Improved oil solubilization in oil/water food grade microemulsions in the presence of polyols and ethanol

Microemulsions based on five-component mixtures for food applications and i mproved oil solubilization have been studied. The compositions included wat er, oil phase [such as R(+)-limonene and medium-chain triglycerides (MCT)], short-chain alcohols (such as ethanol), polyols (propylene glycol and glyc erol), and several surfactants and their corresponding mixtures (nonionic, such as ethoxylated sorbitan esters, polyglycerol eaters, sugar ester, and anionic, such as phosphatidylcholine). The phase behavior of these systems is discussed with respect to the influence of polyols and short-chain alcoh ols on the degree of solubilization of oils in the aqueous phase. The alcoh ol and polyols modify the interfacial spontaneous curvature and the flexibi lity of the surfactant film, enhancing the oil solubilization capacity of t he microemulsions. The solubilization of R(+)-limonene was dramatically imp roved in the presence of the alcohol and polyols, whereas the improvement o f solubilization for triglycerides containing MCT was less pronounced. In s ome systems high oil solubilization was achieved, and some of them can be e asily diluted to infinity bath with the aqueous phase and with the oil phas e. Viscosity measurements along selected dilution lines [characterized by a single continuous microemulsion region starting from a pseudo binary solut ion (surfactant/oil phase) to the microemulsion (water/polyol corner)] indi cate that at a certain composition the system inverts from a W/O to an O/W microemulsion.