Proximate and Mineral Composition, Protein Quality of Hibiscus Sabdariffa L. (Roselle) Seeds Cultivated in Two Agro Ecological Areas in Cameroon

Abstract

The chemical composition and protein quality of raw, boiled, toasted and soak-toasted roselle seeds harvested in the North (area I) and West (area II) regions of Cameroon were investigated in this study. To conduct the growth and nitrogen balance study, sixty albinos wistar rats of 21 to 25 days separated into ten groups of six rats/group were used and fed for fourteen days with 10% (w/w) isoproteinous experimental diets. These groups were Protein free diet (D0), egg white-standard reference protein diet (D1) and raw (D2I, D2II), boiled (D3I, D3II), toasted (D4I, D4II) and soak-toasted (D5II, D6II) roselle seed diets. Transaminases, serum creatinine, haematocrit, lipid parameters were also assessed in the rats. Results showed that crude protein, lipid, fiber and ash content of seed samples ranged respectively from 22 to 26, 18 to 22, 18 to 23 and 4.3 to 6.4%. The contents of Ca, Mg, K, Na, P, Fe and Zn were ranged from 1054 to 1920, 1670 to 2083, 26.45 to 272.7, 14 to 22, 10.58 to 90.78, 137.3 to 169.22 and 10.13 to 70.11 mg/kg respectively. Food intake was higher (P<0.05) for groups D1, D3I and D3II than for others groups. The rats fed with reference diet followed by boiled seed diets had the highest (P<0.05) weight gained, protein efficiency ratio (PER), net protein ratio (NPR), feed efficiency (FE), efficiency of food utilization (EFU) and true digestibility (TD). Aspartate aminotransferase and alanine aminotranferase were highest (p<0.05) in the rats fed raw roselle seeds. Compared to reference diet, the total cholesterol (TC), triglycerides (TG) and LDL-C of rats fed with diet D5II decreased while the HDL-C did not show any significant changes in these rats (p˃0.05). These findings show that roselle seeds cultivated in Cameroon have important amount of macronutrients and minerals. Proteins of roselle seeds are of good quality especially from the boiled seeds and are not influenced by the agro ecological region. Consumption of roselle seeds might be beneficial for cardio protective effect and no toxicity was observed as far as transaminases are concerned except that for the raw seeds which showed significant hepatotoxicity.