Pretreatment of the Leaves of Ethiopian Cassava (Manihot esculenta Crantz) Varieties: Effect of Blanching on the Quality of Dried Cassava Leaves

Abstract

The aim of this work was to study the effect of blanching and drying on the quality of four Ethiopian cassava varieties (Chichu, Hawassa-4, Quelle, and Kello). Cassava leaves were subjected to blanching at 100 °C in plain water, 0.2% NaHCO3, and 0.4% NaHCO3 for five minutes. Cassava leaves without blanching were considered as a control. The drying temperature was set at 60 °C with a constant air velocity of 0.14 ms−1. A high reduction in vitamin C (95.6% in Chichu, 95.0% in Hawassa-4, 94.9% in Quelle, and 94.4% in Kello) was noticed in leaves blanched in the 0.4% NaHCO3 solution. After blanching, the reduction in the ash content was higher for those blanched in plain water. The crude fiber and protein content were improved by blanching. Blanching in clear water was more effective among the different solutions in reducing the cyanide content in the leaves of Kello, Quelle, and Chichu by 51, 33, and 60%, respectively. While for Hawassa-4, the reduction was higher (47%) with the 0.2%NaHCO3 solution. After blanching, the h° values decreased, while a*, b*, and c* increased. Plain water blanching resulted in a better nutritional quality, while Hawassa-4 exhibited the best nutritional value among the four varieties.