Unlike traditional green tea, matcha preparation involves covering the tea plants with shade cloths before they’re harvested. This triggers the growth of leaves with better flavor and texture, which are hand selected, steamed briefly to stop fermentation, then dried and aged in cold storage, which deepens the flavor. The dried leaves are then stone-ground into a fine powder.
Sejak (세작; 細雀; lit. "thin sparrow"), or dumul-cha (두물차; lit. "second flush tea"), is made of hand-picked leaves plucked after gogu (20–21 April) but before ipha (5–6 May). The tea is also called jakseol (작설; 雀舌; lit. "sparrow tongue") as the tea leaves are plucked when they are about the size of a sparrow's tongue. The ideal steeping temperature for sejak tea is 60–70 °C (140–158 °F).
Shade grown: All matcha is made from shade-grown tea leaves—a labor-intensive process where tea bushes are protected from the sun and light is filtered to the bushes in a very controlled manor. Shading boosts the chlorophyll production in the plant, giving the leaves a rich green color. The lack of sun reduces the plant’s photosynthesis of the leaves, which in turn alters the naturally occurring levels of caffeine, flavanols, sugars, antioxidants, and theanine. By controlling the sun exposure, tea producers can significantly alter the chemical make-up and flavor of the final tea leaves.