Comparative Assessment of some Mineral, Amino Acid and Vitamin Compositions of Watermelon (Citrullus lanatus) Rind and Seed

The mineral, amino acid and vitamin compositions of the rind and seed flours of Charleston gray variety of watermelon (Citrullus lanatus) were investigated, using standard methods. The mineral (mg/100 g) in the rind and seed, respectively viz: calcium (28±0.01, 54±0.02), phosphorous (129.7±0.01, 614.3±0.02), sodium (11.4±0.04, 87.0±0.06), potassium (21.7±0.00, 524.0±0.04), magnesium (30.4±0.01, 509.1±0.03), manganese (1.30±0.01, 6.40±0.04), iron (4.63±0.00, 7.08±0.01), copper (0.4±0.01, 0.7±0.00) and zinc (1.25±0.01, 10.13±0.02) was, aside that of copper (±0.3), significantly (p<0.05) higher in the seed. The value of the amino acids (g/100 g) in the seed sample viz: glutamate (11.43±0.01) followed by arginine (6.12±0.06), isoleucine (4.27±0.10), aspartate (2.81±0.01), glycine (2.47±0.03), leucine (2.09±0.01), valine (1.71±0.03), alanine (1.43±0.04), lysine (1.01±0.04), histidine (0.80±0.00), tryptophan (0.40±0.00) and cystine (0.39±0.02) was higher (p<0.05) than the corresponding value (0.00±0.00) in the rind sample. The vitamin composition in mg/100 g for the rind and seed, respectively for retinol (vitamin A) (50.15±1.41, 70.10±1.04), niacin (vitamin B3) (0.04±0.1, 3.32±0.00), ascorbic acid (vitamin C) (7.23±0.02, 6.8±0.03), thiamine (vitamin B1) (0.03±0.01, 0.20±0.00), riboflavin (vitamin B2) (0.02±0.1, 0.15±0.04) and pyridoxine (vitamin B6) (0.04±0.00, 0.09±0.01) was higher (p<0.05) in the seed flour for retinol and niacin. The preponderance of these nutrients in the, especially seed, samples, may be of nutritional and physiological importance warranting further studies to increase the dietary use of these food wastes and reduce the attendant burden in the environment.