Why extra yeast in Sourdough Breads?
The night before, I refreshed my starter. Here's my routine for refreshing: to 1 TBSP of old starter, I add 200g of both ww flour and water, and that gives me just over 400g of starter (at 100% hydration) that I can bake with in the morning. I usually only use 200g of it, leaving plenty left over to play with and refresh.
With the rest of the spent starter last night, I made what I have been calling a "stiff starter". Generally I add about 100g of ww flour to 200g of my old starter, giving me 300g of starter that is very stiff indeed -- so stiff, it takes a fair bit of effort to even mix it thoroughly. This too I let sit overnight, to bake with in the morning.
Last night, I only had 78g of old starter, but I still added only 100g of ww flour to it. With even less hydration than normal, it was extremely stiff to mix up by hand. It left me with a pretty stiff starter, a tight little ball.
By the time I was ready to bake the next morning, however, my stiff starter was ready to bake with, but my 100% starter was slightly old. It had already peaked, and would not float in my water. This meant that it was past the point where the Tartine Bread recipes would work well.
|Yeast added to dough on left|
|Stretching and folding Q30min. Dough on left is silky faster.|
|Another stretch and fold: the dough on the left is effervescent.|
|The yeasted dough is ready, the sourdough-only dough is not, yet.|
|Preparing the banneton with a few leaves for fun.|
|One of the loaves is a bit misshapen. As usual!|
Curiously, the stiff starter did float. This tells me that the yeasts are growing at a slightly slower rate than they would in a higher hydration. I used this tight ball of stiff starter alone in a Tartine-style pan integrale (100% whole wheat), at 85% hydration (using the non-standard Tartine baker's math) -- that's the dough on the right. This was the wild yeast loaf. To the other dough (on the left), I added 4g of yeast. I did it with reluctance, because I haven't used baker's yeast much for some time now. But I did it because I felt the starter was past its peak.
Sourdough purists would be shaking their heads in dismay. Polluted bread, they would say. It's no longer a sourdough bread, its a hybrid, they would say. An unholy bastard-spawned corruption of a loaf.
But several of my bread books (including Tartine Bread, and Ortiz's Village Baker) describe this as a viable technique, used fairly frequently in bakeries, even in France, which is often considered by the rest of the world a nation of bread purists.
I was also guided by a recent article I'd read, which studied the amount of folate in bread.
The Buzz about Folate
By now, most of us will appreciate the need for folate in our diets. It is especially important that pregnant women get enough folate in their diet to have their children born healthy. But we all require folate. We get it mostly from our diet, lots of it in the form of green leafy vegetables, but it is in wheat germ too. Too bad most of the wheat flour we get in the stores has most of the wheat germ removed, because otherwise the flour would turn rancid quickly. All purpose flour and bread flour have had both bran and germ removed.
But its okay that we take out some wheat germ (some who defend wheat will say), because now our governments insist that our processed flour be fortified with folate. Usually the fortification consists of folic acid, though. The use of synthetic folic acid in place of naturally occurring folate is controversial, and some would have us believe that it can even be dangerous, if we take too much of it (you want 400mcg/day but no more than 1000mcg/day, according to the established limits). Others suggest that folic acid is more readily bio-available than folate (therefore even better for you), and the supplementation is necessary and doing all kinds of good.
But many nutritionists will tell you that you really ought to get your folate from your diet. If you eat lots of green leafy veggies daily, you'll probably get enough and you certainly won't get too much. If you eat a lot of processed food, you probably need supplementation: and by law, those who deplete the folate in grain by their processing of food are required to fortify their flours, breads and pastas.
But there are still concerns whether food preparers are fully complying with the fortification regulations. Then again, I've seen other studies that suggest that we have too much fortification already, and the amounts of folic acid delivered is problematic. So the controversy continues.
The whole point of folate fortification boils down to this: if your diet is deficient in folate (and it is, if you are eating processed food without fortification), you can be in big trouble. The debate is over, here in Canada and the U.S. The governments have opted for folate enhanced processed grain products. Elsewhere in the world, governments are struggling with the issue for their own constituents. As I write this, the controversy is still raging in New Zealand prior to adoption of regulations.
Wheat used to be believed to be a decent source of folate because it came to us with the germ intact: but that was before most flour was delivered to us by fast grinding through roller mills and sifting away of bran and germ.
