THE DEVELOPMENT OF STATE DIAGRAMS FOR CEREAL PROTEINS

The glass transitions of zein, gliadin and glutenin have been studied as a function of moisture content using mechanical spectrometry and differential scanning calorimetry. All three cereal proteins are plasticizable by water, suggesting that their hydrophilic domains play an important role in determining their theological properties at low water content. The plasticization effect can be predicted by the Gordon-Taylor equation. Temperature sweeps using small-amplitude oscillatory measurements suggest that all three proteins undergo crosslinking reactions in the temperature range 70-160 degrees C; above 160 degrees C, all proteins show characteristic softening. This information has been used to develop state diagrams for each protein, which can be used to predict behavior during processes such as baking and extrusion.