Since the subject matter of using kefir to make bread and pizza dough is still fresh in my mind, I thought that I would record my thoughts.
The first thing that I noticed from my research is that just about all of the kefir bread dough and pizza dough recipes I found through Google searches, and there were quite a few of them, appear to be the creation of home bakers and cooks rather than professionals, with a strong emphasis on health and nutrition and using ingredients (e.g, specialty grains like kamut and spelt) that are typically not used to make pizza dough. It's possible that someone somewhere is using kefir in a commercial setting, particularly for bread dough, but I don't recall evidence of such use from my reading. I am not sure what to make of this. Maybe kefir does not lend itself well to commercial bread/pizza dough production, or maybe professionals are not aware of kefir and its potential for bread/pizza dough making. Or kefir may be like other natural yeast cultures. As you know, there are not many professionals using them to make pizza dough. Also, during my reading, I read many accounts of where people failed in their efforts to successfully make doughs using kefir. Apparently there are a lot of variations in the incubation of kefir, which can be as short as 10 hours and up to three days, in varying room temperature environments, and apparently there is an optimum time to use the kefir to make dough. Otherwise, the finished bread or pizza crust apparently can end up too sour.
The second thing I noticed is that using kefir to make pizza dough seems to be an afterthought and extension of using kefir to make bread dough. Apparently after succeeding using kefir to make bread dough, the thought occurred to people to use the same dough to make pizzas. In this vein, I noticed that the same general approach is used to make pizza dough as used to make bread dough. For example, after the kefir is prepared, a sourdough starter is made and then used to make a pizza dough after achieving a particular volume expansion (such as a doubling). The sourdough starter is incorporated with other dough ingredients as part of the final mix and the resulting dough is used fairly shortly thereafter, typically after another rise in the dough, much as is done when making bread. To achieve a relatively fast rise, the amount of sourdough starter typically represents a large percent of the total formula flour, as much as 40-60% based on my calculations. I did not see any recipes that called for using relatively small amounts of sourdough starter (e.g., below 15%) as a percent of total formula flour (or total formula water or total dough weight) and then cold fermenting the final dough over a period of several days, just as you have been doing with your Lehmann preferment dough and your more recent Ischia Lehmann doughs. I saw one example of a three-step protocol where a "thin" kefir sourdough starter, much like a poolish, was prepared and then used to make a sponge, which was then combined with other ingredients as part of the final mix. I am not sure whether this three-step method was necessary or just another fortuitous creation of a home baker.
The third thing that I noticed is that the sourdough starters can have different hydration values. Some of the sourdough starters are thin and somewhat watery, much like a poolish, and some are thicker, like a sponge or biga. These could have evolved as much by accident as by plan based on the science of kefir dough making. I also did not read anything about whether there are "break points" for kefir sourdough starters as there are with poolish and sponge to signify that the sourdough starters are ready to be used. Rather, a simple test such as a doubling seemed to be the most common test used.
At this point, I don't have a good feel as to whether using a small amount of sourdough starter and a long cold fermentation of several days will work and fit your conditions at market. In theory, it seems to me that such a protocol should be possible but never having worked with kefir I can only speculate as to how this might be done. There is a part of me that says that it might be useful to gain some experience working with kefir sourdough starters and learning how they work before taking the next step but there is another part of me that says to just go for the jugular and fashion a dough formulation that fits your three-stage protocol that has worked so well for you at market. In this context, I would tend to lean toward using preferment quantities of sourdough starter rather than solely leavening quantities (Marco's method). An example of what I have in mind is a milk kefir version of the Lehmann dough formulation that you posted at Reply 104 at http://www.pizzamaking.com/forum/index.php/topic,11700.msg110725.html#msg110725
but using a hydration of 62% that you requested be used in the opening post in this thread. For purposes of using the expanded dough calculating tool at http://www.pizzamaking.com/expanded_calculator.html
, I would treat the milk kefir as I would the water part of the sourdough starter. As noted at the nutritiondata.self website at http://nutritiondata.self.com/facts/dairy-and-egg-products/69/2
, whole milk with a milkfat content of 3.25% contains about 88% water. That means that using equal weights of milk kefir and flour to make the sourdough starter will not technically be a poolish but it will be quite close. Moreover, you can always tweak the recipe to get the dough to the same condition as your present doughs. Treating the milk kefir like water for our purposes will also allow us to use the expanded dough calculating tool without having to go through all kinds of contortions to adapt it to your specific purpose.
Once you have had a chance to digest what I have presented above, please let me know how you think you would like to proceed, and when you would like to do so.