2003 Volume 52 Issue 12 Pages 639-645
The effects of polyglycerol behenic acid esters on the crystallization of palm oil were studied using optical microscopy and X-ray diffraction. Polyglycerol behenic acid esters were added in an attempt to promote the crystallization of palm oil. Optical microscopy observation confirmed that palm-oil crystals with the addition of 1 wt% of polyglycerol behenic acid esters were smaller and the number of palm oil crystals larger than without the additives. This indicated that the polyglycerol behenic acid ester promoted nucleation and inhibited crystal growth of palm oil. X-ray diffraction patterns of palm oil without the additives revealed that palm oil crystallized in the α-form after rapid quenching of melted palm oil at 10°C. During the heating process from 10°C to 45°C, the α-form transformed to the β′-form around 15°C, and the β′-form changed to the β-form around 40°C. The X-ray diffraction patterns of palm oil with the addition of polyglycerol behenic acid esters showed that palm oil crystallized in the β′-form at 10°C, and did not transform to the β-form during the heating process. Furthermore, the crystallization of the β′-form was promoted at 20°C and 25°C, but retarded at 28°C by the additive.
