Effect of fermentation on microbiological, physicochemical and physical characteristics of sourdough and impact of its use on bread quality

The chemical, microbiological, and texture characteristics and rheological properties of sourdoughs were studied in the course of fermentations at 25 and 35°C over a period of 72 hours. After 6 h of fermentation, pH decreased rapidly in the sourdough at 35°C. However, after 72 h the pH values were slightly lower in the sourdough at 25°C. To obtain sourdough with an optimum pH, 11 h were required at 25°C and 9 h at 35°C. Acidity increased more slowly in sourdough at 25°C. However, values were similar in both types of dough after 24 h, but higher in dough at 25°C after 72 hours. Counts of lactic acid bacteria were slightly higher in sourdough at 35°C after 6 h, but after 24 h the sourdough at 25°C showed higher counts. Sourdough evinced elastic behaviour, with a larger elastic modulus in dough at 25°C. Both the phase angle and the relationship between elastic and viscous modulus indicated that dough was an elastic solid that lost elasticity over time. The best mechanical characteristics were noted in dough fermented at 25°C during 24 hours. Bread made with sourdough was rated more highly.