Study of the Emulsifying Ability of Olive Oil Endogenous Compounds in Co-surfactant Free Olive Oil w/o Nanoemulsions with Food Grade Non-ionic Surfactants

In the present work, the preparation of olive oil w/o nanoemulsions was studied using non-ionic surfactants (Tween 20, Span 20) without the addition of a co-surfactant. Different olive oil endogenous compounds with an amphiphilic character (gallic acid, apigenin, quercetin, and trans-cinnamic acid) were dispersed into the aqueous phase, and their impact on the nanoemulsions stability and properties ability was determined. The stable nanoemulsions were presented in pseudo-ternary phase diagrams (oil-aqueous phase-surfactant) for each surfactant and endogenous compound. The nanoemulsions properties were evaluated in relationship to compositional components. The results of this study concluded that stable w/o olive oil nanoemulsions without use of a co-surfactant were obtained and moreover, the most efficient type of emulsifier and its ratio of addition in the system were determined. The incorporation of olive oil endogenous compounds resulted into more stable emulsions. In particular, gallic acid was proven to be the most efficient compound since it enhanced the emulsion properties prolonging simultaneously the emulsions' stability.