Pre-roasting treatments significantly impact thermal and kinetic characteristics of pumpkin seed oil

Abstract

In this study, pumpkin seed oils obtained from roasted and unroasted seeds of the two genotypes called as "Nevsehir cercevelisi" and "Urgup Sivrisi" belonging to the species Cucurbita pepo were analyzed for thermal and kinetic properties. Oil extraction from seeds subjected to three different pre-treatments (unsalted, dry salted and wet salted) before roasting and sun-dried unroasted seeds was carried out by means of a screw press. Thermal characteristics (cooling-melting curves and the oxidative induction time (IT) at four different isothermal temperatures (110 degrees C, 120 degrees C, 130 degrees C and 140 degrees C) were determined using differential scanning calorimetry (DSC). Kinetics parameters of the oil oxidation process such as reaction rate constants (k), activation energies (E-g), enthalpies (Delta H-double dagger), entropies (Delta S-double dagger) and Q(10) values were also calculated. Our results indicate that an increase in the DSC isothermal temperature resulted in a decrease in induction time (IT), and the highest IT was observed in the oils obtained from sun-dried unroasted seeds.