Microwave pre-treatment of niger ( Guizotia abyssinica) ) seeds: Impact on stability, physicochemical characteristics, bioactive and fatty acid profiles of extracted oil

The study explored the impact of microwave pre-treatment (MPT) at different powers (360, 540 and 720 W) and exposure times (2, 4, 6 and 8 min) on the qualitative characteristics of niger seed oil (NgO). The changes in physicochemical characteristics, oxidative stability index (OSI), phenolic constituents, Maillard products, tocopherols, pigments and phytosterols in NgO were elucidated after MPT of seeds. The NgO yield increased from 33.19 % to 38.76 % and OSI augmented from 2.69 to 3.93 h upon MPT at 540 W and 720 W for 8 min, respectively. The tocopherols and phytosterols levels augmented upon MPT at 540 W for 4 and 6 min, respectively while declined by further elevating power (720 W) and exposure time (8 min). The total hydroxycinnamic (27.41 mg/kg) and hydroxybenzoic (1.48 mg/kg) acids and total flavonoids (115.83 mg/kg) were highest upon MPT at 720 W for 6 min while viscosity (56.71 mPa.s), chlorophylls (0.12 mg/kg), carotenoids (0.85 mg/kg) and 5-hydroxymethylfurfural (1.38 mg/kg) were highest upon MPT at 720 W for 8 min. In conclusion, the MPT promoted the release of bioactive compounds and lowered the generation of harmful oxidative by-products. The results highlight the potential of MPT in enhancing quality attributes of NgO for use in the food, cosmetics, and pharmaceutical industries.