Influence of Temperature and Screw Pressing on the Quality of Cassava Leaf Fractions
Haimanot Hailegiorgis Ayele, Sajid Latif, Joachim Müller
Abstract
In this study, the development of a mild processing method for cassava leaves to remove cyanogenic compounds with minimum nutritional loss is evaluated. Fresh leaves were reduced in size using a mixer at temperatures of 25 (room temperature), 55, 80, and 100 °C for 1 min before screw pressing to separate the juice and press cake fractions. Cyanide content in the fresh leaves was reduced by 60% at 100 °C and by 57% in the juice sample processed at 25 °C. The press cake cyanide content was low (210 ppm) in both the control and the sample that was processed at 55 °C. An increase in the temperature for processing cassava leaves to 100 °C resulted in a loss of 5–13% of the CP and 7–18% of the vitamin C content. The press-cake fraction had high beta-carotene, lutein, and chlorophyll a and b content, and low values were registered for the juice fraction. Processing fresh cassava leaves at 25 and 55 °C resulted in fractions with high beta-carotene and lutein content. The protein quality of press cake was better than that of juice for feed. Short thermal shredding with pressing resulted in minimal loss of nutrients and a significant reduction of cyanide in the leaves.