Identification and Quantification of Phenolic Compounds in Grains of Biofortified Cowpea Cultivars, Before and After Cooking

Objective: This study aimed to identify and quantify phenolic compounds in the grains of biofortified cowpea (Vigna unguiculata) cultivars before and after cooking. Methods: We analyzed two cultivars of genetically improved cowpeas, namely BRS Aracê and BRS Tumucumaque. Raw and cooked samples of the cultivars were analyzed (in triplicate). The concentrations of phenolics, flavonoids, anthocyanins, and flavanols, as well as the antioxidant activity, were determined. Phenolic compounds were identified and quantified using high-performance liquid chromatography. Results: Grains of cultivar BRS Tumucumaque had higher concentrations of total phenolic compounds before (297.23 ± 4.24 (mean ± standard deviation) mg/100 g) and after (147.15 ± 6.94 mg/100 g) cooking, and higher concentrations of total flavonoids before (49.36 ± 2.02 mg/100 g) and after (23.97± 0.67 mg/100 g) cooking. Anthocyanins were not measured in the grains of either cultivars. There was a statistically significant reduction in the concentration of total flavanols after cooking, with the greater retention in BRS Aracê. Similarly, the antioxidant activity was significantly reduced after cooking, with greater reductions in BRS Tumucumaque than in BRS Aracê. Five phenolic acids were identified and quantified, including gallic, caffeic, and ferulic acids. Conclusion: We conclude that cooking affected the concentrations of phenolic compounds in the cultivars, as well as the antioxidant activity exhibited by these cultivars. The cultivars contained beneficial compounds that can contribute to disease prevention and health maintenance.