Effets spécifiques des sites et des méthodes de cuisson sur les rapports oxalate-minéraux dans quelques espèces d’hibiscus de la province de Kwilu / République Démocratique du Congo

Odon Sawubu Mabaya; Jean Sungula Kayembe; Maurice Kalukul Nsikungu; Yvonne Bomangwa Ibebeke; Junior Tinatina Kindala; Oscar Mihigo Shetonde

doi:10.59228/rcst.026.v5.i2.311

Site Specific and Processing Effects on Oxalate–Mineral Ratios in Hibiscus from Kwilu Province / DR Congo

Authors

Odon Sawubu Mabaya Author
Jean Sungula Kayembe Author
Maurice Kalukul Nsikungu Author
Yvonne Bomangwa Ibebeke Author
Junior Tinatina Kindala Author
Oscar Mihigo Shetonde Author

DOI:

https://doi.org/10.59228/rcst.026.v5.i2.311

Keywords:

Energy potential, Renewable energy, drinking water supply, tidal turbine sizing, Kenge town

Abstract

This study examines the mineral composition and the oxalate-to-calcium, magnesium, and iron molar ratios in five Hibiscus species, considering both their provenance and traditional processing methods. Mineral analysis revealed the presence of Ca, Mg, K, P, Fe, Se, and trace amounts of Zn. The highest iron content was recorded in Hibiscus acetosella red shield (HARS) from Idiofa (0.71 g/100 g of dry material), while the lowest occurred in H. acetosella cranberry (HAC) from Kikwit (0.09 g/100 g). Selenium levels were greatest in HARS from Kikwit (0.53 g/100 g) and lowest in H. cannabinus (HC) from Idiofa (0.04 g/100 g). Potassium was most abundant in H. sabdariffa var. altissima (HSA) from Kikwit (0.96 g/100 g). The highest Ca and Mg concentrations were found in HSA and H. sabdariffa var. sabdariffa (HSS) from Kikwit, with 0.33 g/100 g Ca and 0.28 g/100 g Mg, respectively. Molar oxalate/Ca ratios were below 1 for all species except HC, indicating generally good calcium bioavailability. In contrast, oxalate/Fe ratios exceeded 1 in all species except HSA, suggesting limited iron bioavailability. Sun‑drying increased oxalate–mineral molar ratios despite previously reported reductions in oxalate content, and oven‑drying caused an even greater increase. Prolonged soaking of dried leaves resulted in substantial mineral losses and a marked rise in oxalate–mineral ratios. Conversely, the traditional use of artisanal potash reduced these ratios, thereby enhancing mineral bioavailability.

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