Physicochemical, textural and microbiological properties of optimised wheat bread formulations as affected by differently fermented sourdough

The aim of the study was to evaluate the physicochemical properties, microbiological and textural features of optimised wheat bread formulations consisting of sourdough (A) prepared with two different fermentation methods [spontaneous fermentation (F1) versus starter of lactic acid bacteria (LAB) added fermentation (F2)], instant active dry yeast (B) and wheat bran (C) during their shelf life. The optimised levels for F1 fermentation type 11.45% for sourdough, 1.10% for dry yeast and 1.58% for wheat bran; and for F2 fermentation type 6.99% for sourdough, 1.02% for dry yeast and 38.84% for wheat bran were determined according to results. The acidic content of the sourdough improved the crust thickness, volume and colorimetric properties of the bread, significantly (P<0.05). The effects were much more pronounced in optimised bread (OB)F₂. The retrogradation phenomenon during the shelf life was evaluated with the result of rate of staling (RS) and loss of springiness (LS) values which determined by using texture profile analysis parameters, and diferential scanning calorimetry (DSC) thermograms obtained during the shelf life. RS (7.14 for CB, 4.55 for OBF₁, and 2.90 for OBF₂), and LS (62.1 for CB, 51.6 for OBF₁, and 39.7 for OBF₂) decreased significantly (P<0.05) by addition of sourdough. Therefore, CB had the most hardness texture at the end of the shelf life. All bread samples exhibited moisture loss during their shelf life especially in the first three days but demonstrated different tendencies. OBF₂ sample had the highest moisture content in contrast to CB. Although no endothermic area could be determined on DSC thermograms on day 0, the initial tendency of the bread samples, especially CB and OBF₁ was clearly seen. On day 5 thermograms, an increase in endothermic peak areas due to starch retrogradation was observed (413.792 mJ for OBF₁, 510.107 mJ for OBF₂ and 768.962 mJ for CB). The results showed that sourdough improved the staling properties of bread. We found that the textural properties, the loaf and staling qualities of sourdough breads (OBF₁ and OBF₂) were higher than that of CB. Furthermore, the F2 fermentation method had a much more pronounced effect in terms of textural properties examined.