Fabrication and characterization of high internal phase emulsion stabilized solely by modified hemp protein isolate

This study systematically investigated the structural (e.g., surface hydrophobicity) and functional properties (e.g., interfacial tension, emulsification) of hemp protein isolate (HPI) modified by high intensity ultrasound (HPI-U), pH-shift (HPI-pH), or their combination (HPI-pU). The results showed that the combined method enhanced the emulsifying activity index of HPI-pU by nearly twofold compared to HPI. This is because the combined method was able to break down HPI into its subunits such as trimer, while inducing conformational changes into a flexible structure, leading to increased surface hydrophobicity (82.26 a.u.) and a shift in the isoelectric point (pH 6.5) compared to HPI. As only HPI-pU was able to fabricate high internal phase emulsion (HIPE), the effect of pH (7.0 & 3.5) and salt concentration (50 & 200 mM) on its properties was studied. Among them, HPI-pU stabilized HIPE at pH 3.5 (HIPE-3.5) exhibited the smallest emulsion droplet size (45 μm) for future applications.