Thermal shock is a post-fermentation technique developed in Colombia, most associated with the producer Diego Samuel Bermúdez.
The method
After a controlled fermentation, the coffee is washed first with hot water — around 40 °C — and then immediately with very cold water, near 10 °C.
The abrupt temperature change is said to arrest fermentation cleanly and to affect how the remaining mucilage and the bean’s cell structure behave.
What it produces
Unusually clean intensity: pronounced fruit and floral character without the funk that long fermentation often brings.
That combination — intense but clean — is what has made the technique influential, and it now appears on competition tables regularly.
Why it costs
Heating and chilling large volumes of water at a farm is expensive and requires equipment most producers do not have. Lots processed this way are priced accordingly.
The wider point
Thermal shock is part of a broader shift: coffee processing has moved in fifteen years from a handful of traditional methods to an experimental field borrowing openly from winemaking and food science.
Whether that is progress or a distraction is genuinely contested within the industry.
Brewing it
Filter, very light roast, clean brewer, good water.