Ultrasonic assisted phenolic elicitation and antioxidant potential of common bean (Phaseolus vulgaris) sprouts.

Abstract

Limited literature is available concerning the phenolic biosynthesis and antioxidative potential of common bean sprouts induced by ultrasound elicitation. In this study, common bean seeds were treated with ultrasound at different power (0, 180 and 360W) and time (0, 30, 45 and 60min) levels, before they were subjected to sprouting (24, 48, 72 and 96h). Stress markers (H2O2, catalase and guaiacol peroxidase), activities of defense phenolic triggering enzymes (phenylalanine ammonia-lyase and tyrosine ammonia-lyase), phenolic contents (total phenolic acids, total flavonoids and anthocyanins) and antioxidant capacities (DPPH, ABTS and Fe2+ scavenging) were monitored. Results showed that, ultrasound elicitation (especially 360W, 60min) significantly increased accumulation of stress markers at 96h of sprouting, leading to elevated activities of defense phenolic triggering enzymes, and final accumulation of phenolics and antioxidant capacities at significant levels compared to control. Ultrasound treatment at 360W and 60min reduced sprouting time by 60h, compared to control. Results from principal component analysis clearly differentiated latter stages of sprouting and high ultrasound levels from other sprouting conditions as distinct treatments for the production of phenolic-rich common bean sprouts. Overall, results from this study indicated that elicitation with ultrasound can be a green and novel approach for producing phenolic-enriched common bean sprouts as an organic nutraceutical vegetable.