Nutritional and phytochemical profiles of common pepper (Capsicum spp.) foliage consumed as leafy vegetables in Southeast Nigeria

Abstract

Pepper foliage is consumed as a secondary plant part and as a traditional leafy vegetable in some climes. The six commonly consumed pepper species namely Cayenne, Anaheim, Bell, Bird’s eye, Scotch Bonnet and Habanero were analysed for their nutrient and phytochemical contents on a fresh weight basis. Proximate composition, vitamins were evaluated while minerals were analysed by the dry ash extraction method. Phytochemicals namely alkaloids, saponins and flavonoids were analysed by gravimetry; tannin and phenols by spectrometry; oxalate by titrimetry and hydrogen cyanide were analysed by alkaline picrate assay. Results indicated a significant difference (p<0.05) in the nutrient and phytochemical contents of the pepper foliage. Moisture ranged between 86.90 to 88.6% while their energy densities ranged between 34.33 to 45.66 kcal/100 g. Anahiem had the highest crude protein while Scotch Bonnet had the highest carbohydrate contents of 3.50% and 2.70% respectively. Bird's eye, Bell and Scotch Bonnet had the highest ash, fat and crude fibre contents respectively. The order of concentration of vitamins in the pepper foliage was in this order: Vitamin C > Vitamin A > Vitamin E > Vitamin B2 > Vitamin B1 > Vitamin B3. Scotch Bonnet had the highest calcium and magnesium contents, Cayenne had the highest phosphorus, potassium and iron contents while Anahiem and Bell had the highest zinc and sodium contents respectively. The phytochemical profile indicated that oxalate content of the foliage ranged between 0.14 to 0.28 mg/100 g and this classifies them as low oxalate vegetables. Bird's eye had the highest hydrogen cyanide content (9.45 mg/100 g) while Cayenne had the highest phytate content (12.72%). Results indicated the presence of tannins, alkaloids, phytosterols, phenols, flavonoids and saponins. These phytochemicals in the pepper foliage can be beneficial for human wellbeing based on their health-promoting effects.