The good ones go in the cup, the bad ones go in the trash! There are a number of defects in coffee beans that make them unsuitable for roasting. For example, Quaker. In the industry, this is the term for unripe, undeveloped coffee beans that cannot be roasted properly. These are usually caused by unripe green coffee or by infestation by insects or microorganisms. How these beans affect the cup profile, how often you find them and much more about this coffee defect can be found here.
What is a Quaker?
A quaker is an underdeveloped coffee bean. Either because the coffee cherry was picked unripe or for other reasons such as pest infestation etc. These beans are unripe beans that have a higher concentration of amino acids and a lower concentration of sugar. The beans are considered a defect in the coffee. To be considered premium coffee, for example, there must not be more than three quakers per 300 g of coffee beans . They are easier to detect in the washed processing than in the natural processing.
How do you recognize them?
This coffee defect can be recognized primarily by its appearance. If the cherries are unripe, they will simply be green. If they are not ripe for other reasons, it is more difficult. They are easier to detect with wet processing. They are noticeable as floaters, i.e. floating coffee cherries, because the cherries with ripe, developed beans sink. With dry processing, it is more difficult to detect these defective coffee beans, as this can only be done visually or manually: Here you can only detect them if you look very closely. In this form they already have a slightly shriveled surface and a very shiny, almost too green color. Another way of detecting them is with automatic density separators, such as those from Oliver. Otherwise, Quaker beans can be easily distinguished from other beans, especially after roasting, as you cannot really roast them.
What happens to quakers when roasted?
Since they are usually unripe coffee cherries, they are most common in countries where the coffee is harvested by machine , such as Brazil. Here, however, it also depends more on the sorting. You can also buy green coffee based on existing defects, thus reducing the risk of quakers, if you often buy well-sorted coffee with few defects. Furthermore, because they are difficult to find before roasting, these defective beans are more likely to be found in naturally processed coffee than in washed coffee. With the natural method, the flesh of the coffee cherry is not removed after harvest. Instead, the whole coffee cherries are dried. They have to be turned frequently so that they do not over-ferment and no pockets of moisture or rot can form. Lower quality unwashed coffee in particular, where the cherries have not been turned frequently enough, can have a higher proportion of quakers.
How often does this happen?
Since Quakers are usually coffee cherries picked when they are unripe, they are most common in countries where the coffee is harvested by machine , such as Brazil. Here, however, it is more a matter of sorting. You can also buy green coffee based on existing defects, thus reducing the risk of coffee defects if you often buy well-sorted coffee with few defects . In addition, because they are difficult to find before roasting, Quakers are more likely to be found in naturally processed coffee than in washed coffee. With the natural method, the flesh of the coffee cherry is not removed after harvest. Instead, the whole coffee cherries are dried. They must be turned frequently to prevent them from over-fermenting and moisture pockets or rot from forming. Lower quality unwashed coffee in particular, where the cherries have not been turned frequently enough, can have a higher proportion of defects.
How does Quaker affect taste?
Not positive. However , a negative effect on the taste depends on the amount of croakers in the roasted coffee. The more unripe beans a coffee contains, the poorer its quality. This poor quality is mainly shown by a kind of dryness in the mouth, the so-called astringency, which the coffee then leaves behind when drinking. The more croakers the coffee contains, the stronger this dryness. An unpleasant peanut aroma is also produced by these unripe beans. In some cases, when the defects are caused by pests or fungi, even a single defective coffee bean can ruin an entire pot of coffee. These coffee beans usually taste like mold, fungi, plastic/rubber or phenol/medicine.
Study on Quakers and taste
Mariane Rabelo, from the University of Lavras in Brazil, conducted a study to show how much Quakers affect the taste in the cup. She put together a group of trained Q-graders and had them brew and taste several samples of the same coffee with an increasing percentage of Quakers. Rabelo distinguishes between three categories of Quakers: the classic, the brownish-yellowish and the brownish. Surprisingly, the brownish Quakers had no significant effect on the taste of the coffee at any threshold. The brownish-yellowish and classic, on the other hand, led to a noticeable increase in astringency and bitterness and a decrease in sweetness. But this effect was only noticeable at a proportion of 9 percent. This means that the likelihood of a bad coffee in the cup due to Quakers is very low.
Out or not?
Well, as discovered in the study, the Quakers have to make up on average just under 10 percent of the ground beans to have a negative impact on taste. So if we assume a double espresso with 19 grams and a weight of 0.2 grams per coffee bean, around 100 beans would have to be used for a double espresso. A good ten of these beans would have to be Quakers for the espresso to go bad. And these ten beans would be easy to recognize, as they remain quite light even after roasting. These defective beans are also easy to recognize among roasted coffee beans because of their slightly wrinkled and dried out surface. And then you could sort them out by hand before grinding. So should you sort them out or not? Yes, if you come across defective coffee beans, you're always on the safe side if you sort them out. But that doesn't mean that you should be suspicious of every bean that is slightly lighter.
P.S .: If so many defective coffee beans (9 percent of the weighed amount) fall out of the pack when weighing, then I would definitely contact the roaster and have a serious talk.
Quakers aren't that common?
Well, quakers occur primarily in natural processing and in countries where coffee is harvested with machines. But the most common influencing factor is quality. With inferior or very cheaply produced coffee, nobody cares how many defects there are among the coffee beans. With high-quality coffee, it is different. For example, this is almost certainly a rare occurrence at our partner Community Coffee Rwanda . There, beans are sorted by hand several times before processing/preparation. This is also done by many other coffee producers with high quality standards. So it is very unlikely that defective coffee beans will reach roasters like us if you buy from high-quality farmers and without middlemen. And it depends on the purchase of green coffee; if you buy cheap and therefore less well-sorted coffee, there may be more quakers. If, on the other hand, you buy more expensive and therefore higher-quality green coffee, the likelihood of quakers is very low.
Conclusion
Quakers do occur, it is almost impossible to prevent it. The better you buy, the higher the probability of being free of Quakers. For example, you will hardly find any or none at all in our coffees . Our farmers have already sorted out any potentially defective beans in the green coffee, as we make sure to buy very high-quality green coffee. And if an unripe bean does slip through, it will be discovered and removed after roasting at the latest. And in the very unlikely event that you discover one or more defective coffee beans in a pack of coffee bought from us, you can simply remove them. Or leave them in, because as Mariane Rabelo's study has shown, Quakers only make themselves noticeable in terms of taste when they make up just under 10 percent of the beans. So one Quaker bean in just under 100 beans (for a double espresso shot, that's around 95 beans) is certainly not noticeable. But you don't have to take any risks, so get rid of the unripe ones if you find any.
