How to be a better baker through understanding heat transfer

Anyone who studied basic physics in high school will remember that there are three forms of heat transfer. 

 BREAD BAKES from the outside in. (photo credit: Scott Brayley/Unsplash)
BREAD BAKES from the outside in.
(photo credit: Scott Brayley/Unsplash)

Have you ever wondered why a baker is called a “baker?” Why do we not call her/him a “kneader,” “mixer,” “braider,” etc.? Baking in the oven is only the last phase in a multi-stage process required to create bread. 

The reason is because, as they say, the proof is in the pudding. The final stage, the baking in the oven, is the litmus test that will determine if all the prior stages were done satisfactorily or not.

It is therefore surprising that most bakers, while well equipped with knowledge and experience in kneading, mixing, braiding, rising etc., are notoriously lacking in knowledge about when it comes to the crunch – the final stage in the process, what goes on in the oven from the moment you put the bread in to the moment you take it out. Better understanding the ways an oven puts the final touches to the finished product – bread, allows you to play around to achieve different and better results.

First we need to understand how an oven bakes bread. There is transferal of heat from a heat source to the bread being baked. Anyone who studied basic physics in high school will remember that there are three forms of heat transfer. 

THE FIRST – radiation – is the transferal of heat in the form of waves. The heat source (usually a metal coil/element in the walls/floor/roof of the oven) generates heat waves that radiate out in all directions (the oven wall is designed to direct them inward to the oven chamber), strike the oven trays and the bread and heat them. It is a similar concept to the waves of radiation heat from the sun striking your skin and giving you sunburn. A microwave also uses waves, except in the case of a microwave, the waves are a much higher frequency and cause the molecules in the food to vibrate, thus generating heat. 

The second – conduction – is the transferal of heat from one object to another when the two are in close contact. This is the kind of heat transfer that occurs between the metal/ceramic bread pan and the hot tray in the oven. Heat is conducted from the tray to the pan and then to the bread – very much like electricity is conducted from one surface touching another.

The third – convection – is the circulation of ambient heat uniformly around the oven chamber. The radiation heats the walls/trays of the oven that heat the air inside the oven chamber, which is distributed using a fan to all parts of the oven chamber.

I would like to tell you that these principles are universal in every oven, but the reality is that every oven is different – even two ovens of the same model, made by the same manufacturer. 

Bread bakes from the outside in. The crust will bake before the inside is fully baked. This incidentally is what gives bread much of its flavor – the caramelization and Maillard reaction, which darkens the crust and releases aromatic compounds. Breads with higher sugar content tend to caramelize quicker than breads that don’t and the oven temperature needs to be adjusted accordingly. Usually the recipe takes this into account, but you may need to play around with it according to your own oven.

THE BEST upgrade a baker can make to a regular home oven is the addition of a pizza stone that is preheated with the oven before baking. The stone absorbs radiation heat and, due to something called “thermal mass,” then radiates it back onto the bread in a longer wavelength than that of the electric element. This combination of different radiation wavelengths and increased quantity of radiation energy bakes the bread more uniformly. The ultimate upgrade would be a stone on the tray above and a second stone below the bread pan. This simulates a brick oven – the ultimate baker’s oven.

The addition of steam during the bake also improves results. On the lowest tray in the oven, place an empty, metal pan (no plastic handles) when you preheat the oven. Just before putting the bread in to bake, boil up a kettle of water. Put the bread in the oven and then pour some boiling water into the hot pan in the oven, which will then bubble and steam. Quickly close the oven door to trap this steam inside the oven chamber. The steam makes the crust crispier and is especially useful for crusty breads like baguettes.

A baker needs to learn the idiosyncrasies of their own oven and how to compensate for them. Some ovens have “hot spots” – areas in the oven that are hotter than others (convection sometimes helps in this regard, but not always). You may need to rotate your bread in the oven or move it to a different spot mid-bake to achieve a uniform bake. This is what makes baking so interesting and enables you to “make waves” in your own kitchen. 

The writer, a master baker originally from Johannesburg, South Africa, lives in Karnei Shomron with his wife Sheryl and four children. He is CEO of the Saidel Jewish Baking Center (www.jewishbakingcenter.com), that specializes in baking and teaching how to bake healthy, traditional Jewish bread. He also manages the Showbread Institute (www.showbreadinstitute.org) which researches the biblical showbread.

Homemade Pocket Pita 

Makes 6 pitot – The fastest oven bake in the world (1-2 minutes flat) – in your own kitchen oven.

· 3½ cups flour· 1½ cups water· 2 tsp. salt· 2 tsp. sugar· 1 tsp. instant dry yeast

Mix and knead dough for 10 minutes by hand. Leave to rise for one hour. After 30 minutes of rising, place a pizza stone on the upper tray in the oven and turn the oven on to the upper grill setting at the highest temperature possible. Preheat the oven and pizza stone for 40 minutes. After one hour of rising, punch down the dough and divide into six round balls. Flatten each with your hands or a rolling pin into round pita (disc) shapes, approximately the thickness of your index finger and place on a baking tray (or two) and leave to rise for another 10 minutes. Bake, one tray at a time, on top of the pizza stone for between 1 to 2 minutes, or until all the pitot have ballooned up. Immediately remove hot pitot from tray (with spatula), stack one on top of each other, fully cover with a towel and leave to cool until warm.