What are "quakers" in coffee grading?

In the world of coffee grading, a 'quaker' is one of the most common and easily identifiable defects. During the roasting process, healthy, mature coffee beans undergo chemical changes—specifically the Maillard reaction and caramelization—that turn them from green to shades of brown. Quakers, however, do not have the necessary sugar content to undergo these reactions. As a result, they remain pale, yellowish, or light brown, standing out starkly against the rest of the roasted batch.

Quakers are primarily the result of harvesting unripe coffee cherries. When a picker selects a cherry that hasn't reached full maturity, the seed inside is underdeveloped. While modern sorting technology at the mill can remove many of these beans based on density or color, some inevitably make it through to the roaster. This is why high-quality specialty coffee producers place such a heavy emphasis on careful, selective harvesting and rigorous post-harvest sorting.

When you brew a cup of coffee that contains quakers, the impact is immediate. These beans contribute unpleasant, papery, grassy, or peanut-like flavors that can ruin the complexity of an otherwise excellent coffee. Even a small percentage of quakers in a batch can be detected by a trained cupper, which is why they are a key metric in the grading process. A 'specialty grade' coffee must have a very low tolerance for these defects.

For the consumer, finding a quaker in your bag of beans is a sign that the quality control process could have been more rigorous. While it is nearly impossible to eliminate them entirely, a high-quality roaster will often perform a final 'post-roast' sort to remove any light-colored beans that slipped through. If you find them, you can simply pick them out before grinding to ensure your cup remains clean and free of those unwanted, underdeveloped flavors.