Authors: Haji M. Khamis, Lusweti J. Kituyi, Haji M. Haji
Red-fleshed watermelons (Citrullus lanatus) contain a high level of lycopene, and small amount of β-carotene which have been reported to have many important health benefits. However, very little is known on the quantity of all trans-lycopene, cis-lycopene and β-carotene found in watermelons grown in Zanzibar. The objective of this study was to quantify all trans-lycopene, cis-lycopene and β-carotene carried by watermelons available in Zanzibar Islands. Samples were collected from Mkokotoni area in Zanzibar, a representative of the Zanzibar Islands and extracted by using solvent system of hexane/acetone/ethyl acetate (4:2:1 v/v/v). The extracts were filtered and the lycopene layer separated from the filtrate, washed, dried by rotary evaporator and then dissolved in hexane. The concentrated hexane solution was then subjected to column chromatography on silica gel. The all trans-lycopene, cis-lycopene and β-carotene fractions were collected, dried by nitrogen gas and weighed. The dilute hexane solutions of all trans-lycopene, cis-lycopene and β-carotene were scanned using a UV-VIS spectrophotometer. The results obtained showed that mass (in μg/g) of all trans-lycopene varied from 93 to 1929, cis-lycopene varied from 67 to 827 and β-carotene varied from 25 to 881. The fruit contains considerable amounts/quantities of food nutrients beneficial to human health.