A Study of Oxalate Content of Some Selected Species of Hibiscus Cultivated in Kwilu State/Democratic Republic of Congo

Aims: This work aimed to determine the total content of oxalate on some species of Hibiscus collected at Kwilu state/Congo-Dr, and to determine the variation of this anti-nutritional factor according to the plant age and after the removal of first cooking water.

Study Design: Different species of Hibiscus are as well consumed in Kwilu state (DRC), where they are often dried in order to be consumed during the dry season. To date, it is well known that high-oxalate diets may increase the risk of kidney stones and others health problems in susceptible people.

Place and Duration of Study: Different samples of Hibiscus were collected in rain season (January to April 2016), in Kwilu state (DRC). Laboratory analyses were done at the Department of Chemistry (Lacoren/Unikin).

Methodology: Ten species of Hibiscus were collected, and their oxalate content was determined using volumetric titration’s method with a standard solution of potassium permanganate.

Results: The results showed significant oxalate content, ranging from 1056.12 +/- 34.43 mg/100 g to 422.40 +/- 23.71 mg/100 g of fresh weight. The elimination of first cooking water reduces this anti-nutritional factor to more than 70%. The oxalate content variation with the age of three selected Hibiscus has been investigated which shows a maximum level of high oxalate content between 55 to 60 days of plant development.

Conclusion: A non-negligible concentrations of oxalate were found from the ten species of Hibiscus used in this work, regardless to the plant age. The removal of first cooking water may serve to greatly reduce the oxalate content.