Innovative infant formulas from lentil and chickpea protein isolates: a comprehensive study of chemical, sensory, and textural attributes

Legumes, as protein-rich products, have wide applications in the food industry. In this work, the functional and chemical features of green lentil protein isolate (LPI) and chickpea protein isolate (CPI), isolated by isoelectric precipitation, were studied to formulate infant formulas with various base formulations. The maximum nitrogen solubility was 79.1% for LPI and 73.3% for CPI at a concentration of 0.6 M NaCl. The foam capacity (FC) and foam stability (FS) were obtained 77.66%, 73.00% and 44.58%, 45.75% for LPI and CPI, respectively. The emulsion activity index (EAI) was 56.47 m2/g for LPI and 52.54 m2/g for CPI, while the emulsion stability (ES) of 10.99 min for LPI and 11.77 min for CPI was reported. The moisture and ash content of both isolates were lower than 2.6% and 1.2%, respectively. The protein and lactic acid content of both isolates was higher than 22.00% and lower than 0.15%, respectively. Sodium dodecyl sulfate–polyacrylamide gel electrophoresis (SDS-PAGE) analysis of LPI and CPI demonstrated an enrichment of basic and acidic subunits of legumin, vicilin subunits, and convicilin legumin subunit. Also, the two protein isolates revealed good thermal stability. Three powdered milk base formulations were prepared using different proportions of LPI and CPI (Formulation 1: 8.5% LPI and 8.5% CPI, Formulation 2: 3.4% LPI and 13.6% CPI, and Formulation 3: 13.6% LPI and 3.4% CPI). Antioxidant properties of the base formulations were evaluated using DPPH radical scavenging activity, inhibition of ascorbate autoxidation, angiotensin-converting enzyme (ACE) activity, protein efficiency ratio (PER), and biological value (BV). Three infant formulas were formulated for babies from birth to 6 months with different base formulations (Stage 1), for babies from 6 months to the end of 1 year with different base formulations (Stage 2), and for children over 1 year old with different base formulations (Stage 3). Sensory evaluation of infant formulas indicated high consumer acceptance for LPI and CPI-enriched infant formulas with formulation 1. Proximal characteristics of formulated infant formula (stage 1, stage 2, and stage 3) showed that the moisture content (less than 5%), fat (20.7 to 27.3%), acidity (0.49 to 0.66%), protein (15.98 to 17.74%), carbohydrate (48.16 to 52.00%), and ash (below 5.4%) were within standard ranges. The results of this study showed that the protein isolates studied have the potential to produce formulations of infant formula in different age groups.