“Two type 0 Triticum aestivum flours were used . . . Sourdough production and propagation were established based on the most diffuse and traditional used for brad making the central and southern areas of Italy . . . A control sourdough, without starter, was also produced under the same conditions. The 10 sourdoughs (9 with individual L. sanfranciscensis strains and the control) were incubated in sterile plastic beakers at 30 ºC for 8h. After fermentation, sourdoughs were stored at 10ºC for about 16 hours and further used for propagation.
“Each sourdough was then propagated for 10 days by daily back-slopping. Cell densities after each sourdough fermentation [were recorded] . . . The lowest value was found after the first day of propagation . . .
“After the third day of propagation, the control sourdough, without starter added, reached almost the same stable cell numbers . . . Only three of the nine starters used dominated throughout the 10 days of propagation carried out under rigorously standardized conditions. The others were outcompeted by autochthonous population of the wheat flour and disappeared progressively starting from the first day of propagation . . .One autochthonous strain of L. sanfranciscensis was found to be dominant in all sourdoughs . . .
“Although this study was carried out under laboratory conditions that might have differed from bakery environmental conditions, the following was shown about wheat flour: (i) it is the source of the autochthonous lactic acid bacteria that can associate with or outcompete starter lactic acid bacteria and (ii) it plays a key role in establishing the stable microbial consortia within a short time . . . Apart from the starter used, all sourdoughs propagated by using the two types of wheat flour harbored L. sanfranciscensis strains.”
“Taxonomic Structure and Monitoring of the Dominant Population of Lactic Acid Bacteria during Wheat Flour Sourdough Type I Propagation Using Lactobacillus Sanfranciscensis Starters,” Siragusa, di Cagno, Ercolini, Minervini, Gobbetti & De Angelis. Appl. Environ. Microbiol. 2009.