Elemental composition and nutritional value of the edible fruits of Harpephyllum caffrum and impact of soil quality on their chemical characteristics

Abstract

Harpephyllum caffrum is a medicinal plant and common street tree distributed throughout the eastern part of South Africa. The elemental concentration in the edible fruit of H. caffrum was determined to assess for nutritional value and health impact. Concentrations of metals in the fruit and growth soil were determined from samples acquired from eight different sites in eastern KwaZulu-Natal, South Africa, to evaluate the impact of soil parameters on elemental distribution in the fruit. Typical elemental concentrations (μg g⁻¹, dry mass) in soil (Exchangeable/Total) and fruit samples, at Umhlanga, north of Durban, were Ca (1221/696 and 3333), Co (2.5/2.1 and 0.16), Cr (35/0.8 and 5.8), Cu (14/9 and 21), Fe (9424/394 and 116), Mg (199/139 and 915), Mn (268/187 and 13), Ni (2.8/0.51 and 3.4), Pb (36/32 and 1.2), and Zn (26/21 and 15). The analytical results showed that metal interactions in soil influenced their availability, but uptake was to a greater extent controlled by the plant. The concentrations of elements in the fruits were found to be in the order of Ca > Mg > Fe > Cu > Zn > Mn > Cr > Ni > Pb > Co. The concentrations of toxic metals, arsenic and lead were low. The fruits can contribute to the health and nutritional needs of individuals for most elements. It has potential to improve the Fe status and contribute towards a balanced diet.

Keywords:

• Elemental distribution
• Harpephyllum caffrum
• edible fruit
• nutritional value
• impact of soil quality
• toxic metal