The Influence of Processing Parameters on Food Protein Functionality III. Effect of Moisture Content on the Thermal Stability of Fababean Protein

Abstract

The effect of moisture content on the thermal behaviour of a fababean protein isolate was investigated. Under limited moisture conditions, the two major storage proteins present in the fababean isolate, legumin and vicilin, behaved independently. At water levels below 1.5g water/g protein, the denaturation temperature (Td) associated with the legumin molecule increased as the moisture content was lowered. With vicilin, the same relationship was true but the dependency of Td on moisture content did not occur until the moisture level was reduced to 0.9g water/g protein or below. This increase in protein stability was probably related to the removal of water associated with the primary and secondary hydration phases of the protein. The amount of water available to the native protein, and consequently its denaturation temperature, could be controlled by the inclusion of partially or totally denatured protein in the study system. The effectiveness of this stabilization was dependent on the moisture content of the system as well as the degree of denaturation of the added protein.