The Matcha Journey; Part 6: Steaming

Steaming gives Japanese tea its unique, fresh taste. Read part 1 of this series here

 

Within 24 hours of the harvest, the tea leaves are leaves are sent to a processing factory. Before undergoing a major step, the leaves are sent to a vibrating belt to sift out any unwanted materials. 


The leaves start becoming aracha


There are 3 steps in the primary processing of tea: steaming, drying and roasting; at the end the leaves finally come out as a tea, albeit crude and grassy and not really sold for commercial use.

 

This is called ‘Aracha’ or ‘farmer’s tea’. For now, let’s examine the process of steaming. 


Steaming’s main purpose is to prevent the oxidation of leaves, which in other tea cultures is a necessary biological process, but not in Japanese tea. During oxidation, oxygen is absorbed causing natural oxidation reactions, and in the context of tea, causes the following to happen: altering the flavor, appearance, and chemical composition of the tea. The most radical example is black tea, the flavor of which is the complete opposite of the freshness that green tea should have. This is the key difference in Japanese and other types of teas.


To stop oxidation, heat needs to be introduced, of which the preferred Japanese way is through steaming. 


Steaming needs to be precise even if it happens for only 20 seconds because the heat and moisture easily penetrates through the soft and thin leaves. The leaves take a quick trip to a rotary steamer, and the process is done. Steam gently cooks the leaves just enough to stop oxidation and retain the green colors, without giving it any dark, roasted flavors.   The subtleties in the process affect the final tea. 


How steam alters tea


Color is greatly affected by steaming time. The longer the steaming, the easier the leaves’ membrane breaks down during later processing; which in turn leads to a cup of tea with a cloudy color.

 

For comparison, light steaming for 20 seconds results into a clear, light green cup of astringent tea with a strong aroma; 120 seconds of special steaming will give you a cup of darkish green, full-bodied tea with a weak aroma. 


Other effects of scalding the leaves include the removal of grassy odors and other bad smells that could taint the resulting matcha further down the line. The leaves are now easier to be modified during the later stages.


Moist and a bit more flaccid than when they first started, the leaves ride the conveyor again for yet another ride, this time in columns of air.


The leaves have just been steamed, but they have yet to undergo drying and roasting to become aracha. After that, there’s still a bit more before it finally becomes matcha. The end of our journey is getting nearer