How do I extend the rise time of my bread?
Factors affecting rise time
Let Me Take You On A Slow Rise
Years ago I saw "The Magic Christian", a marvelous, if somewhat cynical, comedy starring Peter Sellers as Sir Guy Grand, an insanely rich eccentric British member of the aristocracy, and Ringo Starr as Youngman Grand, a street person Sir Guy adopted to be his heir.
At one point, Sir Guy and Youngman Grand joined a duck hunt with a group of aristocratic English hunters who were obsessing about their shotguns and the value of a "quick, clean kill". Without giving away too much, Sir Guy and Youngman redefined the term "quick, clean kill" for the hunters.
Similarly, sourdough bakers obsess about a "long, slow rise" and for good reasons. We want to give the lactobacillus time to create the sourdough taste that we are working for, to give the bacteria time to create the acidity that helps preserve the bread and unlock some of the nutrients in the flour that would otherwise be unavailable.
There is reason to believe that we'll do almost anything to achieve our goal.
The rest of this discussion assumes that you understand that there are two components to a sourdough starter. If you aren't fully up to speed on what sourdough is, and how it works, you might want to check out our What is sourdough tutorial.
In any case, here are some strategies that work...
Of course, adjusting the amount of starter means changing the amount of flour and water in the recipe to keep the consistency of the dough right.
However, it is worth noting that commercial bakers yeast has been bred to work at lower temperatures than sourdough. The reports of the effectiveness of retarding sourdough based dough are variable, perhaps because different people have different sourdough cultures. Also, with regards to flavor development, the sourdough baker wants to speed up the lactobacillus with respect to the yeast, so the flavor development will be acceptable by the time the bread has risen.
There are many anecdotal reports that chilling the dough does this.
But there is evidence to suggest that this just isn't so. In one of his recent newsletters, Dr. Ed Wood commented that he had retarded some dough and the flavor was not what he expected. In a later test, he elevated the temperature of the dough. And the bread was great. This had him scratching his head, as it was the reverse of what he was expecting.
More evidence is found on page 53 of Alan Scot and Dan Wing's book, "The Bread Builders". Two charts show the activity of L. san-francisensis and C. milleri at different temperatures, plotting how long it takes the organisms to double. I've combined the two charts into one, and included it below, so a lower number means the organism is reproducing faster.
It is interesting to note that the lactobacillus is reproducing faster than the yeast at all temperatures. However, the difference in their metabolic rates remains pretty constant at lower temperatures. However, at higher temperatures the yeast component slows markedly in comparison to the lactobacillus. This begins around 90F. The down side if this is that keeping a culture much above 90 for too long can kill the yeast.
Scott and Wing suggest that the optimum temperature for the lactobacillus fermentation - as opposed to reproduction - is around 93F or 34C. They also comment that the optimum temperature for yeast is around 86F or 30C.
However, there is a large body of anecdotal reports that suggests that a refrigerated dough becomes more sour than a non-refrigerated dough, it is possible that different cultures may respond differently. It is also possible that some people observe what they want to observe.
Some recent discussions in the Bread Baker's Guild mailing list may have clarified some of the ambiguity. When a home baker chills dough, it is usually at home refrigerator temperatures, around 34 to 38F. When a commercial baker retards their dough, it is at temperatures ranging from 45 to 68F, depending on the bakers needs. This difference is the difference between a dough that is virtually frozen in time and a dough that's slowly rising and developing. Craig Ponsford said he cannot make an acceptably sour bread without retarding it.
As with so many other topics, the more world class bakers you talk to, the more conflicting information you get. It makes it hard for us mere mortals to know what to do. The best answer is to try experiments and see what works for you. Remember, you probably don't have the same strains of bacteria and yeast in your starter that Craig Ponsford, Dr. Wood, Alan Scot, Dan Wing or I have. Part of learning to bake with sourdough is learning what works with your culture no matter what an expert tells you - you need to become the expert on how your culture behaves.
If you want to experiment with slow rises for flavor development, I suggest looking around for a cheap, but working, refrigerator or freezer. You can find them in garage sales, local shopper papers, and sometimes appliance repair shops will give away a customer's old refrigerator when the customer buys a new one - giving it away is better than paying a disposal fee.
The ideal appliance is an upright freezer. Refrigerators waste space with a freezer section, and a chest freezer's space is hard to use efficiently. An upright freezer is all freezer space and there are lots of racks. You can, with a bit of ingenuity, add more racks.
Put a homebrewer's thermostat on your "new" refrigerator or freezer. These run less than $50 and allow you to set the refrigerator or freezer's temperature where you want it. Let's say 68F. They hold the temperatures quite accurately. At these higher than home refrigerator temperatures, I think you'll get the results you wanted. If not, you'll find more information in the Retarding Dough For Flavor Enhancement and Process Control page.