Method for drying a material
The invention relates to a method of drying a material, that includes the steps of: providing a gaseous atmosphere with superheated steam in a housing, transporting a material into the housing, and drying the material in the gaseous atmosphere. Thereafter, transporting the dried material out of the housing and extracting from the gaseous atmosphere volatile substances which escape from the material into the gaseous atmosphere, especially flavors. The invention is also direct to an apparatus for drying the extruded material.
1. A method of drying a food, comprising the steps of:
transporting an extruded food comprising a flavor into a housing having a heated gaseous atmosphere therein,
wherein the gaseous atmosphere comprises a superheated steam having a varied density in a vertical direction and a varied temperature in the vertical direction,
drying the extruded food in the heated gaseous atmosphere to form a dried food and a flavor containing steam,
transporting the dried food out of the housing,
condensing a portion of the flavor containing steam to form a flavor containing liquid,
extracting the flavor from the flavor containing liquid; and
introducing the flavor into a packing container during a packing process.
2. The method as claimed in claim 1 , wherein the dried food comprises a water content selected from the group of less than 50% by weight, less than 40% by weight, less than 30% by weight, or less than 20% by weight.
3. The method as claimed in claim 1 , characterized in that wherein the dried food comprises a water activity value (aw) of less than 0.6 aw, 0.5 aw, or 0.4 aw.
4. The method as claimed in claim 1 , wherein the heated gaseous atmosphere comprises at least one horizontal partial layer selected from the group of consisting of more than 100° C., 120° C., 140° C., 160° C., or 180° C.
5. The method as claimed in claim 1 , wherein the heated gaseous atmosphere is a mixture of a first component comprising CO2, nitrogen, or another inert gas, and a water vapour, and, in at least one horizontal partial layer, has a steam content selected from the group consisting of at least 50% by weight, 60% by weight, 70% by weight, 80% by weight, 90% by weight, 95% by weight, 98% by weight or 99% by weight.
6. The method as claimed in claim 1 , wherein the heated gaseous atmosphere comprises at least one horizontal partial layer having an oxygen content of less than 15% by volume, less than 10% by volume, less than 8% by volume, less than 5% by volume, less than 2% by volume, or less than 1% by volume.
7. The method as claimed in claim 1 , wherein the heated gaseous atmosphere an oxygen content which decreases in the vertical direction.