Matcha Production Tencha Shading and Stone Grinding

Japan — matcha production from Song dynasty China, introduced to Japan in 12th century; Uji, Kyoto as the historical production centre; Nishio, Aichi as the largest modern producer

Matcha (抹茶) production is the most precisely controlled segment of the Japanese tea industry — a three-stage process of shade-growing, harvest, and stone grinding that transforms standard green tea (Camellia sinensis) into a uniquely nutritious, vibrantly coloured powder. The defining technique is ōishita (覆い下, shading) — a period of 20–30 days before harvest when the tea plants are covered with shade cloth or straw (kanreisha) blocking 70–90% of sunlight. The shading triggers two responses: the plant increases chlorophyll production (producing the vivid green colour and grassy, marine fragrance); and it inhibits the conversion of L-theanine (an amino acid responsible for matcha's characteristic umami and calming effect) to catechins (the bitter astringent compounds that dominate unshaded green tea). The result is a tea with dramatically higher L-theanine, lower catechins, higher chlorophyll, and consequently a sweeter, less bitter, more umami-forward flavour than standard sencha. After harvest, the leaves are steamed (to fix colour and prevent oxidation), dried, and destemmed and deveined to produce tencha (碾茶) — the raw material for matcha. Tencha is then stone-ground in granite or ceramic disc mills at extremely slow speed (20–30 RPM) to produce the fine powder — frictional heat above 40°C at faster speeds damages the aromatic compounds, so grinding must be slow, producing only 30–40g per hour from a single stone mill. Premium matcha grades: ceremonial (usucha and koicha); culinary (food-grade, for baking and cooking).

The vibrant, grassy marine sweetness of shade-grown L-theanine — a bitterness that is mild and pleasant rather than sharp, backed by an umami depth that distinguishes matcha from all other teas