Extraction process in manufacturing of instant tea

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.

Instant tea processing begins with extraction of the selected tea leaf blend. Generally a fermented black tea type is used – one chosen for reddish color, relative freedom from haze and strong flavor when brewed. The extraction process is one with heated water in a static system consisting of three to five cells.

Modern extraction systems are based ion counter-current flow and either batch or continuous systems may be used.  About ten parts of water are combined with one part of tea leaves by weight in the extractors and extraction is carried out at temperatures between about 60 ° C and 100 °C for 10 minutes.

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 yield of solids during extraction frequently ranges from 25% to 35%. To maximize aroma preservation a process known as aroma stripping can be instigated between extraction and concentration. The aroma is removed through the medium of a stripping gas and is quickly fed back to existing tea concentrate.
 Extraction process in manufacturing of instant tea 

Production of instant tea

Instant tea powder is extensively used in large quantity in various tea premixes. The main objective to produce instant tea powder is to save time & effort of mankind in preparation of tea and feel the people the actual taste of tea as & when they want to have a cup of tea.

Instant tea Instant tea is used almost entirely to prepare iced tea. The basic objective in the manufacture of instant tea is to extract the water soluble solids from a pure tea brew, and convert them into a powdery form. The instant tea ingredient must be an extract processed from the leaves, buds, and tender stems of the varieties of the species Camellia sinensis or Thea sinensis known to be suitable for making tea for consumption as a beverage.

It is manufactured by a fairly exhaustive extraction of black tea with hot water. After separation of leaf matter from the extract, the latter is usually stripped of volatile substances (aroma) and concentrated.

Drying of such a concentrate without further processing would result in a product incompletely soluble in cold water, so the extract is precooled to precipitate cold water-insoluble fractions, known as 'cream'. These may be processed to improve solubility and then added to the main extract. The preserved aroma fraction is added back ta the total extract concentrate before spray or freeze drying.
Production of instant tea

Instant tea: Cream processing

On cooling, a tea solution becomes opaque and lightens in color. This is due to the formation of tea cream, a colloidal substance which contains the same components as the original extract.

Tea cream is a coacervate formed of a complex between caffeine, catechins, and the oxidized catechins of black tea.

The conditions under which cream forms determined the chemical composition of the complex and its physical properties.

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

Tea cream causes particular problems in production of instant tea for the US market, which is required to be of clear, bright appearance when reconstituted with cold water.
Instant tea: Cream processing 

Production of instant tea

The commercial production of instant teas began in the 1940s, 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 the country.

These products are hot and cold water soluble, iced tea concentrates, carbonated tea etc.

Instant tea processing begins with extraction of the selected tea leaf blend. Generally, a fermented black tea type is used, chosen of reddish color, relative freedom from haze and strong flavor when brewed.

It also may be made from semi-fermented or green dried tea leaves, it may also be used of partially fermented undried leaf.

About 10 parts of water are combined with 1 part of tea leaves by weight in the extractors, and extraction is carried out at temperature between about 60 and 100 ° C for 10 minutes.

In the case of instant green tea it is also necessary to ensure the leaf is heated to at least 70 °C to inactivate enzymes.

The final extracts contains about 4% solids, which represents approximately 85% of the soluble solids in the leaves.

Concentration of the extract is effected by evaporation of the water under reduced pressure at a moderately elevated temperature.

Spray dryers used in the production of instant tea usually complete the drying operation with the drying chamber, producing a powder with a moisture of 3-5%.

Instant tea is largely used in making iced tea because of its solubility in cold water. However, the flavor and aroma of instant tea is less full than that of the beverage freshly prepared from tea leaves.

Production of instant tea