Effect of roasting on nutritional compositions and bioactive compounds of two different varieties of flaxseeds (Linum Usitatissimum L.)
Nguyen Van Toan, Dang Nguyen Phuong Dung
The aim of this study was to investigate the effect of roasting temperature (160oC, 180oC and 200oC) and roasting duration (5 minutes, 10 minutes and 15 minutes) on nutritional compositions as well as amounts of bioactive compounds of brown and golden flaxseeds. Determination of lipid contents, protein contents, carbohydrate contents/fiber contents, Total Phenolic Contents (TPC), Total Flavonoid Contents (TFC) and Antioxidant Capacity (AC) were thoroughly carried out. In general, the roasting process affected significantly (p<0.05) on nutritional compositions and bioactive compounds of two different varieties of flaxseeds. As the roasting temperature and time increased, both brown and golden flaxseeds decreased in lipid contents and protein contents, meanwhile carbohydrate contents/fiber contents, TPC, TFC and AC of flaxseeds increased. Among roasting conditions, both brown and golden flaxseeds roasted at 180/15 (temperature/time) produced a highest amount of TPC (2.33 ± 0.03, 2.59 ± 0.03 mg GAE/g defatted meal, respectively), TFC (0.49 ± 0.02, 0.52 ± 0.03 mg RE/g defatted meal, respectively), AC (47.49 ± 0.12, 46.92 ± 0.40%, respectively) with acceptable lipid contents around 36.33 ± 0.30, 36.23 ± 0.36%, respectively, protein contents around 13.32 ± 0.29, 14.44 ± 0.09%, respectively, carbohydrate contents around 33.12 ± 0.01, 33.76 ± 0.22%, respectively and fiber contents around 31.46 ± 0.01, 32.07 ± 0.21%, respectively. As a result, 180/15 roasting condition was suggested to be used to roast flaxseeds for consumption. Besides, there was no significant difference between the two selected varieties of flaxseeds regarding their lipid, protein and carbohydrate contents.