Abstract In this study, potatoes and onions were fried in sesame oil, canola oil and commercial frying oil at 180 °C for 8 and 4 minutes respectively. The process was performed at three steps. Fried potatoes and onions were evaluated by the measurements of parameters such as fatty acid, tochopherols. The results showed that in terms of changes in fatty acid profile in fried samples, the linolenic acid content in sesame and canola has been decreasing. The highest levels of tocopherol were found in fried samples of sesame oil. Finally, it can be concluded that sesame oil has been shown to be better in terms of resistance to other oils studied in this study.

Abstract Bleaching is an important part of the oil refining process, in which pigments, impurities, traces of metals, and oxidative-molecular components of oils are removed. In this regard, the optimization of bleaching conditions can be effective to increase oil quality. In this study, de-gummed and neutralized sunflower oil was bleached at 80, 90, 100, 110, and 120 °C for 15, 25, 35, 45, and 55 min by acid-activated bleaching clay with the concentrations of 0.4, 0.6, 0.8, 1, and 1.2% under laboratory conditions. At that point, peroxide, anisidine, plus Totox values, free fatty acid content, Rancimat, and specific UV absorption at 232 and 270 nm were analyzed via the RSM method. The model optimization using the RSM method revealed that the optimal conditions were 37.31 min, temperature 92.7 °C, and clay concentration 1.18%; this circumstance can meet 86.7% of the expectations as could be met for reducing the factors effective for oxidization during bleaching.