The Fresh Loaf

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Wheat starter behaving strangely - rising and collapsing two times per feeding!

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ACH6's picture
ACH6

Wheat starter behaving strangely - rising and collapsing two times per feeding!

Hi,

Over the last few days I've been checking the activity of my wheat starter (100 % hydration) in a somewhat different manner than I'm used to. I've kept it in room temp the last three days (I normally keep it refrigerated and feed it once a week when I am not baking, which I usually do about 1-2 times per week) and I've been feeding it according to what most people generally seem to recommend here on TFL: every 12 hours with a 1:2:2 ratio (starter:water:flour). The feedings consist of a low protein wheat flour (10 % protein) and regular tap water (no additives). However, during this period I've been noticing some rather strange things...

My starter usually doubles (200 %) in size in about 4-4.5 hours. But then, a while after it reaches its first peak, it collapses a bit and levels out at maybe 150-175 % of its original volume, at the same time creating a small cluster of soapy bubbles at the center of its surface. But then, a couple of hours later, it rises AGAIN, and finally when its been active for a total of about 8-10 hours it levels out at around 200 % (or more). Some short time after this second peak it finally collapses down to its original size. It never tripples in size or anything, as I've been reading that others starters do here on TFL

Now, I haven't really read anything earlier on TFL that describes this scenario. Is anyone else experiencing this kind of starter behaviour? Also, when would you recommend using the starter for baking (or feeding) - at its first peak or at its second?

Thanks in advance for all your help!

 

Regards,

 

Adrien

dmsnyder's picture
dmsnyder

You have a very active starter there! Liquid starters have less "food" for the yeast than firm starters. And a liquid medium at room temperature is the ideal for most rapid yeast multiplication. Liquid starters have less structural support to rise also.

So, the first collapse occurs when the structure of the batter cannot support it's weight. The effect on the starter is like a stretch and fold or a "punch down." So, it rises again. After the second collapse, there is not enough sugar left to support further active fermentation, so it just sits there.

You have several choices: 1) Convert to a firm starter; 2) Resume refrigerating between feedings; 3) Feed the starter 3 or 4 times a day. Eventually, you could "train" your starter to thrive on a twice a day feeding schedule, I'm sure.

David

 

ACH6's picture
ACH6

Thanks for your reply, David.

When would you use the starter for baking then? At the first peak or the second? Am I wrong in thinking that the activity is at its maximum just before the 2nd collapse and therefore it would be optimal to use the starter or feed it at just that moment?

dmsnyder's picture
dmsnyder

(See entry below.)

David

Mini Oven's picture
Mini Oven

Use it on the first peak.  Activity declines after the first peak.  We do have a video link somewhere of two starters racing a wheat and a rye.  They both fall back and rise a second time.  :)

Welcome to TFL!

ACH6's picture
ACH6

I'll do just that then. Thanks for the help! And thanks for the warm welcome! :)

Please let me know if you come across that link. I can't seem to find it myself... I'll start feeding and using the starter just before the first peak collapses. I can't wait to try this new tactic out! 

drips's picture
drips
Doc.Dough's picture
Doc.Dough

I don't know what your kitchen temperature is, but this time of year I am guessing that it is about 23°C/73.4°F. A 1:2:2 feeding at that temperature will take 7 to 10 hrs to consume the available food (depending on how much time you allow for lag phase and what you define as "all the available food").  So your 12 hr feeding schedule is fine.  By the time you feed it the population has not dropped substantially from the peak.  If the temperature is above 25°C/77°F you should be feeding more often. 

If you have access to a pH meter or some indicator strips, you might check the post-refresh pH to make sure it is above ~4.8- 5.0 .  The LAB do not grow fast enough or long enough to fully replace themselves if the starting pH is too low, and when you take your refrigerated starter out after a week it is likely to have a lot of acid to be neutralized by the flour you use for refreshment. 

When you refrigerate your starter, you should feed it at 1:10:10 or higher if you will not be baking for a week.  And it is very sensitive to refrigerator temperature - at 4°C the LAB can grow by 20X and the yeast by only 2X in 7 days.  Thus the general guidance to refresh a couple of times at room temperature before you bake with it after taking it out of the refrigerator.

