Determination of the role and technological importance of gluconatransferases belong to the lactic acid bacteria at the sourdough fermentation

Daha sonra doldurulacaktır.Starch is a carbohydrate composed of glucose monomers called amylose and amylopectin and is very common in nature. Starch, which is widely used in many industrial areas with its cheap, accessible, degradable and renewable properties, can be modified by various methods. In this way, inherent negative features such as low resolution and easy gelatinization can be eliminated. The presence of starch-modifying enzymes in lactic acid bacteria has enabled the use of these enzymes for starch modification. 4,6 and 4,3 α-GT enzymes in the GH70 enzyme family convert starch into α-glucan with a straight or branched structure through disproportionation reactions. In the first part of this thesis study, the effect of 4,6 and 4,3 α-glucanotransferase producing cultures on the microbiota was demonstrated by using them as starters in sourdough. Glucanotransferases encoded by the gtfB gene carried by Limosilactobacillus reuteri PFC 338 and Limosilactobacillus fermentum PFC 282 strains in sourdough significantly increased the survival rate of the strains in the microflora. In addition, it was observed that sourdough breads prepared using these strains had lower enthalpy change during storage and lower hardness values at the end of storage compared to the control bread. Moreover, it was observed that the glycemic index (GI) of sourdough bread prepared with PFC 338 strain was lower than white bread. In the second part, where recombinant enzymes were used directly, their staling and GI-lowering effects were detected without affecting the sensory acceptability of the products. The fact that enzyme-added bread and pastries showed lower hardness values compared to control products during storage reveals the textural profile improving effect of enzymes. In the study, it was observed that glucanotransferases not only affected the fermentation microbiota, but also affected the technological properties of bread. In addition to recommending the use of lactic strains producing these enzymes as starter cultures, it has been understood that the use of the enzyme itself is also important for bakery products technology.