a roux, the first thing that occurs is that some vapour can be seen initially leaving the mixture - this
vapour is water from the butter and flour evaporating. Once all the water has evaporated,
temperatures are able to reach greater than 100 °C. This encourages many chemical reactions.
Amylose has a very floury taste. Pre-heating with butter ensures that high enough temperature are
reached that some of the amylose responsible for this taste, that is located on the surface of the starch
granules, can be broken down into smaller and smaller sugars, removing this undesired “floury” taste.
Additionally, the sugars formed are able to react with the amino acids exposed in the denatured flour
proteins via Maillard reactions to generate aromatic molecules. The mixture will colour and start to
develop characteristic tastes and flavours.
Cooking length: The more the roux is cooked, the more it browns because the more the carbohydrates
will be broken down into smaller sugars that can then contribute to these browning reactions.
However, if a roux is cooked for too long, so much of the starch will be broken down that there will be
much less available to thicken the sauce, and to gel on removing from the heat source.
The presence of fat: The presence of the fat in preparing a roux has an important role in taste
perception in a similar way to any fat, and additionally it acts to surround the starch grains and prevent
them from lumping together once the liquid is added.
Repairing sauces: If a sauce prepared with flour is not thick enough, a flavoured butter may be added
nearer the end of the cooling. The presence of butter prevents the flour from lumping together, by
slowly releasing it as it melts. However, flour added at this moment will have a floury taste, so is not an
Flour and its ability to form doughs
If the sticky mass produced by mixing flour and water is taken by hand and folded, pressed and
stretched, (i.e. “kneaded”), the gluten network becomes strong and elastic.
Kneading: The physical action of stretching and folding the dough will cause the bonds (mainly the