2.5. Emulsion preparation and characterization

CP emulsions with 10% (w/w) oil content were prepared by dispersing canola oil in 0.5–2.0% (w/w) CP aqueous mixtures and shearing with a T25 Ultra-Turrax (IKA, Breisgau, Germany) for 60 s at 24,000 rpm. Chitin emulsions with 5.3% (w/w) oil and 0.72% (w/w) chitin were taken from the stable emulsion layer following emulsifying capacity and emulsifying-chitin content measurements, as described above. CP emulsions were further homogenized by a high-pressure two-stage homogenizer (GEA Panda, GEA; Columbia, MD) operating at 10,000 PSI, whereas chitin emulsions were not further homogenized due to the potential damage to the homogenizer valve from solid particulates. All emulsions were sealed and stored at 23 °C.

Creaming index (CI) of emulsions during storage at 23 °C was measured by height of the cream layer in relation to total height of liquid from digital images using ImageJ software (National Institutes of Health; Bathesda, Maryland). Mean emulsion droplet diameters, including surface-volume mean diameter (D₃₂) and volume mean diameter (D₄₃), were determined by static light scattering (Mastersizer, 2000; Malvern Instruments, Worcestershire, England) using refractive indices of 1.335 and 1.495 for the continuous and dispersed phase, respectively. All emulsion samples were vortexed for 25 s and diluted to an obscuration of 12–13% prior to scattering measurements.

Chitin-stabilized emulsion droplets were imaged on covered glass slides using a Nikon A1-Rsi confocal laser-scanning microscope (Nikon Instruments Inc.; Melville, NY) with a 60× oil immersion objective lens.