Tea Processing: Withering
Withering brings about physical and chemical changes in the shoots and leaves to produce quality tea. It also provides flush to tea leaves for rolling in subsequent step by reducing turgor pressure. Withering is generally achieved by thinly spreading the flush on mats or in thicker layer in trough for 8 – 20 hours, depending on condition of leaf. During this period, the moisture content of leaf drop between 60 – 65 % (in soft withering) and 50 – 55 % (in hard withering). The physical part of withering can be achieved quickly by passing blast of hot air (35°C) through the leaves but this may adversely affect quality of tea because of inhibition of full biochemical changes. Moisture evaporation in leaves takes place through stomata and highly through the epidermis. The rate of loss of moisture not only depends on external condition but also on the leaf standard. Leaves and buds loose moisture more easily than the stalk and shoots. Read more