Physico-chemical and functional properties of spray-dried sourdough in breadmaking

In present study, spray-dried sourdough was produced using a pilot scale spray dryer and the physicochemical and microbial characteristics of the obtained sourdough powder were investigated. The application of the spray-dried sourdough at different levels (3%, 6%, 9% and 15%) in breadmaking was also evaluated. Bulk density, wettability and suspensibility of the sourdough powder were 0.6 g/cm(3), 98 s and 29%, respectively. The most of the powder particles were in a range of 106-250 mu m. The spray-dried sourdough had a moisture content and ash content of 3.72% and 1.9% (db), respectively. The pH and total titratable acidity of the sourdough powder were 3.26 and 59 (mL of 0.1 N NaOH/10 g powder), respectively. Spray drying reduced lactic acid bacteria population of the sourdough to 2 x 10(5) CFU/g compared to the initial value of 10(9) CFU/g. Iranian traditional flat bread (Sangak) made with different levels of the sourdough powder had significantly (p < 0.05) lower pH and higher total titratable acidity compared to those of the control. The results of sensory evaluation showed that Sangak breads containing 15% sourdough powder were slightly darker and sourer than the other breads. Incorporation of spray-dried sourdough delayed bread staling, as judged by sensory panel. The results suggest that spray-dried sourdough at the level of 9% can be successfully used for Sangak breadmaking, leading to bread with an improved flavor and delayed staling.