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