Oast house

The kiln is a well known since ancient device for drying of food and consumer goods with the help of heat.

History

Since the Neolithic people know that cereals for a damage-free storage may have to be dried. An early device which is held for a kiln, found himself at Bab edh - Dhra the Dead Sea. Even in Roman settlements Darren were found, for example, in the Roman settlement Tegel mountain in the Eastern Allgäu. In Wales threshing barn of Collfryn from the 15th century and 2002, the kiln was discovered and excavated by Lion Court in 1982 during excavation work. In England, " Corn Drying Kiln " by Kilnsey Green in North Yorkshire was excavated. On the find site Dull there was a Scottish kiln. The Darren in Ireland are zurückdatierbar by number of recent archaeological excavations to the Bronze Age.

Usage

Darren can be classified according to the material to be dried:

Threshing barn

When the grain Darren is primarily for preservation. Since grain only below 14% moisture is safe shelf life, is subject to weather conditions but also threshed with a higher moisture content, the moisture must be removed by drying. If the storage place at damp, infestation with fungi and pests would result. Also, by moisture in the grain spontaneous combustion take place. During the subsequent grinding of the grain, it may be necessary, this again " aufzunetzen " on 16-17 % moisture, depending on the " glassiness " of the grain ( to wet ), since the dry shell when grinding too much splinter and a separation between would complicate bran and flour.

Another desirable effect of Darren's may be the production of roasted flavor during roasting of cereals. A typical product, which receives its typical aroma through the kiln, is green core. These are harvested unripe spelled grains and kiln-dried.

Malt kiln

In malting the green malt is dried as a third processing step after steeping and germination on the kiln, that is kiln-dried. The heat and the associated extraction of moisture malt will not only be stored but also gets his typical " malty " flavor.

The kiln consists of a fine wire mesh or a slotted hole sheet, called Horde, on the green malt is coated. From below by hot air flows the " pile " and cut him down the humidity.

The heating of the air takes place indirectly in modern malting plants by oil or gas burner directly heated air transfers the heat energy via a heat exchanger to the air flowing through the green malt from. The indirect lighting, the malt remains free of pollutants and off-flavors of fossil fuels and the formation of nitrosamines is minimized. The direct firing is almost exclusively only used for the production of aromatic specialty malts. So is smoked malt, which is used for smoke beer, produced by a beech wood rarely also an oak wood fire under the kiln. For the manufacture of peat Whiskymalz is burned under the kiln, that the malt whiskey and the prepared therefrom gives a phenolige note. Specifically, the Islay whiskeys from the Scottish island of Islay are known for their peaty taste. Lately beers with malt whiskey are also increasingly being produced.

Hopfendarre

Hops has a water content of 75-84 % at harvest and must be dried immediately after harvest to a moisture level of 9-10% for the preservation of shelf life. The drying time is depending on the type and dimensions of the kiln about 3-5 hours. For best drying results, a drying temperature of 62-68 ° C at a bed height of 20-35 cm and an air velocity of 0.30-0.45 m / s is required on a hop kiln.

Other Darren

• For dried fruit in fruit-growing areas
• For tobacco
• Shrimp that are too small and therefore unsuitable for human consumption are for husking by hand ( the Gammel ) are dried to Darren and then fodder, particularly for chickens processed.
• Wood drying equipment, in which timber (also firewood ), from its moisture
• On the Samendarre viable seeds are dried from pine or pine cones. So a Samendarre was from 1882 to 1925 in Lingen by Saxon model operated. In the 45 years of the existence of this "Royal Hanoverian Darre " were about 30,000 kg pine seeds " geklengt ". Fuel for drying were the empty cones. This kiln was for the cultivation of pine in the Emsland region and for the supply of other forest districts throughout northern Germany is of great importance.
• Linen or flax for fiber production (clothing, Seilereiwerk ) is also dried in the kiln.

Designs

Hopfendarre. The fan ( B) drawn through the tube ( b ) heated air from the floor of a low-lying area on and blows it covered under the kiln area ( A) with the hurdles (a) is

Prehistoric grain circulation

Old monastery Darre Diesdorf

Hopfendarre in Healdsburg, California. The kiln was built in 1905, is one of the few surviving examples in the formerly important hop growing area in northern California