Physico-chemical properties of globular tiger nut proteins

This study investigates the properties of globular tiger nut proteins by determining the average molecular mass, protein fractions, denaturation temperature and the isoelectric point. Tiger nut proteins (TNP) prepared by aqueous extraction had a purity of 83.5 % w/w on dry mass. Fractionation of TNP revealed that glutelin was the constituent with the highest concentration (> 47.5 % w/w), followed by albumin (31.8 %), globulin (4.7 %) and prolamin (3.8 %). A residual protein fraction of 12.2 % appeared as electrophoretically similar to glutelin. TNP had an apparent molecular mass (m (m)) of 5.3-88 kDa. Both albumin and globulin fractions had m (m) of 5.3-73 kDa, whilst prolamin and glutamine fractions were 5.3-46.2 and 5.3-30 kDa, respectively. TNP had an onset temperature (T (o)), denaturation temperature (T (d)) and enthalpy of transition (a dagger H) of 54.40, 69.61 A degrees C and 5.43 J/g, respectively. In decreasing order of T (o) and T (d) among the protein fractions were prolamin, albumin, globulin and glutelin. Albumin and glutelin showed the highest and lowest a dagger H, respectively. Finally, the isoelectric point of TNP was 4.90. Fundamentally, the properties of TNP show that they might be useful for the techno-functional application in tiger nut-based food systems.