Characterization and bio-evaluation of some indigenous legume protein isolates for complementary foods

Abstract

In present investigation, extraction, characterization and bio-evaluation of protein isolates from different indigenous legumes i.e. chickpea, lentil, broad and kidney beans were carried out to develop complementary foods. In tested legumes, after inactivation of anti-nutritional factors, protein isolates were prepared through isoelectric precipitation method. The highest protein yield as 80.47±5.71% was estimated in lentil protein isolates (LPI) followed by 73.14±3.44% in chickpea protein isolates (CPI) and 67.58±3.70% in broad bean protein isolates (BPI) while the lowest yield 52.83±3.36% was in kidney bean protein isolates (KPI). Moreover, protein isolates were assessed for their functional properties like bulk density, oil & water absorption, emulsifying & foaming properties etc. Maximum bulk density was revealed in LPI followed by CPI, KPI and BPI. Likewise, higher water absorption capacity was recorded in CPI tracked by LPI and BPI whilst the lowest in KPI. Maximum foaming capacity (FC) was revealed in BPI followed by KPI and LPI, respectively and the minimum in CPI. Electrophorogram through SDS-PAGE showed that legume protein isolates had protein bands in the range of 4 to 70kDa. Amino acid quantification was also performed with reference to requisite profile for the pre-schoolers. Among the essential amino acids, higher lysine content (4.54±0.21g/100g) was found in KPI followed by CPI (3.70±0.09g/100g) and LPI (3.66±0.20g/100g) whilst BPI showed minimum values (3.51±0.21g/100g). Simultaneously, amino acid scores were also determined with values of 39.6, 40.0, 40.0 and 56.0 in CPI, LPI, BPI and KPI, respectively. Bio-evaluation of respective isolates was performed through growth study parameters. Among the resultant protein isolates, the highest values were observed in LPI followed by CPI and BPI while the lowest for KPI regarding protein efficiency ratio (PER), net protein (NPR) and relative net protein ratio (RNPR), respectively for the year 2009-10. Similarly, nitrogen balance study parameters showed the highest values for true digestibility (TD), biological value (BV) & net protein utilization (NPU) in LPI tracked by CPI and BPI whereas the lowest values for these traits were recorded in KPI. However, BV value was high in KPI as compared to BPI. Similar trend for growth and nitrogen balance studies was observed in the next year 2010- 11. On the basis of overall yield, functional properties and bio-evaluation, two best protein isolates namely LPI and CPI were selected along with control for complementary foods preparation. The prepared formulations based on LPI (C1) and CPI (C2) congregated the FAO criteria for supplementary infant foods. The developed weaning foods were analyzed for chemical composition, energy value, bulk density, reconstitution index, viscosity and amino acid profile. Additionally, gross calorific values were observed as 401.70±20.42, 401.15±20.50 and 410.16±20.90kcal/100g for C1, C2 and control complementary foods, respectively. The essential amino acids were found to be sufficient in lentil and chickpea protein supplemented weaning foods. In addition to amino acid quantification for infant formulations, amino acid scores were also estimated. In complementary foods, maximum calorific value was contributed by fat followed by protein. Formulations in current study are capable of delivering 120.22±6.80, 122.49±6.36 and 123.27±6.09kcal per single meal for C1, C2 and control, respectively. Hedonic response regarding various sensory attributes also showed acceptance towards developed complementary foods. The acceptability appraisal of prepared infant formulations was conducted through short term infant feeding trial with the help of nursing mothers. The acceptability remained as 61.40 to 65.00% at the initiation of study and reached to 80.80 to 83.20% at the end of trial. Correlation studies also showed strong association among various variables and refelect their positive and negative contributions. The upshots of this project indicated that indigenous legumes have potential to yield protein isolates with appreciable functional and nutritional quality for application in array of foods with special reference to complementary foods.