Nutrient composition of niger seed (Guizotia abyssinica (L. f.) Cass.) cultivated in different parts of Ethiopia

Abstract

The levels of essential and non-essential metals in niger seed (Guizotia abyssinica (L. f.) Cass.) cultivated in different parts of Ethiopia were determined by flame atomic absorption spectrometry after wet digestion using 2.5 mL of HNO₃ (69.5%), 1 mL HClO₄ (60%) and 0.5 mL of 30% H₂O₂ at 210 ^oC for 150 min. Sampling was carried out randomly from nine different sites from Ethiopia and one sample from Eretria for comparison. The following metal concentration ranges (μg/g) were determined in niger seed samples, respectively: Na (159–736), K (5594–8203), Ca (340–680), Mg (2404–4656), Mn (13.4–34.3), Fe (31.6–370), Cu (9.5–61.2), Zn (23.4–46.2), Cr (4.0–16.8), Co (4.9–27.3), Ni (13.0–32.4), Pb (15.5–19.3) and Cd was not detected in all the samples. The analysis of variance indicated the presence of significance difference at 95% confidence level among niger seeds collected from different sites. Pearson correlation coefficients indicated that there were significant correlations among some metals in the niger seed. The study revealed that niger seed is good source of essential metals and free from toxic metal such as Cd and hence safe for human consumption. Generally, the metal concentration in niger seed is comparable with other oil seeds.

KEY WORDS: Niger seed, Guizotia abyssinica, Nutrient, Metal, Ethiopia

Bull. Chem. Soc. Ethiop. 2015, 29(3), 341-355.

DOI: http://dx.doi.org/10.4314/bcse.v29i3.2