Sourdough Rise Data
Sourdough Fermentation Data
We all know that all other factors being the same, the more sourdough starter in the dough, the faster the rise during bulk fermentation.
Since your starter may resemble dough (60 to 70% hydration), others may use a liquid starter (200%+ hydration), and mine is the consistency of mashed potatoes (100% hydration), The percent of flour used in the starter (as percent of total flour) is unaffected by hydration. This is a concept I’ve seen in print somewhere and one I find very useful.
The goal in this experiment was to determine the fermentation rates at various percentages of flour in the starter to total flour. Another way to view it would be the time required for the dough to double at various percentages of flour in the starter to total flour.
Using the same totals for ingredients (85g flour, 57g water and 2g of salt), 4 doughs were made.
The sourdough starters used in the doughs contained 10%, 20%, 30% and 40% of the flour (9g, 17g, 26g, and 34g). For example, the total flour in the dough was 57g. if the % total flour in the stater was 20%, then 17g would be in the starter. For my 100% hydrated starters, the total starter weight was 34g. Each dough weighed 114g.
These were kneaded 20 strokes, placed in straight sided glasses and were stretched and folded 3times every 20 minutes. The dough levels were measured at the same time every 20 minutes at first, then every 30 minutes until the volumes had doubled. The glasses were marked with the percentage of total flour in the dough’s starter and photos taken prior to measurements. The times for the dough are shown in photos taken. Only 2 are shown here.
The data are shown in the table below.
The curves for each dough show growth of dough vs time. The 40% dough (40% total flour in the starter) was the fastest growing dough and doubled in 120 minutes and the dough with 10% of the flour in its starter took 270 minutes to double.
As the percent flour prefermented increased, so did the color in the bread, the taste, and the openness of the crumb. Proof times took 45 minutes to 90 minutes depend on the percent flour in the starter. I made a deli rye tonight with 20% of the total flour in the starter. The rye conformed to the tables and graphs.
There’s nothing new here, just data specific to my dough and a guide for making future sourdough breads.
Comments
Thanks for doing this "Frequent". I want to try this analysis on some of my recipes. There is a school of thought that the amount of fermentation after proof is the key to flavor and texture. Can I fairly deduce that your experiment shows that the percentage of pre-fermented flour might also have an important effect (aside from speed of rise)?
GregS
what was temperature during this time? in a proofer or ambient? the temperature would affect rate of expansion too, wouldn't it?
Leslie
I think the amount of pre-fermented flour affects rise time which affects flavor, crust color and crumb. I'd like to understand more about your comment about fermentation after proofing.
Temperatures were measured occasionally, and remained at 71 to 72 F throughout the test. I did move the doughs into a closet that runs a few degrees warmer however, the dough was insulated by the fermentation bubbles enough at that time that the temperatures remained fairly constant. The rate of expansion or rise rate is what the amount of starter is affecting.
I'm guessing you could use Ganzel's reproduction data of yeast at various temperatures to extrapolate the times to double for various temperatures and pre-fermented flour amounts. I think Doc.Dough did some spreadsheets on this too.
Well done and Happy baking
I looked up some of Ganzel's work and have a whopper of a headache for my efforts. :) I also read over Doc Dough's work. Don't know much about that science. I relate more to rates of reactions which I thought might be similar.
I'll have to dig into that some more. Thanks for the comments.
FF
Ganzel;s data where you put in the temperature and it tells you how long it will take for the LAB and Yeast to double in numbers. Very cool but if it showed double in volume instead then it would be even more cool.
happy baking
The formulae I saw in Doc.Dough's posts called for temperature in Fahrenheit which surprised me as most rate equations are in absolute temperature. Like I said, I had a headache at the time. :)