Green coffee, that is raw, can be quality or poor, based on its organoleptic properties, therefore the pleasant taste, but also and above all for the quantity of defects present.
The term “quality” is too often used, or rather abused, without a real correlation with the coffee in question.
This term is used to describe more of a subjective aspect, that is to express whether the coffee I drank is akin to my tastes or not.
However, we should strive to distinguish subjective pleasure from objective quality.
Let me explain: a quality coffee must reflect a series of parameters and be included in internationally valid tables, established by the professional experts of the sector registered with the world coffee associations, so as to give a valid parameter to anyone, at any time and in any part of the world.
It is also normal for each of us to have our own favorite taste, but let’s remember that it is not certain that if we like it then it is necessarily of high quality.
Our tastes are personal and must remain so.
Therefore, in this article we will first understand how the classification of defects in green coffee works and then list them all.
The Classification of Green Coffee Defects
The main bodies that regulate the marketing of coffee are:
- ICO (International Coffee Organization) – which regulates relations between producers and consumers;
- ECC (European Contract for Coffee) – which defines the commercial rules for the sale within the European territories, such as the maximum humidity allowed in the beans, the maximum weight loss, the tare weight of the bags, the rules of boarding, arbitrage, etc.;
- New York & Sugar Exchange – the exchange for the marketing of Arabica coffees;
- London – the Robusta coffee marketplace.
As you can see, the quality of green coffee is not a marketing parameter!
What does it mean? A non quality coffee, although full of defects and with an unpleasant taste, can still be sold.
This is why not all the coffees on the market are quality coffees, quite the opposite.
However, there is a defect assessment table, namely the New York one, which indicates what these defects are and their severity.
In this way we can categorize commercial coffee and give it a value from 2 to 8 to understand its actual quality (NY2, NY3, NY4, …).
And remember: the classification of defects is not used to understand if you can sell coffee or not, but to understand its price: a bag with many defects will have a MUCH lower price than one without defects.
How does the classification work?
- A sample of 300 g of raw coffee is taken;
- Bean by bean is analyzed;
- Defective ones are set aside, grouped by type of defects;
- Finally, they are counted and all are added together;
- Then, looking at the reference table, a number from 2 to 8 is assigned.
The table used, as already mentioned, is that of New York:
So: if in a sample of 300 g we find a maximum of 4 defects, then NW2 is attributed to it. If, on the other hand, up to 160 defects are found in a 300 g sample, then NW7 is attributed to it and so on.
How are defects calculated? With another reference table:
In this case: if we find a large wood or stone, we have already reached a score of 5 defects, if instead we find 5 immature grains, we will have only 1 point, etc.
This is why the Roaster must be a skilled and trained selector, as it will never be possible to have a final good roasted coffee if the starting raw material has defects.
What are the green coffee defects?
Parchment beans – secondary
The beans are still covered with a thick and hard film that wraps the same. This should be removed on the plantation, before exporting the coffee, with the process called depilonatura.
If instead it is roasted, it burns, thus bringing a strong bitterness to the cup.
Black beans – primary
The bean is rotten due to a late harvest, or due to lack of water during fruit ripening, or due to excessive fermentation during the processing process.
In the cup it brings bitterness, harshness and hints of ash and fermented.
Dried cherries – secondary
The bean is still inside the drupe, that is the cherry, which should be removed on the plantation before export, during the decortication process.
If roasted it chars, bringing hints of burnt and ash to the cup.
Shells beans – secondary
The beans are concave and / or have a large internal cavity, resulting almost “empty”.
These burn before the other beans in the roaster, being thinner, thus bringing more bitterness and hints of ash and smoky to the cup.
Bianconi beans – secondary
The beans have a spongy consistency, because they have been excessively fermented due to bacteria or for prolonged storage in humid and unventilated environments.
In the cup they bring bitter and woody notes.
Moldy beans – primary
They are therefore beans infested with molds and / or yellowish spores due to excessive fermentation, too slow drying or storage in humid environments.
It is easy to guess that they will bring hints of mold and stincker to the cup.
Green beans – secondary
The beans are still unripe due to an early harvest or due to prolonged drought. It is not possible to recognize them raw, but only in the roasting phase, as they do not cook and therefore remain lighter than the others.
In the cup they bring bitterness and astringency, as well as metallic hints.
Broken beans – secondary
During decortication or depilonatura they broke.
Since these are smaller, in the roaster they burn before the other beans, bringing bitterness and hints of ash into the cup.
Malformed beans – secondary
They are beans with abnormal shapes and / or with an off-center cut, due to physiological factors during growth.
Like the previous ones, they cook at different times, always bringing bitterness and astringency to the cup.
Brown beans – secondary
The silver film, a thin skin that wraps the beans, is over-fermented, due to a delay between the harvest and processing phases, or due to excessive fermentation, or even due to the use of dirty water.
In the cup they bring sourness and acetic scent.
Insect infested beans – primary
The beans are perforated or damaged by insects, first of all the “Broca”, the typical parasite of coffee plantations. This black beetle digs into the drupe, that is the icing containing the grains, and lays the eggs inside, which once hatched emerge from the other side.
Other insects instead attack the grains during storage when badly stored in warehouses.
In the cup we will have bitterness and notes of tar, as well as an overall loss of aroma.
In Specialty Coffees there must be none of these primary defects with a maximum of 5 secondary defects!
Do you understand how important it is to use the term “quality” only when you actually have all the correct requirements in the coffee presented and sold?
In the next articles we will talk about roasting defects instead!