Proximate, mineral, fatty acid composition and quality of the oil obtained from landrace and improved sesame (sesamum indicum) seeds grown in northern Uganda

Abstract

Uganda is the seventh sesame-producing country in Africa and ninth in the world. Sesame is a non-traditional cash crop with tremendous export potential. Data on composition of sesame in Uganda is scarce, making the planning of the sesame value chain a challenge. Landraces (Ajimo, Otara, Arut) and improved sesame seeds (Sesim I, Sesim II and Sesim III) were obtained from MAAIF Vegetable Oil Development Project (VODP-Phase 2) and NaSARRI, respectively. Proximate composition was determined using methods of the Association of Official Analytical Chemists (AOAC). Fatty acids (FA) were determined as FAME using GC-FID. Minerals were determined using Atomic Absorption Spectrophotometry (AAS). Quality parameters; refractive index (RI), acid value (AV), peroxide value (PV), and iodine value (IV) of oil extracted from sesame seeds were determined by AOAC and the American Oil Chemists Society (AOCS) methods. Findings from the study showed a significant difference in moisture, fat, protein, crude fibre, crude ash and carbohydrates between the landrace and improved seeds. FA composition was variable between landraces and improved sesame seeds. The major FA of sesame oil were oleic acid (18:1ꞷ9), linoleic acid (18:2ꞷ6), palmitic acid (16:0) and stearic acid (18:0). Unsaturated FA predominated over the SFA. Landraces had a higher content of 18:2ꞷ6 than the improved sesame seeds while improved sesame seeds had higher amounts of 18:1ꞷ9. Mineral concentrations varied from 521.45 to 665.15 mg/100 g for P, 315.70 to 458.22 mg/100 g for K, 199.60 to 363.16 mg/100 g for Mg, 69.29 to 83.15 mg/100 g for Na, 50.42 to 56.40 mg/100 g for Ca, 2.32 to 2.86 mg/100 g for Fe, 1.12 to 2.77 mg/100 g for Zn and 1.13 to 1.59 mg/100 g for Cu. Oil quality parameters were within the international standards for oils meant for human consumption. These findings provide insights on nutrient composition of sesame seeds in Uganda, highlighting their potential health benefits and quality for culinary use and oil extraction.