The defects of green coffee

When it comes to green coffee, it is essential to take into consideration its quality and the defects that can influence it . However, the concept of "quality" is often used improperly, without any real correlation with the objective characteristics of the coffee itself. It is important to distinguish between the subjective taste and the objective quality of coffee. While tastes may vary from person to person, the quality of the coffee should respond to well-defined parameters established by industry experts at an international level.

sacco con chicci di caffè verdi

The coffee market is regulated by various international organizations and bodies:

  • The International Coffee Organization (ICO) plays a crucial role in promoting fair and sustainable trade in coffee globally.
  • The Specialty Coffee Association (SCA) focuses on promoting the excellence of specialty coffee and sets quality standards for the industry.
  • The Common Authority for Controls in the Coffee Sector (ECF) collaborates with producers and companies to guarantee the quality of the coffee and compliance with international standards.
  • The European Coffee Agreement (ECC) regulates the trade of coffee within the European Union. E the New York and London stock exchanges are important trading centers where the prices of green coffee are established.

These bodies play an important role in monitoring and regulating the coffee market, establishing standards and procedures to guarantee a certain quality of the coffee beans that are marketed.

sacchi caffè verde

The quality of green coffee is not a marketing parameter, which means that even if a coffee is of poor quality and full of defects, it can still be sold. Unfortunately, this means that not all coffees on the market are of high quality, but there are methods for classifying defects and attributing a value to coffee based on these defects.

The classification of green coffee defects is based on a evaluation table, such as that of New York (Arabica) or London (Robusta), which lists the defects and their severity.
For example, the New York table, used for Arabica coffee beans, ranges from NY2 for coffees with fewer defects to NY8 for those with more defects.
Likewise, the London table is used to classify the defects of Robusta coffee beans.
The Specialty Coffee Association (SCA) also identifies several defects in green coffee beans. Some of these defects include green or unripe kernels, black or rotten kernels, kernels with malformed shells or grains, and insect infested kernels.

These defects can affect the flavour, aroma and texture of the final drink. These evaluation tables allow to standardize the process of classification and evaluation of defects, providing a common basis for the operators of the sector.

The classification of defects is carried out by taking a representative sample of raw coffee and by analyzing each bean individually. Defective beans are separated and grouped according to the type of defect. Subsequently, the total number of defects is counted and a score is assigned according to the reference table. This classification process makes it possible to assess the overall quality of green coffee and determine its value on the market.

tabella difetti caffè verde - qualità caffè

When it comes to green coffee, it is essential to take into consideration its quality and the defects that can influence it.
The defects of green coffee beans can be divided into two main categories: defects primary and minor faults. Understanding this distinction is essential to evaluate the overall quality of green coffee.

1. The primary defects are considered the most serious defects and significantly affect the quality of the coffee. These defects can affect the flavour, aroma and appearance of roasted and extracted coffee. Some examples of primary defects include:

  • Mouldy grains: these are grains infested with mold and yellowish spores due to excessive fermentation, too slow drying or storage in humid environments. These beans will bring hints of mold and stincker into the cup.
  • Black grains: the grains are rotten due to a late harvest, lack of water during fruit ripening or excessive fermentation during the manufacturing process. In the cup, these grains will bring bitterness, tartness and hints of ash and fermented.
  • Insect-infested grains: these are grains that are perforated or damaged by insects, such as the "Broca", which lays its eggs inside the drupe, i.e. the cherry that contains the grains. Other insects can attack the grains during storage in inappropriate storage conditions. These beans will offer a bitter aftertaste and intense hints of tar in the cup, accompanied by a decrease in the overall aroma.

2. The secondary defects are considered less serious than the primary defects, but they can still affect the quality of the roasted coffee. These defects can have an impact on the flavor, aroma and texture of the drink. Some examples of minor defects include:

  • Grains in parchment: the grains are still covered in a thick, hard film called parchment, which should be removed during the depilling process. If the beans are roasted without removing the parchment, they will burn and bring a strong bitterness to the cup.
  • Dried cherries: the kernels are still inside the drupe which should be removed during the hulling process. If the beans are toasted with dried cherries, they will become charred and bring burnt and ash flavors into the cup.
  • Grains or shells: the grains have a concave shape and/or have a large internal cavity, resulting almost "emptied". These beans burn earlier than the others in the roaster due to their subtlety, bringing bitterness and hints of ash and smoke into the cup.
  • White grains: the grains have a spongy consistency due to excessive fermentation caused by bacteria or prolonged storage in humid and non-ventilated environments. In the cup, these beans will bring bitter and woody notes.
  • Green grains: the grains are still unripe due to an early harvest or prolonged drought. These beans do not cook during roasting like other beans, bringing bitterness, astringency and metallic hints to the cup.
  • Broken grains: during the husking or depiloning process, the grains break. Being smaller, they burn before the other beans during roasting, bringing bitterness and hints of ash into the cup.
  • Malformed grains: these are grains with anomalous shapes or decentralized cuts due to physiological factors during growth. Like broken grains, they burn at different times during roasting, bringing bitterness and astringency to the cup.
  • Brown grains: The silvery skin that surrounds the grain is over-fermented due to processing delays, excessive fermentation or use of dirty water. In the cup, these grains will bring tartness and acetic hints.

It is important to note that the presence of primary or secondary defects can vary depending on the growing conditions, the harvesting process and the green coffee processing. Therefore, a careful selection of green coffee beans, free from primary defects and with a minimum number of secondary defects, is essential to obtain a high quality and tasty drink.