Bekri Melka Abdo
Roselle is a medicinal plant claimed to lower blood pressure and cardiovascular disease. Besides, its beverages are known in many parts of the world for inducing lactation during the weaning period. However, huge potential of Roselle plant is there in the western part of Ethiopia, but not exploited for purpose. Recently, the herbal tea and soft drink of Roselle has the emerged popular. Therefore, determination of anthocyanin content of Ethiopian Roselle genotypes was an aim for this study. Besides, the superior anthocyanin that yielded Roselle genotype was selected and determined its nutritional profile and standardized the herbal tea preparation protocol from the calyx. The standardization was governed by determining the principal active constituent (anthocyanin) based on the pH differential method through UV-Visible spectrophotometer. Acidic methanol solution extracts of dried calyx of the Roselle genotype had a total anthocyanin content of in the range 0.05-4.45%, which was expressed in terms of cyanidin-3-O-glucoside. The Roselle of WG-H-Sudan variety was yielded superior total anthocyanin content (4.45%) with having color intensity value of 1.85. The proximate analysis of the calyx of Roselle from WG-H-Sudan variety revealed that, moisture (10.2 %), ash (6.9 %), fiber (13.9 %), protein (6.64 %), fat (6.7 %) and a total of 311.84Kcal energy was obtained from 100g dried Roselle calyx. While, the mineral analysis of 100 g dried Roselle calyx showed to contain K (20.42 mg), Na (0.13 mg), Fe (8.24 mg), Zn (23.64 mg), Cu (0.67 mg) and Mn (18.49 mg). The optimization plots of different modes of herbal tea preparation showed that hot water (500 mL) infusion of 0.5 g powder of Roselle calyx for 3 minutes stirring acquired maximum total anthocyanin content of 26.85 mg. This value is used to set the amount of Roselle calyx consumption in different drink products.