An Introduction to Green Coffee

Before a coffee makes its way into your cup, it is grown, harvested and processed in its country of origin. It is during this time that the coffee’s intrinsic characteristics and personality are formed. The relationship between the coffee’s variety, terroir and processing shapes its sensory attributes. This is the most important stage of the coffee’s journey.
  • Definition – Simply put, coffee is the seed of the coffee cherry fruit. After flowering, it takes an average of nine months for the cherry to ripen before it’s picked.

 

  • Varieties – There are many different coffee varieties, each with their own distinct attributes relating to taste and texture. The yield and disease-resistance of each variety also varies. Bourbon, for example, is known for its balanced and sweet cup profile and for being low yielding. Caturra on the other hand, is known for having a higher acidity profile and being higher yielding.

 

  • Terroir – A coffee’s attributes are also influenced by the soil, temperature, sun exposure, rainfall and altitude of the area in which it is grown. Most volcanic soil, for example, has a greater level of sulphur, which can contribute to a more complex cup profile. Coffees with a longer maturation period, due to higher altitudes and lower average temperatures, tend to produce a denser bean displaying higher acidity.

 

  • Selection – One of the most integral parts of the coffee journey is the selection of uniform ripe cherries and the elimination of defective and unripe cherries

 

  • ProcessingThere are two main processing methods, unwashed and washed:

 

Unwashed (natural) – The ripe cherries are picked, sorted and ideally left to dry on raised beds over a period of several days. During this time, the mucilage on the cherry dehydrates and its sugars are absorbed by each seed. This process is known for producing coffees with greater body, intense sweetness and dried fruit flavours.

Washed – The ripe cherries are picked, sorted and pulped to remove the skin from the outside of the coffee seed. The seeds are then placed in fermentation tanks for anywhere between 12 – 48 hours until the mucilage has been removed. When fermentation is complete, the seeds are moved onto raised beds to dry for between 7 and 14 days. This process is known for producing coffees with higher acidity and greater complexity of flavour.

  • Dry MillingAfter processing, the coffee is dry milled. Through applied pressure and friction, the remaining layers of outer skin, parchment and silverskin are removed. They are then sorted by colour, density, screen size and the removal of defects.

 

It’s important to remember that coffee is harvested annually and as such is a seasonal product. Each coffee has an optimal usage cycle and should be roasted within 8-12 months of harvest. The storage and transportation of the coffee beans strongly influences the quality and longevity of the final product. Ideal storage conditions include a stable environment where the coffee is sealed in GrainPro bags and temperature and humidity are maintained at approximately 24 degrees Celsius and 60 degrees relative humidity.

Next time, we’ll look into the roasting process and the impact it has on your espresso experience.

Paul Bassett
World Barista Champion