“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.
Interesting...I take this to mean support your argument that lactic acid bacteria native to wheat will always outcompete other bacteria. One of Debra's most oft-quoted articles (http://www.thefreshloaf.com/node/10901/pineapple-juice-solution-part-2) seems to suggest that this is just to help a starter skip the "stink" phase of its development. Are you suggesting that using your temperature-controlled method, sans acidification, that there is no "stink" phase?
ReplyDeleteBut even asking a question about a "stink phase" misunderstands everything I have been writing about, as a "stink phase" is completely irrelevant to understand the maintenance of a sourdough microfloral culture; please see my helpful hints to maintaining a successful starter.
ReplyDeleteAfter further reading I understand your response & approach much better. And seeing mariana_aga's photographic guide to your process (as well as sight/smell descriptions) clarified a couple of things:
ReplyDelete1. given the right substrate, temperature and schedule, L. sanfranciscensis will outcompete any other stinky bacteria and
2. the stink phase is irrelevant because of #1; yes it still happens but who cares.
3. because of #1, the finished product, which contains a thriving L. sanfranciscensis that remains in log growth.
I'm trying out the approach myself, we'll see how it turns out. I can say that even after the initial 12 hours or so, it is extremely active/foamy/fizzy!