Tea Drying and Sorting

The principal difference between black teas and other forms of teas like green tea and oblong tea is the presence of condensed catechins, i.e. polyphenols of higher molecular weight formed through enzymatic oxidation with the help of enzyme polyphenol oxidase (PPO) and peroxidase (PO).

The next production process objective is, therefore, to allow intimate contact of the catechins with the respective enzymes, which oxidize these catechins in presence of oxygen. The temperature and Relative Humidity also have a role in these oxidation reactions and should be kept at a levels at which the enzyme activity is at the peak.

Drying

The main objectives of drying are:

• To arrest enzymic reaction as well as oxidation,
• To remove moisture from the leaf particles and to produce a stable product with good keeping quality.

Sorting

Despite more or less intense sifting, bulk obtained after drying are still heterogeneous. Tea ranges in size from that of a speck of dust to a leaf approximately 4 cm long and 1cm wide. The fractions are to be brought to the desired sizes and forms with adequate uniformity and cleanliness conforming to trade requirement. Tea is, therefore, sorted into pieces of roughly equal size. Four main sizes are produced, namely, Whole Leaf Grades, Broken,

Fanning and Dusts

Within each of these sections tea is further split up into grades of varying qualities. Whole Leaf Grades are the largest sizes produced and depending on the actual grade within the section may range from a long and wiry stem, 1cm to 2cm in length, to a round and knobby twisted leaf similar in size and shape to that of a small garden pea. Of the former style there are the Orange Pekoes and long Leafed Pekoes.

Testing

The dry leaf is generally placed on a piece of white paper and the following points are recorded:

• Grade: The teas have to be classified as per their grades.
• Color of the leaf: Grayness in tea is not desirable as it denotes faulty manufacture; generally during sorting.

The thin and varnish like coating on the dry leaf is rubbed off and results in a grey color. This coating is soluble in water and plays an important part in liquoring properties. If absent, the tea must necessarily have been deprived of its fullest liquoring capabilities. A brown appearance, on the other hand, is often unavoidable with very tippy tea. The reason for this is the hair growth down the shoot, which has been picked for manufacture. The second leaf may have a quantity of hair insufficient color. Also during rolling some hair may be rubbed off the bud and possibly the first leaf and deposited on the coarser leaf. During firing this hair is affixed to the leaf and results in a brownish leaf appearance.

Some teas produce a reddish appearance at certain times of the year. This is generally found during the autumnal period when growth is slow and the tea shoots become less succulent tinged leaf throughout the year. A reddish appearance in dry leaf is undesirable if caused by coarse plucking. In this case the red appearance brought about by hard and coarse leaf is considerably emphasized by the presence of red stalk.