January 9, 2012 - 4:45pm
Converting to stiffer starter - no bubbles, help
Hello,
I've been maintaining my 100% hydration starter for over a year and this past week decided to convert a bit into a stiffer starter (for a Bertinet recipe).
The first evening I took 50g of my 100% hydrated starter, mixed it with 50g bottled water and 100g AP flour. The next day I could see some bubbling activity so I discarded and fed it the same ratio of water and flour.
I've been doing this for 5 days now. The starter has risen, but there are no bubbles. I think I may be doing something wrong. I'd appreciate any advice, thank you!
Mira
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You are making small batches of 60% hydration bread dough with no salt.
That is almost tasteless bagel dough.
I would not expect bubbles.
Mira,
Doc.Dough is essentially right, continue doing what you are doing and you shouldn't expect bubbles at that hydration.
However, based on your feed schedule it appears you are building a 50% hydration starter (not 60% hydration as Doc suggested), which will be very firm and dry, so you will see very little visual activity. The theory is that the less water in a starter, the slower the yeast & bacteria will distribute and the slower it will grow.
If you bump your new starter up to 60% hydration I think you will see more signs of life.
Cranbo - thanks for the catch. I didn't run the series to convergence, just the first iteration. Fifty percent hydration is so stiff I am pretty sure I can't mix it in any machine I own. But it should ship well to somebody who needs a new start - and it would hardly be sticky when it got there. Since it is so dry it should be slow relative to a 100% or higher hydration and thus the feeding schedule is probably less often - perhaps 1:10:10 per 24 hrs at an average room temperature of 22°C (daytime + nighttime)/2. I would still expect it to expand to between double and triple the post-mix volume - sort of like any good loaf. Another option is to go with a 1:4:4 and add a pinch of salt to slow it down (but the amount of salt is fairly critical and depends on the real temperature).
And not a problem.
I make my kaiser rolls at 50% hydration and they do ferment, rise and they do have a nice crumb. Bubbles may be smaller than those in a 100% hydration but they are there. If they were not there, there would be no rise. :)
The trick with the starter is to let it double or expand fully and collapse before removing a portion from the middle to feed. Do not feed it too soon. With each feeding, the time it takes to peak will shorten until it stabilizes and settles into a predictable time span for whatever temperature you have.
With AP you are probably right. There is a table of approximate water absorption capacities for various flours but I can't find it right now. I wanted to see what the effect would be of substituting AP for high gluten flour in a 55% bagel dough. It might take only a 10% difference in water absorption to make them have the same viscosity.
As the sugar in the flour gets consumed there is water produced as a byproduct which (I think) contributes to the soft center of a stiff ball of starter. And of course the CO2 inflation makes the dough less dense as well so it would not exhibit the same modulus in either tension or shear.
I was thinking this AM about the appearance of blisters on the surface of some products and not on others and went back to look at photos to see where it was most noticeable. It was the low hydration doughs where I found it to be most obvious. On high hydration doughs the bubbles can penetrate the bulk of the dough because of the increased compressibility and the balancing of surface stresses suppresses the blister.
Hey why not reverse your thoughts... what do you get when you combine CO2 and H2O? ...club soda, hmmm, a product of fermentation?
Water is produced inside a stiff ball of starter?
I think water also just migrates from the outside to the inside as yeast cells die off passing their water on to absorbing yeast buds. The innermost cells in the firm starter being protected most from drying out. Eventually the whole thing just dries up if unattended. (But dry does not mean death or the end of life. ...!spores!...)
So what kind of moisture are we talking about? Should we have a discussion on the thickness or strength of yeast cell walls?
Hey, do you suppose that yeast grown in a liquid starter may have weaker cell walls than say those growing in a firm starter? Osmotic pressure and all that jazz? Interesting idea, never thought about it before. Do you suppose that an apparent decline in yeast activity when making a firm starter from a more liquid one might mean the death to many yeast cells? Lots of crazy thoughts. Do popped yeast cells release thiol compounds or cause an increase in said compounds? Does the yeast cell material provide or spur growth or send out chemical signals forming stronger thicker walled yeast cells to form?
Think there might be a paper on it?
Mini -
When someone asks for a starter sample, I take a small amount of my 100% starter and knead it with enough flour to make it just barely pliable (about like a piece of bubble gum before you put it in your mouth) then bury it in a sandwich bag containing about 1/2 cup of flour, burp the air out and seal it. The dough ball is usually about 3/4" to 1" in dia at the beginning, but if I am traveling it will grow in size and become much softer over a day or two. I just keep tossing it to keep flour on the outside so that it doesn't stick to the bag (often unsuccessfully).
Try it at home and after 48 hrs chill it in to near freezing the refrigerator so that it is again stiff and section it so that you can look at the structure. You will find that not only are there bubbles in the center, but there is also a fair amount of liquid - at least it is not as stiff as the original piece of bubble gum. Where did the liquid come from
I think it comes from glycolysis:
To extract chemical energy from glucose, the glucose molecule must be split up into two molecules of pyruvate. This process also generates two molecules of ATP as an immediate energy yield and two molecules of NADH by the reaction:
C6H12O6 + 2 ADP + 2 Pi + 2 NAD+ → 2 CH3COCOO− + 2 ATP + 2 NADH + 2 H2O + 2H+
Thus you get 2 moles of water for every mole of glucose consumed. More amylase activity produces more sugars, and more sugars lead to more water byproduct. This really deserves a quantitative assessment which I have not done but my observation is that a dough ball gets sticky without external help.
Now I have to add the disclaimer that I know almost nothing about microbiology so I could be completely off base - and would be happy to be educated by somebody with credentials.
Thank you for sharing all of your thoughts! I'm still a newby at breadmaking and I need a 50% hydration starter for a particular recipe(s). I don't want to add salt to this starter. My 100% hydration starter is still humming along in case I screw this one up.
I will take Mini's suggestion and otherwise continue what I am doing.
Thanks again!
Mira