Melting Behavior and Hydrogenation

Sample

Sunflower Oil

Conditions

Measuring cells: DSC27HP, DSC30

Pan: Aluminum standard 40 µl, with pierced lid

Sample preparation: 18.8 mg sunflower oil has been mixed with approx. 0.2 mg Raney nickel moistened with ethanol. This acts later as a catalyst for hydrogenation.

DSC measurement: Heating from -50 °C to 30 °C at 5 K/min to determine the original melting behavior. Hydrogenation in the DSC27HP, heating from 25 °C to 250 °C at 5 K/min. The melting behavior of the final product then is determined, heating from 25 °C to 100 °C at 5 K/min.

Atmosphere: Nitrogen, 50 cm3 /min in the DSC30, hydrogen, stationary environment at a pressure of 1 MPa in the DSC27HP

Interpretation

The effect of hydrogenation is investigated by observing the melting behavior with the DSC. With increasing saturation of the double bonds the temperature of the melting peak increases from below 0 °C to almost 70 °C.

Safety remark: The DSC27 with sample inserted is pressurized with nitrogen to 1 MPa and the pressure then released. This procedure is repeated in order to remove the oxygen. Finally the cell is pressurized with hydrogen. After the measurement, the hydrogen is released into a vented area for safety reasons.

Evaluation

Conclusion

The melting behavior is one of the most important characteristics of edible oils and fats and affects organoleptic properties. DSC not only shows the shift of the melting range to higher temperature as a result of hydrogenation, but also allows the chemical reaction itself to be performed in the measuring cell.

^{Melting Behavior and Hydrogenation | Thermal Analysis Application No. HB 1013 | Application published in METTLER TOLEDO TA Application Handbook Food}