Sunday, March 25, 2012 - Sauerkraut und Sauerteig
This week Margot Levy, a fan of this web page (thank you Margot!) asked a question I was ready to just blow off. Anyone who has spent much time at Sourdoughhome knows that I really think that flour and water are necessary and sufficient to start a sourdough starter. You don't really need anything beyond that. Moreover, in all the cases I've found the critters in whatever else you use - be it bakers yeast, cabbage leaves, grapes, yogurt or what not - are the wrong types to start a sourdough starter. These other things might get your starter off to a rip-roaring start, but it won't be a sourdough starter until that stuff dies off.
Margot asked, "what about sauerkraut? Can I use sauerkraut juice to start a sourdough starter?" My knee-jerk reaction was "NO!" However, I know that sauerkraut is fermented by lactobacillus bacteria, the same bacteria that make sourdough sour. The question is whether they are the same strain.
I did some Googling and came across this web site: Professor Lindquist's site where he talks about all sorts of interesting sauerkraut related things. (Sadly, the original site is no longer available, so the link takes you to the saved version of the site at the truly amazing Internet Wayback machine.) Interesting, there is a very predictable progression of bacteria in the sauerkraut. I've made sauerkraut a few times and found this page fascinating! Also found on another page is that two of the final bacteria are also active in some sourdough cultures. (L. Brevis was one of them.) Having made a number of batches of sauerkraut, I highly recommend that you give it a try. The product you make at home will be richer and milder in flavor than the store bought stuff. In addition to the link above, there are a number of YouTube videos that tell how to make sauerkraut. I'd look for ones made by German or Scandinavian grandmothers.
In Professor Lindquist's web page there are some critter counts from the sauerkraut that shows how effectively the succession of critters occurs. I shared this with the impeccable bread guru Debbie Wink and she sent me some papers that show a very similar progression occurs in sourdough. I'll comment on them when I have a chance to read them.
An interesting difference between sauerkraut and sourdough - with sourdough we cultivate and keep the starter using it to make subsequent batches of bread. We feel that the starter gains in strength, flavor and general goodness as it develops. With sauerkraut attempts to make the next batch with the culture from the current batch are not satisfactory. Each organism contributes to the final product, and much like reading a mystery novel racing to the end really doesn't improve things. Sauerkraut depends on the succession of bacteria to develop its flavor.
This lack of reuseability in the sauerkraut juices means that the manufacturers have a lot of salty liquid to dispose of. It's an industry wide problem.
So, what about starting a sourdough starter with a bit of sauerkraut juice? It's time to equivocate a bit.
I have no idea if commercial sauerkraut is typically made by natural fermentation today. Industry trends for the past century have been to get rid of natural fermentation whenever possible. It is, in my biased view, a mistake, but it is a trend. Having owned a bakery, I am convinced that fermentation scares health inspectors - they tend to see it as perishable food at room temperature rather than food in a process. In any case, if the sauerkraut wasn't naturally fermented, it won't have the critters you're looking for to start a sourdough starter.
Next, if the sauerkraut was pasteurized, the critters were killed off.
You'd want nice fresh, unpasteurized sauerkraut, if the critters are what would help a sourdough starter.
If you look at the nutrition label of the sauerkraut, you'll see its a high sodium food. You need about 2 1/2% salt to make the fermentation work. I have no idea what that much salt would do to a sourdough starter. One of my sourdough starters uses a little salt (less than 1% of the flour weight).
As I was dithering Margot sent me another email. She decided not to wait on my advice (probably wise, all in all), and used some sauerkraut juice and her starter just took off like a rocket!
So... what happened? One thing that happens as sauerkraut ferments is that it becomes more acidic. And if sauerkraut is made by other methods, they would acidify it to give it it's characteristic bite.
In the standard sourdough progression, the Leuconostoc bacteria have their day in the sun. And its not a real sourdough starter until they are killed off. Which is the big reason I comment I wouldn't use a sourdough starter that is less than a week old. Leuconostoc bacteria foam up like nobody's business, but they don't have enough strength to raise bread. As the sourdough starter becomes more acidic, the Leuconostoc bacteria die off and the lactobacillus bacteria take over. Debbie Wink found that if you acidify the sourdough starter using pineapple juice rather than water to start the starter, the Leuconostoc bacteria never get going allowing the lactobacillus bacteria to develop more quickly. This has spared a number of sourdough beginners a lot of anguish!
So, if Margot used a nice fresh, non-pasteurized sauerkraut, the lactobacillus bacteria in it might have kick started her sourdough starter. Otherwise, the acidity could have just killed off the pesky Leuconostoc bacteria and opened the field for the bacteria we like having around.
All this talk about baked goods and sauerkraut makes me wonder if Kolache Haven is open today. They're a decent little bakery in Denton, TX that makes a really nice sauerkraut and sausage Kolache. Maybe on the way to work tomorrow....
Thanks to Debbie and Professor Lindquist for their insights. As always, the people whose ideas I "borrow" have the insights, I just add errors and typos.