At some point, an abnormally pale bean may emerge from a coffee roaster.
That light coloured bean is not under-roasted, it is a quaker. Typically found in natural coffees, quakers are immature beans that do not contain enough sugars to caramelise during a roast.
They are particularly difficult to identify during hand sorting and green bean inspection. As a result, they are often only discovered during a roast.
If too many quaker coffee beans end up in a bag, it can impact the flavour, typically resulting in a dry cup with papery and cereal notes.
The Specialty Coffee Association (SCA) requires coffee to be free of defects – including quakers – in order to be considered specialty. However, given it takes a significant number of quaker coffee beans to affect the final cup, is it worth roasters removing them?
To learn more about quaker coffee beans, I spoke with three-time barista champion, Nicole Battefeld-Montgomery.
What are quaker coffee beans?
Quaker coffee is the term used for a faulty – most commonly under ripe – coffee bean.
They are commonly, but not always, caused by poor soil conditions that inhibit the coffee cherry’s development.
This affects the maturation of sugar and starch, which give the bean its desired flavours. As the cherry receives insufficient nutrients, it is immature, unripe, and under-developed.
“The flavour of a quaker is very underdeveloped,” says Nicole, who is also a roaster and SCA trainer. “Like a green banana, it tastes extremely dry and sharp. Almost chalk-like, and sour like an unripe plum. They can make a nice coffee taste sharp and unbalanced.”
Alongside immaturity, there are three additional ways a bean’s sugar can be compromised. Each results in a different type of quaker that will impact the cup in different ways.
A quaker caused by an immature coffee bean is the most common, and is often referred to as a tame quaker.
These can muddle a coffee’s taste and reduce the cup’s quality if there are a number of tame quakers in a roast. That said, their impact is considerably less severe than other quaker types.
Those caused by insect or microbial attacks are called “stinky” or “defective” quakers. As their name suggests, these quakers can give coffee an unpleasant, rotten flavour. This is because they often contain mould, fungus, or bacteria.
The final fault in beans is under or over roasted quakers. These are caused by issues during a roast, for instance, when a bean gets stuck in the roaster.
Depending on where it is stuck, this could mean the bean is kept at either a significantly high or low temperature. These beans will appear much lighter or darker than the rest of the batch, making them easy to identify.
Why is quaker coffee a problem?
While quaker beans are often labelled as a roast defect, the problem usually occurs at origin.
However, spotting a quaker bean is much easier after roasting due to its comparatively lighter colour. This characteristic colour is caused by the nature of quaker coffee beans’ flaws, rather than them being under roasted.
In addition to lacking the typical deep, sweeter flavours of defect-free coffees, quaker beans are known to have a dry, ashy and papery mouthfeel.
Numerous studies have been done to identify the impact quaker beans have on a cup. Some specialty professionals suggest they can bring more fruity notes and actually have a positive effect. However, the general consensus is that quaker beans usually have a negative impact on the cup.
SOVDA coffee took 100 quakers beans from an Ethiopian Natural grade two coffee. After grinding and analysing the beans, they found that fewer than ten of these beans had positive aromas.
Furthermore, researchers found that by eliminating all quakers, naturally processed coffees can gain a clarity that brings out less muddled fruity flavours. A few quakers in a cup can affect the coffee’s cupping score, but four or more immature beans will have a statistically significant impact.
As the SCA requires specialty coffees to be completely free of quakers, it is advised that roasters remove them.
What can roasters do to avoid quaker coffee beans?
Quaker coffee beans are most commonly found in naturally processed coffees.
This is because, during the water processing method, faulty beans float to the surface of the floatation tank. This allows producers to remove any potential quaker beans from the rest of the crop.
In comparison, the sun-drying method of the natural process involves sorting the beans by hand. As quaker coffee beans have little or no visual distinctions, they can be difficult to spot.
As a result, it is not uncommon for them to be missed during inspection. Therefore, roasters working with wet processed coffees have less cause for concern.
“Unfortunately, quakers often go hand in hand with natural processed coffee,” Nicole says. “So, if you want to make sure you have a quaker-free coffee, you will have to sort the coffee post-roasting.”
One of the best ways roasters can reduce the number of quaker coffee beans in their product is to educate the farmers they work with.
“Stinky” quaker beans have the most impact on coffee. However, these are often the easiest to spot as the cherries usually have holes in the fruit where the insect has eaten its way in. Or the fruit will be rotten, which suggests a microbial attack.
Roasters can help coffee farmers understand how to identify this defect and why it is crucial they are removed.
Additionally, roasters should explain how this extra effort will also benefit farmers. By removing these defective beans, they can increase the cupping score and overall grade of their coffee crop, allowing it to be sold at a higher price point.
In reality, one or two tame quakers may have little effect on the cup, and some over roasted beans may slip through the net. The best thing roasters can do is stay vigilant and remove any quaker coffee beans they see.
That said, Nicole suggests roasters remove quakers manually or invest in specialist equipment.
“Bigger companies use lasers to detect the light coloured beans, and air to blow them out. Or, roasters can hand-sort the lighter coloured beans.”
By working with farmers to prevent stink quakers tainting their coffee crops, roasters can help keep this risk to a minimum.
At MTPak Coffee, we have a dedicated Education Centre to help those in the specialty coffee sector learn more about effective roasting techniques, sourcing green beans directly from origin, and more.
Additionally, we work with roasters around the world to provide sustainable packaging services that range from concept and design to manufacturing, printing, and delivery.
Our range of high-quality recyclable, biodegradable, and compostable packaging options will preserve the freshness of your coffee and showcase your commitment to sustainability. You can also include additional recyclable components, including degassing valves and resealable zippers.