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The Anatomy of a Bake

by Les Saidel - November, 2011

Despite the numerous tasks that a baker must perform - mixing ingredients, kneading dough, shaping into loaves, leaving the bread to rise and finally baking it in the oven, these other preparatory tasks have not come to signify the essence of a baker.

The very fact that a baker is called a "baker" and not a mixer, a kneader or a shaper seems to indicate that the final process, baking - in which the bread is inserted in a hot oven to bake - is the culmination of all the preceding, preparatory processes and it is this crowning culmination that has been selected to typify this profession.

So the essence of a baker, or a bakery, is the process of inserting dough into a hot oven and leaving it to bake for a fixed period of time.

That said, it would seem obvious that this final stage - baking - would be the most well understood of all the stages required to make bread. However, do you really know what happens during the actual baking process?

The purpose of this article is to give a blow by blow, detailed description of what happens when bread is baked. A full understanding of this process will help you achieve better results with your baking.

Note: For the purposes of this discussion we are assuming that you are inserting a dough that is ready to be baked - a dough that has risen to required degree and that has been given the final preparations before baking, such as basting and scoring. For more information about these processes, see the articles Prod your Challah (Dec 2010) and Obtaining a Perfect Crust (May 2011). We are also assuming that the dough being baked is a bread loaf and not a pita bread or a bialy - breads that are baked at extremely high temperatures and the total baking process for them from beginning to end is less than 5 minutes. The time frames below do not apply to them as everything is highly accelerated.

Let's start at the beginning.

Before baking, the oven should be at the correct temperature, so that when the bread is inserted, the oven is not still playing "catchup" to reach the relevant temperature. It is advisable to start heating the oven well in advance of the bake, so that when ready, the dough can immediately be placed in the oven.

It is extremely important to handle your breads with care while inserting them into the oven as at this stage of rising they are delicate and lack of gentleness in handling can cause them to deflate or even collapse.

Also remember that as you open the oven door to insert your bread, cooler outside air will mix with the hot air in the oven and the oven temperature will lower slightly. For this reason it is advisable to heat the oven to a slightly higher temperature just before inserting the bread and immediately after inserting the bread and closing the oven door to reduce the temperature to the correct temperature for the bake.

During the first 4-6 minutes of the bake, the sudden increase in temperature gives the yeast a "jumpstart" and puts them into "hyperdrive", increasing their metabolism exponentially.

This causes an increased amount of CO2 to be created which makes the bread rise in the oven, a process known in the baking world as "oven-kick" or "oven-spring". (If the dough had over-risen before it was baked, this increased inflation will have the opposite effect and cause the dough to collapse rather than rise further. See the article Prod your Challah, Dec 2010).

When the dough temperature reaches 50°C (122°F), the yeast cells begin to die and the starch granules in the flour begin to swell.

At 60°C (140°F) the swollen granules of starch burst, releasing many chains of starch, thus forming a very intricate matrix of gelatinized starch. This process is called gelatinization. When the bread cools after the bake, it is this gelatinized starch that forms the crumb structure of the bread.

At 63°C (145°F) all the yeast is now dead, however the CO2 gas bubbles they have formed begin to expand from the heat and the bread continues to expand in size.

Until this stage, it is imperative that the dough crust remains flexible. If it is already dry and cracking before the bake starts, this will inhibit the oven spring and your breads will not achieve their full height. If the crust dries out prematurely, the inner part of the bread continues to expand against an inflexible, hard crust and results in the crust cracking and the dough "bursting" through, creating an unattractive loaf shape.

To maintain moisture and flexibility you may either spray the bread with a mist of water before baking. Alternatively you may create steam in the oven by using a metal pan on a lower rack that you pour boiling water into as the bake starts, thus creating steam.

An aside here - The function of yeast in bread is biotechnology at its best, using a living organism to perform a specific task beneficial to mankind and then disposing of it with no left over waste products that harm neither man nor the environment.

At 74°C (165°F) the protein gluten begins to coagulate and the gluten strands begin to solidify. It is similar to the process of frying an egg. The egg albumen (also a protein) as it increases in temperature, coagulates and changes from a see thru liquid into a white, rubbery solid.

At this point the loaf has achieved its final volume and does not expand further.

When the surface of the bread reaches 100°C (212°F), boiling point, the moisture from the crust begins to evaporate and the beginning of the crust is formed.

When the crust reaches 140°C (284°F) and higher, the sugars present in the crust begin to caramelize, i.e. become darker in color. The degree at which this process occurs is dependant on the sugar content of the dough. The more sugar, the darker the crust will be, the less sugar, the lighter in color.

All breads, whether they have sugar added to the dough or not, have sugars in the crust created by the enzyme activity of the yeast that converts the starch into simpler sugars. This is not always enough and to achieve the deep golden-brown hue of a good looking loaf, it may be necessary to supplement with additional sugar (or malt - if you do not want to increase sweetness).

As the sugars in the crust caramelize they also undergo a reaction called the Maillard reaction. In this process, the sugars in the crust combine with amino acids (proteins) that intensify the color and the aroma of the crust. This reaction is very similar to what happens to the crust of the meat when you roast beef.

The Maillard reaction provides the crust with a flavor and aroma that is more intense and distinctive than the internal crumb of the bread. It is basically what gives the bread most of its character and bouquet.

When the internal temperature of the bread rises above 94°C (200°F), the bread is fully baked. At this point you may remove it from the oven. As you remove it, if you lightly tap the bottom crust you should hear a hollow sound. This also provides an indication that the bread is fully baked. If there is no hollow sound, but simply a dull thud, the bread may not be fully baked yet.

When removing the bread from the oven, it is important to handle it gently, not to press it too hard, jar it or drop it, as the structure of coagulated gluten is still delicate and does not harden fully until the bread cools. Lack of gentleness at this point can cause the bread to collapse or deflate.

It is essential to allow the bread to cool fully before slicing. Only when the bread has cooled completely will its structure be fully "set". Some people prefer not to slice into breads such as ryes, sourdoughs etc. for a full 12 hours after baking to allow the complex aromas to fully permeate the entire loaf.

That then is the anatomy of a bake, all the "secret" things that go on inside the bread while it is baking in the oven.

The stage of baking is the final act in a well orchestrated production. All the preceding, preparatory stages "come together" in this final climax. If you have done everything correctly then this finale will end with an encore and your loaf will be a wonder to behold.

Les Saidel


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