Shading

Shading fundamentally alters tea leaf chemistry by manipulating the balance between amino acids and catechins. In full sunlight, the amino acid L-theanine synthesized in the roots and transported to the leaves is rapidly converted to catechins (which produce bitterness and astringency) through photosynthesis. By blocking 70-95% of sunlight with covering materials, this conversion is suppressed: L-theanine accumulates to levels three to five times higher than sun-grown tea, while chlorophyll increases to compensate for reduced light, producing intensely green leaves. The three major shaded Japanese teas differ by shading duration: kabusecha (covered tea, 7-10 days), gyokuro (20-30 days), and tencha/matcha (20-30 days). Traditional honzu shading uses reed and straw canopies, while modern methods employ black synthetic fabric. The investment in shading materials and labor contributes significantly to the premium pricing of these teas.