Some green tea appears yellow because of compounds called thearubigins, which are formed during oxidation of polyphenols.
While green tea is intentionally processed to minimize oxidation (unlike black tea), a small amount of oxidation can still occur, leading to the formation of thearubigins. Thearubigins are responsible for the yellow color, and in larger amounts, the brownish-red color found in black tea. Here's a more detailed breakdown:
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Minimal Oxidation in Green Tea: The key difference between green and black tea is the oxidation process. Green tea production aims to halt oxidation as early as possible, usually through steaming or pan-firing the leaves.
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Polyphenols: Green tea is rich in polyphenols, especially catechins, which are antioxidants.
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Formation of Thearubigins: Even with careful processing, some oxidation of polyphenols can occur. This oxidation converts the catechins into thearubigins.
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Color Change: The presence of thearubigins results in a yellow hue. The more oxidation, the more thearubigins are formed, and the darker the yellow becomes, potentially leading to a brownish-red color if oxidation is excessive.
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Other Factors: Other factors that can influence the color of green tea include the specific cultivar of the tea plant, the growing conditions, and the processing techniques used. However, thearubigins are the primary reason for the yellow color.
In summary, the yellow color in some green tea indicates a slight amount of oxidation where polyphenols are converted into thearubigins.
