BACKGROUND: With increasing demand for new protein sources, research on plant protein extraction and evaluation of the functional properties of protein isolates is necessary. In this study, pH and NaCl concentration, as two parameters affecting protein extraction of fenugreek seed, was investigated and the condition of fenugreek protein isolate (FPI) extraction was optimized using response surface methodology. RESULTS: FPI had significantly (P< 0.05) higher protein and essential amino acid content (891.00 and 387.41 g kg−1, respectively)compared with soy protein isolate (SPI). FPI was rich in Asp and Glu, confirming the presence of bands in the acidic region (30–39 kDa) of its electrophoretic pattern. Differential scanning calorimeter thermography of both FPI and SPI showed two peaks with high denaturation temperature, confirming the presence of high protein content and hydrophobic amino acids.Protein solubility, foaming capacity, foam stability and emulsion stability of FPI were higher than SPI; moreover, both FPI and SPI showed pH-dependent protein functionalities. CONCLUSION: Fenugreek seed protein extraction was optimized by control of pH and NaCl concentration. FPI could be used as a protein source with remarkable functional properties.

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