Fatty acid composition, total phenolic contents and antioxidant activity of white and black sesame seed varieties from different localities of Ethiopia

Authentication of food and agricultural products is important to trace out the right product and ensure the customer’s preference and their health. Sesame (Sesamum indicum L.) is one of the most important crops used for food and medicine in Ethiopia and different varieties and cultivars are produced in different regions of the country. This study was undertaken to determine the total flavonoid content, total phenolic content, antioxidant activity, and fatty acids profile of black and white sesame seed varieties. Samples were obtained from three major sesame seed-producing districts of Ethiopia. The total phenolic content (TPC), total flavonoid content (TFC), and the half-maximal inhibitory concentration (IC50) were ranged from 2.95 to 6.95 mgGAE/g, 2.13–4.99 mgCE/g and 8.3–16.8 AAE/g of the sample, respectively. In general, white sesame seed samples showed the highest TPC, TFC, and antioxidant activity than the black variety. Location wise, samples collected from the Metema district were found to contain a relatively higher concentration of the phytochemicals. The white seed variety was characterized by significantly higher content of oil (53.2–58.2% by mass of the sample) than the back variety (47.6–51.4%).The oil content of the seeds was found to contain nine identifiable fatty acids (FAs). The total unsaturated fatty acids constituted more than 82% of the total FAs, while the saturated FAs were lower than 18% of the total FAs. Among the unsaturated FAs, linoleic acid (C18:2, omega-6 FAs) was the dominant FA (42.5–44.3%) followed by oleic acids (37.2–38.9%). On the other hand, palmitic acids (9.35–11.2%) and stearic acid (5.78–6.52%) were the dominant FAs among the saturated FAs. The studied samples had higher concentration of linoleic acid (omega-6 FA) than oleic acid, as opposed to other reported accessions of sesame seeds. Furthermore, white sesame seeds were richer in oil content than the black variety. The high concentration of unsaturated FAs, omega-6 FA, and phenolic compounds make sesame seeds nutritionally and medicinally important for the human diet. Unlike the fatty acids profiles, the level of phenolic compounds in sesame seeds was highly dependent on the geographical region and varietal type of the seeds.