| Abstract
| - The preparation of nonaqueous microemulsions using food-acceptable components is reported. Theeffect of oil on the formation of microemulsions stabilized by lecithin (Epikuron 200) and containingpropylene glycol as immiscible solvent was investigated. When the triglycerides were used as oil,three types of phase behavior were noted, namely, a two-phase cloudy region (occurring at low lecithinconcentrations), a liquid crystalline (LC) phase (occurring at high surfactant and low oil concentrations),and a clear monophasic microemulsion region. The extent of this clear one-phase region was foundto be dependent upon the molecular volume of the oil being solubilized. Large molecular volumeoils, such as soybean and sunflower oils, produced a small microemulsion region, whereas the smallestmolecular volume triglyceride, tributyrin, produced a large, clear monophasic region. Use of the ethylester, ethyl oleate, as oil produced a clear, monophasic region of a size comparable to that seenwith tributyrin. Substitution of some of the propylene glycol with water greatly reduced the extent ofthe clear one-phase region and increased the extent of the liquid crystalline region. In contrast, ethanolenhanced the clear, monophasic region by decreasing the LC phase. Replacement of some of thelecithin with the micelle-forming nonionic surfactant Tween 80 to produce mixed lecithin/Tween 80mixtures of weight ratios (Km) 1:2 and 1:3 did not significantly alter the phase behavior, althoughthere was a marginal increase in the area of the two-phase, cloudy region of the phase diagram. Theuse of the lower phosphatidylcholine content lecithin, Epikuron 170, in place of Epikuron 200 resultedin a reduction in the LC region for all of the systems investigated. In conclusion, these studies showthat it is possible to prepare one-phase, clear lecithin-based microemulsions over a wide range ofcompositions using components that are food-acceptable. Keywords: Phospholipids; food-acceptable microemulsions; triglycerides; ethyl esters
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