# Microwave-Supported Modulation of Functional Characteristics of Gluten-Free Breads
## 3 Results
The highest chewiness value was noted for the BTB sample after 7 days of storage. Problems with teff incorporation into the bread matrices were also reported by other researchers [35; 36]. The smooth incorporation of teff and buckwheat into bread matrices is highly problematic. This is why a lot of studies have been dedicated to improving the quality of bread making using those two native gluten-free flours and applying different means of treatment [36; 37; 38; 39; 40; 41; 42]. The color changes in buckwheat and teff breads are shown in Figures 1 and 2, respectively. The changes in the L*a*b* components were strongly dependent on the flour; however, most of the samples, except brown teff, had moderate impact on the control bread's L*a*b* parameters. In the crumb, the yellowness-blueness axis was more pronounced and for the crust, the opposite trend was observed for brown teff. After 7 days, the brownish notes were increasing for the Polish buckwheat bread's crust and crumb, probably due to water escaping and the increased visibility of fiber particles. Figure 1: Color of the buckwheat breads the day of baking (**A**) and after 7 days (**B**). Control—100% rice flour bread, PBB—bread from blend of native Polish buckwheat flour and rice flour, 50:50 (\(w/w\)), PBMWB—bread from blend of Polish buckwheat flour after microwave treatment and rice flour, 50:50 (\(w/w\)), SBB—bread from blend of Spanish native buckwheat flour and rice flour, 50:50 (\(w/w\)), SBMWB—bread from blend of Spanish buckwheat flour after microwave treatment and rice flour, 50:50 (\(w/w\)). Lowercase letter means significant difference at \(p=0.05\). The total, soluble, and insoluble polyphenol content in the flours, treated flours, and resulting bread are shown in Figure 3 for buckwheat samples and Figure 4 for teff samples. Figure 3: Polypphenols type and content in raw and processed buckwheat flours and breads made. PBF—Polish buckwheat flour, PBMWF—Polish buckwheat flour after microwave treatment, PBMWB—bread made from Polish buckwheat flour after microwave treatment and rice flour, 50:50 (\(w/w\)), SBF—Spanish buckwheat flour, SBMWF—Spanish buckwheat flour after microwave treatment, SBMWB—bread made from Spanish buckwheat flour after microwave treatment and rice flour, 50:50 (\(w/w\)), GAE—gallic acid equivalent. Figure 2: Color of the teff breads the day of baking (**A**) and after 7 days (**B**). Control—100% rice flour bread, WTB—bread from blend of native white teff flour and rice 5%:50 (\(w/w\)), WTMWB—bread from blend of white teff flour after microwave treatment and rice flour, 50:50 (\(w/w\)), BTB—bread from blend of brown teff flour and rice flour, 50:50 (\(w/w\)), BTMWB—bread from blend of brown teff flour after microwave treatment and rice flour, 50:50 (\(w/w\)). Lowercase letter means significant difference at \(p=0.05\). The changes in flour polyphenol content were strongly dependent on variety. Higher total polyphenols were observed in Spanish buckwheat vs. the Polish sample, and the content subsequently decreased after the MW-HMT of flours. The same trend was observed for teff flours; however, the reduction was not as large as in the buckwheat samples. The percentage of bio-accessible polyphenols calculated as soluble fraction vs. total content in different matrices changed after the thermal treatment of flour, resulting in a significant decrease in the teff sample. Baking in the bread matrix further changed the characteristics, showing a subsequent decrease in bio-accessible polyphenols for buckwheat flours and contrary behavior for the teff-based breads (Figure 5). Figure 4: Polypphenols type and content in raw and processed teff flours and breads made. WTF—white teff flour, WTMWF—white teff flour after microwave treatment, WTMWB—bread made from white teff flour after microwave treatment and rice flour, 50:50 (_w/w_), BTF—brown teff flour, BTMWF—brown teff flour after microwave treatment, BTMWB—bread made from brown teff flour after microwave treatment and rice flour, 50:50 (_w/w_), GAE—gallic acid equivalent.