Effects of different roasting conditions on the nutritional value and oxidative stability of high-oleic and yellow-seeded Brassica napus oils

Abstract

This study was conducted to evaluate the possibility of enhancing the nutritional value and oxidative stability of rapeseed oil obtained from seeds subjected to thermal treatment prior to pressing. The yellowseeded and high-oleic B. napus lines, harvested in Poland, were roasted prior to pressing for 1 h at 100 and 150 °C. This study highlighted how rapeseed breeding lines affect the quality profile of the oils obtained both before and after the roasting process. In principle, the high-oleic B. napus was accompanied by a nearly 2-fold increase in oxidative stability compared to the yellow-seeded B. napus, most likely due to a higher content of oxidation-resistant oleic fatty acids (∼74.24% vs. ∼60.76%) and a decreased concentration of oxidizable PUFAs (∼16.32% vs. ∼31.09%). Similar to the case of roasting black-seeded rapeseed, the thermal pre-treatment of yellow-seeded and high-oleic B. napus prior to pressing did not alter the composition of their fatty acids. Based on the results obtained in this study, it can be concluded that roasting seeds prior to pressing does not reduce the amount of tocopherols in the oil; moreover, a slight increase in γ-tocopherol content was observed.