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Sourdough air pocket distribution problem

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redif2003's picture
redif2003

Sourdough air pocket distribution problem

Dear skilled bakers of TFL,

I have been baking bread for around a year now (mainly flat bread). Recently, I have developed an interest in sourdough bread; and in the past month, I have attempted Tartine country bread a couple of times (4 times actually). My most recent bake was last night, and given it was a weekday bake, it turned out alright and tasted fantastic. However, I yet have a very long way to master my scoring skills.

The bread had beatiful irregular air pockets on the sides of the loaf, however, when I sliced the middle of the boule, there were not too many. I am wondering if anyone could tell me why I am not getting too many air pockets in the middle section of my boule.

Side cuts (abundant irregular gelatenized holes)

 

Middle cut (some pockets but not too many)

 

 I am using a sanfransisco sourdough starter that I purchased online and activated. The levain was made on Monday night, fed on Tuesday morning. Mixing happened Tuesday night and I let the dough bulk ferment in a steel bowl surrounded by ice water (the dough bowl was put in a bigger bowl which had ice cubes in it) .Stretched and folded 3 times. By Wednesday mirning the ice was melted and dough was still cold. Boul was Shaped Wednesday evening and proofed for about 2 hrs. Baked on a pre-heated stone and covered with a moistened tin foil cap.

Thank you

 

 

Wild-Yeast's picture
Wild-Yeast

I'll venture a guess the uneven alveoli distribution is predicated upon uneven fermentation within the dough. 

Try mixing the water into the levain to thin it before adding the flour in the recipe - it will be more evenly distributed this way.

The stainless steel mixing bowl in ice water may have had an effect due to the dough next to the bowl being near freezing while the interior was at a warmer more fermentive temperature. Stretch and folds should have distributed the temperature effect but then maybe not[?]...,

Wild-Yeast 

redif2003's picture
redif2003

Thank you Wild yeast for your response,

I highly doubt that un-even fermentation is the cause since I did mix water into the levain before adding it to the flour. As for the ice water, chances are you might be right, however, I did stretch & fold the dough a good bit in the morning before pitting it in the fridge. Also shaping involved some light turning and mixing of the dough and as you mentioned, it should have distributed the un-fermented dough.

Now that I think, my foil pan is a bit short (in height) and it made contact with the top of my bread. Could it be that the extra weight of foil pan prevented the middle section from developing pockets?

Davo's picture
Davo

I've got a bit of a theory which of course could be wrong, but I often notice that the ends of my (oval) loaves (somewhere between a boule and a batard) have bigger holes than the middle, too. I do largish loaves (usually around 920 g each). I reckon that what happens is that the bubbles expand most quickly on the outside of the loaf, where there is heat to cause this - basically the bubbles that are made in the bread are the little gas balloons that are getting blown up by the heat, like a plastic bottle in the sun. A lot of people put oven spring down to a "last minute burst of yeast activity", but while I would imagine this has some input, I reckon it's more just the expansion of existing bubbles (that after all have been forming for hours at optimal rate if you look at temp/activity graphs for yeasts) under the influence of temperature.

Now, after about 10-15 mins, I'm guessing the crust and those bigger bubbles under it in the outer parts of the loaf might start to "set" a little, which will tend to prevent further expansion from the middle part of the loaf as that heats up. End result - biggish holes in outer parts, not so big in inner parts. Also, if you watch a SD loaf in the first 10 minutes in the oven you will notice it sag before springing back up. This is basically the skin going elastic before the temperature expands those bubbles. I'm guessing the sag factor (which will tend to pull the skin down in the middle part of the loaf mroe than on the edges) also provides some resistance to rise in the middle part of the loaf, and may explain why you don' get bigger bubbles (unless you get the flying top type bubbles which I have another theory on!) just under the upper skin - which should otherwise also expand rapidly based on the temperature effect like the dough in the outer edges of the loaf does.

When you bake smaller loaves, I reckon you see less of this effect, and I reckon it's because more of the inner part of the loaf gets to expand by heat before the crust sets, and there's less "sagging skin tension" compressing the middle part of the loaf during the critical rise period.

Matybe bake smaller loaves, or put some deepish slashes through the middle part of the upper skin of the loaf before it goes in, and maybe keep it steamy for as long as possible...

Another possibility is that there is some inhibition of fermentation in the middle of a larger loaf - I'd be really interested to cut a proved ripe loaf open before baking just to see if there was a variation in holes sizes between edges and middle before baking, but that would waste a loaf (well I suppose you could still bake the pieces, but they'd be a bit of a mess)! Maybe an experiment for you if you are game!

redif2003's picture
redif2003

Your theory explaination was very comprehensive and easy to understand. I agree with you on the weight effect, however, I am wondering whether that is the case with professionally baked breads too or not (probably it isn't).

I kind of suspected that my scoring pattern had some effects on the final results. Maybe a deeper score at the middle of the skin helps with air pocked development in the middle section of the bread. I'll try it next time.

CB85's picture
CB85

This happens to me all the time too. I haven't figured out why yet, although I've experimented with a couple different factors. It really frustrates me!

Wild-Yeast's picture
Wild-Yeast

How do you form and shape the bread prior to proofing?...,

Wild-Yeast

redif2003's picture
redif2003

For shaping, I let the dough (which has gone through bulk fermentation and has been sitting in the fridge for 8-9 hours) come to room temperature, divide it and pre-shape it. I let it rest for 30 minutes, then perform the standard boule shaping technique similar to what is shown in this video:

http://www.youtube.com/watch?v=3CQsBmieDS8

Then I let it proof in a pre-dusted plastic bowl (I dont have bannetons yet) for about 90 minutes before baking. 

My plastic bowls have steep walls, can this be a reason why the pockets are not forming in the middle?

Thank you

 

Wild-Yeast's picture
Wild-Yeast

That's more than enough distribution of the dough in forming.  

I now wonder how active your starter is.  If it is very active in its leavening ability - 120 minutes might be too long. My hypothesis here is that the center is overproofed, collapsing under its own weight while the thinner ends remain inflated. Reducing the proofing time might prove interesting - pun intended. Try proofing for 90 minutes or so...,

One other point; are you placing the plastic banneton into a plastic bag to prevent it from drying out? I don't think the vertical sides will have much effect on the proofing dough.

Wild-Yeast

redif2003's picture
redif2003

I am not very experienced with wild yeast starters but I think my starter is pretty active. I usually let it sit outside and feed it twice before baking (feed, discard, feed). it takes a good 18 hrs for it to reach its peak where it grows to 2.5 times its original size. 

Overproofing might very well be a reason. In weekdays, I don't get to practice the standard tartine routine because of time limitations, so I get creative with other methods (like ice container method), which in turn I pay with an overproofed bread.  

And yes, I do cover my banettons with plastic to avoid drying. I guess in my case, I'll need lots more of trial end error to make the perfect loaf.