The Chemistry of Bread

The Chemistry of Bread

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Today we talk the chemistry of something that besides being part of human history and one of the most important foods in our diet, is delicious hot and with butter. You guessed it, it’s bread!

We’ll talk about the chemical composition of its ingredients and some of the chemical reactions responsible for this healthy, versatile and delicious food.

A typical recipe of bread in our country has flour, water, yeast and salt. Wheat flour consists primarily of starch, that is, sugar chains, and proteins, that is, amino acid chains.

Let’s start by kneading the dough, which in terms of chemistry is more than just mixing flour and water. These mechanics are necessary for the several proteins to settle in layers surrounding starch granules and give the dough its characteristic consistency.

Salt is added to the dough and not just as a matter of taste. The presence of sodium and chloride ions is essential for the convergence of protein chains, contributing for the formation of a stronger and less sticky tough.

Then, the dough ferments. During this rest period, the yeast or leaven, which is a fungus, causes the decomposition  of sugar, with the release of CO2. It’s the formation of CO2 bubbles, trapped in the gluten network that makes the dough grow and produce the” perforated” texture of bread.

At this stage there is also an important number of chemical reactions involving natural oxidants of the flour, through which the links between protein chains are broken and remade elsewhere repeatedly, thereby enabling the dough to “stretch” without losing its structure.

Then we just have to bake. And by the way, the golden-brown colour of bread after baking is the result of the Maillard reaction, so named after the chemist who found that the heat of the oven causes a reaction between amino acids and sugars which gives a golden colour to baked goods.

Who said chemistry can’t get in the kitchen?


Other Resources

  • Credits: Science Office / University of Aveiro Starch ( VIDEO )
    10.29.2012 ( 3 MB )DOWNLOAD

    Credits: Science Office / University of Aveiro

  • Credits: Science Office / University of Aveiro Sodium chloride ( VIDEO )
    10.29.2012 ( 1 MB )DOWNLOAD

    Credits: Science Office / University of Aveiro

  • Credits: Science Office / University of Aveiro Leaven bread dough ( VIDEO )
    10.29.2012 ( 24 MB )DOWNLOAD

    Credits: Science Office / University of Aveiro

Química 2011 Science Office Universidade de Aveiro QREN Compete