Why We Choose a Medium Roast.

At Copala, medium roasting is not a compromise between light and dark. It is a deliberate choice.

Our coffee is grown on our family estate in Zambia’s Copperbelt. By the time the beans reach the roaster, their character has already been shaped by the variety, soil, altitude, climate, ripeness, harvesting, and processing. Our job is to develop that character—not roast it away.

For us, the ideal medium roast creates developed sweetness, a rounded body, and pleasant acidity while allowing the coffee’s individual character to remain clear in the cup.

Developing Sweetness and Aroma

Green coffee does not yet have the aroma most people recognise as coffee. That aroma develops during roasting, when heat triggers a complex series of chemical reactions.

Amino acids react with compounds formed from sugars through what is known as the Maillard reaction. Together with the thermal transformation of sugars, these reactions create many of the aromas associated with caramel, cocoa, toasted nuts, and freshly baked foods.[1,2]

A very light roast can preserve delicate fruit and floral notes, but it may not develop enough sweetness, body, or roast-derived aroma for the flavour profile we want at Copala.

As roasting continues, sweetness-associated aromas and body develop. Taken too far, however, the coffee begins to lose some of its more delicate character as bitter, smoky, and burnt flavours become increasingly dominant. Sensory research generally associates darker roasting with greater bitterness and lower perceived acidity, fruitiness, and sweetness.[3,4]

Medium roasting gives us the balance we are looking for: enough development to create sweetness and body, without allowing the flavour of the roast to overwhelm the coffee itself.

Preserving the Character of Our Estate

A coffee’s flavour begins long before it reaches the roaster.

Its variety, growing environment, altitude, ripeness, and post-harvest processing all influence the chemical composition and flavour potential of the bean.[5] These factors can contribute floral, fruity, nutty, spicy, or chocolate-like characteristics.

Roasting does not simply reveal these flavours. It transforms them.

Lighter roasting tends to preserve more of the coffee’s bright, floral, and fruit-like qualities. As the roast becomes darker, the flavour increasingly shifts towards compounds created by the roasting process itself.[3,4]

At Copala, we want you to taste where the coffee comes from. A carefully developed medium roast allows the character of our Zambian estate coffee to remain recognisable while adding the sweetness, body, cocoa, toasted-nut, and caramel-like aromas that make the cup rich and satisfying.

The roast should introduce you to the estate—not erase it.

What Happens to Coffee’s Antioxidants During Roasting?

Flavour is our first reason for choosing a medium roast, but roasting also changes coffee’s naturally occurring antioxidant compounds.

Coffee beans contain chlorogenic acids, often abbreviated as CGAs. These plant compounds belong to the broader family of polyphenols and contribute significantly to coffee’s measured antioxidant activity. They are sensitive to heat, and research shows that their concentration generally decreases as roasting becomes darker.[6]

That does not mean roasting simply “destroys all the antioxidants.” The chemistry is more interesting than that.

As chlorogenic acids decline, roasting also creates new compounds. Among them are melanoidins—the brown, high-molecular-weight compounds produced mainly through Maillard reactions. Melanoidins contribute to coffee’s colour and body and can also display antioxidant activity in laboratory tests.[7,8]

The result is a balance between compounds retained from the green bean and new compounds created during roasting. Different studies and antioxidant tests do not always produce identical results, but the overall pattern is consistent: darker roasting causes greater losses of chlorogenic acids, while lighter and medium roasting preserve more of them.[6–8]

In one study, antioxidant capacity reached its highest level around the light-to-medium range in most of the laboratory assays used.[7] Another found a general decrease in antioxidant capacity as coffee was roasted more slowly and to darker degrees.[8] Research on brewed coffee has also reported greater radical-scavenging activity in medium-roasted coffee than in green coffee, followed by a decline at the dark-roast stage.[9]

Compared with dark roasting, medium roasting generally retains more of the coffee’s original chlorogenic acids while still developing antioxidant-active melanoidins.

For Copala, that fits naturally with our roasting philosophy. We apply enough heat to develop sweetness, aroma, and body, but we stop before unnecessary roasting begins to strip away more of the bean’s distinctive flavour and naturally occurring compounds.

Is Light Roast Too Acidic?

Not necessarily. Acidity is an important part of good coffee.

In a well-roasted cup, acidity can taste bright, crisp, or fruit-like, with qualities reminiscent of citrus or berries. Many excellent light roasts are intentionally designed around this style.

However, controlled sensory studies generally find that lighter-roasted coffee has greater titratable acidity and stronger perceived sourness than darker-roasted coffee.[4,10] Titratable acidity measures the total amount of acid that can react in the beverage and appears to predict perceived sourness more reliably than pH alone.[10]

Research following coffee throughout the roasting process found that titratable acidity generally reached its highest level around first crack and then declined as roasting continued towards second crack.[11]

This helps explain why a lightly developed coffee can taste brighter or, in some cases, sharply sour. Additional roast development generally softens that intensity while increasing sweetness, body, and roast-derived aromas.

