Insight into the Gluten-Free Dough and Bread Properties Obtained from Extruded Rice Flour: Physicochemical, Mechanical, and Molecular Studies

• Published in: Applied sciences 2023-03, Vol.13 (6), p.4033
• Main Authors: Różańska, Maria Barbara, Kokolus, Patrycja, Królak, Jakub, Jankowska, Patrycja, Osoś, Agata, Romanowska, Magda, Szala, Łukasz, Kowalczewski, Przemysław Łukasz, Lewandowicz, Jacek, Masewicz, Łukasz, Baranowska, Hanna Maria, Mildner-Szkudlarz, Sylwia
• Format: Article
• Language: English
• Subjects: Bread; Dough; dough rheology; extrusion; Extrusion dies; Flour; Fractions; Gluten; Gluten-free diet; Granulation; Hardness; Hydrothermal treatment; Laboratories; LF NMR; Mechanical properties; Moisture content; Molecular dynamics; NMR; Nuclear magnetic resonance; Particle size; pasting properties; Recipes; Rheological properties; Rheology; Rice; Sorghum; Specific volume; structure; Surface hardness; Velocity; Viscoelasticity; Viscosity; Water absorption; Water activity; water behavior; Water content
• ISSN: 2076-3417; 2076-3417
• DOI: 10.3390/app13064033

The present study aimed to evaluate the effect of the extrusion process and particle size on the properties of rice flour (microstructure, pasting properties), gluten-free dough (rheological properties), and bread (texture, specific volume, water absorption capacity, low-field nuclear magnetic resonance (LF NMR) relaxometry). Rice flours were extruded at 80 and 120 °C with feed moisture (15 and 30%) and with the same particle size (132–200 µm). Significant differences were observed between the pasting profiles of the flours before and after extrusion. The pasting profile of extruded flours confirmed that hydrothermal treatment partially gelatinized the starch, decreasing the viscosity during heating. The water binding properties increased with the extrusion temperature and moisture content and also with the particle size of the flour. The most important parameter influencing the mechanical properties of the dough was the moisture content of the flour and significant differences were observed between fine (132–200 μm). The molecular dynamics of particles containing protons in the bound and bulk fractions in each sample do not depend on the extruder parameters or granulation of the obtained fraction. LF NMR results confirmed that extrusion of rice flour led to a significant decrease in the T21 value compared to the control sample and an increase in the T22 value in breads made with flours with particle size