Bakers Journal

Tricks of the Trade: August September 2011

August 18, 2011

Steam injection makes a big difference in the quality, appearance and flavour of your bread

Steam injection makes a big difference in the quality, appearance and flavour of your bread

The injection of steam, or vapour, during baking plays an important role in the development of bread. The beautiful scarification (knocks from a blade), the sharpness of the crust and the shine of the bread can all be altered with steam or vapour. The quantity of vapour to be injected is variable according to the following factors: the desired qualities of the finished product, the type of oven and the baking temperature.

Bread quality
Breads baked with vapour are more attractive to consumers than other varieties. Place a few breads baked without vapour beside their vapour-baked counterparts and you will see the difference. When baking breads such as a rustic round loaf, vapours change the crust and improve the flavours of the bread.

Par baked breads necessitate baking with steam to avoid colouring the bread and forming a crust during the initial bake. The colour change means caramelization occuring during the formation of a crust. The crust will flake from the friction of breads in the packaging if allowed to form too early. Vapour is also important during the second stage of baking par baked goods, which restores the colour of the bread and further prevents the crust from peeling off.

Type of oven
There are several types of ovens that can be used:

  • fixed or rotating deck ovens with a sole of stone or metal
  • the rotative rack oven with single or double racks
  • rotative shelf ovens, including four to 10 tablet mobiles or a traveller for 12 tablets or more
  • vertical or horizontal tunnel ovens
  • convection ovens

These ovens may be heated with oil, natural gas, propane, electricity or wood.

The bigger the oven, the bigger the baking chamber will be, and the more steam will have to be supplied. In the case of a very big oven, an independent kettle is connected to the oven to supply the vapour.

The timing of the vapour injection will vary according to the system used and the specifications for the finished product. The injection time may be as short as three seconds or injection may happen continuously during baking. It all depends on the variety of bread.

Baking temperature
The steam injected during baking has to condense on the surface of the bread to develop a finer crust and avoid drying out the bread. This moist vapour also softens the dough and allows the knocks of a knife blade of open cuts in the loaf.

Baking determines the appearance and the taste of the final product. The oven temperature should be between 425 and 480 F (220 and 250 C). It is important to have a hot oven because the addition of vapour can facilitate the transfer of heat in products. The injection of steam brings a drop in temperature and, if the oven is not hot enough, the baked bread will have to stay in the oven longer and will lose weight as a result.

The bread enters the oven at a temperature of 77 to 95 F (25 to 35 C), depending on whether it is fermented in a proofer or on a couche at room temperature. At 130 F (54 C) the starch in the bread begins to swell. At 145 F (63 C) the yeast dies. At 165 F (74 C) the coagulation of the gluten begins and at 190 F (88 C) all activity stops. Excess humidity is liberated, some as carbon dioxide and some as alcohol. Finally, at 208 F (98 C), the bread is baked. Throughout the baking process, the temperature of the crust can exceed 392 F (200 C).

It is important to know how long it takes to heat your oven to the desired temperature; it must reach this temperature before you start baking the bread. Some vapour systems inject steam by a water inlet on the internal wall of the oven and if this is not warm enough, you will not have the right quantity of steam. Determine the type of production your bakery requires before purchasing an oven to ensure your new equipment will meet your needs.

 Vapour requirements for breads

  • Bread variety      Vapour requirements
  • Enriched
    white bread          Not required
  • Soft rolls
    (hot dog,
    hamburger)          Not required
  • Crusty bread
    (any shape)         Required for a beautiful crust
  • Crusty rolls
    (round, long
    or kaiser)             Moderate
  • Baguette
    (on the sole, pan
    or net)                 Important for open cuts
  • Cereal bread         Necessary to avoid tearing
  • Sourdough bread
    (miche au levain)  Needed to prolong development
  • Rye bread 
    (any variety)        Required throughout baking
  • Par baked bread
    (any variety)        Essential at beginning and end of baking

Mario Fortin is an international bakery consultant and owner of FORMA-LAB, a consulting service for bakers and suppliers. For technical information, send your questions to

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