Functional and physicochemical properties of a protein isolate from AluProt-CGNA: A novel protein-rich lupin variety (Lupinus luteus)

This study describes the isolation of proteins from the novel lupin variety AluProt-CGNA (Lupinus luteus) and the influence of pH and NaCl on their functional properties. AluProt-CGNA variety showed to have a great protein content in dehulled seeds (60.60 g protein/100 g, dry matter), which is higher than soybean and other lupin varieties. A lupin protein isolate (97.54 g protein/100 g) from AluProt-CGNA, LPIA, was prepared from lupin flour by alkali solubilization and isoelectric precipitation. The solubility profile of the LPIA was affected by pH, where the minimal values were observed at pH values close to its isoelectric point range (pH 4-5). The highest values of water absorption capacity (1.71 cm3 H2O/g protein), oil absorption capacity (1.43 g trapped oil/g protein), emulsifying capacity (61.94%), emulsion stability (96.43%), foaming capacity (114.29%), foam stability (65.69%) and least gelation concentration (20 g/100 cm3) were observed at pH values lower and higher than its isoelectric point. In the presence of 100 mM of NaCl, their functional properties were improved. SDS-PAGE showed that LPIA mainly contained high molecular weight proteins (α and β-conglutin). These results are useful for increasing the utilization of this protein isolate as a potential functional ingredient in food industry.