The diversity and nutritional value of the gluten-free products is challenging because of the increasing segment of population with celiac disease. In order to address this issue, the effects of different proteins (powdered eggs, soy, lupin, sodium caseinate and whey) to the gluten-free formulation based on rice and maize flours were assessed. The dough hydration was varied from 55 to 105 %, and dough rheological properties and bread characteristics were tested. The nature of the proteins and water level added to the gluten-free bread recipes has a decisive role on product quality. The best results in terms of rheological behavior were recorded for samples with powdered eggs, soy and lupin protein addition, at water absorption of 95–105 %. Concerning the bread quality, our results showed that protein addition to the rice and maize flours gluten-free formulations allows the improvement of crumb texture.

The effect of select parameters (i.e., rye flour ash content, temperature, and dough yield) of the sourdough fermentation on the fermentation activity of different starter cultures (lactic acid bacteria Lactococcus lactis ssp. Lactis, Weissella confusa, Lactobacillus plantarum, Lactobacillus brevis, Lactobacillus helveticus, and yeast Kluyveromyces marxianus subsp. Marxianus) was determined. The major metabolic end products of fermentation (D, L-lactic acid, acetic acid, ethanol and glycerol) and the evolution of total phenolic content and folic acid during bread making were measured. Lactobacillus helveticus and Kluyveromyces marxianus allowed obtaining sourdoughs with the highest lactic acid/acetic acid ratios. The mixed starter culture with Lactococcus lactis and Saccharomyces cerevisiae generated the most important quantities of D/L lactic acid. The maximum values of ethanol concentration were obtained in case of the sourdoughs from whole rye flour fermented at lower temperature (30°C) with mixed starter cultures containing Sacchomyces cerevisiae. The fermentation process and type of starter culture are also tools to increase the bioactive compounds, enabling the increase of the phenolic content of the sourdough.

The effect of brewers’ spent grain addition on the thermo-mechanical properties of white and wholemeal wheat flour was investigated. The possibility to improve bread quality and antioxidant properties by using the sourdough fermentation was also considered. Increasing the level of brewers’ spent grain caused the increase of water absorption from 58.1 to 65.2% and from 63.8 to 73.6% in case of white and wholemeal flour, respectively. Similarly, the dough development time increased from 1.27 to 6.18 min, and from 3.37 to 5.42 min. Starch gelatinization significantly increased ( p <0.05), while the stability of starch gel, starch retrogradation, and cooking setback significantly decreased ( p <0.05) with the level of brewers’ spent grain. The specific volume of the wheat bread significantly decreased ( p <0.05) and crumb hardness increased ( p <0.05) by incorporation of brewers’ spent grain. Sourdough addition improved bread characteristics and the total phenolic content and antioxidant activity of the bread with brewers’ spent grain.