Liquid-liquid phase separation in acetone solutions of palm olein: Implications for solvent fractionation
2007
Smith, Kevin W. | Cain, Fred W. | Favre, Loek | Talbot, Geoff
The quality of palm mid fractions (PMF) obtained by dry fractionation has increased, but the best-quality PMF for application in many confectionery fats are still produced by solvent fractionation. In the present study, liquid-liquid phase separation has been observed in acetone solutions both for pure triacylglycerols and for palm olein. The temperature at which phase separation occurs increases as the oil concentration is increased and linearly as the water content of the system is increased. The triacylglycerol compositions of the two liquid phases that form do not differ. However, the oil-rich phase is depleted with respect to the polar components. The temperature at which liquid-liquid phase separation occurs is reduced by about 0.2 and 0.4 °C per percent of free fatty acids and diacylglycerols, respectively. When oil-rich droplets appear, crystallisation occurs within them rather than in the oil-depleted phase, due to the higher oil concentration. Thus, liquid-liquid phase separation prior to crystallisation raises the nucleation temperature but may lead to a greater concentration of entrained olein in the filter cake, leading to a poorer-quality PMF.
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