Effect of extrusion temperature on the solubility and molecular weight of lentil bean flour proteins containing low cysteine residues

Lentil flour was extruded at die temperatures of 135, 160, and 175 degrees C. The soluble protein content in the extrudates decreased by 40.1% in the extracting buffer (1% sodium dodecyl sulfate in 50 mM sodium phosphate buff er, pH 6.9) as the extrusion die temperature was increased to 175 degrees C . The most insoluble proteins in the extrudates extruded at die temperature s of up to 175 degrees C could be resolubilized by using sonication. The to tal disulfide content and sulfhydryl content in the extrudates decreased. T he SDS-PAGEs showed that the molecular weight distribution of proteins in t he lentil flour changed little before and after extrusion as well as during reduction. The results from this study show that the extrusion temperature had less effect on the solubility and molecular weight of the lentil prote ins, which contain a lower level of cysteine residues than wheat proteins.