Proximate Analysis and Phytochemical Screening of Citrus sinensis Fruit Wastes

Citrus sinensis (sweet orange) is one of the most commonly consumed fruits in Nigeria. This study evaluated the proximate composition and phytochemicals present in the fruit wastes (flavedo, albedo and seeds). Proximate analysis was carried out on the dried and ground wastes while phytochemical screening was carried out on ethanolic and hydroethanolic extracts. Proximate analysis showed that the flavedo and seeds are rich sources of oil, containing 10.00 ± 0.58% and 12.00 ±1.15% respectively. Ash content ranged from 0.85 ± 0.03% in the albedo to 2.00 ± 0.06% in the seeds. The albedo had the highest moisture and nitrogen-free extract contents (15.00 ± 0.58% and 78.22 ± 0.58%) respectively with the lowest protein, ash and lipid contents. The flavedo had the highest fibre content (13.43 ± 0.03%) while the seeds had the highest protein content (6.13 ± 0.51%). Phytochemical screening revealed the presence of alkaloids and steroids in all the extracts. Alkaloids were highly detected in both flavedo extracts and the ethanolic albedo extract. Steroids were highly detected in all extracts with the exception of the ethanolic seed extract. Tannins were highly detected in the flavedo extracts and mildly in all other extracts with the exception of the ethanolic seed extract. Flavonoids were mildly detected in all extracts except the hydroethanolic albedo extract. Saponins were not detected in the ethanolic seed extract while high levels were detected in hydroethanolic flavedo extract. Mild levels of terpenoids were detected in the hydroethanolic albedo extract and both flavedo extracts with cardiac glycosides found in the hydroethanolic seed extract as well as both albedo extracts. Our results showed that value-added products of varied industrial application may be available in the seeds and peels of sweet orange.