Whole wheat flours still do not have to be fortified, but the levels of folate vary widely in the actual grain and therefore the ww flour, even before considering the differences in milling.
So we have all this info about folate. And I was curious about how much folate is being delivered with whole wheat flour, using sourdough, and how much is lost in the baking process. I had been googling around for info on this, when I came across Kariluoto's work.
What the article said about sourdough and folate
I've often heard it said by sourdough enthusiasts that sourdough bread has more folate in it than even enriched commercial bread has. This is one of those widely touted but largely unsubstantiated claims. Folate is conserved in sourdough, but the real science that was done by Kariluoto et. al. reveal a slightly different scenario than what the sourdough mavens predicted. It would appear that wild yeasts and lactic acid bacteria both produce folate, but not in very significant amounts. Furthermore, some bacteria in these wild cultures also consume it, so there is often not much of a net gain. Kariluoto's team discovered that while the sourdough environment does not harm the amount of folate, nevertheless adding bakers yeast to a sourdough will significantly improve folate levels. Thus it is assumed that baker's yeast makes folate. At least in rye sourdough. Although there are many limitations to this study, it still caught my attention.
Kariluoto S. et. al. "Effects of yeasts and bacteria on the levels of floats in rye sourdoughs". (2006, Feb) Int J Food Microbiol 106(2)pp 137-43.
So it was right after I heard of this article that I decided it was okay to add a bit of baker's yeast to my sourdough mixture. Especially since I believed the sourdough starter was slightly past its peak by a couple of hours.
I mixed up the sourdough as usual. Salt gets added with 50g of water after a short autolyse. That's the time I added the extra yeast: and the yeast had been sitting in that 50g of water for about 20 minutes, so it had time for the outer coating of the dried yeast to soften, and the living yeast within the coating to awaken and perk up a bit. But there was no food for it in the pure water, so the water didn't get foamy.
The extra yeast caused the dough to rise quickly. I felt the effervescence in this dough at least 1 1/2 hours before the sourdough-alone dough. I baked this dough in boules. In the bottom of the banneton, I placed some leaves of herbs from our garden. There's mint on one, oregano on the other.
The other 2 loaves were baked a couple of hours later. Despite the higher hydration, these loaves held together nicely. Both one of the boules and one of the more elongated shapes are a bit sloppy, due to the way they hit the pan. That's life.
|Pan Integrale (100% whole wheat made with wild yeast only). 85% hydration.|
|All 4 loaves. Two of these will be gifted to a friend.|
My wife liked the yeast-fortified loaf, and I was quite proud of the way it had risen, and that I had recognized by the look of it that the sourdough starter was spent before using it, and by feel of the dough that it was ready to bake long before the other loaves mixed at the same time. I personally thought that the taste was a bit flat because there was less time for fermentation. But again, it is one of my wife's expectations that bread itself shouldn't have much taste, but should carry the taste of the jam or other topping. That seems to be the expectation of a lot of people, frankly.
I liked that the crumb was soft, the crust flexible. I much preferred the wild-yeast only loaf for taste.
I was also happy that I could handle an 85% hydrated whole grain dough. I never used to be able to do that.
I gave away half of these breads, and the other two disappeared quickly.
Notes to Myself
- Lousy camera has only a couple of different settings for the often low-light conditions that I must photograph my loaves in. Never sure which setting works better. The greyish cast to the one setting makes the bread look very unappetizing. The reddish cast to the other makes it look toasted. The flash bleaches out most of the texture. I still haven't got a new camera to replace the last one that got all doughed-up.
- For an brief discussion of some of the additives in our bread flours, take a look at this fascinating essay, "The Bread We Eat" (14 April 2007) for Grain's publication "Seedling" (April 2007), by Andrew Whitley, author of "Bread Matters: the state of modern bread and a definitive guide to baking your own" (2006)
It contains a pretty good overview of the state of industrialized bread and the reasons why I bake my own.
- This was the first I'd heard about GRAIN as well:
"GRAIN is a small international non-profit organization that works to support small farmers and social movements in their struggles for community-controlled and biodiversity-based food systems"
- I have looked at certain additives in our fortified flours previously in this blog, including folate See here, for example. At that time, I said of folate that we haven't had enough studies to determine whether we have the right amount of fortification. Here, I said that white flour has only 39% of its folate left after refining compared to its whole wheat equivalent. That is why it needs to be supplemented.