  High-pressure homogenizers, typically used for producing nanoemulsions at the
industrial scale, are energy and maintenance intensive, and limited to produce
only dilute, low viscosity nanoemulsions. We propose an alternative approach to
produce dilute to concentrated food-grade nanoemulsions with droplet size
ranging between 100 and 500 nm using rotor-stator homogenization. Gum Arabic
(GA) or modified starch (MS) was used as both viscosity modifier and emulsion
stabilizer. GA and MS have relatively low surface activity compared to the
common low-molecular-mass surfactants used typically for nanoemulsion
preparation. The main differences between GA and MS are the lower viscosity of
the GA solutions, compared to MS solutions, and the faster adsorption of MS, as
compared to GA. The obtained results show that stable nanoemulsions are formed
by rotor-stator homogenization when the rapidly adsorbing MS is used as
emulsifier. Much larger drops are formed during emulsification with GA, which
is due to significant drop-drop coalescence in the respective emulsions. The
experimental results for the nanoemulsions prepared with MS are well-described
by the theoretical expression for emulsification in turbulent viscous regime,
after proper account for the effects of temperature and drop-drop interactions
in the sheared emulsions.
