Abstract:
The dough functionality of the storage proteins in “gluten-free” grains has been studied for almost 25
years. Zein, maize prolamin, when isolated as a-zein can form a wheat gluten-like visco-elastic dough
when mixed with water above its glass transition temperature. There is good evidence that its doughforming
properties are related to a change in protein conformation from a-helix to b-sheet and association
of the molecules into fibrils. Stabilisation of b-sheet structure and visco-elasticity can be enhanced
by inclusion of a co-protein. No other isolated cereal or pseudocereal storage protein has been shown to
form a visco-elastic dough. Many treatments have been applied to improve “gluten-free” storage protein
functionality, including acid/base, deamidation, cross-linking by oxidising agents and transglutaminase,
proteolysis, disulphide bond reduction and high pressure treatment. Such treatments have some limited
positive benefits on batter-type dough functionality, but none is universally effective and the effects
seem to be dependent on the composition and structure of the particular storage protein. Research into
mutants where prolamin synthesis is altered appears to be promising in terms of improved dough
functionality and scientific understanding. Research into how treatments affect the functionality and
structure of isolated storage proteins from “gluten-free” grains other than maize is required.
