Open Crumb and Crust

An “open crumb” in a sourdough loaf is the Holy Grail for most sourdough bakers.  A light, open crumb is evidence of a beautifully fermented, shaped and baked loaf.  The crumb tells the story of the loaf.  

However, an open crumb is the accumulation of all of the prior steps, so achieving an open crumb is a complex interplay of all the variables in the recipe and process.  This is what makes the quest for open crumb so challenging, but also so rewarding. 

The vast majority of what you see in the crumb of a sourdough loaf is created in bulk fermentation.  All of the other variables have small, but noticeable impacts.  But as I say in many of my videos, “bulk fermentation makes the bread!”

To achieve a desirable open crumb, first focus on mastering bulk fermentation, then move on to the other variables to fine-tune your approach.   

Higher hydration will produce a more open crumb. But be aware that at every type of flour has a maximum saturation point and can only handle so much water. Here are some general guidelines on hydration:

• 65-70% Low Hydration. More closed crumb.
• 70-75% Moderate Hydration: Opening crumb.
• 75-80% High Hydration (e.g., Tartine style) Open crumb.
• 80-90% Very high hydration. Requires higher protein flour or whole grains.
• 90%+ Super high hydration. Pain de crystal, ciabatta, et al.

Underproofing or overproofing your dough can cause it to be flat.  First determine if your loaf is properly proofed.  Assuming it is not under or overproofed, the way to build dough height is to leverage all of the element of the “gluten structure chain.”

1. Flour Protein Level – use higher protein flour
2. Mixing Methods – develop gluten earlier in the process with mixing methods such as Rubaud method.
3. Bulk Fermentation Handling – create more layers in the dough in bulk fermentation with coil folding, lamination and/or stretch and folds.
4. Pre-shaping – Do strong pre-shaping of the dough
5. Final Shaping – Do strong final shaping of the dough with folding, rolling and stitching, for example.

There are many causes of dense crumb including:

• Whole grain or low gluten flours such as rye, spelt and einkorn.
• Low hydration percentage (70% or lower)
• Underproofing or Overproofing
• Excessive handling of the dough, especially late in the process
• Very tight pre and/or final shaping
• Baking at low oven temperatures

There is a process known as “curing” where after your loaf is fully baked, leave it on an oven rack in the oven as the oven cools down for approximately 20 or 30 minutes.  This will make the crust crispier and will continue to remove some of the moisture from the loaf.

Not everyone desires an open crumb. 

There are many ways to get a more closed crumb: 

1) use a lower protein flour, like all-purpose, 2) push the bulk fermentation time / rise, longer, 3) add a higher percentage of whole wheat flour, 4) de-gas the loaf when shaping.

Under-proofing a loaf will also create a more closed crumb but that is undesirable.  

Check out the video “When is Bulk Fermentation Done, Episode 4: Overproofing Problems,” for great examples of what happens to the crumb as you push the fermentation past peak openness.  You can start with the chapter “Comparison of Loaves,” to see the final results. 

In the video, “Bulk Fermentation – Mastering Temperature and Time,” I bake 4 loaves with different bulk fermentation temperatures and times.  I cut off the bulk fermentation rise at the same point (25% rise) and compared the loaves.  The crumb was virtually identical.  Check out this video clip for the summary of the experiment.  Note, these are unshaped loaves.  This is bulk fermented dough with no shaping to isolate the impact on the crumb. 

The crust of a sourdough loaf impacts the flavor, texture and appearance of the loaf.  Typical crusts styles include: 

1. Thick, artisan crust
2. Soft, sandwich style

The thick “artisan” style crust is typically what you would think of when you envision an artisan loaf in a rustic bakery.  A thick, dark, caramelized crust with a pronounced ear and beautiful open bloom on the scoring with gluten strands visible across the bloom.  This is an example of classic “artisan” style loaf. 

The soft, “sandwich-style” crust is usually lighter in color, thinner and softer than the artisan-style crust. 

Many photos of artisan breads show a tall “ear” on the top of the loaf.  It looks like a dorsal fin down the spine of the loaf.  Is an “ear” desirable? 

Does my loaf need to have an ear?  How do you create one? 

There is great debate on this topic and some people believe the ear is simply for looks and is not desirable.  In reality, the ear is often and indication of perfect fermentation, good ovenspring, tall loaf structure and many other aspects of a “good” loaf.  The ear is not really an objective in itself, but rather in indication that everything else worked.  

For this reason, when people ask, “How do I create an ear?” it is complicated because it is the accumulation of many, many prior steps.  

In my experience, producing an ear is primarily the result of perfect fermentation, which is probably 80% responsible for the creation of an ear.  A loaf needs to be shaped well, have good structure, and needs to be baked at the proper temperature to produce an ear.  

Some people believe that scoring and the angle of the blade significantly impact the creation of an ear.  I have not found this to be the case.  The ear is essentially created by what happens on the inside of the loaf, more than the scoring.  A simple slash with a sharp blade will produce an ear if the loaf is ready to spring on the inside for the reasons described above. 

If you’re not getting an ear, your scoring is probably the last thing to change.  Ears are primarily dependent upon what happens on the inside of the loaf.  

Many of my videos in the “When is Bulk Fermentation Done” series demonstrate loaves with beautiful ears that are created with no pre-shaping, no final shaping and a simple scoring method.  Check these out. 

There are a few techniques for getting a softer crust: 

1. Add some oil or fat to your recipe
2. Brush butter on your loaf after it comes out of the oven
3. Put your loaf in a plastic bag overnight
4. Cool your loaf on a cutting board instead of a cooling rack for a softer bottom crust. 
5. Sometimes longer fermentation will produce a more tender crust and crumb.