When Yeast Dies

• After being nurtured through the stages of feeding, fermenting and proofing, yeast has one more vital task to perform in the role of rising your bread. As the dough slowly get hotter, the yeast cells also get warmer, which increases their fermentation activity. This last burst of fermentation creates additional layers of flavor and more carbon dioxide bubbles for your bread. Simultaneously, the heat causes both the new and old gas bubbles to swell, further expanding the dough. This process happens during the first seven to 10 minutes of baking, until the dough reaches 140 degrees Fahrenheit, after which all the yeast cells are destroyed and no more gas bubbles are formed.

Inside the Bread

• There is a small period after the yeast dies and before the bread sets where the gas bubbles alone continue to rise the bread. Once the internal temperatures of the dough reach 160 F, however, the gas bubbles no longer expand because the dough begins to set. The proteins in the starch coagulate and the starch goes through a gelatinization process. As the dough gets hotter and hotter, the gluten, starch and liquids all work together to create the final product we know of as bread. Different bread recipes are baked at different oven temperatures according to the ingredients in the dough.

Lean vs. Rich

• It’s important to bake your dough according to the temperatures specified in the recipe, because different ingredients set at different temperatures. Dough made with little fat such as French baguettes and Italian ciabattas are made with what is known as lean dough containing a few simple ingredients. Lean dough is baked at higher temperatures – between 425 to 450 F – because the interior begins to set sooner than dough made with rich ingredients such as eggs, butter and milk. Rich dough is baked at lower temperatures – between 350 to 375 F – so the outside crust doesn’t harden before the bread has finished expanding.

Outside the Bread

• Once the crust becomes firm, the bread will no longer expand. However, the browning of the crust is an important part of the baking process, adding flavor to both the inside and outside of the bread. An oven too cool produces flat, cardboard-tasting bread with poor texture; too hot an oven results in dry bread with a hard crust and shortened shelf life. To prevent over-browning or for a softer crust, turn down the oven once the crust has set. Brushing your crust with cream or eggs will give it a nice glossy sheen. Misting the inside of the oven with water will produce steam, giving your crust a nice flakey crunch.