Experiment - Effect of retarding 0 days, 1, 2 and 3. [Picture included]
I am trying to create a white sourdough with a light, crispy crust and a fluffy crumb. I attended SFBI last week for their Artisan Breads II - Mastering Sourdough class, and learned the effects of refrigerating dough at different stages of the process. When you refrigerate shaped loaves, it is referred to as retarding. In this part of the process, the pH will continue to decrease (more acidic), and the protein will slowly break down with the chemical activity over time. We were instructed to retard for 24 hours, but I tried an experiment this week with retarding dough for longer.
I used King Arthur All Purpose Flour and Whole Wheat Flour, and a stiff sourdough starter fed twice after a 2 week stint in the fridge. I shaped 4 loaves, baked one after a 1.5 hour proof, 1 after a 1 day retard, 1 after a 2 day retard, and 1 after a 3 day retard. I found that the best results can from the 2 and 3 day retard, with a better flavor on the 3 day retard. You can see the longer retard as you move up from the bottom in the picture.
| Baker's % | Kg | |
| Starter | ||
| Flour | 95.00% | 0.269 |
| Whole Wheat Flour | 5.00% | 0.014 |
| Water | 65.00% | 0.184 |
| Starter | 50.00% | 0.142 |
| Final Dough | ||
| Flour | 100.00% | 1.361 |
| Water | 68.00% | 1.081 |
| Salt | 2.50% | 0.034 |
| Levain | 50.00% | 0.609 |
| Total Formula | ||
| Flour | 95.83% | 1.630 |
| Whole Wheat Flour | 4.17% | 0.071 |
| Water | 74.40% | 1.265 |
| Salt | 2.00% | 0.034 |
Great experiment! I see the volume decreases and the holes get larger the longer the loaf is retarded. Actually, I am quite suprised your 2 and 3 day retarded loaves held up so well. I would have expected them to be flatter and with even more of those big holes.
I have to say I am most impressed with the way you have stacked those loaves at such zany angles. It looks like something out of a Dr. Seuss book! :)
Regards,
Syd
I guess that different flours will behave differently in the fridge, supposedly the higher-gluten ones will benefit more from a longer retardation, while on the contrary weaker flours will bear only shorter rests in the cold.
Method:
Mix: Hand
Knead: 4 minutes
Dough Temperature: 80 degress
Bulk Fermentation: 3 hours with folds at 45 minute intervals (total of 3)
Preshape: Boules
Rest: 10 Minute
Final Shape: Boules
Baking Temperature: 450 degrees
Each of the retarded loaves were rested for 45 minutes out of the fridge just before baking, and I used the same temperature. The bread got progressively more complex in flavor as they were retarded longer. I am enjoying the 3 day right now as a peanut butter and banana sandwich!
And I agree with Syd, the picture is straight out of Dr. Seuss.
One thing I note is that the larger holes in the bread retarded 2 -3 days point to what I think is probably the collapse of the cell structure of the crumb. It's brought about by the protein degradation you learned about at SFBI. In this case, however, the protein that's degraded is the very gluten which provides the crumb structure to your bread.
Jeffrey Hamelman counsels never to retard beyond 24 hours, and aside from the change in flavor he notes, is that very extended retarding will result in a loss of gluten structure, so that you end up with bread with holes that mice could nest in.
Thanks for sharing!
Larry
Did you have any instrumentation on the dough temperature during the retard phase? And what starter are you using?
If the temp is low enough, the activity of the LAB and the yeast almost stop and other chemical processes probably dominate the activity. I believe that the retard temperature used in most commercial bakeries is somewhere between 40°F and 55°F because that is where the sweet spot is between capital investment in cooler space and production timing (typically cycles of 4, 6, 8, or 12 and 24 hrs).
If you look at the work of Gänzle et al, there are two temperatures at which the ratio of LAB growth rate to yeast growth rate are maximized. One is at about 10°C and the other is where the yeast stops growing at high temperature (~36°C). All of the evidence says that the 36°C point is not of interest. However, if you ferment (retard) at 10°C for 24 hrs you get the same total LAB population that you would get if you fermented at 24°C for 4 hrs, but you have only about 64% of the yeast population (and thus low loaf volume). If you extend the retard time to 44 hrs (all other things being equal - which they are not), you might wind up with 6.8x the LAB population and the same yeast population that you would have after 4 hrs of 24°C fermentation. The important element is probably the availability of glucose and maltose to support the longer fermentation. We know that the yeast have enough food to reach the end point at 24°C but it is not clear that the LAB have enough to last for the full 44 hrs without depleting all of the maltose in the dough (though the LAB will switch over to glucose when maltose is fully depleted at which point they compete with the yeast and just hasten the race to starvation). Thus at 10°C, with 15% of the flour in the preferment, the optimal retardation time should be somewhere between 24 and 44 hrs. If the retard is at a lower temperature, the processes goes slower; if you use a higher fraction of prefermented flour it will take less time.
I suspect that other cultures (other than SF) have somewhat different growth rate vs temperature curves for the constituent species of LAB and yeast so that there is a different optimal temperatue and time for retarding dough made with them. If anyone has or can point to a source for reliable growth rate vs temperature data on other cultures, I would be interested in modeling the result to see how much different the results might be.
Doc
So TerryTB, did you travel 3000 miles to attend SFBI ?? (I hve also attended that class)
Did you look at other classes on the East Coast ??
I actually live in Nashville, TN now, and I flew out there as a vacation to take Artisan II at SFBI. I loved it!
I did not think to take temperatures of the dough while retarding, but my refrigerator hovers around 40 degrees. I wasn't sure what to expect at this low of a temperature, as it is my understanding that yeast will begin dying at about 43 degrees.