Crumb is a term that bakers use to define the inside of the bread. By looking at the way the cell structure of the crumb is formed, and the shape and size and color of the cells, a baker can analyze the hydration, flour types, and yeast amounts as well as how the dough was mixed and shaped. By looking at the shape and crust a baker can see how the bread was baked, flour types, fermentation balance, and moulding techniques.

Commercial pullman loaves, so named because their shape is similar to a passenger train car, typically have tight crumb. You can see the machine moulding technique in the defined swirl in the middle of the slice. Commercial loaves are made with a lot of yeast, "strong" flour and low hydration, qualities that are not associated with hand crafted bread. Hand crafted pullman loaves have a more irregular shape. You can still see the swirling pattern in the middle, but it is less defined because the dough is handled and shaped gently. This example has whole wheat flour and walnuts, which accounts for the color difference. Notice the larger, more irregular hole structure due to the long fermentation time, higher hydration levels and care in handling.
This commercial baguette has a flat, regular shape and small hole structure due to the same ingredients and processing as the commercial pullman loaf. Notice also that the crust is very thin and lightly browned which makes it chewy instead of having the traditional crunchy texture of a baguette crust. This hand crafted baguette has a fuller, rounder shape and a thick brown crust, signifying that there was steam in the oven and the dough was allowed a good amount of fermentation and baking time. The large holes are also caused by a high hydration as described below. The warm yellow color shows that the flour was not overprocessed or bleached. These are visual signs that the bread will have a full flavor,

The amount of water in a dough defines the type of bread it will make.The next four examples show how the difference in hydration changes the size of the hole structure and creates an open crumb. Although differences in shaping and baking techniques account for the differences in appearance and crust , the basic ingredients of flour , water, salt, and yeast are always the same, so it is the hydration that gives the dough its defining quality. A dough with a 70% hydration that was shaped and baked like a bagel would never be a bagel.

Bagels traditional have a dense tight crumb creating a chewy texture. They are made with the same ingredients as crusty loaves of artisan bread but a different baking process and the low hydration give bagels their distinct texture and appearance.


As hydration increases, the hole structure of the crumb gets larger and more irregular. Artisan breads generally have at least a 60% hydration level. You will notice that with the lower hydrations it is easier to see the swirl formed from the shaping process.


This example of an Artisan Bakers baguette has 70% hydration. (A typical formula for a French baguette dough would be 60% water. This is due to the difference in the rate of water absorbtion between French and American flours.) In comparing the color of this example with that of the ciabatta below you will notice the brown flecks indicating that this baguette has some whole wheat flour in it and that the ciabatta does not.


The extra large hole structure of this ciabatta is caused by very high hydration levels and long fermentation times. Holes this large are considered difficult to achieve in the craft of baking. Mistakenly, a bread with holes this big is not considered a good sandwich bread because the filling might leak out the holes and be messy. But if the bread is sliced lengthwise, the large cells fill up with juices and the top and botton crusts keep the juices in. There is not a better bread for making a sandwich.