Steaming
Under the steaming or vapors is meant the feeding of water vapor (steam) during the insertion of dough in the oven.
effect
Yeast dough pieces that come out of the proofing room have a surface temperature of around 30 ° Celsius. The water vapor introduced into the oven at the beginning of the baking process is over 100 ° Celsius and condenses on the cooler surface of the dough pieces. This causes water to settle on the surface of the dough (condensation).
This has decisive advantages:
- The surface of the dough remains elastic, as the incrustation only begins after the condensed water has evaporated
- The dough volume can increase significantly at the beginning of the baking ( oven shoots ) without the dough surface tearing immediately
- The crust of the finished baked product is browned more ( dextrins dissolve in water)
- The crust gets a pleasant shine
Due to the heat, the yeast cells (up to approx. 50 ° C) develop a strong gas formation activity (CO 2 ). The second reason for the increase in volume of the dough pieces is the proportional expansion of the existing fermentation gas by the heat ( gas law from Gay-Lussac ). This increases the pressure inside the dough, which significantly increases the volume of the baked goods.
The moisture also ensures the formation of dextrin, which contributes to the optical impression (shiny surface), but also to the taste. After baking, dextrins migrate into the crumb as it cools down due to the resulting negative pressure and thus influence the taste of the pastry. An effect that is particularly important for wheat biscuits (rolls).
If the steam is not added, the pastry will remain small and dull. Cracks appear, i.e. uncontrolled bulges . The effect is used with certain, rustic types of bread. They are baked without steam, with cuts being made specifically where the bulge should be. At this point the pastry pops open, increasing the surface and crust.
With the steam supply, pastry errors can also be avoided in some cases. If, for example, the dough has proofed too much, the baked goods can still be saved with less steam, as the fermentation gases can escape through the surface.
Baked goods that are not baked with steam:
- Pretzels (pretzel, pretzel rolls)
- Pastries that have been coated with egg yolk
- Sand and batter
- Pastries made from shortcrust pastry
- gingerbread
- puff pastry
technology
Steam generation systems are integrated in the baker's ovens, which can evaporate several liters of water in the first 60 seconds of baking (cascade systems). This makes it possible to steam even large baking surfaces evenly and quickly. Since the formation of steam is explosive (1 liter of water produces approx. 1700 liters of steam at a pressure of 1 bar and a temperature of 100 ° C), the baking chamber must have an overpressure flap. Excess steam can escape through this flap, as can the steam generated during baking. To improve the formation of the crust, the baker can open a venting flap (pull the “pull”) so that the water vapor can escape even better, especially towards the end of the baking process. It is used to regulate the water vapor content in the baking chamber. For rolls z. B. the steam flap remains closed during the entire baking time until just before the end. In the case of breads with a high rye content (> 70%), on the other hand, the vent flap must be opened for approx. 10 minutes after a baking time of approx.
Normal household ovens do not have these devices. To generate steam, one or two cups of water can be placed in the cooking space or poured onto an additionally inserted baking sheet. Some newer models now offer the option of blowing in steam while baking. The manufacturers call this, among other things, climate plus .
Commercial kitchens often work with combi steamers , which, with certain restrictions, are also suitable for baking.
Individual evidence
- ^ Josef Loderbauer: The baker's book in learning fields . Verlag Handwerk und Technik, Hamburg 2008, ISBN 978-3-582-40205-9 .