Gluten-free bread making success is closely linked to the biophysical behaviour of dough. Quality of these doughs is largely determined by the properties of their proteins and starch. This study aimed to explain, at the structural level the rheological behaviour of gluten-free rice-field bean dough compared to that of soft wheat. The conformational aspects of proteins and starch were studied using Fourier transformed infrared spectroscopy (FT-IR). Doughs of soft wheat, rice, field bean, mixture of rice-field bean flour and the same mixture where a portion of rice flour underwent hydrothermal treatment were studied. The results show that viscous and viscoelastic components of gluten-free doughs were changed by supplementation of rice with field bean flour. Most of gluten-free doughs possessed a higher storage modulus in comparison with soft wheat dough. Analysis of FT-IR spectra in the amide I region conveyed to find the differences relative to soft wheat flour dough showed that in non-gluten doughs the increase in β-sheet content was observed at the expense of β-turns. These results were confirmed by amide I deconvolution. Gluten-free doughs contained more β-sheet structure as compared to soft wheat dough and less β-turns inducing high structuralization level that characterized this type of dough matrix. Concerning starch, the supplementation with rice-field bean generated the reorganization of field bean and rice doughs starches approaching that of wheat dough. Electronic supplementary materialThe online version of this article (10.1007/s13197-019-03602-2) contains supplementary material, which is available to authorized users.

This work aimed to examine the rheological properties and structural features of newly developed gluten-free doughs with maize (M), field bean (FB), maize-filed bean (MFB), and maize-field bean improved with hydrothermally-treated maize (IMFB), and compare them with soft wheat (SW) dough as a control. The relationships between viscoelastic characteristics, pasting properties of dough, and structure of non-gluten proteins analyzed using FT-Raman spectroscopy were investigated. All gluten-free doughs showed significantly higher values of the elastic modulus than SW dough. The low values of tan δ for doughs of M, MFB, and IMFB formulas indicated strong contribution of the solid character in their structural formation as compared to SW and FB doughs. Protein backbone of maize and maize-based doughs was characterized by the absence of pseudo-β-sheet structure and a high content of β-sheet accompanied with a low content of antiparallel-β-sheet. According to principal component analysis (PCA), a strong relationship was found between protein secondary structure, tan δ, gelatinization temperature, and between aromatic amino-acid chains, peak viscosity, and breakdown. The mechanism of non-gluten protein network establishment was based on the formation of β-sheet and α-helix structure. The study results indicate the significant involvement of trans-gauche-gauche (TGG) and trans-gauche-trans (TGT) disulfide bridges in the formation of the non--gluten protein matrix rather that gauche-gauche-gauche (GGG) conformation. PCA analysis showed that the water absorption of the starch granules increased with the greater exposition of the tyrosyl residues.