There is one more factor that probably contributes to your double rise and fall phenomenon. You are using a relatively low protein/low water absorption flour which as David points out is not strong enough to hold a 3:1 expansion at 100% hydration.  With a higher protein flour you might not see two such definite cycles.

ACH6's picture
ACH6

You mention that my 12 hr feeding schedule is fine. Does this mean that you don't agree with the above posts concerning using or feeding the starter at its first peak for maximum "performance"? In that case, what would be your recommendation?

Doc.Dough's picture
Doc.Dough

You are getting bacteria and yeast from the starter, so the most important thing is to have healthy, active critters and high population density.  If you go look at the literature, both the yeast and LAB slow down as available sugars become scarce, but don't go into a survival mode for quite a while.  In between, you are good to go.  You can test this hypothesis if you like by refreshing a "very active" starter and at the same time refreshing some of the (12 hr old) starter it was made from and see how different they behave during the growth period. I generally refresh at 1:4:4 to 1:20:20 depending on when I want it ready to use (I try to time it so that it is past peak volume by an hour or two). The LAB always stop growing first (they stop because they make the pH so low that they can't stand it any more) while the yeast finishes last and is done only when it has depleted the available sugars.  The yeast is not dying off, just not multiplying as fast as they are capable of. The bubbles leak CO2 faster than it is being generated and the volume shrinks as a result.  The LAB continue to produce acid even after they stop multiplying (down to about pH 3.8) which is why refrigerated starter can have a high level of total titrateable acid (TTA).

 In your specific case, your first peak is not peak population density and perhaps not even max growth rate.  You can use Ganzle's model (below) to calculate the population levels as a function of time and temperature (and pH, and ionic strength, and acetate, and lactate if you want but I have only included time and temperature here).  I find them to be absolutely right if you add one doubling time for lag phase delay.

Model and parameters from Michael Ganzle

Model form:

Growth rate =  a * (K-t)^b * exp[c*(K-T)] = ln(2)/generation time

Generation time = ln(2)/{ a * (K-T)^b * exp[c*(K-T)] }

K=41 for LAB, K=36 for yeast; T = temperature  in °C

Species population N=N0 * 2^{t / [ a * (K-T)^b * exp(c*(K-T)) ] }

where t is time in hours

a, b, & c derived by curve fitting lab data to parametric model

  L. SF I        L. SF II         Yeast (C-Milleri)

a  0.1267     0.0682        0.0124

b  1.5404     1.9782        2.981

c  -0.1931    -0.2233      -0.3355

ACH6's picture
ACH6

Wow - that seems  to be pretty complex stuff. Its been a while since I've activated the math part of my brain, but I'll give these calculations a go when I have the time.

However, I find it interesting that we now seem to have two different views on when I should use the starter. David and Mini seem to say that the first peak is optimal, whereas you say a later point in time is the way to go. This is starting to get confusing... 

ACH6's picture
ACH6

So far, then, we seem to have two different ways of reasoning. 

1) use and/or feed the starter at its first peak, or

2) use and/or feed the starter after its first peak - probably closer to its second peak if I don't misinterpret Doc.Dough.

What do you think should be the verdict? :)

mrfrost's picture
mrfrost

I view these a slightly different. Not really that confusing.

If you are feeding it to use for baking. Yes you want it near the absolute(and first) peak. If you are just feeding to maintain, it is ok if the starter has receded a couple or few hours from the peak.

ACH6's picture
ACH6

Well, Doc.Dough seems to be arguing that the first peak isn't the peak in population density and/or growth rate. So, according to what I understand, this would imply, on his POV, using the starter for baking at a later time than the first peak.

Or am I missing something here? As I see it, what you are saying constitues yet another method:

3) use and/or feed the starter for baking at its first peak, and feed the starter for maintenance after its first peak (according to what Doc.Dough has said above)

mrfrost's picture
mrfrost

I tried...

Good luck.