Friday, December 19, 2008

Instant Tea Processing

Instant Tea Processing
The commercial production of instant teas began in the 1940, and this form of tea has grown in popularity in the United States to the extent that it now comprises 42% of tea sales in that country, although on a worldwide basis instant tea accounts for only a very small proportion (less than 5%) of consumption.

The demand in the United States is for instant teas soluble in cold water, because it is iced tea which is the real basis for the success of instant tea in that country.

In the other countries, hot tea is the preferred beverage and it would appear that here the popularity of tea bags has been the factor responsible for the limited consumption of instant teas.

The methods used for instant tea production have been protected by patents, and the patents published up to 1969 have been reviewed in 1977. The basic steps in the preparation of instant teas are extraction of tea solids from fermented but unfired tea leaf black tea, or green tea, followed by concentration of the extract, and drying of the concentrate to a powder. Extraction may be effected by a variety of method among which counter current extraction and percolation methods have been widely used.

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.

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.

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.

The importance of instant teas to the World Tea Industry may be gauged by the intense activity which is current in the field, and this activity is itself an indication that a truly acceptable instant tea has not been yet produced.
Instant Tea Processing

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