The Fresh Loaf

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Initial Proliferation - Yeast vs LAB

DanAyo's picture
DanAyo

Initial Proliferation - Yeast vs LAB

When a starter or levain begins fermentation is the yeast or the LAB first to start fermentation?

  1. I am interested is exploring the young levain. Initial experimentation has produced a stronger dough over the same conditions of fermentation compared to a matured levain.
  2. One concern is extending the time for the starter to get down to PH 4.0. It seems that below PH 4.0 the dough begins degradation. (Benny can explain)
  3. Considering using bran to buffer the PH, but concerned that it will accelerate fermentation. I would like to ferment long and warm (78F for 16-17.5hr) to develop higher TTA.

The goal is to produce bread with a distinct and intense Lactic Sour Flavor.
To accomplish this it is important to develop a dough with low PH and high in TTA.
It is my understanding that the dough will start degrading at or around PH 4.0.

NOTE -
It is my understanding that the lower the PH the more sour the flavor. AND it is also important that the TTA be high so that the sour flavor is intense.

Looking forward to learning...
Danny

DanAyo's picture
DanAyo

I believe the LAB are active first. If this is the case is my goal benefitted or hindered if bran or whole grain is used  in the levain to buffer the PH, thus allows more LAB and the resulting acids to multiply?

These types of questions have a way of leading me down deep hole. <LOL>

headupinclouds's picture
headupinclouds

> When a starter or levain begins fermentation is the yeast or the LAB first to start fermentation?

Assuming I understand this question correctly, I believe the lag phase for yeast is shorter than that of LAB, and that the discrepancy increases with larger feeds.  I have been thinking about this response (and related discussion) to a question you posted a while ago and whether there are any rough models or rules of thumb we can use to exploit this phenomenon when scheduling our levain builds.  I'm interested in this thread, but for achieving the opposite of what you are looking for in my whole grain bakes (increasing pH for a given rise).

suave's picture
suave

 "that the lower the PH the more sour the flavor"

That's true in simple systems, but rarely deal with a simple system outside of a test tube.  First, there are different kinds of sourness, for example, anyone can easily distinguish lactic, citric, and acetic sour tastes.  Second, sourness is not a function acidity, that is at the same concentration a solution of lactic acid will have lower pH as compared to acetic acid.

DanAyo's picture
DanAyo

“ Second, sourness is not a function acidity, that is at the same concentration a solution of lactic acid will lower pH as compared to acetic acid.

I may need help understanding that statement. Are you saying that if you had 2 glasses containing 300ml of distilled water and 1 glass had 30ml of lactic acid and the other had 30ml of acetic acid that the glass with lactic acid would have a lower PH?

Thanks,
Danny

suave's picture
suave

Yes.  These things depend on how you count - if by 30ml you mean 100% pure lactic and acetic acids, then you have to take into account density and molecular weight, and the same volume of acetic acid will contain about 30% more acid, but the difference in pKa ("strength") is sufficient for the lactic acid solution to have lower pH.

Benito's picture
Benito

Danny, just a point I believe to be true, your taste of acid is likely more related to the TTA and which acid compound it is.  I believe our mouths “feel” the pH.  Perhaps someone with more knowledge of food science can chime in.

So you probably want your bread to be baked by a pH or 4-4.1 so the gluten hasn’t become degraded, but you want a high TTA.  You’ll probably need to use flour with high ash content to achieve this and you’ll need to control fermentation well because the high ash flour will ferment more quickly.

Benny

Benito's picture
Benito

Regarding gluten degradation and pH, it is primarily the proteolytic enzymes native to the flour that cause gluten breakdown.  These enzyme become most active when the pH drops below 4.  Our lEva is usually peak when the pH is around 3.8 so this is why our mature levains feel looser than our just mixed levains.  If one was using pH to decide on when to end bulk fermentation then I think the ideal would be when the pH reaches 4.4 and then to bake by the time the pH reaches 4.1.  This way our dough doesn’t suffer gluten breakdown before being baked and has the best chance of good ovenspring and crumb.

DanAyo's picture
DanAyo

Good PH info. I tried to follow the PH guy in Instagram,  but am not IG savvy. 

Do you have any other sources for bread baking/PM related information?

 Our starters usually peak when the pH is around 3.8 so this is why our mature starter may feel looser than our just mixed starter.”
Very interesting, I’ll have to monitor the PH during starter fermentation.

BTW - it is a breeze with a spear tipped probe.

