Effect of roasting treatments on total phenol, antioxidant activity, fatty acid compositions, and phenolic compounds of teff grains

Background and objectives: Teff grains are subjected to several treatments, such as cooking and baking, and studies on the impact of thermal treatments such as roasting on the bioactive properties, phenolic compounds, fatty acids, and minerals of teff grains are scarce. The objective of this study was to evaluate the effect of microwave and oven roasting processes on total phenol, antioxidant activity, fatty acid compositions, and phenolic compounds of teff grains. Findings: Roasting treatments greatly influenced the biochemical content and bioactive properties of teff grains. Roasting increased oil, carotenoids, total flavonoids, and antioxidant activity of teff grains with the highest values being observed in microwave-roasted grains, except total flavonoids of soluble fraction which was highest in oven-roasted grains. It also increased total phenolic of soluble fraction and most phenolic compounds in both soluble and bound fractions with the highest values being found in conventional oven-roasted grains, except gallic acid, trans-cinnamic acid, naringenin, and isorhamnetin which were high in control samples. In addition, oven roasting increased palmitic acid, linoleic acid, nickel, and boron, whereas microwave roasting increased the content of stearic acid, calcium, magnesium, sodium, iron, copper, zinc, and lead of teff grains compared to controls. Conclusions: The findings of this study indicate that teff grains are suitable sources of nutrients and bioactive compounds that could be enhanced by roasting. Significance and novelty: The teff grains have high nutritional value, antioxidants, fatty acids, and phenolic compounds which are improved by roasting treatment and hence probable potential application in functional foods. Studying the effects of processing treatments such as roasting of teff grain will help in promoting the worldwide utilization of this important gluten-free cereal.