The Fresh Loaf

News & Information for Amateur Bakers and Artisan Bread Enthusiasts

Maximizing Yeast in SD Starter

DanAyo's picture
DanAyo

Maximizing Yeast in SD Starter

Michael Wilson’s use of the highly yeasted Levito Madre (Pasta Madre) have interested me for years. Unfortunately (as far as I know) all of the definitive literature is written in Italian. Because of this I have not ventured into this endeavor.

I recently got in touch with Debra and asked her for help to develop a sourdough starter which prioritizes the yeast population over the LAB. Below is her reply, which has been posted with her permission. Hopefully others will find the information useful.
<Thanks, Debra>

You're in luck. It's not that difficult to shift the balance, and it can be done rather quickly, although changes in the organism profile will likely follow more slowly. The best way is to reduce hydration to a firm dough, 50-60% or whatever gets you to something that isn't sticky after you knead the flour in. Feed it 3x a day if you can. (If you want to see it lose all sourness, feed every 4-6 hours for a day or two.) Like always, you need to work out feeding ratios that get you to the next feed without being overripe or deflated, because that's when LAB are forging ahead. You don't need high temperatures for this, room temp works best, especially now that the weather is cooling off. The warmer it is, the more frequently it will need to be fed to keep LAB from increasing too much.

With a strong ap like King Arthur, I usually go 60% on the water and feed 1:3:5, 3:3:5, 5:3:5, or even 8:3:5 depending how long it will be going between feeds --- 12, 8, 4-6 hours or less, accordingly, or depending on temperature. You know the drill. You develop your own routine as you go. Taste along the way, because that and how much rise you get will tell you everything you need to know about the balance. You'll probably get about 4x rise once it has transitioned and stabilized, provided you have the gluten structure to support that.

So the factors that favor yeast are: white flour, low hydration, more frequent feeding, and moderate-low temperature. This kind of starter makes great pain au levain, and I'll bet it would be the perfect choice for sourdough baguettes too. I don't know if high temperature is essential for the right species profile of a good panettone starter (it could be), but if you choose that route, just remember the higher the temp, the shorter the feeding intervals need to be to keep LAB in check.

breadforfun's picture
breadforfun

Interesting that white flour would favor yeast over LAB. Why is that?

-Brad

DanAyo's picture
DanAyo

Brad, my best guess would be the minerals in the bran favor the LAB. I hope someone has an authoritative answer for us.

I plant to give Debra’s advice a try. But at 3 or 4 feedings a day at somewhat cool temps, I’m thinking 5:3:5 or 8:3:5. May even go 50% hydration (since I often do 60%) with something like 5:2.5:5.

 

Debra Wink's picture
Debra Wink

Less buffering capacity

:)

breadforfun's picture
breadforfun

...please let me walk through it to make sure. 
We are talking about TTA here and not pH. Buffering allows the pH to remain slightly higher than the pH that would kill off the LAB, so they can produce more acid, rendering the starter more acidic without lowering the pH. 

Using white flour, without the buffering capability, the acid will continue to lower the pH, reducing the LAB population, but not affecting the yeast. That, then, will increase the yeast:LAB ratio. 

Do I have that correct?

It begs another question: I’ve always understood that firm starters favor acetic over lactic producers. Do the frequent feedings minimize the acetic acid?

-Brad

For other readers who want to read more on this, there are several other TFL threads like here and here

Debra Wink's picture
Debra Wink

Hi Brad,

Using white flour, without the buffering capability, the acid will continue to lower the pH, reducing the LAB population, but not affecting the yeast. That, then, will increase the yeast:LAB ratio. 

Yes, that's the general concept. Without buffering, the pH drops faster with less acid, and LAB are more sensitive to pH than yeast are. However, the pH isn't really low enough to limit LAB in this scenario as much as the low water activity of a firm dough and frequent feeding at cooler temperatures. It was part of the list so I included it. You would be able to taste a difference in acidity between a firm white starter and a desem, which is essentially the same thing in whole wheat. 

I've always understood that firm starters favor acetic over lactic producers. Do the frequent feedings minimize the acetic acid?

The acetic and lactic producers are one and the same. They simply produce more acetic when they have the raw materials to do so, and the conditions influence that. But that doesn't really matter because reduced hydration with more frequent feedings reduce LAB in relation to yeast, and so it decreases all acid production in relation to leavening power. It's not so much about what they're producing, as how many there are to produce it. It's all relative to population sizes which is what we're trying to rebalance here.

dw

breadforfun's picture
breadforfun

Hi Debra,

Thanks for the explanation and for the clarifications. It makes a lot of sense.

