The effect of the refining process on the interfacial properties of palm oil

The interfacial tension of palm oil against water at 60°C was determined in the presence of monoglycerides with (i) different acyl chain lengths, (ii) the same acyl chain length but with different unsaturation, and (iii) different phospholipids. The interfacial tensions of the oil/water interface were depressed, albeit to different extents, by the presence of these substances, depending on the acyl chain length, unsaturation, and the chemical structure of the species adsorbed. The adsorption of the saturated monoglycerides C12∶0, C14∶0, C16∶0, C18∶0 and the unsaturated monoglycerides of C18∶1 and C18∶3 is consistent with a Langmuir isotherm at the palm oil/water interface. However, fitting of the data for C18∶2, l-α-phosphatidylcholine, and lysophosphatidylcholine to the Langmuir isotherm is less satisfactory. The surface areas of the materials adsorbed at the palm oil/water interface are much larger than those of liquid condensed films and closer to those for liquid expanded films. The influence of the nature of the oil (triglycerides), the minor components in the oil, and thier interactions with the added lipids at the oil/water interface are briefly discussed. The effect of the refining process on the interfacial properties of palm oil against water was also studied. The efficiency of the refining process in minor oil contaminants’ removal and the quality of the oil obtained as reflected by the interfacial properties of the oil is discussed.

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