Comparative Analysis of Minerals, Heavy Metals and Amino Acids Compositions of the Seeds and Juice of Cucumis metuliferus

Abstract

The aim of this study was to compare the minerals, heavy metals and amino acids compositions of the seeds and juice of Cucumis metuliferus. The minerals and heavy metals content were evaluated using FS240AA agilent atomic absorption spectrometer according to the method of American Public Health Association while the amino acids content was evaluated using High Performance Liquid Chromatography (HPLC). From the mineral analysis, concentrations of calcium (23.416 ppm), aluminum (0.094 ppm), manganese (0.242 ppm) and iron (1.243 ppm) were higher in the juice than in the seeds with respective values of 20.084 ppm, 0.079 ppm, 0.221 ppm and 0.934 ppm while the concentrations of magnesium (29.749 ppm), zinc (4.184 ppm), copper (0.125 ppm), sodium (8.927 ppm) and potassium (7.594 ppm) were higher in the seeds than in the juice with respective values of 20.592 ppm, 1.271 ppm, 0.030 ppm, 8.594 ppm and 6.833 ppm. The juice had higher concentrations of heavy metals such as arsenic (20.082 ppm), lead (4.135 ppm), cobalt (0.178 ppm), silver (0.074 ppm), selenium (7.246 ppm) and mercury (4.609 ppm) as against the seed with respective values of 0.578 ppm, 1.455 ppm while cobalt, silver, selenium and mercury were not detected. However, the concentrations of cadmium (0.389 ppm), chromium (0.545 ppm) and nickel (0.288 ppm) were higher in the seeds than in the juice with respective values of 0.082 ppm, 0.252 ppm and 0.016 ppm. From the result of amino acid analysis, 18 amino acids were found in both the seeds and juice which include 9 essential and 9 non-essential amino acids respectively. The qualitative composition of amino acids in both the seeds and the juice was same, but the quantitative contents differed although non-significantly from each other with prevalence of amino acids in the seeds. Aspartate was the most abundant of the amino acids found while cysteine was the least.  These results suggest that the seeds and juice of Cucumis metuliferus contain adequate essential minerals which are beneficial to human health. The contaminant levels of heavy metals highlights the necessity on the quality and safety concerns about their use and handling. The amino acids analysis showed that both the seeds and juice of Cucumis metuliferus are good sources of amino acid and could be used as food supplement. The amino acid content may also provide useful information for determination of the protein quality of Cucumis metuliferus.