I am not unhappy with my loaf volume or with the flavors my loaves have developed. Now I understand that while it is not optimal, my 67% hydration starter kept at San Francisco room temperatures of around 65˚F does, in fact, tilt towards favoring the yeast.

You are a great resource for this community, much appreciated.

-Brad

albacore's picture
albacore

I currently keep an "ersatz" lievito madre starter as well as a normal one. The LM is all BF at 50% hydration, the normal one is 25% rye/75% BF at 80% hydration.

As part of of my recent focus on pH, I checked pH on both after 4 days storage at 9C.

  • LM 4.19
  • normal 3.82

Confirmation that there definitely is more yeast/less lactics in a stiff 100% white starter.

Lance

DanAyo's picture
DanAyo

Lance, all things being equal, will the LM raise a larger bread?

What are the diffrences in the breads produced from each starter?

Debra Wink's picture
Debra Wink

With less acidity comes less proteolysis, which translates to more gas-holding potential and lighter, milder breads.

Just refreshed
Stiff levain refreshed

At peak
Stiff levain at peak

 

DanAyo's picture
DanAyo

I posted this to a new topic (strong flour for long fermented Levain), because it is pertaining to another subject. 

Debra Wink's picture
Debra Wink

I think Lancelot would be overkill for this starter, or a levain made from it for a mild bread. In general I get better flavor and crust from the lowest protein flours that are high enough to do the job. And that for me is usually a strong all-purpose. I use stronger flours only as needed. With whole grain flour, the best is usually whatever's the freshest, although luckily for me, that happens to be a strong flour.

Here is a pain au levain I made using KA all-purpose (11.7% protein winter wheat) with the firm starter pictured above. 

pain au levain

mwilson's picture
mwilson

Hi Debra, that is some lovely looking bread. Perfect 👌

Debra Wink's picture
Debra Wink

Coming from TFL's panettone king, I consider that high praise :)

albacore's picture
albacore

I would think so, Danny,as Debra explains - less proteolysis so you are probably nearer to a pure yeast fermentation.

I guess you could view the stiff starter in a similar vein to a biga and, yes, I would say to use a high gluten flour again as used in a Biga. Maybe something about W320 or more (Italian measurement).

Lance

Benito's picture
Benito

Doc and I were chatting about pH and the effects of pH on the LAB.  Hopefully he doens’t mind me quoting his reply to me here.

Doc said “ The LAB stop replicating at around pH 3.8 but continue to metabolize sugar and produce acid until either the sugars are depleted or the pH gets down to around 3.4 (which is really low and takes a long time - especially when refrigerated). What I found was that while the LAB are sensitive to pH, they are also sensitive to both lactate and acetate concentrations (Gänzle's paper) which means that if you run the levain at a very high hydration you dilute the lactate more than you impact the pH and you get more acid in the levain.  So a levain that is propagated at a hydration of 250% will have (2.5X) more total lactate in it than a 100% hydration levain at the same pH”

So it would make a lot of sense for the corollary to be true that a lower hydration levain will reduce the LAB population.

Rob1's picture
Rob1

Hello Everybody, Hello Debra

I would like to talk about the connection between Yeasts and Ph.

We know that yeasts are dormant in the initial phases of creating our sourdough, we must lower Ph to get the yeasts going (about Ph 3.5).

Once the yeasts  will appear can we raise the Ph of the starter? From what I read it seems affirmative...this avoiding proteolysis for example.

But if we decide to raise the Ph will the LAB still "help" the yeasts in fermenting complex sugars? And raising the Ph we will not give the bad Leuconostocs a chance to increase in number?

The big problem is when we use our starters in our dough..

We keep our starter well balanced, well feeded, we taste it, we measure (ph) it.. and so on.. BUT we MIX it in our doughs in a completely different enviroment with differen flours, different temperature, different Ph ...and the problems are unavoidable..because our starter does not recognize the new "pattern"..

Debra how can we avoid this really big problem?

 

Debra Wink's picture
Debra Wink

Once the yeasts  will appear can we raise the Ph of the starter?

Yes. It will rise naturally.

And raising the Ph we will not give the bad Leuconostocs a chance to increase in number?

They don't seem to be active where yeast are fermenting. Perhaps the alcohol is toxic to them.

The big problem is when we use our starters in our dough.

If results are evidence, it's not a problem :)

We keep our starter well balanced, well feeded, we taste it, we measure (ph) it.. and so on.. BUT we MIX it in our doughs in a completely different enviroment with differen flours, different temperature, different Ph ...and the problems are unavoidable..because our starter does not recognize the new "pattern".

Sourdough microorganisms are highly adaptable to changes in their environment. 

My best