Physicochemical and functional properties of proteins isolated from local beans of Turkey

Amino acid composition, physicochemical and functional properties of proteins isolated from five local beans of Turkey were investigated. Minimal variation was observed in amino acid composition of the bean protein isolates except for the hydrophobic amino acids. The isolates were found to be rich in essential amino acids leucine, lysine and phenylalanine while their methionine content was limiting. Denaturation temperature of isolates ranged between 90 and 152 °C and β-layer structure was found to be the dominant secondary structure. Maximum solubility (~97%) and net surface charge (~−23 mV) were observed at pH 9.0. Emulsion capacity and emulsifying activity index of bean protein isolates were found to be 402.7–468.5 g oil/g protein and 15.6–22.0 m²/g, respectively. The isolates with significantly higher net surface charge and solubility were observed to show better emulsifying and foaming properties compared to the other isolates studied. No significant correlation was observed between the thermal characteristics and gelation properties of isolates.