Effects of Two Composite Modifications on the Emulsifying and Potential Gel Properties of Palm Kernel Cake Glutelin-1

Palm kernel cake glutelin-1 (PKCG-1) can be used as a novel emulsifier, contingent upon enhancement of its emulsifying functionality. This study investigated the influences and underlying mechanisms of ultrasonication-assisted gallic acid-binding or arabinose-glycosylation on the emulsifying properties of PKCG-1. The results demonstrated that ultrasonication-assisted gallic acid-binding yielded the greatest improvement in emulsifying ability (from 91.03 to 159.74 m²/g), attributed to a concomitant decrease in molecular mass (from 59.2 to 48.4 kDa); increases in hydrophobicity (from 681 to 770), random coil content, and interfacial adsorption capacity (from 102.62 to 244.41 μg/mL); a reduction in the emulsion's loss factor; and augmentation of zeta-potential (from -39.55 to -65.96 mV) and centrifugal stability (from 57.80% to 84.14%). Alternatively, ultrasonication-assisted arabinose glycosylation was best at enhancing the emulsion stability of PKCG-1 (from 79.77% to 98.36%) by increasing its solubility (from 28.35 to 73.85 g/100 mL) and random coil (from 25.9% to 46.9%), enhancing zeta-potential (from -39.55 to -84.81 mV) and viscosity; and reducing droplet size (1.10 to 0.64 μm) and loss tangent. Furthermore, the solubility, emulsifying activity, and emulsion stability of PKCG-1 decreased as pH increased from 2.5 to 8.5. Nevertheless, the application of the modified PKCG-1s as gels requires further studies.