Examining the amino acid composition, secondary structure, and physicochemical and functional properties of proteins isolated from local lentil landraces of Anatolia

Background and objectives: Providing information on protein structure and functionality is essential for evaluating the potential of specific agricultural commodities to be utilized as plant-based protein sources. Amino acid composition, secondary structure, surface charge, thermal, and functional properties of proteins isolated from five local lentil landraces were investigated. Secondary objective of the study was to investigate if a relationship exists between the amino acid composition and the physicochemical or functional properties of the isolates. Findings: Aspartic acid and glutamic acid were found to be the dominant amino acids in the isolates while they were poor in methionine. Denaturation temperatures of isolates ranged between 96–108°C and their secondary structure mainly consisted of β-sheet. Emulsion capacity, emulsifying activity (EAI), and emulsion stability indices (ESI) of isolates were found to be between 403.8–468.2 g oil/g protein, 18.8–24.2 m²/g, and 43.4–125.5 min, respectively. Foaming capacity of the isolates changed between 71% and 91% whereas their least gelation concentration varied between 110 and 150 g/L. Conclusions: Yusufhan isolate which had relatively higher acidic amino acid content showed the highest net charge and solubility at acidic pH. Tigris isolate which had higher hydrophobic amino acid content compared to the other isolates showed relatively high thermal stability, EAI and ESI. Significance and novelty: Findings of the study make a contribution toward the potential use of local lentil landraces as sources for extracting protein-based ingredients.