Thermal dependent effects of roasting on the volatiles, phenolics, and sensory properties of faba leaves (Vicia faba)

Faba leaves containing high amounts of l -dopa are a promising food matrix with broad application potential. Since the unfavorable odor of the raw leaves limits their consumption, roasting is a straightforward method that is known to improve the flavor of faba leaves. However, it is not well known that roasting conditions affect faba leaf quality. Roasting temperature and time effects on the volatiles, phenolics, antioxidant activity, and sensory qualities of faba leaves are evaluated. Roasting up to 180 °C showed bright green color and the maintenance of l -dopa and antioxidant activities of the leaves with improving sensory properties by removing low molecular weight (MW) compounds causing unpleasant odors and increasing high MW volatiles. An increase in kaempferol glycosides and a decrease in quercetin glycosides were observed across all roasting temperature treatments. It was concluded that l -dopa was the key factor of antioxidant activity based on correlation-coefficiency analysis. Roasting until 15 min at 160–180 °C did not decrease the antioxidant levels, whereas it significantly affected to the preference of sensory evaluation. Roasting for 5–10 min showed the most favorable preference of faba leaves. These results indicate that suitable roasting conditions for faba leaves can optimize both their nutritional and sensory qualities, offering a promising approach for their utilization in the food industry. • Roasting can change volatiles affecting food quality in herbal leaves. • Roasting produced 210–400 MW volatiles but reduced lower MW volatiles. • Temperatures below 180 °C maintained l -dopa content during roasting. • Roasting increased kaempferol glycosides and decreased quercetin glycosides. • Suitable roasting conditions are 10 min at 160–180 °C for faba leaf processing.