Why Coffee Roasting Is Both a Science and an Art: Factors That Make Every Batch Unique

If you’ve ever noticed very subtle differences between batches of your favorite roast, you’re not imagining things. Even when coffee beans come from the same origin, farm, or even the same harvest, each bag can roast a little differently. Since coffee beans are an agricultural product, it’s almost impossible to have two roasts with exactly the same quality. From the environmental conditions of the roaster to the variation between bean batches, we can fine tune each roast for maximum consistency, but ultimately there are still small taste differences when cupping between different roasts of the same coffee.

One of the biggest factors is moisture content. Beans in different bags, stored under different conditions, or even positioned differently in transport, can retain or lose moisture at varying rates. This directly impacts a roast because higher moisture beans take longer to heat up, while drier beans roast faster, potentially leading to different flavor profiles. For example, beans stored directly in jute bags have been more exposed over the past season than beans stored in a GrainPro bag. The exposure can lead to a drying time of up to a minute faster than normal, potentially leading to problems with inner bean development if not appropriately managed.

Also, the way coffee is processed at origin (washed, natural, etc.) affects how beans behave during roasting. Washed coffees tend to roast more predictably due to their cleaner profile, while natural-processed coffees, which retain more fruit and sugars, can caramelize differently, leading to unique flavors. Natural beans inherently vary more, and typically have to be watched more closely during a roast.

Even before the beans reach our roastery, how they’ve been stored and transported can impact their roasting behavior. Factors such as humidity, temperature fluctuations, and how long they’ve been in transit can subtly alter their structure. Coffee stored in high-humidity environments may reabsorb moisture, while those stored in dry conditions may lose it- both of which influence how they respond to heat.

Ultimately, these small differences are what make the craft of coffee roasting so special (and challenging). No two batches are exactly the same, and that’s part of the charm. Every cup tells the story of the farm, the environment, and the meticulous care that goes into roasting each bean.