Comparative, nutritive and physico-chemical evaluation of cassava (Manihot esculenta) leaf protein concentrate and fish meal

Leaf protein concentrate (LPC) from cassava (Manihot esculenta) and fish meal were analysed and compared for their proximate chemical composition, gross energy, mineral constituents and functional properties. Also their amino acid profile and in vitro multi-enzyme protein digestibility were determined. The cassava LPC contained on the average (g/100 g DM) 41.7 crude protein (CP), 6.3 ether extract (EE), 0.5 crude fibre (CF) and 8.1 ash while the fish meal contained 65.7, 9.6, 0.5 and 14.9 g/100 g DM, CP, EE, CF and ash, respectively. The CP, EE and ash content of fish meal were generally higher than those of the LPC while the gross energy was higher in the latter than in the former. Among the major minerals Na, K, Mg and Zn were generally higher in the LPC while Ca, P and Fe were more abundant in the fish meal. Higher variation in concentration were generally observed in the major minerals as indicated by the high coefficients of variation (CV) ranging from 56 to 133%. The mean value for water absorption capacity (WAC), emulsion capacity (EC) and emulsion stability (ES) in cassava LPC (158.0, 55.4 and 56.9%, respectively) were similar to those of fish meal (200.0, 47.9 and 47.7%, respectively). The fat absorption capacity, foaming capacity and foaming stability of cassava LPC were generally lower than those of fish meal as indicated by the very high CV (%) ranging from 115 to 136%. Protein solubilities of the two protein concentrates were generally higher in both the acid and alkaline media. Amino acids scores, with egg as reference, for fish meal were generally higher than for LPC while the in vitro multi-enzyme protein digestibility indicates that the cassava LPC was more digestible (86.3%) than the fish meal (74.9%).