PhD Oral Defence: Elicitation of phenolic biosynthesis and antioxidative capacities in common bean (Phaseolus vulgaris) sprouts
PhD Oral Defence of Josephine Ampofo, Food Science and Agricultural Chemistry
Common bean (Phaseolus vulgaris) offer additional health benefits due to the presence of bioactive compounds such as phenolics. Thus, there is need to enhance phenolic yield in common bean, especially in the cultivars with limited concentrations using appropriate technologies. This study investigated the influence of chemical, ultrasonication and thermal elicitation strategies on phenolic accumulation and antioxidative properties of common bean at different sprouting stages. Mechanisms of the phenolic accumulation were also studied. Among the different concentrations of chemical elicitors (Glutamic acid and NaCl) studied, 5 mM glutamic acid optimally stimulated activities of phenylpropanoid triggering enzymes, correlating with its significant elevations of oxidative stress and final accumulation of defense phenolic compounds. For the range of ultrasonication power and time studied, 360 W (60 min) yielded the highest folds of phenolics and antioxidant capacity, by its significant stimulation of oxidative stress at non-lethal levels against activities of phenylpropanoid triggering enzymes. Also, among investigated thermal elicitation levels, the intensities of oxidative stress induced at 30°C were non-toxic against stimulatory activities of phenylpropanoid triggering enzymes, reflecting in its maximum accumulation of phenolics and antioxidant potential, compared to higher temperatures. The findings of this study give details on how different elicitors can be applied in designing processing systems targeted for the production of phenolic enriched functional foods.