Processing parameters and techno-functional properties of lentil protein concentrate as an ingredient for the plant-based market

Lentil (Lens culinaris) is a protein-rich pulse culture with potential to be a source of alternative protein for human nutrition. The aim of this study was to determine the best processing parameters of protein extraction from the whole grain, as well as to analyze the techno-functional properties of the protein concentrate (LPC) and its flour (LF). The processing route comprised the grain milling with a 0.8 mm sieve to generate the flour, followed by the alkaline extraction and acid precipitation of proteins which were further washed and spray-dried into powders. The evaluated parameters along the processing were as follows: For the alkaline extraction: pH from 8.0 to 9.5, extraction time from 10 to 25 min and solute:solvent ratio from 1:6 to 1:16. For the acid precipitation: pH from 4.0 to 5.5 and time from 10 to 25 min. After the best conditions were achieved, the samples were analyzed for their techno-functional performance, evaluating eight different properties according to the Guide for Techno-Functional Characterization of Protein Ingredients for the Plant-Based Market. The best results obtained for the lentil protein processing comprised the alkaline extraction at pH 9.0 (15.85 mg/mL soluble protein), solute:solvent ratio of 1:10 (16.13 mg/mL soluble protein) and no difference was found for the extraction time, adopted as 20 min for this study (15.47mg / mL soluble protein). As for acid precipitation, the best conditions were observed at pH 5.0 (77.77% total protein) with no difference in the precipitation time, which was adopted to be 10 min for this study (77.15% total protein). For the ingredients techno-functional properties the results for the flour (LF) and the protein concentrate (LPC) were as follows: Ingredient solubility (LF pH 3, 41.75%, LF pH 9, 92.21% , LPC pH 3 45.17% and LPC pH 8, 93.22%), water holding capacity (LF = 2.39g/g and LPC = 1.58g/g), oil holding capacity (LF = 1.90g/g and LPC = 1.54g/g), foaming capacity (LF = 80.00% and LPC = 84.44%), foam stability up to 60 min for both samples, emulsifying capacity (LF = 24.09m2/g and LPC = 53.90m2/g), emulsifying stability (LF = 19.87min and LPC = 21.30min) and the lowest degree of gelation for LF and LPC was in the concentration of 18%. The results showed the best processing conditions for the protein extraction from the whole lentil grains and the techno-functional properties presented compatible results in comparison to other alternative protein ingredients from the market, positioning lentil protein as a promising alternative protein source to produce ingredients for the plant-based market.