Agricultural and Biological Research

Antioxidant activity and nutritional potential of the most cultivated sweet potato varieties in Benin

Camel Lagnika*, Abdou Rahouf Sangani, John Nsor-Atindana, Abdou Madjid Olatounde Amoussa and Latifou Lagnika

Sweet potato is a highly valuable food crop that is widely consumed in many parts of the world. However, the skin of sweet potatoes is often discarded during consumption, even though it contains some nutrients and phytochemicals. Indeed, a study was conducted in southern Benin to evaluate the nutritional potential, antioxidant activity and phenolic compounds of the five most commonly grown sweet potato varieties. Spectrophotometric methods were used to measure the levels of Total Polyphenols (TP) and Total Flavonoids (TF). The antioxidant activity was assessed using 2,2-diphenyl-1-picryl-hydrazyl.

The results showed that TP content ranged from 2.93 ± 0.03 to 7.95 ± 0.50 mg Gallic Acid Equivalent (GAE)/g in the flesh samples and from 3.52 ± 0.01 to 7.88 ± 0.35 mg GAE/g in the whole sweet potatoes (flesh+skin). TF content ranged from 20.48 ± 0.39 to 36.64 ± 0.11 mg/g in the flesh samples and from 21.00 ± 0.71 to 40.33 ± 0.82 mg/g in the flesh+skin.

Among the different sweet potato varieties studied, 'Deux couleurs' and 'Vobodouaho' had the highest levels of phenolic compounds in their flesh. For whole samples, the 'Deux couleurs and Djowamon' varieties had the highest content of total phenolic compounds. Additionally, sweet potato samples with colored skin (red or purple) had higher TF content compared to those with white skin.

In terms of antioxidant activity, the 'Deux couleurs' variety exhibited the highest activity with an Inhibitory Concentration (IC₅₀) of 4.76 mg/ml, while the 'Vobodouaho' variety had an IC₅₀ of 51.4 mg/ml.

Overall, the study suggests that 'Deux couleurs' and 'Djowamon' varieties have the potential to contribute significantly to food and nutritional security, as well as the prevention of chronic diseases.