Some Nutritive and Antifungal Properties of Citrus sinensis (Sweet Orange) Peels and Seeds

Abstract

Introduction: Citrus sinensis (sweet orange) fruit is widely consumed the world over for its sweet juice. The peels and seeds may have some nutrients and antifungal properties but are essentially discarded with attendant waste generation. Aim: The study evaluated some nutritive and antifungal properties of the peels and seeds of Linnaeus osbeck variety of Citrus sinensis (sweet orange) fruits purchased from Eke-Okigwe market in Imo state, Nigeria. Study Design: The peels and seeds were respectively investigated for some minerals and vitamins content and for activity against some fungi. Place and Duration of Study: The study was conducted at the Department of Biochemistry, Michael Okpara University of Agriculture Umudike, Nigeria between May and August, 2015. Methodology: The minerals and vitamins content in the respective sample flour and the antifungal activity of the respective sample crude ethanol (95%) and water extracts were determined by standard methods. Each extract (100 mg/ml) was tested against two fungi – Candida albicans and Aspergillus flavus. Results: Results showed that the vitamins content of the orange peels and seeds respectively for vitamin A (IU) (85.71±0.63, 22.51±18.04) was highest followed by ascorbic acid (mg/100 g) (12.91±1.02, 7.04±1.76). The content of the other determined vitamins in the samples was low (0.09±0.00 to 0.81±0.01). The minerals (mg/100 g) in the peels were higher than that in the seeds. The calcium content in the peels (49.05±26.24) was highest followed by magnesium (41.83±5.59), sodium (19.44±1.58) and potassium (14.90±32.94). The ethanol extracts of the peels and seeds showed activity (mm) against the tested fungi (Candida albicans and Aspergillus flavus). However, the activity of the aqueous extract of the peels against Candida albicans and Aspergillus flavus respectively (12.33±1.15, 6.67±0.58) was higher (p<0.05) than that of the seeds (7.00±1.00, 0.00±0.00). The observations, aside the difference in the riboflavin and thiamine content and the activity elicited by the ethanol extracts of the peels and seeds, were significant (p<0.05). Conclusion: The sweet orange peels could be a better source than the seeds for these nutrients, hence may offer higher nutrient benefits while ethanol may be preferred solvent to water for extracting the active phytochemicals in the samples. The higher nutrient mix in the peels probably accounted for the higher antifungal activity of the peels extracts against the tested fungi. The study provides basis for exploiting these sweet orange fruit wastes in diets and drugs, warranting further studies to harness the present findings.