Nutritional Quality Assessment of Omena (Rastrineobola argentea) Sourced from Warehouses, Markets, and Schools in Nairobi, Murang’a, Homabay, and Makueni Counties

Omena (Rastrineobola argentea), a small pelagic fish native to Lake Victoria, offers a valuable source of nutrients for consumers in Kenya. This study investigated the nutritional composition of omena sourced from various counties. A purposive sampling technique was employed to collect samples in the supply chain: warehouses (3), open markets (2), and school stores (3), as well as cooked omena from market places (2) and school kitchens (4) in Nairobi, Makueni, Homabay, and Murang’a counties. Proximate analysis, including moisture, ash, crude protein, crude lipid, and crude fiber content, was conducted alongside mineral and vitamin determinations using standard analytical methods. Results revealed significant variations (p < 0.05) in the nutritional composition of omena from different sources. Crude protein content in stewed omena ranged from 19.3% to 23.75%, while crude lipid content varied from 5.4% to 14.29%. Mineral analysis indicated significant levels of calcium, potassium, iron, magnesium, and zinc in omena samples. Notably, stewed omena from school 3 exhibited the highest calcium content (3669.3 mg/100 g), while sun-dried omena collected from school store of school 4 had the highest levels of potassium, (10.50 mg/100 g). Furthermore, sun-dried omena from the warehouse 3 and deep-fried omena from market 2 exhibited the highest iron content (5.892 mg/100 g and 6.481 mg/100 g, respectively). This study highlights the nutritional potential of omena as a valuable food source. However, the observed variations in nutrient composition emphasize the need for improved quality control and standardization within the omena supply chain to ensure consistent nutritional benefits for consumers.