DIFFERENTIAL SCANNING CALORIMETRY OF LUPIN AND SOY PROTEINS

Differential scanning calorimetry (DSC) was used to study the 7S and 1 1S globulin fractions extracted from lupin seed (Lupinus luteus) flour . In agreement with previous work on other lupin species, the isolate showed three denaturation peaks compared to the two observed with soy. By comparison with the isolated globulin fractions, the denaturation peaks at the two higher temperatures in the lupin isolate were assigne d to the 11S and 7S globulins. The denaturation temperature of the lup in 7S globulin was about 10 K higher than that for the corresponding s oy globulin, whereas the values for the 11S globulin were similar. All globulins displayed increasing thermal stability with decreasing mois ture contents. Possible reasons for the differences in behaviour of so y and lupin protein isolates are discussed.