Oxidation is an important part of how many traditional teas develop their character during processing. After tea leaves are handled or rolled, reactions involving oxygen and leaf compounds help change their colour, aroma and flavour.
Why tea types differ
Black, green and oolong teas can come from the same plant species, Camellia sinensis, yet be processed differently. Black tea manufacture allows substantial oxidation. Green tea processing uses heat to limit the relevant enzyme activity, while oolong production involves a more limited, controlled oxidation.
Those differences are part of the reason teas from the same species can look and taste so unlike one another. Processing matters alongside origin and plant variety.
Is oxidation the same as fermentation?
The words have sometimes been used interchangeably in tea descriptions, but they are not a precise match. Enzymatic oxidation is different from a process driven by microorganisms. Some other tea styles involve microbial changes, which is a separate subject.
For a simple first reading, think about controlled leaf processing rather than imagining that every dark tea has been fermented like yoghurt or bread dough.
What about herbal tea?
Dried herbal ingredients do not automatically fit a black-to-green-tea oxidation scale. Hibiscus and lemongrass are different plants with their own preparation histories. Calling one darker than another does not tell you how it was processed.
When reading a packet, identify whether it contains traditional tea, herbal ingredients or both. That makes descriptions such as oxidised, dried and blended easier to interpret in context.
Understanding the term helps you read tea articles more confidently without assuming all drinks called tea are manufactured in the same way.
Related reading: Herbal Tea vs Black Tea: What’s the Difference?.
Further reading: Japan Tourism Agency: processing different tea types.
Explore our free Herbal Tea Wellness Guide for more about K&M Herbs. For a product question, contact us.