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Help me understand proofing.

Anonymous baker's picture
Anonymous baker (not verified)

Help me understand proofing.

OK, so, this has been on my mind for awhile now, but I simply do not understand the process of bulk fermentation. I've been making the Norwich Sourdough for quite awhile now, and have followed the instructions blindly to what has been written down. However I would like to know why during the bulk fermentation process the folds are at 50 and 100 minutes. What sort of texture and consistency should I be looking for? I understand that bread will proof faster, or slower, depending on the temperature of the room and would like to learn how to adjust my bulk rising time for that.

I apologize if this seems like a silly question, but my rather excited sourdough filled brain really, really wants to understand the science of these things. As a side note, I have been Googling this question for the past few days and am not sure if I am looking at the answers that are correct or not. Some resources would be wonderful as well. Thank you in advance for everyone's help.

jcope's picture
jcope

The adjustments I use, based on the Gaenzle study of yeast and lactobacillus activity is below.  I use 65F as my basis.  So if that is 100% of normal time to ferment, the adjustments are:

40F992%
45F613%
50F381%
55F239%
60F152%
65F100%
70F69%
75F50%

At 75F it takes about half as long.  At ~56F it takes about twice as long.  At ~49F it takes about 4 times as long.  Around 42F it takes 8 times as long.  At refrigerator temperatures it takes 11 or 12 times as long.

This is assuming you don't vary other things such as water, salt content or the amount of starter you use, percentage-wise.  (The only other variable I've tried to test is varying starter percentage.  As that goes down, fermentation time increases at a rate I'm not sure about.  I have decreased my starter percentage from 55% to 35% and measured about 20% increase in time to ferment.)

Between the mid-50s and maybe 80F the yeast and lactobacillus are equally active, meaning the flavor will be pretty mild.  Outside that range, the lactobacillus dominates, and the bread will be more sour.  Particularly above ~80F.  The bacteria continue to increase in activity as the temperature increases above that, while the yeast start to give up.

I distinguish proofing from fermentation.  Bulk fermentation, as I understand it, is the long process right after mixing, during which you allow the yeast and bacteria to multiply and permeate the dough and the flavor develops.  After fermentation, I shape, and then set aside for the final proof, which takes around 2 hours, with some gut-feeling adjustment for temperature.

Others on the site have more experience and expertise and can correct me where I'm wrong.  I'm still climbing the learning curve.

Another, far more developed, reference is here:  http://www.thefreshloaf.com/node/5381/sourdough-rise-time-table.

As far as stretch/fold goes, I stumbled onto the idea that with longer fermentation times (either due to cool temperatures or less starter) it seems not to be necessary.  It also doesn't hurt.   I think at 6 hours or longer, you could skip it.  I think.  At shorter times, the gluten will need some help, so I'd try to fit 4 or 5 stretch/folds in.

This has been a fascinating process for me, so I'm always looking for ways to learn more about it.  I would expect that mastery is going to require years, but in the meantime I'll have some good bread to eat and a pretty constant state of mess in the kitchen.

Mini Oven's picture
Mini Oven

Bulk fermentation is the (act of waiting) measure of time for gas to collect in the dough matrix.

 "Baking 911"  site has been changed to "Crafty Baking"

https://www.craftybaking.com/how-baking-works/yeast

lazybaker's picture
lazybaker

The folds help re-distribute the yeast, so that they could find more food. I find that if I fold and let it rise for the second time, I get fluffier airier texture.

dabrownman's picture
dabrownman

showing the reproductive rates of 2 SF LAB and a yeast for a SD culture and how they each relate to temperature changes.

Reproduction Rates of LAB and YeastL/Y 
T(°F)T (°C)L. SF IL. SF IIYeastRatio
     36        20.0190.0160.0053.787
     39        40.0260.0220.0083.147
     43        60.0350.0310.0132.634
     46        80.0470.0430.0212.222
     61      160.1440.1500.1141.265
     64      180.1870.1980.1631.145
     68      200.2390.2590.2251.064
     72      220.3010.3320.2951.021
     75      240.3740.4160.3651.024
     79      260.4530.5080.4141.094
     82      280.5350.5980.4171.284
     86      300.6090.6720.3461.760
     90      320.6580.7060.2023.255
     93      340.6570.6710.05013.127
dobie's picture
dobie

Hi dabrownman,

I was wondering, is there any flavor profile differences between L SF I and L SF II?

Thanks,

dobie

dabrownman's picture
dabrownman

SF LAB strains just shows that they aren't exactly equal, but close, when it comes to reproduction rates at different temperatures.  Since we don't know exactly what LAB we have in our cultures, we don't know exactly how this data might reflect accurately for it.  I just use it as a general rule of thumb and it seems to be close enough for my SD culture.

dobie's picture
dobie

dabrownman,

Thanks for the response, I was just curious.

I hope this question is appropriate for this thread.

If attempting to control sour/less sour flavor in a sourdough bread, the LAB to Yeast ratio favors less sour (with a sweet spot) between 61 and 82F. More sour is favored cooler and warmer, greatest at 36 and 93F. Do I have that wired up right?

Any idea what happens cooler than 36 and warmer than 93F?

Thanks - dobie

mickeyk44's picture
mickeyk44

IT GETS MORE SOUR because the yeast grows slower

drogon's picture
drogon

worth 1000 words (or numbers), etc.

This is from this site: http://hans.fugal.net/blog/2006/07/03/sourdough-critter-growth-rates/

In essence, the LABs always produce more of their "stuff" than the yeast does, and at either ends of the scale, production is very low. (So my refrigerated starter is almost dormant at 6C) Peak yeasty temperature is about 27C (80F) and peak LAB temperature is about 33C (91F) but at that temperature the yeast activity is so diminished it's not adding much.

I like to try to keep my doughs/starters somewhere between 20 and 24C (68-75F) and I seem to be lucky in the way my kitchen works for that. My breads have just a hint of sourness in them.

-Gordon

alfanso's picture
alfanso

http://forums.egullet.org/topic/82234-demo-proving-bread/

comment by JACKAL10

31 January 2006 05:38PM

dabrownman's picture
dabrownman

Alan.  Nice link.

dobie's picture
dobie

Thank you Gordon for the graph. Exactly what I needed.

Thank you alfanso for the link about proving on egullet. It'll take me a bit to read thru it all but from what I've read so far, it also seems to be just what I need on the subject.

I appreciate your efforts - dobie