Evaluation of Nutritional Potential and Effect of Processing on Improving Nutrient Content of Cassava (Mannihot esculenta crantz) Root and Leaves

Abstract

Cassava (Manihot esculenta crantz) is a major food crop in Sub-Saharan Africa, Asia, the Pacific, and South America, where it feeds around 800 million people. Its roots are an excellent source of energy, and its leaves are rich in minerals, vitamins, and protein, which could substantially supplement the current starchy diets if properly detoxified since they contain some toxic anti-nutritional factors. The objective of this study was to provide information on the nutritional profile of cassava root and leaves and role of processing in enhancing and stabilizing their valuable nutrients. Two cassava varieties, kello and qulle, obtained from Areca Agricultural Research Center were used in this study. Roots and leaves were processed (fermented, boiled, and fluid bed dried), and nutritional, anti-nutritional, and functional properties were assessed using AOAC (Association of Official Analytical Chemists) standard procedures. As compared to leaves, roots had higher carbohydrate contents, ranging from 81.0 to 87.1 g/100g, whereas leaves had higher protein (21.2 to 28.4g/100g), total carotenoid (234.1 to 987.9 g/g), fiber (16.1 to 22.9 g/100g), Ca (499.8 to 545.4 mg/100g), K (1193.4 to 1211.0 mg/100g), Mg (274.5 to 340.5 mg/100g) and Fe (129.1 to 146.1 mg/kg) contents. Anti-nutritional factors were slightly higher in the leaves than in the roots, with toxic cyanides ranging from 10.1 to 61.0 mg/kg in the leaves and from 1.8 to 47.5 mg/kg in the roots. However, the processing of leaves decreased cyanide content from 61.0 mg/kg to 10.1 mg/kg. Similarly, other anti-nutritional factors, such as condensed tannins, oxalates, and phytate were reduced from 52.0 to 21.0 mg/100g, 156.5 to 25.9 mg/100g, and 35.9 to 4.0 mg/100g), respectively. Hence, the fermentation of leaves and roots followed by boiling and drying is an interesting approach to reduce anti-nutritional factors significantly and ensure their nutritional quality. This study revealed that variety kello had a relatively better nutritional profile than variety qulle, for both root and leaves, except for total carotenoid content, which was higher in the latter. Genetic background and processing methods can greatly affect the nutritional profile of cassava varieties, so it is critical to analyze diverse cassava germplasm and refine the processing method to identify highly nutritious and healthy varieties.