Traditional Maturity vs Tartine Float

[pizzablogger]

As mentioned in Chad Robertson's excellent book, Tartine Bread, one measure to use in order to determine if a levain is ready to be incorporated/mixed into a formula is if the levain is able to float when placed into slightly warm water.

This is an interesting and incredibly simple metric to utilize.

The more traditional method is to keep an eye on the levain and use it as close to peak maturity, or at "break", as possible.  This is the point where the levain is no longer rising in volume and has reached its maximum height, before beginning to recede and becoming over-mature (under or over mature levain may help create a final product different from what was intended).

I am interested to see how close the float occurs to the actual break-point over repeated trials. If there is a large enough time disparity, I'd like  to try and determine what impacts using the starter at those different points would lend in pizzamaking, if any.

I will post more details later when I get home from work, but would welcome any other people willing to do some experimentation, even if the end result proves to be meaningless. --K

[StrayBullet]

I know for me there's enough time difference for it to have made an impact on me.  I fed my starter this afternoon at 1pm, I fully expect it to pass the float test at 4pm.  I would imagine there's at least 2 hours if not more to reach the dome point you describe.

Mark

[Jackie Tran]

What a great experiment Kelly.  I'll participate in whichever way I can.  I have never used the traditional method allowing the dome to recede before using a starter.  I have always just eyeballed it relying on visual cues of starter activity to tell me when to use it.   Looking back now, I suspect I have been using a much more mature starter.  However, since making tartine bread, I have come to prefer the results I get from a young leaven for both bread and pizza.   IMO, I notice a big difference between using a young starter/leaven vs a more mature one.   This is one of the most important aspects of dough making for me as it can have a big impact on gluten structure and final product.  

[dellavecchia]

My natural starter will float within an hour of feeding it, but I know from experience that I need to wait at least until it has domed to start using it. The float test is just one indicator of the readiness of your starter.

John

[pizzablogger]

Time to float is as much an indication of the level of CO2 in the starter from fermentation activity as anything else.

It's important to realize the feeding protocall from Tartine uses a relatively small ratio of starter to the amounts of flour and water used to feed it.

The ratio of starter to feeding amounts would impact time to float. Everything else being equal, 100g of active starter fed 50g water and 50g flour is going to float sooner than the same 100g active starter fed with 200g water and 200g flour.

I definitely want to do a controlled test, as much as such a thing is possible given the nature of the beast.

More details later and thanks to anyone willing to see what happens here.

[dellavecchia]

More details later and thanks to anyone willing to see what happens here.

Looking forward to seeing your results. This is a really cool experiment.

John

[apizza]

The Lab staff appears ready. 

[pizzablogger]

It may be Sunday or Monday before I can further elaborate. Actually already started taking some pictures of starter rising, doming, etc

But time is short and I already have another committment to a member here I need to try and finish by Monday night so their name can go up on Slice on Tuesday 

[scpizza]

Time to float is as much an indication of the level of CO2 in the starter from fermentation activity as anything else.

Yes, and the amount of CO2 trapped in the starter would not only be a function of fermentation activity but also:

- the level of gluten development in the starter (how much the starter got mixed)
- the type of flour used in the starter (e.g. whole wheat flour will not trap as much CO2)
- the hydration of the starter

That's why I'd be nervous about using flotation as a measure of starter activity.  It seems to me that pH would be a better measure.  Actually, professional baking literature says pH plus TTA is the optimum way to identify levels of starter development (http://www.lallemand.com/BakerYeastNA/eng/PDFs/LBU PDF FILES/1_11PREF.PDF). 

Having said all this, I admire the drive to experiment and post results.  I think this board benefits enormously from that.

[foolishpoolish]

Sadly I couldn't read the above document (link doesn't work for me) but as a layman (not a scientist) I would speculate that TTA would be a more useful measurement. If we have to take into account wholegrain flours, pH alone would not be sufficient, due to their buffering effect in starter cultures (which, as I understand it, is one of the reasons why using wholegrains can indirectly achieve a more sour result, due to the differing sensitivies of lactobacilli and yeast).
The question is - what fermentation activity are we specifically trying to measure?
LAB activity? Lactate production? Acetate production? CO2 production? Yeast metabolism?
The lactobacilli population in a culture does not grow at the same rate as the resident yeast nor are their respective growth patterns a simple linear or even exponential function.
 

[scpizza]

Excellent points.  If we take "starter activity" to mean aggregate culture metabolism rate, TTA does seem like the least bad indicator of that.  Better than pH and far better than flotation.

Might want to try the link again as it works for me though the host site seems to be having issues right now.

[foolishpoolish]

Excellent points.  If we take "starter activity" to mean aggregate culture metabolism rate, TTA does seem like the least bad indicator of that.  Better than pH and far better than flotation.

Might want to try the link again as it works for me though the host site seems to be having issues right now.

Thanks. I still had no luck with the website but I managed to grab a copy off wayback machine
The article explained something which I had considered but didn't have the scientific basis to query, namely the difference between weak and strong acids (lactic vs acetic) and how that affects pH readings, which was their (lallemand's) basis for suggesting TTA.

[Mick.Chicago]

A visual clue I've noticed with my 'Goldfish bowl starter' is that the Plastic Wrap will dome from the gas being developed. Tonight when I fed it I took note of how it looked. We'll see later if it's doming again.

