Roasting coffee is just like cooking. You need to follow a recipe if you want any semblance of consistency.
If only it were that easy.
We all know how food can taste totally different even when we follow a recipe to the T (or so we think).
So, what is the recipe for coffee roasting and how do we ensure and measure consistency in our roasts?
At Compound Coffee Co., our recipe consists of a roast log with various roast data as a measure of quality control. It includes these factors:
- Bean Moisture Content, Pre & Post-Roast.
- Batch Size Pre-Roast and Weight Loss Post-Roast
- Whole Bean Agtron Color & Ground Agtron Color
- Master Roast Profile ( Time vs Temperature Graph )
- Cupping and Cupping Notes
Impact of each measure:
Bean Moisture, Pre-Roast: Once the coffee arrives at our warehouse, we immediately measure the moisture content of the coffee across multiple samples. This helps us to establish the baseline and starting moisture of the coffee. Over time, we continue to measure the coffee to see how the moisture content changes as the coffee ages. Significant changes to the moisture content accompanied by changes in the final taste signals a need to tweak the roast profile.
Bean Moisture, Post-Roast / Weight Loss Post- Roast: As coffee is roasted, most of the moisture in the bean is evaporated and there is a resulting moisture/weight loss. Multiple organic acids and various other chemical compounds are also broken down. Generally, the more the coffee is roasted, the larger the moisture and weight loss. An inconsistent moisture or weight loss from batch to batch could indicate possible errors with the roast consistency.
Batch Size: The batch size affects the heat transfer within the drum roaster. The ratio of convection currents: drum surface area:coffee beans mass in the roaster could result in a very different tasting coffee even if the other measures are closely followed.
Agtron Color (Whole Bean): The Agtron color is a measure of the caramelization of sugars and development of certain acids and chemicals within the bean. A Proprietary scale by Agtron, this measures the roast degree from the outside of the coffee bean.
Agtron Color (Ground): A better gauge of the true Agtron color; measuring the roast degree when is the coffee is ground allows the roaster to also measure the inner coffee bean’s roast degree instead of just the outside of the bean.
Roast Profile: Probably the most important part of roasting recipe, a Time / Temperature graph documenting the relationship between the temperature of the bean over time throughout the roast. In this graph, the red line represents the environmental temperature (temperature of the air in the roaster). The blue line represents the bean temperature (combination of the air temperature and the surface temperature of the coffee beans). Some graphs can also include the air pressure / air flow within the drum and the gas (heat) profile of the roaster’s gas burners.
Cupping: Absolutely the most essential step among all of the quality control measures. Tasting the coffee after the it is roasted is the most important as all the other measures could be the same but just like a recipe, following it does not guarantee the exact same taste every time. Ultimately it is still essential to taste the final product and ensure that it tastes as intended. At Compound Coffee Co. we have specific cupping notes and flavour profile for each coffee. Coffees which fail to meet our specific standards do not get served.
Consistency with our coffee roasts is one of the things we are obsessed about at Compound Coffee Co. Anything less would be an injustice to the coffee farmers and producers, who put in so much hard work to cultivate such amazing coffees. We also view consistency as a duty to our customers, who trust us to provide them with fresh and perfectly roasted coffee, every single time. Do you know of other ways which coffee professionals ensure consistency with their coffee roasts? Let us know so we can include them in our routines!
PS: You can also check out some of our coffees at our online shop.