Effect of Glycation on the Flocculation Behavior of Protein-Stabilized Oil-in-Water Emulsions

Abstract

Glycation of proteins by the Maillard reaction is often considered as a method to prevent flocculation of protein-stabilized oil-in-water emulsions. The effect has been suggested, but not proven, to be the result of steric stabilization, and to depend on the molecular mass of the carbohydrate moiety. To test this, the stabilities of emulsions of patatin glycated to the same extent with different mono- and oligosaccharides (xylose, glucose, maltotriose, and maltopentaose) were compared under different conditions (pH and electrolyte concentration). The emulsions with non-modified patatin flocculate under conditions in which the zeta potential is decreased (around the iso-electric point and at high ionic strength). The attachment of monosaccharides (i.e., glucose) did not affect the flocculation behavior. Attachment of maltotriose and maltopentaose (Mw > 500 Da), on the other hand, provided stability against flocculation at the iso-electric point. Since the zeta potential and the interfacial properties of the emulsion droplets are not affected by the attachment of the carbohydrate moieties, this is attributed to steric stabilization. Experimentally, a critical thickness of the adsorbed layer required for steric stabilization against flocculation was found to be 2.29-3.90 nm. The theoretical determination based on the DLVO interactions with an additional steric interaction coincides with the experimental data. Hence, it can be concluded that the differences in stability against pH-induced flocculation are caused by steric interactions.

The Improvement of Nanoemulsion Stability and Antioxidation via Protein-Chlorogenic Acid-Dextran Conjugates as Emulsifiers

“…Firstly, the PCD conjugates had the lowest MDD in the initial stage, as shown in Figure 4 a, so that they could more effectively suppress droplet aggregation. Secondly, previous studies have found that the attachment of polysaccharides with a molecular weight ≥5 kDa (the molecular weight of dextran used in this experiment was 40 kDa) could provide steric repulsion of protein emulsifiers films and made nanoemulsions with stability against droplet aggregation [ 48 ]. The thicker droplet interfacial membranes were formed after the dextran compounding, so that the steric repulsion effect of the PCD conjugates that adsorbed on the interface was enhanced.…”

Towards potato protein utilisation: insights into separation, functionality and bioactivity of patatin

“…Patatin can be conjugated with xylose, glucose, maltotriose and maltopentaose. It has been observed that glycation of patatin with maltotriose and pentatose leads to improved emulsion stability against pH‐induced flocculation owing to steric repulsion (Delahaije et al ., ). Similarly, Seo et al .…”

Glycation of Plant Proteins Via Maillard Reaction: Reaction Chemistry, Technofunctional Properties, and Potential Food Application

“…In addition to electrostatic repulsion, emulsions formulated with glycated proteins also provide steric repulsion due to the added carbohydrate moiety. Upon adsorption, the carbohydrate part of the molecule is anchored at the interface between oil and water by the amphiphilic protein part and is exposed to the aqueous phase due to its hydrophilicity, where it physically hinders van der Waals attraction between oil droplets, especially at pH values close to the isoelectric point where electrostatic repulsion is low [85,260]. The thicker the interfacial layer, the better the resistance of oil droplets to aggregation and coalescence during storage and under the influence of mechanical stress and high shear forces (e.g., during unit operations such as mixing and pumping) [261][262][263].…”