2.6. Melting and crystallization profile
Differential scanning calorimetry (DSC) was performed for describing the
melting and crystallization profiles of the fats, oils and their blends.
The equipment (2920 DSC, TA Instruments, USA) was calibrated with pure
indium (TA Instruments), naphthalene, cyclohexane and decane (purities
> 99.9%, Sigma-Aldrich). Samples of fats, oils, and
prepared blends were weighted (4.93 ± 0.80 mg) using aluminum pans, and
hermetically sealed with aluminum covers. An empty hermetically sealed
aluminum pan was used as reference. In order to insure a
quasi-equilibrium state along the experimental run, and based on
previous works on fat and oils, scanning rates of 5 °C/min were employed
(Tan & Che Man, 2002). To erase the thermal history and induce
crystallization of the most stable polymorphic forms of the samples,
they were heated to 70 °C and maintained at this temperature for 10 min.
They were then cooled to -70 °C at 5 °C/min to generate the
crystallization curve. Samples were maintained at -70 °C for 10 min and
then heated to 70 °C at 5 °C/min to generate the melting curve. The
thermograms were analyzed with the Universal Analysis 2000 software (TA
Instruments, New Castle, USA) according to onset (Ton),
offset (Toff), peak temperatures (Tpeak)
and enthalpy (ΔH) for both crystallization and melting curves.