Investigation of the functional effects of different grain sources in sour dough and sour dough bread production

The formation of taste, aroma and texture in traditional sourdoughs depends on the presence of Lactic Acid Bacteria (LAB) and their metabolites that they produce during fermentation process. One of the important factors in the formation of these effects is the production of exopolysaccharide (EPS) by LAB species. The effect of EPS production on the physicochemical properties of sourdough is a well-known function although this effect can change depending on EPS production level as well as EPS structure in which environmental and genetic factors can play roles. In addition to the available carbon sources in the sourdough environment, the addition of components with prebiotic potentials to the dough formulation may have form positive effects on the characteristics of the dough and bread by encouraging the development of LAB species that provide sourdough formation. In this respect, the aim of this thesis was to investigate the prebiotic potential of immature grains (wheat, rye, oat and barley) in sourdough environment and their role on final sourdough bread. In this thesis, sourdough isolates Lactobacillus rossiae, Lactobacillus plantarum, Lactobacillus brevis and Weissella cibariaand wheat, rye, oat and barley flour from immature grains collected from Bayburt were used for sourdough production. Sugar profiles of those cereal grains and sugar groups of the EPS isolated from sourdough were revealed by HPLC analysis. The sugar groups in cereal grains were glucose, xylose and arabinose whereas the monosaccharides of EPSs were formed isolated from sourdough were glucose, mannose and fructose. The level of EPS produced by different strains in different sourdoughs produced with different immature grains was altered significantly. The effect of the addition of cereal grains at different milk stages on the rheological properties of the sourdoughs produced with different LAB types was detected by determining the elastic (G ') and viscous modulus (G ") values at 0, 8 and 24 h during sourdough formation. Depending on the fermentation process of the results.Similarly, the textural properties of sourdough breads produced with different sourdoughs were determined by textural analysis. At the point of determination of the textural properties of the sourdough samples: the sour dough bread is baked and the results are revealed by texturing analysis. These findings are important in terms of determination of the effects of different sourdough isolates and different immature grains on final properties of sourdough and sourdough bread.