Effect of roasting temperature and time on volatile compounds, total tocopherols, and fatty acids of flaxseed oil

Roasting affects the physicochemical and nutritional qualities of flaxseed oil (FSO). The FSO samples were extracted from the roasting flaxseeds at 10-, 20-, and 30-min points and at different temperatures (140°C, 160°C, and 180°C). A total of 61 volatile compounds were identified, and the quantity of the volatile compounds increased significantly (p < 0.05) after roasting. The maximum aldehyde (25.83%) and heterocyclic content (29.26%) was obtained from the samples roasted at 200°C for 20 and 30 min, respectively. The predominant fatty acid in FSO samples was linolenic acid (46.01%-49.35%), which changed dynamically during roasting. The loss of α-, γ-, and δ-tocopherol after roasting was 28.73, 109.78, and 6.67 mg/100 g, respectively. The principal component analysis and hierarchical cluster analysis results showed good discrimination of the different FSO samples into three groups, which were mainly related to the roasting time. Therefore, it can be concluded that roasting time has a stronger effect on the volatile composition of FSO than the temperature during the roasting process. This work provides a basis for improving the aroma of FSO. PRACTICAL APPLICATION: The roasting process is used to extract flaxseed oil (FSO) from flaxseeds. Studying the physicochemical properties and quality characteristics of FSO under diverse roasting conditions is an important step in producing FSO in the food industry, which can give precise instructions to produce flaxseed oil in factories. The results of this study document the volatile constituents generated in FSO samples extracted from flaxseeds during roasting, which may help manufacturers, who are trying to develop natural and artificial FSO flavors.