The presence of large holes in the crumb structure of bread, such as ciabatta or sourdough, is generally caused by the fermentation process and the way the dough is handled. This phenomenon is indeed normal and often desirable in these types of bread. Here's why:
Fermentation: In bread-making, fermentation refers to the action of yeast or sourdough starter on the dough. During fermentation, yeast or bacteria produce carbon dioxide gas as a byproduct. This gas gets trapped within the gluten network formed by the flour, water, and other ingredients. As the dough rises and proofs, these gas bubbles expand, creating pockets of air in the bread's crumb.
High Hydration: Breads like ciabatta and sourdough often have a high hydration level, meaning they contain a relatively high ratio of water to flour. This high hydration, combined with a longer fermentation process, helps develop gluten and allows for the formation of larger air pockets.
Minimal Kneading: These breads are typically made with minimal kneading or gentle folding techniques, which preserve the gas bubbles created during fermentation. Excessive kneading can deflate the dough and result in a denser crumb.
Large holes in the crumb structure are considered desirable in certain bread varieties, as they contribute to a light and airy texture. They also enhance the visual appeal of the bread and provide an interesting texture and mouthfeel when eating. However, it's important to note that the presence and size of the holes can vary depending on factors such as the recipe, dough handling techniques, and individual preferences.
It's worth mentioning that achieving consistent hole structure in bread can be challenging and may require practice and experimentation. Factors like dough hydration, fermentation time and temperature, shaping techniques, and proofing methods can all influence the formation of holes in the final bread.