Mineral composition of ready-to-eat walnut kernel (Tetracarpidium conophorum) from southeast Nigeria

Walnut is considered a delicacy in Nigeria. Elements were determined in 30 composite samples of cooked walnut kernel from Southeastern Nigeria by atomic absorption spectrophotometry (AAS) after acid digestion. Mean concentrations (mg/kg; dry weight) of K, Ca, Mg, Na, Fe, Zn, Cu and Pb were 2367±160, 882±120, 274±11, 183±67, 73.6±20, 37±7, 15.1±1.6 and 0.021±0.009 respectively. Daily intake (mg/day) of Na (12–14), K (161–178), Ca (60–66), Mg (18–20), Fe (5.0–5.6), Cu (1.0–1.1) and Zn (2.5–2.8) on consuming 68–75 g of cooked walnut kernel were adequate when compared with their recommended daily intakes (RDI). The results indicated that though Pb was present, the daily Pb intake on consuming 68–75 g of walnut kernel is about 0.6% of the RDI (Pb RDI = 0.25mg/day). One-way ANOVA showed that sampling areas significantly influenced the levels of metals in cooked walnut kernel. Principal component analysis (PCA) indicated that metals were of natural source. The results proved Tetracarpidium conophorum kernel to be a rich source of essential minerals with negligible levels of toxic metals. The work contributes to the data on mineral composition of local foods and the results may be useful for the estimation of dietary information

Author(s): Innocent C.Nnorom, Nnamdi E. Enenwa and Ugochukwu Ewuzie

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