Mineral elements analysis and total flavonoids content in the fresh leaves from two varieties of Hibiscus sabdariffa L. consumed as vegetable in Lubumbashi (DR Congo)

Fresh leaves of sorrel (Hibiscus sabdariffa L.) are among the most consumed vegetables in the Lubumbashi in the Democratic Republic of Congo (DR Congo). According to the literature, this vegetable shows the chemical variability depending on the culture area. Two varieties of this species, cultivated and consumed in Lubumbashi have not yet been studied for their micronutrient content, of which fruits and vegetables are the main sources. This study investigated the mineral and total flavonoid content of fresh leaves from red and green varieties of H. sabdariffa L., consumed as a vegetable in the aforementioned city. Fresh leaves of red and green variety of H. sabdariffa were purchased in 10 main markets of the Lubumbashi city. Gravimetric and spectrophotometric methods were used for analyzes of water, mineral and total flavonoids content. Three of the major mineral elements (Na, Ca, Mg) and several trace elements (Cu, Zn, Fe, Mn, Se, Co, Cr) were found in both varieties in elevated quantity in leaves of red variety. These latter were marked by a high content of iron (7 mg/100 g of fresh material) and Manganese (600 μg/100 g of fresh material). Total flavonoids quantification revealed that the leaves of red variety have a high value (28.2 ± 0.3 mg Quercetin Equivalent per g of extract) in total flavonoids compared to the leaves of green variety. Fresh leaves of the red variety of H. Sabdariffa consumed in Lubumbashi could be a source of iron for adults and manganese for children.