Green Leaf Plucking

Plucking

Shoots comprising of 1+ bud and 2+bud are detached either by hand, shears or by machine, put normally in a basket, weighed and taken to the factory either manually or in a multi-tired trolley by a tractor.

Chemical changes after plucking

Once the leaf is plucked the anabolic reactions practically cease and catabolic reactions leading to the breakdown of large organic compounds to simpler molecules start. Burning of sugar molecules produced earlier through photosynthesis provides the energy required to run these biochemical reactions in the shoots.

There is rise in temperature in the mass of the plucked leaf during storage and transportation due to respiration as well as the aforesaid reactions. In the process of respiration organic substances in the cells (usually sugar) get oxidised into carbon dioxide and water with release of fairly considerable amount of water as may be seen from the following equation :

C₆H₁₂O₆ (Glucose) + 6O2 (Oxygen) 6CO2 (Carbon dioxide) + 6H2O (Water) + 674 calories (Heat)

After the leaf is plucked, biochemical reactions are initiated towards biological degradation of the shoots. In this direction, large molecules like cellulose and lignin, which are responsible for the rigidness of the shoots degrade to make the shoots more flaccid. Lipids carbohydrates etc., which are also large molecules, degrade. Carbohydrates degrade to produce sugars, which burn in presence of oxygen and produce energy to run various biochemical reactions, which are enzymatic and temperature dependent. If in the plucked shoots sufficient oxygen is not available, anaerobic reactions take place. Those reactions produce much less energy than aerobic reaction mentioned above. Secondly, the results of anaerobic reactions are different and are not desirable for making quality teas. Adequate oxygen availability is, therefore, a must. The lipids degrade to produce smaller molecules, which are quality attributes. Therefore, if before the lipids are degraded, cell rupture and manufacture are initiated, quality attributes will be missing. It is, therefore, essential to make the lipids degrade by providing proper conditions, i.e. temperature and time.