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Chemical characteristics of oils from naked and husk seeds of Cucurbita pepo L.Pumpkin seed oils from naked and husk pumpkin seeds, produced by an industrial process and by laboratory extraction, were evaluated for fatty acid composition, tocopherol, sterol and squalene content. The major fatty acids in the oils from both varieties were oleic, linoleic and palmitic acid, followed by stearic acid. The ratios of monounsaturated to polyunsaturated fatty acids for husk and naked seed oils were about 0.60 and 0.75, respectively. Analysis of tocopherols in industrially pressed and laboratory-extracted oils showed that husk seed oils had higher amounts of total tocopherols than naked seed oils. Oils extracted in the laboratory had higher amounts of tocopherols than industrial oils. Pumpkin seed oil, in general, had a high level of squalene, which was higher in husk seed oils than in naked seed oils and in extracted than in pressed oils. The total amount of sterols was higher in husk than in naked seed oils and in extracted oil samples. The main sterols were D7-sterols and their content was similar in all samples, but the content of D5-sterols was higher in oil samples of husk pumpkin seed and in extracted than in pressed oils.

This study included olive oil samples produced from the Croatian varieties Bianchera and Busa, and an Italian variety Leccino cultivated in the west Istria region, Croatia. The influence of variety and harvest time on the bitterness and phenolic compounds of olive oilThe influence of harvest time on the intensity of bitterness and the level of phenol compounds in olive oil from the region of western Istria, obtained from 2 local (Bianchera and Busa) and one introduced, Italian variety (Leccino) was studied. Olive fruits were harvested at 3 different harvesting periods, during 4 successive crops seasons. Immediately after harvesting, the fruits were processed under the same conditions in a pilot plant. Basic quality parameters, the content of total polyphenols, o-diphenols and the intensity of bitterness were determined in oil samples. Samples of oil obtained from the Bianchera and Busa varieties were additionally tested for stability at elevated temperature (98 °C) and under the influence of UV-light.The results elaborated statistically showed the level of phenol compounds and the intensity of bitterness to be significantly influenced by both the harvest time and olive variety, with the influence of harvest time being more pronounced. The applied tests for accelerated deterioration of oil indicated a more rapid increase in the peroxide value in oil samples of both varieties exposed to UV-light than in those exposed to elevated temperature. Both tests showed better stability of the oil obtained from the Bianchera variety.

In this study samples of non-refined sunflower oils, obtained in industrial and laboratory scale by cold and hot pressing and hexane extraction, as well as sunflower oils from single refining steps were investigated. The content and composition of carotenoids, sterols, and the content of chlorophylls as well as oxidative stability were investigated. To obtain the data about the acidity and oxidative status of the oil samples, basic quality analyses of free fatty acid content (FFA), peroxide value (PV) and spectrophotometric analyses in UV area (K232, K270 and K) were used.The results showed that the predominating carotenoid in sunflower oil is lutein, and that the total amount of carotenoids during refining process was reduced to about 15% of the initial amount. The major sterol in sunflower oil (about 70%), as well as in other vegetable oils, was -sitosterol. The other important sterols in sunflower oil were 7 -stigmasterol, stigmasterol, campesterol, 5 -avenasterol and 7 -avenasterol. The composition of sterols in non-refined and refined oils was more or less the same, while the content of sterols during refining process decreased by 22%. Among all analysed sunflower oils, the laboratory extracted oil had the best oxidative stability (e.g. the longest induction period, according to Rancimat method), while cold and hot pressed oils were less stable than the fully refined one.

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