Crystallisation kinetics of palm stearin, palm kernel olein and their blends

The kinetics of isothermal crystallisation of palm stearin, palm kernel olein and their blends (20-80 g/100 g palm stearin with 20 g/100 g increment) were determined using differential scanning calorimetry (DSC). The mechanism of crystallisation (n) was calculated by applying the Avrami equation using the crystallisation curves obtained at 10,15 and 20 degrees C. The DSC isothermal crystallisation data at 10,15 and 20 degrees C fitted well into the Avrami equation over the entire fractional crystallisation with correlation coefficient always greater than 0.98. Based on the Avrami exponent obtained, the palm stearin and palm kernel olein have different nucleation and growth mechanisms. The suggested mechanism for palm kernel olein was high nucleation rate at the beginning of crystallisation, which decreased with time, and plate-like growth (n = 2). On the other hand, the mechanism for palm stearin was instantaneous heterogeneous nucleation followed by spherulitic growth (n = 3). For blends of palm stearin and palm kernel olein, the mechanisms of crystallisation were 2 and 3 depending on the composition of the blends and crystallisation temperatures. (C) 2011 Elsevier Ltd. All rights reserved.