produced large droplets (72-259 μm) with multimodal distributions in the pH range of 2-7. The largest droplet size was at pH 4, which was around the pI of PPI. Emulsions were also prone to flocculation, which was most probably caused by a depletion flocculation mechanism due to an excess of maltodextrin in the aqueous phase. In contrast, emulsions made with heated PPI-maltodextrin fibers were monomodal (36-55 μm) at pH 2-7 and only showed a minor increase in droplet size close to the pI of PPI. The improved properties of heated PPI-maltodextrin fibers were ascribed to the enhanced steric repulsion caused by the covalently bound maltodextrin. The results indicate that Maillard-induced glycation of PPI with maltodextrin in electrospun fibers can be used as a novel method to improve the properties of PPI as a plant-based emulsifier.