Abstract:

The isothermal crystallization and melting behavior of palm oil and its mixtures with sorbitan trioleate (Span 85)
were tested using differential scanning calorimetry. The equilibrium melting temperature was calculated by Hoffman-Weeks
method. The parameters associated with the crystallization kinetics were obtained by using the Avrami equation to simulate
the isothermal crystallization process of samples. DSC curves showed that the additive could reduce the crystallization rate
and nucleation rate. The temperature data obtained by Hoffman-Weeks method and the Avrami equation had a good linear
relationship, indicating that the Avrami model could be applied to simulate the crystallization process of palm oil although
there was a deviation in the late crystallization. The Avrami exponent n obtained by fitting the data is between 2.37 and 2.77,
which showed the simultaneous occurrence of two-and three-dimensional crystal growth. Moreover, the crystallization rate k
and the half-crystallization time t1/2 were smaller in the presence of Span 85.

Key words: Avrami equation, differential scanning calorimetry, Span 85, crystallization kinetics