Quaker Beans And Coffee Quality

Vietnamese Coffee Exporter
Quaker Beans And Coffee Quality

What is Quaker?

Quaker is the term used to describe immature beans and therefore does not achieve the same roast and color as other beans in the same roast.

The main reason for having Quakers is unripe coffee berries in the preliminary processing. Unripe coffee cherries can be identified by color (e.g., green) or weight.

Washed coffee often has fewer Quakers than natural because the berries are in the water, so lighter Quakers will float to the surface and be skimmed off.

However, after the eggplant has been rubbed (through the depulp and dehull process), it is tough to identify the quaker in the middle of the green eggplant.

Quakers are ‘revealed’ only after roasting because they are much lighter in color than other coffee beans. Identifying Quakers after roasting is simple: more delicate colored seeds are Quakers.

To be more precise, you can use the Agtron scale (SCA’s coffee color chart) to determine. The larger the Agtron number, the lighter the coffee color.

The Mimosa seed sample below the City+ roast has color 55; meanwhile, Quakers are much brighter, usually between 60 and 70.

Quaker = defect?

The Specialty coffee industry has long classified Quakers as a defect because Quakers produce uneven roasts, resulting in a batch of coffee flavors that can be bitter and dry.

According to SCA’s coffee grading standards, one of the necessary conditions for coffee to be called ‘Specialty’ is that it must be quaker-free.

NOTE: There is still a misconception that good coffee with 80 points or more is a specialty. But the coffee grading process is not simply scoring the taste through cupping.

Normally, a 300gr coffee sample will be ‘under’ scrutiny from unroasted until after roasting and then tasting. SCA lists two groups of defects: primary defect (fundamental defect) and secondary defect ( less severe).

The primary defect group includes several significant defects such as ‘there is a foreign object in the coffee sample,’ or ‘there are full black beans (black coffee beans, the result of damaged coffee beans)’ – even just one error can enough that the batch of coffee is no longer considered ‘Specialty.’ Since the coffee sample must not have Quakers, this is an error that is considered as severe as the primary defect.

SCA lists Quakers as equal to full black has long puzzled many people. For example, when the grain is partially black or insect damage is considered a secondary defect, does the quaker affect the quality more than a grain contaminated with pests?

Does Quaker affect coffee quality?


Purpose: Taste the coffee and see if the quaker affects the taste of the coffee

Method :

– Cupping with six people, including two people from Helena coffee

– Cupping according to SCA standards. Each participant was given a cupping form with ratings for dry, wet, taste, acidity, body, sweetness, aftertaste, clean cup, and overall.

– Volunteers only know about coffee samples after the cupping is done.

Experimental sample: 4 samples of Mimosa coffee cupping (coffee lot prepared and roasted by 96B team), in which:

– A: 1 x 11g Mimosa, with 10% quaker (1.1g)

– B: 1 x 11g Mimosa, 40% quaker (4.4g)

– C: 1 x 11g Mimosa, 60% quaker (6.6g)

– D: 1 x 11gr Mimosa without quaker

  • NOTE: We only got 13gr quaker per 6kg of Mimosa eggplant (quaker ratio 0.2%). The reason for this meager ratio is that before drying, the coffee cherries have been washed and soaked in water —> unripe beans will float and be skimmed off. Then, the green fruits that do not swim in the water are picked up by hand. The beans that have been on the drying rack are mostly ripe red coffee. Before roasting, the beans are rechecked for defects. After roasting, the roaster also picks up Quakers, so you can rest assured that Mimosa from 96B is taken care of in every stage.


Unexpectedly, Quakers affect the perception of coffee, both in terms of smell and taste.

Model D is the standard Mimosa model with dry notes of tropical fruit and dried fruit; When tasting, the dry fruit and chocolate flavors are pretty straightforward, the acidity is light and bright.

With 10% quaker, sample A retains the same smell and taste as D, but the fruit flavor is softer, the aftertaste is shorter.

At 40% quaker, sample B starts to turn woody and slightly smoky, chocolate turns nutty, sour turns somewhat tart.

With 60% quaker, sample C no longer has a fruity smell but has a scent of leather, a strong smoke smell, a prominent wood and bread taste, no acidity, acrid aftertaste, and a dry mouth.

When reading the above results, many of you will probably guess that samples A and D are “delicious” coffee samples – 96B team also thinks that A has very little difference compared to D. However, some of you are very impressed with the model. C (due to the strange smell and difference from regular coffee). This little experiment shows that “good” coffee is your favorite. As I noted in the article on The scent of coffee, we cannot impose our opinion on others: the smell of leather in coffee is a defect for some people, but some people. The smokey taste of coffee for person A may be a roasting error, but for person B, it is a strange highlight.

Similarly, some people only drink washed coffee (thinking that only passed coffee will produce clean cups), but some people are very impressed with India’s Monsoon Malabar (find the rich ‘body’ and the characteristic spice of the method). This preprocessing).

Recently, a scientific paper on Quakers and coffee quality has been published. Focusing on Brazilian coffee (naturally processed), Rabelo et al. (2020) concluded that in small quantities (10% or less), Quakers did not affect the coffee taste. From 10% or more, Quakers have a very bright color (from Agtron 82.8), causing significant changes in smell and taste.

The caramel and chocolate flavors fade away as the quaker ratio increases, replaced by a “green” and dry taste. The perception of sweetness and sourness in coffee samples with more than 10% Quakers decreased sharply; Instead, it is bitter and acrid.

Based on this article, we can see that quaker does not seriously affect coffee quality with a rate of 10% or less.

The writer has personally tried a 15gr coffee sample with a whole black bean (very foul and bitter), a 15gr selection with three seeds with insect damage (bitter, acrid, dry mouth), a 15gr sample with 3–5 Quakers (not seeing much change). So is the SCA’s requirement not to have Quakers in specialty coffee too strict?


If you read some recent blogs about coffee body and aroma, you will know that the sugar groups, amino acids, and proteins in coffee beans have a direct influence on the smell and taste of coffee after roasting.

The roasting process causes the molecular structures of the above chemical groups to change (metabolized polysaccharide sugars, lost simple sugars, producing aroma complexes such as pyrazines, furans, ketones, aldehydes, etc.)

Because Quakers come from unripe coffee beans. They don’t have enough sugar (mainly sucrose) needed to convert into ketone groups during roasting ( ketone groups often have a fatty, sweet, vanilla smell).

Also, most likely, Quakers don’t have enough furan to form a ‘good’ smell complex like caramel, brown sugar, ‘sweet’ smell.

Meanwhile, Rabelo et al. found that methyl pyrazine (belonging to the pyrazine group ) was abundant in quaker coffee samples; This complex smells ‘green,’ or nutty, or bitter almond. In addition, pyridine is abundant in Quakers. Pyridinestrong, burnt, and fishy odors — this can be the critical complex in making Quakers smell so different from standard coffee beans.

So we can conclude that although Quakers are defects, with a small percentage (<10%), they do not affect the quality of your coffee much. I will continue to pick up Quakers if I see a baby that is too bright ^^,’ but maybe I won’t be looking at every gram of coffee like before. How about you?


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