Our aim is not to remove acidity. It is to place it in balance. Copala’s medium roast retains enough acidity to give the cup freshness and structure while developing the sweetness and body needed to make it rounded and approachable.

Does Dark Roast Mean Low-Quality Coffee?

No. Roast colour alone cannot tell you the quality of the green coffee.

A high-quality bean can be intentionally dark-roasted to produce an intense, smoky, bitter-sweet, or traditional espresso profile. Many coffee drinkers genuinely prefer that style.

However, heavy roasting does make the flavour increasingly roast-driven. Darker roasts are generally associated with stronger bitter, smoky, burnt, and roasted notes and lower fruit and acidity intensity.[3,4]

As those flavours become dominant, differences created by origin, variety, growing conditions, and processing become harder to perceive. The roast begins to speak louder than the bean.

That is not what we want for Copala. We have been involved in the coffee from the estate to the final roast, and we want the work completed at every stage to remain present in the cup.

We are not trying to hide our coffee behind the roast. We want the two to work together.

Balance Is Our Objective

There is no single roast level that is scientifically best for every bean, brewing method, or coffee drinker. Personal preference will always matter.

For the coffee we grow and the experience we want to offer, medium roast is our preferred point of balance:

Bright, but not sharply sour.

Sweet and full-bodied, but not burnt.

Developed enough to be rich and approachable, while still preserving the character of its origin and more of its naturally occurring chlorogenic acids than a dark roast.

That is why Copala roasts to medium—not as a middle ground, but as a deliberate expression of our coffee.

References

1. Obando, A. M., and Figueroa, J. G. “Effect of Roasting Level on the Development of Key Aroma-Active Compounds in Coffee.” Molecules 29, 4723 (2024). https://doi.org/10.3390/molecules29194723

2. Hu, G. et al. “Effect of Roasting Degree of Coffee Beans on Sensory Evaluation: Research from the Perspective of Major Chemical Ingredients.” Food Chemistry 331, 127329 (2020). https://doi.org/10.1016/j.foodchem.2020.127329

3. Münchow, M. et al. “Roasting Conditions and Coffee Flavor: A Multi-Study Empirical Investigation.” Beverages 6, 29 (2020). https://doi.org/10.3390/beverages6020029

4. Liang, J. et al. “Sensory Analysis of the Flavor Profile of Full Immersion Hot, Room Temperature, and Cold Brewed Coffee over Time.” Scientific Reports 14, 19298 (2024). https://doi.org/10.1038/s41598-024-69867-6

5. Amalia, F. et al. “Gas Chromatography/Mass Spectrometry-Based Metabolite Profiling of Coffee Beans Obtained from Different Altitudes and Origins with Various Postharvest Processing.” Metabolomics 17, 69 (2021). https://doi.org/10.1007/s11306-021-01817-z

6. Moon, J.-K., Yoo, H. S., and Shibamoto, T. “Role of Roasting Conditions in the Level of Chlorogenic Acid Content in Coffee Beans: Correlation with Coffee Acidity.” Journal of Agricultural and Food Chemistry 57, 5365–5369 (2009). https://doi.org/10.1021/jf900012b

7. Smrke, S. et al. “How Does Roasting Affect the Antioxidants of a Coffee Brew? Exploring the Antioxidant Capacity of Coffee via On-Line Antioxidant Assays Coupled with Size Exclusion Chromatography.” Food & Function 4, 1082–1092 (2013). https://doi.org/10.1039/C3FO30377B

8. Opitz, S. E. W. et al. “Understanding the Effects of Roasting on Antioxidant Components of Coffee Brews by Coupling On-Line ABTS Assay to High Performance Size Exclusion Chromatography.” Phytochemical Analysis 28, 106–114 (2017). https://doi.org/10.1002/pca.2661

9. Sacchetti, G. et al. “Effect of Roasting Degree, Equivalent Thermal Effect and Coffee Type on the Radical Scavenging Activity of Coffee Brews and Their Phenolic Fraction.” Journal of Food Engineering 90, 74–80 (2009). https://doi.org/10.1016/j.jfoodeng.2008.06.005

10. Batali, M. E. et al. “Titratable Acidity, Perceived Sourness, and Liking of Acidity in Drip Brewed Coffee.” ACS Food Science & Technology 1, 559–569 (2021). https://doi.org/10.1021/acsfoodscitech.0c00078

11. Anokye-Bempah, L. et al. “The Effect of Roast Profiles on the Dynamics of Titratable Acidity During Coffee Roasting.” Scientific Reports 14 (2024). https://doi.org/10.1038/s41598-024-57256-y