Comparative Studies on the Proximate, Mineral and Energy Contents of Watermelon and Orange Peels

Abstract

The research was carried out to determine and compare the proximate, mineral and energy contents of two fruit peels, watermelon and orange peels. Standard laboratory procedures were employed in determining the parameters. Results obtained revealed the proximate and energy contents of the two fruit peels as; Watermelon peels: Moisture Content (8.96%), Ash Content (6.48%), Crude Lipid (2.42%), Crude Fiber (10.60%), Crude Protein (2.79%), Carbohydrate (72.42%), Vitamin C (3.63 mg/100g), Energy (25.38 KJ/Mol) and Orange peels: Moisture Content (9.56%), Ash Content (6.74%), Crude Lipid (2.64%), Crude Fiber (12.54%), Crude Protein (12.24%), Carbohydrate (55.12%), Vitamin C (62.86 mg/100g), Energy (19.34 KJ/Mol). It was observed that there were similarities in terms of ash, moisture, crude lipid, and crude fiber contents of the two fruit peels though with little variations. However, the fruit peels were observed to differ in their crude protein, carbohydrate, vitamin C and energy contents. Watermelon peels was observed to contain more carbohydrate and energy, but orange peels showed higher crude protein and vitamin C contents. The moisture and ash contents of both fruit peels were observed to be low which was suggested to be the reason for high dry matter yield resulting to low water retention on drying due to low porosity of surface structure. Similarly, low ash contents of the fruit peels were also observed which was supposedly the reason for the low inorganic/mineral contents of the peels. The mean levels of trace elements in the two fruits peels showed marked differences between the fruit peels. Nine mineral elements (Mg, Fe, Zn, Mn, Cu, Ca, Na, K and P) were detected in the fruits peel samples. Calcium (Ca) was observed to be the highest in both fruits with values of 30.12 mg/100g and 133.58 mg/100g in watermelon and orange peels respectively. Copper was the least in watermelon (0.56 mg/100g) and zinc in orange peels (0.31 mg/100g). It was further observed that the levels of most of the mineral elements were above their WHO/FAO recommended permissible levels in fruits for which the consumption of the fruits without proper monitoring was considered risky health wise.