Investigations on Functional and Thermo-Mechanical Properties of Gluten Free Cereal and Pseudocereal Flours

Abstract

Seven commercial gluten-free (rice, oat, sorghum, foxtail millet, amaranth, quinoa, and buckwheat) flours were investigated in this study from the point of view of thermo-mechanical properties and solvent retention capacity (SRC). Each flour was used to prepare doughs with specific water absorption (WA) to get a consistency of 1.1 Nm (WA1) and doughs with WA2 levels higher than 85% to ensure a sufficient amount of water in the system for allowing the hydration of all components of the flours. Different correlations were established between proteins, ash, pentosans, damaged starch, and amylose contents on the one hand, and the capacity of the flour samples to retain different solvents such as sucrose, sodium carbonate and CaCl₂ on the other hand. Although no significant correlation was found between the protein content of the flours and lactic acid-SRC, the mechanical weakening of the protein was significantly correlated with lactic acid-SRC for both tested WA levels. The doughs with WA1 had higher starch gelatinization and hot gel stability values compared to the corresponding dough systems with a higher water amount. Moreover, lower starch retrogradation and setback torques were obtained in the case of the dough prepared with higher amounts of water.

Keywords: Mixolab; dough consistency; gluten-free flours; solvent retention capacity.

Figure 1

Mixolab curves of the dough samples prepared with rice (a), oat (b), quinoa (c), amaranth (d), millet (e), sorghum (f), and buckwheat (g) flour at different water absorption (WA) levels: WA1 necessary to obtain a maximum torque of 1.1 ± 0.05 Nm and WA2 of 85%. Note: For the oat flour, WA1 and WA2 had the same value of 85%.