Understanding Thermal Shock: Jhoan Vergara’s Signature Post-Harvest Process
In specialty coffee, some techniques attract attention through their name long before they are truly understood. Thermal shock is one of them. Often mentioned and sometimes misunderstood, it deserves to be placed back in its proper context: that of a precise tool serving aromatic clarity, rather than a spectacular processing trick.
At Las Flores farm in Huila, Colombia, producer Jhoan Vergara integrates thermal shock into a broader post-harvest philosophy. A rigorous approach designed to highlight the identity of each variety — especially Chiroso — while maintaining an elegant and readable cup profile.
What does “thermal shock” really mean?
Thermal shock refers to exposing coffee, at a specific moment during processing, to a controlled change in temperature. Contrary to some common misconceptions, it is neither a harsh washing step nor an aggressive mechanical treatment, but rather a short, carefully controlled phase integrated into a wider fermentation protocol.
At Las Flores, thermal shock is applied after the fermentation stages, at a moderate temperature (around 50 °C) and for a limited duration. Its primary role is to stop microbial activity, stabilise the coffee, and lock in the aromatic profile developed upstream.
The post-harvest process at Las Flores
Thermal shock only makes sense when considered as part of a complete processing strategy. At Las Flores, every step is designed as a building block serving the final cup.
For the washed Chiroso processed by Jhoan Vergara, the protocol includes:
- strict cherry selection at optimal ripeness,
- anaerobic fermentation in cherry,
- successive oxidation phases before and after depulping,
- leachate recirculation to ensure consistency and control,
- thermal shock used as a controlled stopping point for fermentation,
- carefully managed drying to guarantee stability and cleanliness.
Rather than seeking excessive or showy aromatics, this process prioritises precision, repeatability and elegance.
Yeasts, micro-organisms and fermentation control
Jhoan Vergara’s work on fermentation extends beyond thermal shock alone. Like other forward-thinking producers in Huila, he explores different microbiological approaches to improve precision and reproducibility.
On certain competition-focused or highly experimental microlots, Jhoan Vergara has used selected yeasts as a way to guide fermentation. On other coffees — such as the washed Chiroso from Las Flores — the protocol relies primarily on carefully managed natural fermentations, including leachate recirculation rich in micro-organisms native to the farm environment.
This approach allows the use of local microflora while maintaining a high level of control. Thermal shock then acts as a complementary tool, helping to stabilise the coffee and fix the aromatic profile.
How does thermal shock influence the cup?
From a sensory perspective, thermal shock is not a flavour-creating technique in itself. Instead, it functions as both a revealer and a stabiliser.
In Jhoan Vergara’s coffees, it helps to:
- preserve aromatic freshness developed during fermentation,
- limit excessive or uncontrolled fermentative notes,
- enhance clarity and definition of flavours,
- increase the perception of structure and tension in the cup.
The result is often a clean, structured and elegant cup, where floral, fruity and gently spicy notes can express themselves without heaviness — an approach particularly well suited to refined varieties like Chiroso.
A coherent vision of specialty coffee
At Las Flores, thermal shock is neither an end in itself nor a marketing argument. It forms part of a coherent set of agronomic and technical choices, all aimed at respecting the work done on the farm, the identity of the variety, and the expectations of the drinker.
This vision of specialty coffee deliberately moves away from spectacular effects, favouring instead a faithful expression of terroir, consistent profiles, and cups that remain readable in both filter brewing and light espresso.
Why should coffee drinkers care?
Understanding thermal shock also means better understanding what we taste. Behind this technical term lies a commitment to precision and restraint, in service of coffees that are cleaner, more elegant and more stable.
At a time when fermentation techniques are becoming increasingly complex, the work of producers like Jhoan Vergara reminds us that technique only matters when it remains firmly in the service of flavour.
Thermal shock is not a promise of excess, but a tool of precision. At Las Flores, it contributes to cups that are clear, elegant and deeply controlled.