[Pete-zza]

I used the WaybackMachine at http://www.archive.org/web/web.php to come up with a copy of the Lallemand article mentioned earlier, at http://web.archive.org/web/20061014185036/http://www.lallemand.com/BakerYeastNA/eng/PDFs/LBU+PDF+FILES/1_11PREF.PDF. So, for those who have been wondering what "TTA" is, they will now know. Sometimes an article found using the WaybackMachine goes into the ethers again, so one should go back to the WaybackMachine and try again.

Peter

[norma427]

I used the WaybackMachine at http://www.archive.org/web/web.php to come up with a copy of the Lallemand article mentioned earlier, at http://web.archive.org/web/20061014185036/http://www.lallemand.com/BakerYeastNA/eng/PDFs/LBU+PDF+FILES/1_11PREF.PDF. So, for those who have been wondering what "TTA" is, they will now know. Sometimes an article found using the WaybackMachine goes into the ethers again, so one should go back to the WaybackMachine and try again.

Peter

Peter, Toby, scpizza, and Kelley,

I didn’t know what TTA was before.  I guess when I was just measuring the pH of my natural starter doughs, that really didn’t tell me enough what was going on inside the doughs with just measuring pH levels.  I wonder if I wanted to help Kelley with his experiment if I could use the NaOH I have at home for making soft pretzels in some way to help this experiment along?  I got some NaOH from a pretzel maker at market when I was on the pretzel thread for pizza.

How does one measure the ph of sourdough
http://www.nyx.net/~dgreenw/howdoesonemeasurethephofso.html

In this article, if anyone is interested it explains sourdough.

http://www.faqs.org/faqs/food/sourdough/faq/section-1.html

I would be interested in helping Kelley with his starter experiment if I could.  I already have a pH meter and NaOH, if someone could guide me how to use them.

Norma

[scpizza]

How does one measure the ph of sourdough
http://www.nyx.net/~dgreenw/howdoesonemeasurethephofso.html
...
I would be interested in helping Kelley with his starter experiment if I could.  I already have a pH meter and NaOH, if someone could guide me how to use them.

That article gives good high level directions on how to determine TTA.  To elaborate on them:

1) Identify the exact concentration of your NaOH and dilute as necessary to create a 0.1N solution.
2) Acquire a burette of proper size, stirrer (magnetic works well), and lab stand to hold the burette.
3) Prepare the sample by thoroughly dissolving the weighed starter and water in a beaker.
4) Stick the pH meter probe and stirrer magnet into the beaker.  Put the beaker under the burette and on top of the stirrer so its constantly mixing.
5) Start adding the NaOH solution, plotting volume added vs. pH value as you go.  The volume of titrant added at the inflection point of that curve is your TTA.  Note: you will need to add a lot initially to get the pH to budge, but as you approach the TTA value the amount needed will shrink to a single drop. 

You'll need to do repeated titrations of a batch of starter at fixed intervals of time (e.g. every 15 or 30 minutes) so you can draw a TTA vs. time curve.  The slope of this curve at any point is a proxy for overall starter metabolism at that time.

Of course to get meaningful results, you'll need to do this under specific, controlled, consistent conditions of starter composition, starting state, and temperature.

[scpizza]

A good technical explanation of why pH is only weakly correlated to acid production in sourdough can be found in Functional Additives for Bakery Foods, Clyde E. Stauffer, p. 216.

http://books.google.com/books?id=ckfdE5sRbqAC&lpg=PP1&pg=PA216#v=onepage&q&f=false

[scpizza]

I'm sorry that no one has picked up the ball with this.  I think it's an interesting and useful undertaking.

I did a series of titrations below to play with it.  I found:
- The equivalency point for my starter was 8.0-8.2 making me wonder why the literature uses 6.6 as an endpoint
- My TTA values are approximate as my titrant wasn't perfectly mixed up.
- I didn't see a large spread between early TTA values and late ones though admittedly I refreshed the starter at 1:1:1

[StrayBullet]

I'm sorry that no one has picked up the ball with this.  I think it's an interesting and useful undertaking.

I'm glad you took it up!  I was in Nuclear Engineering 20 years ago in the Navy and I sure as hell wasn't about to do this with my doughs

Mark

[scpizza]

Below are the results from a full titration trial of a natural starter I did.

Conditions were 15.0g starter at 25C dissolved in 100.0g distilled water.  Starter was refreshed at 1:1:1 from a ~12 hour old starter.  Flour was Caputo Pizzeria.  Samples were taken approximately every 20 minutes and agitated by stir bar at 1000rpm for 5 minutes to break up gluten blobs as much as possible prior to titration.

Titrations were done with well-calibrated lab gear, standardized NaOH, and good lab practices, but I did see more variability in the data than I expected.  I had trouble getting stable endpoints, experiencing persistent downward drift in pH.

Nevertheless, there is a reasonably clear result showing an end to the primary phase of yeast activity at around 6 hours.  According to Lallemand, this point should be somewhat past the point of maximum yeast activity, which I would speculate would be around 4-5 hours.

For those who would look to floatation to indicate starter readiness, this particular starter floated at all points between 2 – 7 hours, so floatation would not be a very good indicator.