Benito's picture
Benito

I just realized I meant to type levain and not starter.

Our levains are usually at peak at a pH of 3.8...I’ll make that edit.

Kristen and also a bunch of professional bakers have also been posting pH information and they are all very similar to what I’ve posted above other than my error with starter instead of levain.

DanAyo's picture
DanAyo

Benny, why would there be a distinction between the starter and levain. Aren’t they basically the same?

Or are you less concerned with degradation of the starter?

Benito's picture
Benito

Yes because there is generally a lot more levain in the final dough compared with starter, it am less concerned about gluten degradation with starter than levain.  But you’re right the pH data is likely the same.  However, I’m just giving you the data that I’ve seen reported.  I don’t have the right type of pH meter (spear like tip) to do readings on dough in this manner so I’m not following pH throughout bulk and proof.  However, I know you have the right equipment and it might be interesting for you to see what you find.

harum's picture
harum

According to this paper, APPLIED AND ENVIRONMENTAL MICROBIOLOGY, July 1998, p. 2616–2623, the answer to the very first question might be: it's the LAB because they not only outnumber the yeast, but also multiply faster even at the temperature optimal for the yeast. 

"It is my understanding that the lower the PH the more sour the flavor."

This might not be true for breads because of the nature of the acids produced by the bacteria.  The pH cannot be made much lower than 4, but TTA can be made pretty high by extending fermentation times.  Both pH and TTA contribute to perceived acidity.

 

DanAyo's picture
DanAyo

Thanks Harum, my bread doughs read about PH 3.7 and I suspect very high TTA.

I’ve dialed in the flavor, but would like to improve the dough strength. Degradation is an issue after the long warm ferment.

harum's picture
harum

Not sure how successful my attempts to get rid of as much acetic acid in the dough as possible have been, but the flavor and the crumb of my breads seem to have improved quite a bit when the starter and doughs were moved to higher temps.  Only done this for rye doughs, never for wheat, though.

While lactic acid is a bit chemically stronger than acetic, its perceived sourness is much higher at comparable molar concentrations.  This might be why acidification of dough with lactic acid doesn't produce too much of off-flavor and off-smell: because it takes much less of it to drive the pH down?  

albacore's picture
albacore

Despite your dislike of IG, check out this post from Kristen, Danny - it's basically what Benny has already said, but with a bit more detail and a nice graph. 

I think what Kristen and Lazlo have been saying lately is to do multiple starter refreshes at 1:1:1 and only refresh at pH 3.8. I don't think this is especially to get sour bread though - more to get an active starter.

I've just tried refreshing mine at 1:2:1.6 (s/f/w) but was only able to get down to pH 3.95 after 7.5hrs and I would say the starter was past peak. Perhaps a 1:1 refresh would have helped. I think I need to try it on an offshoot starter so I don't mess up my main one.

 

Lance

Benito's picture
Benito

When I was regularly collecting starter data, I found that my red fife 100% hydration starter would peak at a pH of 4-4.2.  No in retrospect knowing what I know about red fife and its intolerance to fermentation I wonder if it had actually peaked or in fact maybe it was on the edge of gluten degradation and falling because it was unable to retain the gases as well.  Come to think of it, perhaps that was one of the reasons I had experienced starter sluggishness those times. Perhaps I was using my starter before it actually peaked and it therefore would appear sluggish....

Anyhow, now keeping a 100% whole rye 100% hydration starter and the pH data is quite different.  The rye starter at peak is at a pH of about 3.6

 

albacore's picture
albacore

That figure of 3.6 seems incredibly low, Benny! I've done Detmolders with 100% rye and never got anywhere near that low.

Perhaps I didn't wait long enough.

 

Lance

Benito's picture
Benito

I did a fair amount of testing with my rye starter but nearly as much as when I was using red fife.  I think that rye starters harbor a much higher population of LAB than other starters because of rye’s inherent greater buffering capacity.  My suspicion is that this also makes rye starters more durable and less prone to sluggishness as well.

DanAyo's picture
DanAyo

Here is some info I got from Kristen. Published with her permission.

