Pre-heating in bread , biscuits and cakes
PRE-HEATING IN BAKERIES
Preaheating an oven is the process of setting the oven to the temperature required in the recipe about 15 minutes the food needs to be placed in the oven. The oven temperature will have reached the desired degree before the food is placed int he oven. This is very important when baking cookies, cakes and other bakery items.Preheating is also subjected to water / Steam in the formation of dough.
Heat is transmitted to the dough in three different ways:
1.Radiation Although this mainly happens when there is a "red hot surface" in the oven.During the baking process, the heated internal surface of the oven emanates invisible infrared rays, which are called radiant heat. This heat is absorbed by the exposed surface of the products thus increasing their temperature. Thermal radiation is a process in which energy is emitted by a heated body in the form of electromagnetic radiation. Infrared rays travel at the speed of light directly to the point of absorption. This kind of thermal radiation represents the most complex mode of heat transmission
2.Convection This is caused by the turbulence of the air in the oven.Convected heat is distributed through the baking chamber by the turbulence of the atmosphere and is transferred by conduction to the products when the hot air contacts their surfaces. In general, the more rapid the air movement, the more rapid and efficient the heat diffusion will be. Based on this concept, fans or blowers are used to enhance the efficiency of the heat transfer by convection. However the downside of this technique is that the crust can become dry, a characteristic that is not wanted in for instance hamburger buns.
3.Conduction In this process , dough is in contact with the heated surface either the hearth or the sides of the pan.During the baking process, the side and bottom crusts of the products absorb the heat that is transmitted by the pan walls or the stone hearth and this gradual heating of the interior of the bread is called conduction. Conduction heat and radiant heat raise the temperature of the bottom and sidewalls (in case the product is baked in a pan) and then the heat is transferred into the interior of the products.
It is used in all Information about bread, biscuits & cakes production
Typical parameters of the process
Source:BMWFJ - Bundesministerium für Wirtschaft, Familie und Jugend (2009) Technische Grundlage für die Beurteilung von Einwirkungen, die beim Betrieb von Koch-, Selch-, Brat- und Backanlagen auftreten können und Abhilfemaßnahmen (Technische Grundlage Gerüche).