K Ratusz

Monitoring of rapeseed oil autoxidation with a pressure differential scanning calorimeter

Abstract Samples of rapeseed oils stored at room conditions were used for determination of peroxides values (PV) by iodometric titration and for thermoanalytical parameters ( t ON and t max ) determined with a pressure differential scanning calorimeter when used in the isothermal mode. The assessment of oxidative stabilities and the anticipation of the oxidative fate of oils based on a single PV or on t ON and t max determination is rather uncertain. The linear correlation of t ON and t max vs. PVs makes possible a comparative assessment of the oxidative stabilities of the oils studied. Such assessments can be performed only for oils not reprocessed which show PV ≤ 30 mmol O 2− 2 /kg of oil. The use of pressure differential isothermal calorimetry enables a more rapid stability assessment than the use of PV measurements alone.

Charakterystyka orzechów laskowych trzech odmian leszczyny uprawianej w Polsce

The aim of this study was to conduct physicochemical characterization and oxidative stability evaluation of hazelnuts from hazel cultivars grown in Poland. There were three cultivars considered: Katalonski, Webba Cenny and Cosford. The experimental nut samples were analysed for kernel and moisture content, average nut weight, macronutrients composition and total ash content. Research on hazelnuts fat was undertaken as well. Fatty acids profile, acid value (AV), peroxide value (PV) and oxidative stability using Rancimat method were determined. Results showed differences between studied varieties in protein, moisture and total ash content. Hazelnuts are abundant source of fat which constitutes over 60% of their kernel weight, but there were no differences in fat quantity among tested nuts. Moreover, the fatty acid composition of hazelnuts is beneficial because of low saturated fatty acids (SFA) content and about 90% of the total fat content is made up of unsaturated fatty acids, especially of oleic acid (MUFA).