Here are some of the references I was using when I made my pH posts (seen here and here -- and I've attached my images from my testing of starter and dough with temperature and pH featured).

 https://www.instagram.com/balazlo/ <-- this is the guy, Laszlo, who I talk to about all things pH

https://bread.blog/enzymes-and-ph-matter-troubleshoot-my-loaf/

https://www.mygermantable.com/what-is-sourdough-an-in-depth-guide-to-sourdough-technology-for-bakers/ Just a note: the lowest pH my starter has ever measured was after 36 hours of no feeding - smelled like cider vinegar, super thin consistency - pH = 3.49.I am shaping around pH 4.4 and baking around pH 4-4.05. My starter however peaks right around pH 3.8 :)
slohcooker's picture
slohcooker

I'm eagerly following this thread. I've seen that IG post from Kristen. Danny, who is PH guy you're referring to?

I picked up a simple Hanna Instruments "Checker" pH meter at a thrift store (seriously, they have everything). Anyone know how to calibrate it semi-accurately without buying buffer solutions?

+1 for Benny's explanation of the proteolytic enzymes and gluten degradation. Debra Wink talked about this in one of her legendary treatise posts, and it bears repeating. The gluten degradation that we experience in our starters and doughs is not directly caused by the acid, but rather the proteolytic enzymes, which are more active at lower pH. In other words, correlation not causation. May not be an important distinction on a practical level, but I believe we're well into nerd territory already.

Now I need to get a better handle on TTA vs pH...

Benito's picture
Benito

He goes by the handle of Balazlo https://www.instagram.com/balazlo/

Dan, Doc, Abe and I just had a very long email conversation about TTA vs pH.  My chemistry knowledge is from over 30 years ago and I will try to simplify.  The pH essentially represents the concentration of free Hydrogen ions in a solution, the hydrogen ion coming from the acid, say lactic acid.  The pH of the solution is affected by the buffering effects of things in the solution, in the case of dough, the flour.  The buffering power of flour is related to its ash content.  Whole grains having higher ash contents than white flour and whole rye having I believe the highest, at least for the flours I’m familiar with.

The Total Titratable Acid (TTA) is essentially how much of the acid there is in the solution in our case the dough.  So that would be how much lactate there is for example.  The TTA isn’t affected by the buffering effects of the solution whereas the pH is because it is measuring the concentration of only the free hydrogen ions coming from the acid that isn’t buffered (captured) by the buffer.

slohcooker's picture
slohcooker

Thanks much, Benito. So the idea is that a dough made with a higher ash content flour (like a whole wheat), can have a higher TTA than a dough made with a lower ash content flour after fermenting to the same pH value?

--Steve.

Benito's picture
Benito

Yes that is correct Steve.  The greater the buffering capacity of the flour the more acids can be produced before the pH drops to less than 4 and proteolysis starts to accelerate.

Benny

HeiHei29er's picture
HeiHei29er

A lot to consider when just looking at ash content and its ability to neutralize hydrogen ion.  The form of the mineral (oxide or carbonate) and the mineral solubility.  Oxides are not buffers (they will neutralize though), but carbonates are great buffers.  I haven’t researched what is typically found in the various flours yet.  Also, the mineral needs to dissociate into the water in order to neutralize, which means it needs to be on a wetted surface.  The same flour at a finer grind will have more neutralizing capacity than a coarse grind because it has more exposed surface area.

According to a table I found on the artisan.net, AP flour has an ash content of 0.5-0.6%, and 95% extraction whole wheat is 1.4%.  In a typical 500g flour loaf at 70% hydration, going from 100% AP to 100% whole wheat will give you an additional 11,500 ppm of mineral content assuming 100% of the mineral is able to get into the water phase, which it can’t.  When you break it down to how much additional whole wheat you use, the mineral type, its solubility, and its availability, the additional neutralizing/buffering capacity is something far less than 11,500 ppm.

If I wanted to drastically increase the buffering capacity of my dough, I would replace 1g of salt with 1g of baking soda.  I don’t know how that would impact taste, but the bicarbonate in the soda ash is a very strong buffer with very high solubility, so it will all go into the water.  In a 500g flour loaf at 70% hydration, 1g of baking soda will give you 1,600 ppm of buffering capacity.  The downside...  it will release carbon dioxide as the pH drops and give a false sense of fermentation.  You’d have to degas it somehow, which makes knowing where you’re at in fermentation tough.  Might be able to just use pH if your goal is maximizing TTA.  Again, not sure this is a good idea, but it will give you immediate buffering.

Ilya Flyamer's picture
Ilya Flyamer

But bicarbonate will also react with the acid and not just buffer, but also neutralize them, so will lower TTA? Am I missing something?

