Welcome to Zarza, from Colombia, your latest special release coffee! Our first time working with producers Jhonatan Gasca and Alejandra Muñoz Ortiz, this delicious anaerobic natural Variedad Colombia lot showcases their innovative approach to processing. The result is a beautifully balanced, complex coffee that demonstrates how meticulous attention to detail can enhance cup profile.
Below, our Green Buyer Jamie Isetts shares more about this multi-step process in detail and the influence it has on the final cup profile.
In the first half of the calendar year, we often showcase the evolution of the Colombian coffee industry. Though brand new to our filter selection this season, Zarza weaves into this broader story. Producers Jhonatan Gasca and Alejandra Muñoz Ortiz’s careful, multi-step natural processing creates a cup that reminds us of pineapple, passion fruit, and blueberry.
Zarza Coffee - the name of the Gasca family’s farming and production enterprise - represents a class of farmers we’ve seen more and more in Southern Huila over the last decade. These are producers who meticulously control both the physical process behind their stunning lots, and the abstract marketing of their product and brand. Coffee from Zarza came under the spotlight when 2025 World Barista Champion Jack Simpson used an anaerobic natural Papayo variety from Zarza as part of his winning routine, having competed with another Zarza lot the year before.
This particular lot uses only Variedad Colombia, a disease-resistant cultivar developed by Colombia’s coffee research institute, Cenicafe. The output of this plant varies, but it’s generally considered a “normal” flavour profile without the caché or specificity of speciality darlings like Chiroso or Pink Bourbon. As part of purchasing this lot via importer Cata, we received in-depth detail of the steps used to create this profile - Zarza Coffee’s own processing does the heavy lifting to create this lot’s complexity. Text in italics came directly from the suppliers.
Harvesting
“Manual selection of fully ripe, high-brix cherries”
A Brix Meter is a light refractometer that measures the total dissolved solids available in a sample of coffee cherry juice. This can be connected to a higher availability of sugar for fermentation, but it is necessary for each producer to conduct this process for themselves. Other producers we work with who use this tool take a Brix reading from a representative sample of coffee cherries, then calibrate alongside the touch, colour, and consistency to provide guidance for their picking team. Both human and mechanical metrics contribute to a producer identifying “ideal ripeness.”
“Hand sorting and flotation to remove underripe and damaged fruit”
Visual and density sorting are powerful tools at every stage of the production of speciality coffee. Hand-sorting, though labour-intensive, allows a meaningful identification of damaged fruit, which can have an impact on fermentation. Floating is a simple way to remove any cherries that are less dense than water and often contribute cereal-y and diluting flavours to the cup.
Fermentation Process
“Whole-Cherry Oxidation (Initial Stage, Open Environment): The cherries rest in an open environment for a brief oxidation period, allowing natural yeasts to activate and increasing complexity before controlled fermentation.”
This initial, open-air stage of cherries resting en masse allows naturally occurring microorganisms to establish a culture within the lot.
Extended Whole-Cherry Fermentation
“The cherries undergo an extended natural fermentation, favouring wild microbial activity that enhances winey, fermented fruit, and cacao-like notes. In a sealed or semi-sealed environment, the focus shifts to development of alcohol/fermented aromatics, black-tea-like structure, and deep sweetness.”
At this stage, Zarza takes the wild microorganism culture from the initial oxidation and controls it within the cherry mass by sealing it off to oxygen and monitoring temperature. These two factors are critical to the pH and rate of fermentation; important in maintaining consistent microbial activity and preventing over-fermentation, whilst enhancing the lot’s character.
Drying Process: Slow Natural Drying on Raised Beds
“The cherries are dried under controlled sun exposure for 20–30 days, depending on climate. Regular turning prevents mold, while slow dehydration concentrates sugars and preserves fermented complexity…Once reaching 10–11% moisture, the dried cherries are rested in grain-pro bag conditions for 10–20 days, allowing the profile to stabilise before milling.”
Drying and stabilisation are some of the most important factors in determining the shelf-life of the complexity created by all of the previous steps. As in roasting, Rate and Pattern make a huge difference in the outcome of drying. Since almost all coffee dries in a non-climate-controlled environment, controlling these factors requires keen adaptation of the process to the climate at that moment. With patience, luck, and discipline, good drying can make the coffee more expressive further from the time of harvesting. As with many things, the last 10% determines the difference between a great and an exceptional cup profile.
Resting the dried cherries before milling homogenises the moisture and water activity within the lot. GrainPro is one of several brands of specialised storage bags for coffee, cocoa, and other products that limits exposure to external oxygen and moisture with a one-way barrier. All of Square Mile’s green coffee shipments from origin are lined with this type of bag, but producers like Zarza use them for resting parchment or dried cherry, as well.
The milling process - removing the dried layers of cherry skin and hull from the seed - is somewhat rough, since it uses pressure and friction. This generates heat, making the water molecules in the seeds more energetic, and encourages more movement between the cell membranes. The more gentle and evenly distributed this movement can be, the higher the consistency and greater the retention of precursors to volatile aromatic compounds in the final coffee. Deciding when to mill is all about finding the sweet spot between a rested, even lot, freshness from harvest, and shipping and logistics timelines. It is an art in itself.
Though we’re new to working with this producer, we’re certain that these details of process only scratch the surface of their ethos for cultivation, processing, and export. This focus comes together in Zarza’s cup profile: decidedly tropical and sweet, with a refinement and consistency that is hard to achieve with extended fermentation.
A standout anaerobic natural that stopped us in our tracks; so that it can be shared as widely as possible, Zarza finds its home in our 175g bags. Get yours here.
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