Abstract:
Legumes are one of the most widely grown crops in the world and they are a good source of
minerals and trace elements, bioactive phytochemicals, and proteins, and contain low-fat
contents. This study determined minerals (Fe, Cu, Zn, Mn, and Ni), total phenolic contents
(TPC), total flavonoid contents (TFC), and antioxidant activities (AOA) in four legume species
(chickpeas, beans, peas, and lentils) with cover, without cover, after cooked, and their cover from
a commercial market in Gondar, Ethiopia. For mineral analysis, 1 g of powdered legume samples
was digested with an optimum conditions of 8 mL of HNO3 and HClO4 mixture (5:3, v/v ratio) at
200 °C for 50 minutes and analyzed using Flame Atomic Absorption Spectrophotometer
(FAAS). Aqueous methanol (80%) was an extraction solvent for TPC, TFC, and AOA analysis
in legume samples shaking for 48 hours at 200 rpm with a 1:10 sample-to-solvent ratio. From the
result, the concentrations (µg/g) of minerals in legumes with cover ranged from 67.46 to 100.79
for Fe, 8.75 to 15.60 for Cu, 27.18 to 40.70 for Zn, 2.39 to 18.78 for Mn, and 21.58 to 37.50 for
Ni. Minerals like Fe, Zn, and Ni in lentils, while Cu and Mn in chickpeas were highly detected.
However, Fe in beans, Cu in lentils, and Zn, Mn, and Ni in peas were less detected. Moreover,
levels of metals in legumes with cover > without cover > their peels, this is due to the cumulative
effects of cover and seed of legumes. Based on the overall mean concentrations of minerals in
legume samples were sequenced as: Fe > Zn > Ni > Cu > Mn. The total phenolic contents (in mg
GAE/g) showed 0.853 to 1.77, 0.027 to 1.86, 1.004 to 2.016, and 3.29 to 4.05 for legumes
without peal, with peal, after cooked, and their peals, respectively. High phenolic content was
found in legumes after being cooked next to their peels, indicating cooking of legumes before
eating giving health benefits. Similarly, the total flavonoid contents (in mg QE/g) ranged from
0.27 to 0.682, 0.22 to 0.89, 0.27 to 0.92, and 1.41 to 3.49, respectively. The inhibition
concentration (in mg/mL) at 50% (IC50) of legumes ranged from 1.509 to 2.055, and the IC50
value of ascorbic acid was 1.017 mg/mL. This showed IC50 values of legumes near to the
standard ascorbic acid, indicating potent antioxidant activities. The one-way ANOVA test
showed there was a significant difference (p <0.05) between the species and their process at a 95
% confidence interval for all analyses.
Keywords: Minerals, Legumes, Total phenolic contents, total flavonoid contents, Antioxidant
