The tea masters oversee the careful selection of when and which leaves to pick in the fields. The leaves are not picked until the bud at the top of the bushes have grown to half the size of a full grown leaf. The pickers pluck just the the top three, most tender and most flavorful leaves.

The 2.5 acre estate in the Waikato’s unspoilt environment can product as much as 100 tonnes of tender leaves which are then processed in the state of the art tea factory.

Before learning about tea processing, I erroneously assumed that different teas were derived from different tea leaves. In fact, green, oolong and black teas all start out the same way – picked from the camellia sinensis bush. It is the subtle changes to the tea processing which creates the different appearance, aroma and taste of the different tea types.

Withering (or wilting)

Withering is the process by which the leaves lose 25% - 50% of their moisture. Natural proteins in the leaves break down, caffeine levels rise and the aroma and taste develops. Leaves for green tea go through a short withering period whilst leaves for oolong and black tea are withered for longer. In many commercial operations the withering happens outside where leaves are laid out on tarps near roads and paddocks, exposed to animals and the elements. At Zealong, the process is highly controlled by monitoring and adjusting the humidity, temperature, air-flow and density inside the on-site Zealong tea house. The process involves stirring to distribute moisture evenly. The tea master determines the withering complete by using science (such as the weight of the leaves) and their art comes in by using their sense of smell and touch. 

Tossing

Tossing is a continuation of the withering process and the initiation of the oxidation process. The process of oxidation includes initiation, oxidation and fixing (or stopping) the process at the desired stage. Oxidation initiation in many mass produced commercial tea operations is often achieved through macerating the leaves, quite often using a CTC (cut tear curl) machine to quickly expose lots of the inside of the leaf to oxygen and thereby starting the oxidation process. Zealong use a much gentler and slower way of initiating oxidation called tossing. This is where oxidation is initiated through gentle tumbling of the leaves.

Oxidation

Oxidation is the process of browning the leaves. Depending on the type of tea being produced, the tea maker may prevent oxidation altogether (such as when making green tea) or fully oxidize the leaves (such as black tea) or somewhere in between (when making oolongs). There are a number of chemical reactions that occur in this process such as the chlorophyll in the leaf breaks down and the tannins are released, and these changes create the flavor, color, aroma and strength of the tea.

Heat, humidity, air flow, light and processing time need to be controlled in the oxidation process. At Zealong, in their specialized tea house, the tea masters have full climatic control in their oxidation rooms ensuring this process is perfected. This is not ‘one process’ as such but monitoring and adjustments are made until the tea leaf has reached its desired level of oxidation.

De-enzyming (or fixing or ‘killing the green’)

De-enzyming is the process of killing the enzymes in the leaves and thereby stopping the oxidization process. For green tea this happens early in the process to prevent the leaves from oxidizing at all and this is what gives green tea its high catechin levels. It’s important to time this process just right for the oolong teas (and oolong variations occur with different timing) but is unnecessary for black tea which is fully oxidized.

De-enzyming requires heating the leaves to around 150 F depending on the size and thickness of the leaves and can be achieved through steaming, baking or roasting which also account for tea variations. Extreme control of the fixing process is required for quality tea.  It’s a relatively short part of the process but failing to de-enzyme properly and the tea will continue to oxidize, or fixing for too long will result in too much loss of moisture.