Manufacturing of instant tea

The process of the production of instant tea consists of the following operations: selection of raw materials; extraction; aroma stripping; cream processing; concentration and drying.

Extraction is in most cases performed using water and countercurrent procedures.  Concentration of the extract is effected by evaporation of the water under reduced pressure at a moderately elevated temperature and during this process various methods for trapping the escaping volatile compounds have been devised. These trapped volatiles are concentrated and retained for incorporation into the final dried product.

Tea extract requires concentration before drying; a solids concentration of 40-45% is most common, although concentrations as low as ca. 20% and as high as 51% have been used.

High solids concentrations in the dryer feed are desirable to improve reconstitution properties of the instant tea powder. Thermal evaporation under reduced pressure is most commonly used, evaporators usually being of the falling film or plate types. The concentrated extract is turbid due to the formation of cream and solubilization of this cream is a fundamental problem in the production of instant teas soluble in cold water.

Cream processing can be accomplished by maintaining the temperature above 65 °C or by removal of the cream, for example by cooling and centrifugation. Cream treatment is especially necessary for cold water-soluble instants, which are commonly used for beverages like ice tea.

The finals step of drying the concentrated tea extract is commonly achieved by spray drying, but other methods, such as freeze drying or drum drying are the subject of published patents.
Manufacturing of instant tea