Influence of Geographical Location on Key Nutritional Properties of Watermelon (Citrullus lanatus) Pulp

Abstract

Citrullus lanatus (watermelon) which was only cultivated in Northern Nigeria in the past, is now cultivated in other parts of Nigeria. However, there is no data to show the nutritional quality of C. lanatus as it relates to the location of cultivation. Therefore, this study aimed to evaluate the nutritional properties of the pulp of Citrullus lanatus cultivated in four states, representing four geopolitical regions of Nigeria. C. lanatus samples were collected from the northeast, southwest, southeast and south-south geopolitical zones of Nigeria. They were thoroughly washed, then the pulp was separated, homogenized and freeze-dried.  The amino acid profile, vitamins, proximate and mineral analyses of the freeze-dried samples were done by standard protocols. The amino acid profile results showed the presence of varied amino acids in the different zones, with the southwest giving the highest concentrations of the amino acids and the least concentration obtained from the south-south zone. The presence of vitamin C and A, and the minerals: Ca, Mg, K, Na, Fe, Pb, and Mn were detected in the pulp of C. lanatus at diverse concentrations in the various zones, with samples from the southwest zone also giving the highest composition of both vita by mins and mineral contents.  The proximate composition analysis results revealed a higher (p < 0.05) percentage of moisture, protein and fiber from the southwest sample when compared with other zones, and higher (p < 0.05) percentage composition of carbohydrate, ash and fat contents from the northeast samples relative to other zones. Thus, the nutritional value of the C. lanatus samples was in the order: Southwest > northeast > southeast > south-south. Conclusively, the results showed that the location of cultivation affects the nutritional value of Citrullus lanatus fruit.