The Fresh Loaf

News & Information for Amateur Bakers and Artisan Bread Enthusiasts

Divide to Conquer !

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lepainSamidien's picture

Divide to Conquer !

Hey all,

So, as usual, I find myself searching through the forums for more wisdom on how to control the intensity of the sour punch delivered by my numerous iterations of a Poilane-clone, a lofty ideal that I've been chasing since my first encounter in le Marais this past April while in Paris for the Marathon de Paris (an encounter that was followed by I-don't-know-how-many repeat trips to the various locations throughout the city).

Since then, I've become more attached to my sourdough starter and obsessed with the quest for the perfect loaf. However, I've noticed a great deal of variance in the sourness of my breads: it seems that temperature and time are the greatest role players in both cases (an increase in either typically yielding an increase in sourness), but--alas!--I often find both of these things outside of my control. New England weather is a crap-shoot, and my life is so littered with vagaries that timing often gets in the way of my being able to allow my loaf to fully develop and mature before being sent off into the inferno of my oven.

I read a really interesting post from a while back from Alpine, who mentioned something about dividing up some starter into two camps, 2-3 days prior to baking: one portion to be fed regularly in order to sustain and encourage yeast activity; the other, to be starved to encourage lactobacillus takeover. This division seems to make sense, and I'm looking forward to using it. But, I have a couple of questions:

1. Should I return the portion of starter meant for lactobacillus development to the fridge for the 2-3 days?, or do I keep it at room temperature?

2. Should the yeasty portion of the starter be built-up gradually from small to large, or should there be discards? If there are regular discards, should these discards be added to the lactobacillus starter, or stored separately?

If anyone else uses the Divide and Conquer process described by Alpine here:, I'd be happy to get some delicious insight. Thanks in advance.

Bake on !

dabrownman's picture

of labs and yeast.  At all temperatures labs out reproduce yeast but the best temperature for yeast is 79-82 F and labs best temperature is 90 F.    For sour; retarding starters, levains and dough at 36 F slows down lab and yeast reproduction greatly but the lab to yeast ratio is 3.7 to 1 showing the long you keep then a this low temperature the labs are really building up a base that when released at 90 F for final proof really brings out the sour.

At 36 F the yeast are reproducing 83 times less than their peak rate at  82 F and the Labs are reproducing at 44 times less than their 90 F peak.  So the longer you keep starters, levains and dough at low temperature the more sour you should produce in your bread - within reason.   Yeast live about 7-8 days so I use that as my start to finished dough time line and never worry about restricting yeast too much.

You just want to work out a retarding schedule where the wee beasties don't run out of food to eat.  When going for sour i will usually take my starter refreshed 2 days earlier and make the levain and refrigerate that for another 2 days and then use the levain to develop the gluten and then immediately retard it for 24 - 40 hours after shaping or in bulk.  Then put of the fridge it comes and if it fully proofed it can go straight int a hot oven or proof at 90F until it is ready usually no more than an hour,  

Whole grains used for  the starter levains and dough will also produce more sour too.  Some folks don't like sour and they need to do everything at room temperatures to reduce the sour.

 With a little experimenting you will discover what kind of sour you want and like and fit a schedule of time and temperature to achieve it with one starter.  I don't see a need for two SD starters - one to promote sour and one to promote yeast although I do combine a YW starter with a SD one to reduce the tang and promote the keeping quality of the bread with the SD

Here is a post that describes this increased lab reprodution process in more depth. 

Happy  Baking


Reproduction Rates of Labs and YeastL/Y 
T(°F)T (°C)L. SF IL. SF IIYeastRatio
     36        20.0190.0160.0053.787
     46        80.0470.0430.0212.222
     61      160.1440.1500.1141.265
     64      180.1870.1980.1631.145
     68      200.2390.2590.2251.064
     72      220.3010.3320.2951.021
     75      240.3740.4160.3651.024
     82      280.5350.5980.4171.284
     86      300.6090.6720.3461.760
     90      320.6580.7060.2023.255
proth5's picture

Debra Wink or Dwink (this might get her attention and she might chime in)

She will give you the straight info.  She has done work for a number of bakers whose names you would recognize and studies the microbiology of sourdough quite extensively.

Weather is always a crapshoot - but creating or buying a proofer environment where you can control temperature is most helpful in controlling the flavors in the bread.

Hope this helps.

lepainSamidien's picture

Thanks to both of you for the very helpful information: dabrownman for the detailed analysis of temperature, and proth for directing me to Debra Wink's posts. Both are extremely helpful and interesting, albeit dense. But, no one said the quest for farinaceous glory would be light (at least, no one said that to me).

For anyone who's interested, I found this great entry on Lactic Acid Fermentation from Debra Wink. It's a little science-heavy, but it was a nice little step back in time to sophomore year biology class (when I distinctly remember wondering, "When the hell am I ever gonna use this stuff?!" Answer: Now.)

A very worthwhile read for those of you interested in the biochemistry of levain/sourdough.

Thanks again, guys ! And I continue to welcome new insight, toujours !

dabrownman's picture

now quite famous and helpful post that you linked to many times - every time I see it linked to and learn something new every time  :-)  Here is another one since you are more biology savy than I,

This was the paper that was used to construct the temperature data spreadsheet based on Ganzel's raw data.  It also goes over how acid, salt and alcohol affect labs and yeast.   Debra's post and this research paper are the basis of how I try to create more sour in bread.  But hydration is missing.

The one thing I can't find is research data on how various hydration levels affect labs and yeast and the combined effects of hydration and temperature.    Debra says that labs are effected more by low hydration and prefer higher hydration than yeast but we don't know what are these high and low hydration are or anything in between.  I would love to lay my hands on it though to know if storing and retarding starters at 36 F and 66% hydration is too low for labs or if retarding levains at 36 F at 100% hydration is too low for labs or retarding dough at 36F at 75-80% hydration is too low for labs.

Perhaps Debra will chime in with some insight.