Nutritional, Antinutritional, and Elemental Compositions of Wild Edible Fruits (Syzygium guineense, Citrus medica, and Ziziphus spina-christi) Grown in Ethiopia

Abstract

Ethiopia is home to a variety of wild edible plants that can serve as important sources of nutrition for humans. However, the nutritional value of these plants can be influenced by various factors, including their preparation and drying methods. This study aimed to evaluate the nutritional, anti-nutritional, and mineral contents of the fruits, seeds, and peels of three wild edible plant species ( Syzygium guineense (Willd.) DC., Citrus medica L., Ziziphus spina-christi (L.) Desf.) and to assess the impact of different drying techniques (sun-drying, room-drying, and freeze-drying) on these properties. To analyze the mineral content, inductively coupled plasma optical emission spectroscopy (ICP-OES) was used after microwave acid digestion. The study found significant ( p < 0.05) variations in nutritional, anti-nutritional, and mineral content across the plant species and drying methods. Moisture content after drying ranged from 7.55% to 14.10%, which is too low to ensure safe long-term storage of the fruits. The nutritional components, including protein (0.55–2.52%), fat (0.25–4.98%), fiber (2.03–13.68%), ash (1.92–2.52%), and carbohydrates (2.35–27.61%), varied widely across species and drying methods. Mineral concentrations ranged from 0.31 mg/kg for Se to 6604 mg/kg for K, with no Pb detected in any of the samples. Anti-nutritional factors, including tannins (20.8–155 mg/100 g), oxalates (0.21–0.66 mg/100 g), and phytates (0.23–2.30 mg/100 g), were found to be at levels unlikely to significantly impact human health. The results demonstrate that the drying method affects both the nutritional and anti-nutritional content of the fruits. Freeze drying, while preserving dietary nutrients more effectively and reducing drying time, also retains higher levels of tannins, an anti-nutritional compound. This highlights a trade-off between nutrient preservation and the retention of harmful constituents. In conclusion, the edible parts of these wild plants are valuable sources of minerals and nutrients and, with proper drying methods, could be used as nutritious food options for human consumption.