From Crop to Cup

By Emily Oak

beans on hessian bagThe coffee we know and love as a golden or dark brown aromatic bean, starts off very differently. For coffee, from crop to cup, there is quite a complex journey and every step will affect its final flavour.

The coffee bean as we know it, is actually the seed of a cherry which grows on the tall bushy coffee tree, with the two main species being Arabica and Robusta. Arabica makes up a large percentage of the world consumption – about 70% while the more gutsy Robusta is most commonly used as a booster in some espresso blends or for making instant coffee.To get from the cherry on the tree to the bean ready for grinding, there are a number of steps that need to occur.

The first is ‘processing’ – whereby the outer layers of the cherry are removed to reveal the bean or seed inside. There are four layers that need to be removed – the skin, the flesh, the parchment and the silverskin. The way that these outer layers are removed greatly affects the flavour of the bean as the sugars can be either transferred into or out of the bean.

The skin is a thick, red or burgundy layer. Underneath, the flesh is a similar glutinous consistency to a grape or cherry. Within this still, is the parchment – a hard husk that protects the bean, similar to a peanut shell. Lastly, the silverskin is the flaky outer layer of the bean which is usually removed when the coffee expands during the final roasting process.There are two main processing methods – dry processing and wet processing.

dry processing

Dry processing is the more traditional method – where the cherries are either left on the tree to dry out or ‘raisin’, or they are removed and dried in the sun on platform beds, or in a mechanical dryer. This process removes moisture and intensifies the sugars in the bean, adding to its body and flavour. Dry processed coffees are commonly used for espresso because of this intensifying of the sugars.

 

 

 

 

Wet processing uses water and friction to remove the outer layers of the cherry  – the skin and the flesh. The cherries are soaked in large tubs and an enzymatic reaction causes the outer layers of the coffee to disintegrate, leaving the bean and it’s coating (parchment) intact. The use of water and soaking usually removes some of the sugars resulting in a softer and milder coffee bean compared to dry processed coffees. As a result, washed coffee is more often preferred for plunger or filter coffees.

 

 

  

Following this processing, the beans are dried and stored in their parchment until purchased. A good green coffee will have a shelf life of about 12 months – while it can still be used beyond this time frame, the flavour dissipates noticeably after this time. Once purchased, the hard parchment is removed with friction machinery, and it is weighed and bagged into large hessian bags ready for shipping.

From origin to port can be anything from 6 weeks to 4 months, depending on the usual factors of distance, shipping and customs. The green packed coffee is usually then delivered to a local coffee broker before moving on to a roastery somewhere.

What the roaster then does with the coffee, in terms of time of roasting, temperature, volume, air flow and heat application, also determines a large part of how the coffee will taste as an end product. Green coffees can be roasted individually as origins and then blended, or put together as a green blend to be roasted all together. From here, the packing, storage and ageing (time from roasting to drinking) of the roasted beans will also impact on the final taste.

Before coffee comes to us as a rich golden elixir or mixed with silky milk, there is a whole chain of processes that need to be delicately balanced to ensure the coffee can be as good as it should. Any break in the chain will severely affect the final outcome and destroy the promise of such a delicious experience.

Next time you enjoy your morning coffee, think how far the beans in your cup have travelled to give you those few moments of pleasure and stimulation.

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