Temperature-induced storage quality changes in pumpkin and safflower cold-pressed oils

Cold-pressed pumpkin and safflower seeds oils were stored at 2 ± 1 °C, 20 ± 1 °C and 40 ± 1 °C for 8 weeks. Measurements of lipid quality parameters were performed every 2 weeks. Throughout storage the emission and synchronous fluorimetric spectra of investigated oils were registered and colour L*, a*, b* parameters were determined. It was found that pumpkin oil, regardless of storage temperature, maintains high quality over the entire examined period. Safflower oil demonstrated relatively low oxidative stability, especially when stored at 20 and 40 °C. Evaluated activation energy of oxidation was 82.9 and 36.5 kJ/mol for pumpkin seed and safflower oil, respectively. Emission spectra determined the nature of changes occurring in investigated oils at all storage temperatures. Registered synchronous spectra connected with the principal component analysis (PCA) allowed the crucial factors influencing the oil quality to be identified. In addition, regression models were used to determine the parameters causing the observed colour changes of the examined products.