Food Science Master Student University of Florida Gainesville, Florida
Abstract: Standard Palm Oil (SPO) is widely used as an ingredient due to its physical properties, however, the saturated fatty acid (SFA) content is higher than recommended by the AHA. Palm hybrids yielding oil with < 35% SFA and >50% oleic acid have recently piqued producer interest and are now defined as “palm oil with a higher content of oleic acid” (HOPO) in the Codex Alimentarius. This research compares the thermal and rheological behavior of HOPO with SPO to support its use as a low-SFA alternative to SPO. Iodine Value and FA analysis were taken for each oil. Thermal analysis (DSC) was completed at various cooling/heating rates (5,10,15,20˚C/min) from -70˚C to 70˚C. Shear rheology was assessed at shear rates of 0.1,1,10, and 100s-1 as a function of temperature upon cooling (5˚C/min) from 70˚C-10˚C for SPO and 70˚C-0˚C for HOPO, and then held isothermally for both oils. The SPO thermogram exhibited an onset crystallization temperature (Ton) of 18.1˚C and two peaks, similar to literature data, maxing at 15.65˚C and -0.57˚C; whereas HOPO showed a Ton of 8.69˚C and two wider peaks, maxing at 5.8˚C and -8.11˚C. HOPO’s thermogram suggests a lower melting point (29.5˚C-30.15˚C) than SPO (39.31˚C-39.7˚C). Rheological analysis showed increased viscosity due to crystallization, and more stable curves at higher shears. HOPO’s viscosity profiles were similar to SPO at different shear rates under isothermal conditions. These results facilitate further study on HOPO crystal structure formation (assessed via AFM and microscopy) and the influence on thermal and mechanical properties of HOPO containing products.
