Quakers in Coffee
Coffee quality is a complex interplay of factors, from origin and varietal characteristics to processing methods and roast profiles. However, one often overlooked element that significantly impacts cup quality is the presence of under-developed coffee seeds, referred to as "quakers." While seemingly innocuous, quakers can negatively affect the sensory profile of roasted coffee, leading to undesirable flavors and aromas.
What are Quakers:
Quakers are underdeveloped coffee seeds lacking the full spectrum of sugars and starches, which causes them to roast differently than fully developed beans and prevents them from developing the same Aroma.
They are challenging to detect in green coffee due to their similar physical appearance. However, after the roasting process, quakers reveal themselves as bright yellow or lighter brown beans that stand out from the rest of the batch.
Some quakers are not so simple to detect. They are on a spectrum, with some beans having more nutrients than others. This makes it difficult to manually sort them as it would require a meticulous approach to look at individual beans and test them for the known peanut aroma.
How do they affect Cup Quality: The presence of quakers significantly detracts from the sensory experience of coffee. These immature beans contribute to several undesirable characteristics:
Lower Sweetness: Fewer Sugars in the Quaker lower the overall perceived sweetness of a cup
Astringency: A harsh, drying sensation on the palate that leaves the mouth feeling parched.
Lower Mouthfeel: Lower Sugar Content leads to less Maillard reaction, making the beans less soluble. This leads to a lower TDS and Mouthfeel.
Peanut Aftertaste: Quakers typically leave an unpleasant peanut flavor that overpowers the rest of the bowl or cup.
Optical Sorting Technology:
The rise of optical coffee color sorters has provided a solution for addressing the challenges posed by quakers. Like our Pearl Mini, color sorters utilize high-definition cameras and pre-programmed parameters to differentiate between desirable and undesirable beans. A controlled puff of compressed air then ejects the identified quakers, leaving behind a cleaner and higher-quality batch of coffee beans.
Benefits of Optical Sorting:
Increased Efficiency: Compared to manual sorting, optical sorters significantly increase processing speed and reduce labor costs, allowing roasters to focus on roasting.
Enhanced Consistency: The machine's precise sorting removes quakers with remarkable accuracy, ensuring a consistent cup quality for every batch of coffee roasted.
Elevated Flavor Profiles: By eliminating quakers, roasters unlock the full potential of their coffee.
Problems with Optical Sorting
While Optical Sorters are incredibly powerful tools, they have an incidental downside: carryover. Carryover is a good coffee that has been rejected. This mostly happens when a good coffee bean is right next to a defect being shot out–as the air hits the defect, it can also catch a good coffee bean.
Decent color sorters have carryover rates of less than 20%, meaning that out of 1000g of rejects, there will be 200g of good coffee. Out-of-the-box machines can have carry-over rates as high as 50% or more, meaning one or more good beans are rejected for every defect!
To learn more about how SOVDA avoids high carryover rates, read our article here about SOVDA’s commissioning service:
Quakers are a significant, often accepted, factor affecting coffee quality. Their presence negatively impacts your cup, and removing quakers can dramatically improve quality!
