Optimization of Process Conditions for Isolation of Leaf Protein Concentrate from Pongamia pinnata and its Proximate Nutritional Composition

Abstract

Substantial amount of leaves as biomass residue is produced from Pongamia pinnata (karanj) plantations which has no commercial value and remains underutilized. Feasibility of utilization of this biomass residue for development of protein concentrate as a food/ feed supplement was examined. A process for isolation of leaf protein concentrate (LPC) was optimized through investigating the influence of various process parameters on the yield and protein content of the LPC. The parameters optimized were ratio of fresh leaves to water (1:9), coagulation temperature (90oC) and duration (11 minutes), and pH (4.0). The optimized process was applied for isolation of LPCs from lower, middle and upper canopy of the tree, and the LPCs containing protein 43.77-44.34% were recovered in 7.27-7.34% yield. The proximate nutritional composition (moisture, 6.49-6.58%; fat, 12.54-12.82%; crude fibre, 1.84-1.86%; ash, 3.66-3.97%; carbohydrates, 39.18-39.83%; organic matter, 96.02-96.34%; total free amino acids, 0.056-0.057 % E of leucine; Gross energy, 447.29- 449.77 Kcal/100g LPC; pigments, % (chlorophyll, 0.37-0.38; total carotene, 0.025-0.026; xanthophylls, 0.82- 0.83); minerals, mg/100g LPC (Na, 4.42-4.72; Ca, 1070-1087; P, 746.33-754; Fe, 53.20-55.05; Cu, 12.95- 13.13; Zn, 7.57-8.05; Mn, 0.37-0.38; Mg, 26.62-27.66; K, 20.68-21.05); in vitro digestibility, 82.62-82.95%; total polyphenols, 0.120-0.123%GAE; total saponins, 0.501-0.513%; total alkaloids, not detected) of these LPCs were determined. ANOVA of these data revealed no significant difference with respect to canopy. It was inferred that the Pongamia pinnata leaves hold potential for development of LPC as a food/ feed supplement to combat nutrition deficiency.