2. Experimental
2.1. Materials and methods
Spans are nonproteic emulsifiers with a higher hydrophobic than hydrophilic character (low HLB).
They are sorbitan esters differentiated among themselves by the characteristics of their fatty acid chains.
As a general rule, it is accepted that emulsifiers should have more affinity to the continuous phase than to
the dispersed one thus, Spans are adequate to formulate this type of emulsions. Span 80 (sorbitan
monooleate) was obtained from Sigma-Aldrich (Poland). Mineral oils were obtained from Institute of
Petroleum Technology from Kraków in Poland. The two Newtonian type mineral oils with viscosities
about