Bruising (Yaoqing)
Bruising, or yaoqing, is the repeated shaking or tossing of withering oolong leaves to damage their edges and trigger partial oxidation, building fruity and floral aromas.
Definition
Bruising is the step that makes oolong an oolong. In Chinese it is called yaoqing (摇青, shaking the green) and is part of a longer process called zuoqing (做青, making the green). After a short sun wither and some indoor withering, the leaves are tossed in large bamboo trays or rotated in bamboo drums. The movement knocks leaf edges against each other and the container, breaking cells along the margins. Shaking alternates with resting. During each rest, the damaged edges oxidize and moisture moves from the stems into the leaf. The maker repeats the cycle several times over many hours, often through the night, judging progress by smell and by the color of the leaf margin. The traditional ideal for many oolongs is "green leaf with red edges" (lü ye hong xiang bian): a mostly green leaf with a reddened, oxidized border. Bruising intensity and timing set the oxidation level and much of the aroma. Light bruising suits floral Tieguanyin and Taiwanese high mountain oolong. Heavier work builds the fruit and honey notes of Wuyi rock tea and Dancong. When the aroma is right, the leaf goes to kill-green to stop oxidation.
In Depth
Reading the wet leaf: after brewing, spread an oolong leaf flat. Reddish-brown edges or spots with green centers show bruising. Heavily oxidized oolongs show more red; very green oolongs show only faint margins. Machine-processed, lightly oxidized modern Tieguanyin often shows almost none.
Aroma link: many of the floral and fruity aroma compounds in oolong, including linalool and other terpene-derived volatiles, form or are released during this stress-and-rest cycle. That is why an oolong can smell of orchid or peach without any added flavoring.
Terminology: in black tea, the equivalent cell damage comes from rolling or CTC cutting, which are far harsher and push the leaf to full oxidation. Bruising is deliberately partial. Too much bruising, or bruising that runs too long, pushes an oolong toward a flat, black-tea-like cup.
See Also
- Oolong Processing
- Tea Processing