Nutritional Evaluation of Roselle (Hibiscus sabdariffa L.) and its Application in Biscuit Supplementation

Roselle (Hibiscus sabdariffa L.) plant was analyzed for its chemical and nutritional characteristics of plant parts (seeds, seeds cake, leaves, stems and roots) as well as the effect of the replacement of wheat flour with roselle powder at different ratios either from roselle seeds cake (0, 10, 20 and 30%) or roselle leaves powder (0, 2.5, 5 and 7.5%) on the nutritional and quality properties of biscuits. The obtained results proved that roselle seed, cake and leaves is a rich source of valuable nutrients, i.e., protein (12.32 – 29.06%), lipids (4.45 – 27.83%), ash (5.53 – 15.13%) and crude fiber (14.52 – 20.53%) as well as higher content of essential minerals. Potassium, calcium and phosphorus are to be the highest concentration in roselle parts, it ranged between 7.94-46.30 mg/g (potassium), 5.29-28.80 mg/g (calcium) and 3.23-22.10 mg/g (phosphorus), other studied elements are at the lowest values. Total phenolic compounds ranged between 155.04-3288.33 ppm as gallic acid, so it was the highest in roselle leaves being 3288.33 ppm followed by stem (2086.78 ppm); however it could be used as natural antioxidant. In corporation of roselle cake or leaves powder in biscuit formula improved the nutritional profile and physical characteristics of biscuits. Increasing the incorporation of roselle cake or leaves powder, it increased the nutritive value of prepared biscuit. On the other hand, cocoa biscuit recorded the highest values of the physical properties than vanilla biscuit. Sensory evaluation revealed that the best replacement ratio was 10% 0f roselle cake and 2.5% of roselle leaves which gave suitable attributes for panelists which scored the highest level of biscuit quality. From the obtained results, roselle could be become an excellent economic and valuable source of the nutritional factors which can be used in food supplementation. It is worth mentioning that, roselle seeds and cake are considered a good source of protein and can replace animal protein, especially for vegetarians.