Abstract:

The improved water and oil solubilization in the presence of polyols (propylene glycol, PG, and glycerol, Gly) and short-chain alc. (ethanol) in U-type nonionic W/O and O/W food microemulsions was investigated. The phase behavior of systems based on Tweens (ethoxylated sorbitan esters) was compared with non-food-grade systems based on C18:1E10 (Brij 96v). Short-chain alc. (ethanol in food-grade systems) together with polyols (glycerol and propylene glycol) when added to a three component system (oil-surfactant-water) induce the formation of both water-in-oil (W/O) and oil-in-water (O/W) microemulsions. Alcs. and polyols destabilize the liq. cryst. phase and extend the isotropic region to higher surfactant concns. The total monophasic area, AT, at R(+)-limonene/ethanol of 1/1 (wt./wt.) and aq. phase of water/PG of 1/1 (wt./wt.), was 73 and 64% of the total area of the phase diagram for Brij 96v and Tween 60, resp. The transition from a W/O microemulsion into an O/W microemulsion happens gradually, and continuously without any phase sepn. The total monophasic area depends also on the type of the oil, on the compn. of the polar and apolar phases, and on the nature of the polyol. Solubilization properties are explained n terms of spontaneous curvature, film flexibility, etc. Deviations from the BSO equation are explained in terms of the nature of the oil and surfactants. The difference in temp. sensitivity of PG-based microemulsions vs. temp. sensitivity of Gly-based is demonstrated and explained. [on SciFinder(R)]