Roselle ( Hibiscus sabdariffa   L.) cultivars calyx produced hydroponically: Physicochemical and nutritional quality

The chemical constituents of roselle (Hibiscus sabdariffa L.) vary by environmental stimuli and cultivar. The effect of cultivars produced under hydroponic and greenhouse conditions on the mineral composition, chemical and nutraceutical quality of the calyx was evaluated. An experiment was conducted in greenhouse and hydroponic conditions, in a randomized complete design with three replicates and four plants per experimental unit. Treatments were formed by a six roselle cultivars: Cruza Negra, Criolla Huajicori, UAN25-1, UAN16-2, 4Q4, and UAN6-Puga. Principal component analysis (PCA) showed that ‘Cruza Negra’ is the best cultivar because it presents the highest values of total and insoluble fiber (395 and 260 g kg^-1 dry basis [db]), total phenols (29.178 mg kg^-1 db), anthocyanins (18.133 mg kg^-1 db), 2,2-diphenyl- 1-picrylhydrazyl (DPPH; 645 mg kg^-1 db), and the absorption capacity of oxygen radicals (ORAC; 240 mg kg^-1 db). The highest contribution of minerals was observed in ‘Cruza Negra’ (K, Na, Zn, and Cu) and ‘Criolla Huajicori’ (Ca, Mg, S, and Mn), contributing significantly to the recommended daily intake (RDI). Variability was evident in all the quality characteristics evaluated in the greenhouse roselle calyx. Ash, total and insoluble fiber, phenols, anthocyanins, DPPH, and ORAC contributed the most to the nutritional and nutraceutical quality of the roselle calyx. These variables were influenced by the cultivar.

Keywords
Anthocyanins; composition; fiber; Hibiscus sabdariffa; main components; quality