Effect of high pressure on solubility and digestibility of legume proteins

Proteins of bean, lupin, and pea were treated by high hydrostatic pressure of 200, 300, 400, 600 and 700 MPa. The pressure-induced changes were compared to those caused by temperature. The solubility of proteins pressured at 200 MPa decreased compared to control samples. It was increasing with the increase of pressure, reaching its maxima at 300 MPa for pea and at 600 MPa for bean and lupin, after which the solubility decreased. IR spectra of Amide I showed the highest differences for the bean protein pressured at 600 MPa. The ratios of band intensities of Amide I or Amide II to the band at 1450 cm -1 showed different tendency of changes in pressure- and heat-treated proteins. Pressure-induced protein digestibilities were higher only for bean proteins, being probably dependent on the degradation of 40 and 60 kDa protein fractions. The trypsin-resistant high molecular weight fractions were formed in heat-treated proteins.