Development of high internal phase emulsions using coconut protein isolates modified by pulsed light: Relationship of interfacial behavior and emulsifying stability

Protein-stabilized high internal phase emulsions (HIPEs) are attracting considerable attention in the food industry. Herein, we reported a simple method to fabricate HIPEs by modifying coconut protein isolates. Coconut protein isolates were extracted using isoelectric precipitation, and modified by low-intensity pulsed light (0.76 W/cm2/nm). The influence of protein concentration (1-4%, w/v) on interfacial adsorption behavior was analyzed by dissipative quartz crystal microbalance and interfacial dilatational rheology. The results indicated that the increase of concentration was beneficial to form a thick and more elastic interfacial layer at oil-water interface for modified coconut protein isolates by pulsed light (PCPI). At high concentration, the interfacial layer exhibited the better ability to resist the perturbation of amplitude and frequency sweep. In addition, HIPEs could be stabilized by PCPI solely, all emulsions were dispersed well. Apart from the emulsion stabilized by 1% PCPI, other HIPEs exhibited a gel-like behavior when the containers were inverted. Increasing protein concentration caused a decrease in emulsion particle size, and rheological analysis showed that the viscosity of HIPEs was positively correlated with the content of PCPI. Moreover, the HIPEs stabilized by PCPI exhibited better centrifugal stability. This study demonstrated that coconut protein isolates could be an efficient stabilizer to prepare HIPEs after simple modification, which was useful for developing applications of coconut protein.