 

Benito's picture
Benito

The bicarbonate should neutralize the hydrogen ions of the acid but the acid should remain.  So in our lactic acid example the free hydrogen ions of the lactic acid are neutralized but the lactate remains.  So it doesn’t lower the TTA.  Unless I’m mistaken.

Ilya Flyamer's picture
Ilya Flyamer

Ummm well, my chemistry courses were a while ago, but in a reaction between an acid and a base the result is a salt, and in case of a weak acid and a weak base (like in this case) the final pH is neutral, and no acid... And if just having the acetate or lactate anions is what you are looking for without bothering about pH, then yes, neutralizing with a base such as bicarbonate is enough. But would that make a more sour taste? I don't think so. If you take vinegar and neutralize it partially with bicarbonate, surely it would become less sour?

HeiHei29er's picture
HeiHei29er

Agree.  In this case, it’s both.  The end result is still getting to pH 4, so there’s still the same concentration of hydrogen ion at the end of fermentation.  However, the buffering allows lactic/acetic acid generation to continue before you get to pH 4, so you increase those flavors.

HeiHei29er's picture
HeiHei29er

I assumed the taste/sourness comes from the lactate and acetate anions and not the hydrogen ions.  Generating acetic/lactic acids and then neutralizing the hydrogen ion allows you to build more lactic/acetics in the dough before you reach pH 4.

If it’s the hydrogen ion that provides it, then yes, the bicarbonate will work against you.

Benito's picture
Benito

I believe that the caustic effects of acids are related to the free hydrogen ions and that we may feel this effect in our mouths.  They may affect flavour as this caustic effect may alter our taste buds sensitivities.  However, it is the TTA that we taste, that is why lactic acid and acetic acid taste different.

DanAyo's picture
DanAyo

Balazlo has a large following on IG for PH pertaining to bread and dough. Both Lance and Kristen told me about him.

Search Google for calibration procedure. Hanna makes good equipment. It remains to be seen if the probe is still in working order. The agent at Milwaukee Instruments where I got my meter tells me that the probes have a limited life span and require proper storage. If the probes is not in working order, hopefully you can get a replacement. If possible your best probe will be a spear tip probe. These types of probes are direct insert into starters, dough, and even crumb. The bulb tips require you to dilute the material with distilled water to take a reading. 

albacore's picture
albacore

You will need to calibrate it with buffer solutions. That meter uses pH 7 & 4 calibration buffers. I buy my buffers off Aliexpress as powders and dissolve in deionised water (available nearly anywhere). It's worth upgrading the shipping or you will be waiting a while.

I have checked the accuracy of the buffers against Hach standards and they are good.

 

Lance

slohcooker's picture
slohcooker

Thanks.

DanAyo's picture
DanAyo

lance, I noticed that a lot od bakers are useing the Hanna Bread and Dough Meter. Are the spear tips replaceable? 

albacore's picture
albacore

Not on the most basic food versions. I think you can refill the probe on the Halo - the BT one that gives you nice graphs. Not sure about the other models.

Hanna seem to be top price to me and they load the UK price for some reason, even though a UK company.

 

Lance 

DanAyo's picture
DanAyo

Duplicate Post

albacore's picture
albacore

Here you go Danny: https://www.hannainst.com/halo-wireless-foodcare-ph-meter and looks like there's a -20usd special offer until the 25th.

Interestingly, Hanna won't even let you view that page in the UK, where it costs at least 50% more - I had to use a VPN, otherwise it redirects to the UK site!

BTW, the probe isn't refillable after all. There is a refillable Halo, but it has a bulb tip. 

 

Lance

 

DanAyo's picture
DanAyo

Thanks Lance. Kristen uses that unit and made the 2 charts above with it.

DanAyo's picture
DanAyo

I in the process of learning about pH. How does a pH meter determine the readings. It is not a simple subject for the untrained, and I am definitely untrained.

THIS VIDEO has been a great help.

More resources that are helpful are appreciated.

I started a new post dedicated to pH and PH Meters HERE.

Gadjowheaty's picture
Gadjowheaty

Great topic.  Aside from the interesting conversation on acidity and buffering, albacore mentioned it but have you thought of trying the Detmolder process, emphasizing the acids and in particular, acetic acid (acetic having a sharper, more pronounced "tang" to it.  One thing that comes to mind is malolactic fermentation, to finish out wines)?

DanAyo's picture
DanAyo

I am a huge fan of lactic sour (smooth not sharp), not so much acetic. The long ferment is part of my SFSD breads.