THERMO-MECHANICAL AND BAKING PROPERTIES OF THE GLUTEN FREE ZEIN - STARCH DOUGHS

Thermo-mechanical properties of doughs based on zein and different types of starch (native corn starch, modified corn starch and tapioca) were investigated in this study. The physical properties of the gluten free breads, prepared using the model zein - starch mixtures, were additionally determined. The Mixolab parameters measured while running the Chopin+ protocol indicated that the dough exhibited viscoelastic properties at 39 degrees C, and not at 30 degrees C as in the case of gluten system dough. The type of starch used in admixture with zein to prepare the dough significantly influenced the viscoelastic properties of the samples. The lowest starch retrogradation was obtained for the zein-modified corn starch mixture (C5-C4 of 0.55 Nm), while in case of the samples with native corn starch and tapioca the C5-C4 values were close to 0.74-0.79 Nm. The zein-tapioca sample had the lowest breakdown (C3-C4) of 0.22 Nm, followed by the zein-native corn starch sample, with C5-C4 of 0.53 Nm. Bread samples prepared with zein and native or modified corn starch at high water absorption levels (77% and 85%, respectively) had the highest specific volume values of 3.18 cm(3)/g and 2.22 cm(3)/g, respectively. These results indicate that zein can be successfully combined with starch from various sources for obtaining gluten free products.