Chemistry and quality of Hibiscus (Hibiscus sabdariffa) for developing the natural-product industry in Senegal.

The objectives of this study were to assess and improve the quality of the hibiscus calyces from Senegal over 2 production seasons (2004 to 2005), to develop and adapt new procedures for the determination of hibiscus anthocyanins and analysis of the 2 major ones, delphinidin-3-sambubioside and cyanidin-3-sambubioside. The foreign matter, total ashes, and acid insoluble ashes showed that the calyces harvested in 2005 were produced following hygienic practices, while the color assessment of the calyces and analysis of hibiscus active principles also showed higher amounts of anthocyanins in 2005. A protocol to measure anthocyanins by pH-differential UV-Vis spectrophotometry was adapted to measure the hibiscus anthocyanins from a water extract. The spectrophotometric method for quantitation of total anthocyanins showed a close correlation (r(2)= 0.82) when compared with the HPLC method, suggesting the use of the colorimetric method in quality control programs as an affordable alternative method to assess anthocyanin content in hibiscus. New and raised standards for the cleanliness and active principle content in hibiscus are also proposed. This study demonstrated that the implementation of a quality control program and the application of agricultural good practices in the production and processing of hibiscus calyces can lead to higher quality natural plant products.