The Influence of the Adsorbents Used on Changes in the Quality Parameters of Pumpkin Seed Oil as a Result of a Single-Stage Refining Process

This study aimed to evaluate the impact of low- and high-temperature bleaching processes on the quality parameters of pumpkin seed oil. The research focused on optimizing the process to improve the oil’s physicochemical properties while reducing losses of valuable bioactive components. The bleaching process was carried out using 12 adsorbents in four technological variants, differing in temperature and adsorbent amount (30 °C/2% w/w, 30 °C/5%, 90 °C/2%, and 90 °C/5%). The scope of the analyses included, among others, the determination of acid (AV), peroxide (POV), and anisidine values (AnV), as well as the characterization of the fatty acid profile and the content of phytosterols and tocopherols. The data obtained were subjected to principal component analysis (PCA) to correlate the type of adsorbent with the process effects. It was shown that bleaching partially improves the oil’s quality parameters, though it is associated with a reduction in tocopherol and carotenoid content. Aluminum oxides are very poor adsorbents of vegetable oil components. Finely divided activated carbons exhibit the broadest spectrum of adsorbed components. Furthermore, bleaching earths have different effects on oil components depending on their composition and process temperature.