Got Beans without any Provenance? Advice to a Barista.

Choosing beans by their Appearance

Let's say you are a coffee barista, or just a host making coffee for friends who arrive with some beans they picked up but can't recall any labeling details. So, you have two bags of whole beans in front of you with no provenance for either. One bag "W" has oily black beans. The other bag "D" has grey dusty beans. Both appear to be of high quality. 

From appearance and feel alone, what can you tell about the difference in origin or roasting of the beans in W and D? 

What preparation should you use for the W beans or for the D beans?

Dark or Light Roasting

Dark Roast

Bag W, with its oily black beans, is characteristic of a dark roast.

These beans have been roasted longer and at higher temperatures (typically around 430–450°F or higher), which causes the natural oils inside the beans to migrate to the surface, giving them a shiny, oily appearance. The color turns deep brown to nearly black due to caramelization and carbonization of sugars. 

Dark roasts often originate from regions like Indonesia, Brazil, or parts of Africa (e.g., Sumatran or Ethiopian beans suited for bold profiles), and they tend to have flavors dominated by smoky, chocolatey, or caramel notes with lower acidity and a heavier body.

The extended roasting can sometimes mask origin-specific nuances, emphasizing the roast itself.

Light Roast

Bag D, with its grey dusty beans, suggests a light roast.

These are roasted for a shorter time at lower temperatures (around 350–410°F), stopping just after the first crack in the roasting process. This results in a drier, matte surface without visible oils, and the color is often pale brown or greyish-tan.

The “dusty” aspect could come from residual chaff (silverskin) that’s more apparent in lighter roasts.

Light roasts preserve more of the bean’s original characteristics, so they might come from high-elevation origins like Ethiopia, Kenya, or Central America (e.g., Yirgacheffe or Costa Rican beans), highlighting bright, fruity, floral, or acidic flavors with lighter body and more terroir-driven notes from the growing region and processing method (e.g., washed vs. natural).

In summary, the primary difference is in roasting level—dark for W (bolder, roast-forward) versus light for D (origin-forward, nuanced)—rather than origin alone, though roast choice often aligns with bean varieties best suited to those styles.

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Brew Advice

Both can be high quality if sourced well, but they’ll brew very differently: W beans, the oily dark-roast ones, might suit espresso or French press, while D beans, the drier light-roast ones, excel in pour-over or drip for subtlety.

To learn more about bean roasting and coffee preparation, read one of our books on the craft.

(You may also, like us, consult your favorite GPT assist. One day soon, our kitchen robots may be our own personal baristas.)