If, during the process of a multi-day levain build, I decide to slow one of those days down a bit to develop more flavor in my levain, can I put it in the fridge for 12 hours and take it back out with no ill effect? Will there be any positive effect?
Not sure where I read this, but somewhere in the back of my mind I think I saw somewhere that you could retard a stage in a levain build to increase sourness - something about allowing the LAB to out-produce the yeasties at the colder temperature for just a short while, then back to building the rest of the levain at room temp.
My starter does not smell sour. At all. A bit fruity and yeasty, but definitely not sour. It's 100% with all KA AP. Without adding WW or rye flours, is there anything to this retarding process during a levain build, or...?
That to retard the Levain after maturity will further increase flavour. Whether retarding at any stage will produce the same results I'm not sure. Using a levain at different stages of maturity will also bring out different levels of tang. So just like bakers use a young starter for a mild flavour the opposite end of the spectrum will increase flavour. Using wholegrain will always help too.
I frequently end up stashing my levain in the fridge for hours or days - usually immediately after it has doubled (3 to 4 hours after the build), but sometimes even after it has peaked and receded (12-16 hours after the build). If it was after the doubling, then I bring it out and let it warm up to room temp (and keep fermenting) for at least 3 or 4 hours before using it for the strongest sour flavour, but otherwise will use it straight from the fridge.
All of my levains are whole grain, either rye or wheat or a combination, and I find that I get a bigger impact on the flavour when I put the levain in the fridge door (where it takes much longer to cool to my fridge temp of 37 deg F) than when I put it on a back shelf (where it cools more quickly). It also makes a difference what container the levain is in (a thin glass cools faster than thin plastic which cools faster than thick glass...)
My base starter is either rye NMNF or durum NMNF (60% hydration - kept in the fridge for weeks on end), and always has very tangy results. If that is what you strive for, then it might be worth your time to switch over to a whole grain starter.
Please let us know what your results are!
for a prolonged period of time gets the LAB to produce acetic acid instead if lactic acid. Good SD bread in my book has both where lactic is the base sour and the acetic is the 'tang'. I routinely retard my whole grain levain for 2r-48 hour with no ill effects other than the bread tastes better in the end:)
A famous levain build called Detmolder also uses stiff and cold in the 2nd phase of a 3 stage levain build to bring out other flavors in the levain and resulting bread. This is the same reasoning others use to to retard dough during bulk ferment or shaped final roof - t bring out additional flavors you can't get otherwise.
I have found that if I put all of the liquid into the levain (so that it is maybe 270% hydration), I get more acid production. But I have to run it warm and long rather than cool and long. What I think is going on is that the acid produced by the LAB is diluted by the excess water so that the actual concentration seen by the LAB is down by over 50%. As a result, the LAB can continue to produce acid for a longer period of time. They always leave some residual sugar in the mix but you would like to get that down as low as you can arrange. The technique for measuring progress toward sugar depletion is to weigh the total flour in the levain, then cover the levain bowl with plastic wrap and weigh it. Write the total weight on the plastic with a permanent marker. Now calculate 2% of the flour weight (in the levain only) and subtract it from the total measured weight. That is the target weight of your mature levain with maximum acidity. The plastic wrap will puff up if you use Stretch-tite (because the PVC or PVdC film is much less permeable than LDPE). Just wait for the weight loss. The LAB activity is exponentially decreasing over time as there is less sugar in the levain and more acid and lower pH so it loses weight more quickly at the beginning. And at the end, cut a hole in the plastic wrap and let the excess CO2 out (which can weigh a gram or so depending on the size of the bowl and the dead space under the film.
The other thing you can do, especially if you want to increase the acetic acid component, is to add 2% fructose to the dough. I have data on TTA that demonstrates conclusively that you get an independent bump in acidity as a result. The sweetness of the fructose does not last through bulk fermentation and proofing. You get just the acetic acid (which you generally smell rather than taste).
Another thing to think about as you increase the acidity is the amount of salt that you use. My experimentation tells me to increase salt a little (1.75 to 2%) as you step up the acidity so that you maintain the salt/acid balance. It is speculation, but this may be why Hamelman makes small changes in the salt content of his multiple shades of Vermont Sourdough, with generally more salt in those with higher fractions of whole grain flour.
secret:-) LAB also stop producing acid and make CO2 and ethanol when the 2% fructose originally in the flour is used up and we have yeast for that. I always thought that LAB produced lactic acid in high hydration and temperatures rather than acetic and that LAB produced acetic acid when prompted by the opposite - low hydration and temperatures? So are both correct?