The effect of exopolysaccharide producing Lactobacillus plantarum strain addition on sourdough and wheat bread quality

The effect of addition of exopolysaccharide (EPS) producing Lactobacillus plantarum strains on sourdough and wheat bread quality was determined in this study. The exopolysaccharide production of 40 different L. plantarum isolated from sourdough has been examined. Three different levels (high, mid and low) of EPS producer isolates were selected as additive to sourdough. Two types of flour with different quality properties were used for bread making and commercial yeast and selected EPS producer strains. Ten different dough and bread samples were prepared under controlled conditions. Chemical, physical, microbiological, textural, colour and sensory analyses were performed in dough and bread samples. The pH values of bread dough decreased during the fermentation period and at the end of fermentation the titratable acidity (TTA) value was found to be in the range of 0.29-0.50%. Statistical analysis showed that pH value, TTA value, moisture content (37.95-42.0%), firmness (8.00-13.23 N), bread volume (370-433 ml), specific volume (2.74-3.28 ml/g), bread crumb L (72.61-74.92), and b (14.87-16.39) colour values, bread crust L (42.39-58.29), a (5.64-9.04) and b (13.04-19.64) colour values, organic acid (lactic, acetic and propionic acid) contents of bread crumb and crust differed significantly (P<0.05) according to different treatments. In the sensory evaluation, sourdough and EPS forming strains added breads were preferred by panellists. The best sensory evaluation scores have been obtained with sourdough bread containing a high-EPS producing strain (BioLp57) and flour type A. Consequently, the use of EPS producing L. plantarum and sourdough has contributed positive effects on bread quality criteria, except for bread volume.