A Simple Guide to Coffee Processing and Roasting

From Bean to Cup

OK ! so you are wondering, how does this cherry become a wonderful drink, what’s the process and as we’ve got this coffee connection going I thought that I’d outline a typical arabica’s journey from fruit to drink.

Coffee begins as a cherry fruit, ideally grown in high altitudes on volcanic soil and on slopes. It is picked of the trees very carefully because red ripe cherries can grow alongside unripe green ones. The ripe cherries are placed on a special basket that determines the weight and this incidentally is how some cherry pickers are paid. After that the cherries are sorted out and then go through a drying out phase.

The Processing Methods

Sometimes I’m asked about what makes coffee taste different from different parts of the World and I tend to go back to the processing method and what is favoured in different parts of the World. So, here, it is the low-down on preparing coffee the natural, pulped natural and washed method.

Washed: In this process, water is the emphasis and it is more common in Central and South America. The coffee cherry is brought to the wet mill where it is then pulped (outermost fruit skin is removed). Next, it is put in water with any floaters being discarded as defects. Then, the coffee is fermented (fruit mucilage layer broken down), washed to remove the remaining fruit, and then dried on a patio, raised screen bed, or by using a mechanical dryer. The parchment stays with the green bean until it is milled at the dry mill. With this process, the coffee tends to have flavor characteristics that are brighter, a cleaner cup, and a lighter body.

Natural: Natural or dry processing is the original method used for coffee that consists of more hand labor than machinery. It is more common in Africa, Asia and in Yemen, whereby the beans are laid flat on a special drying mat, turned over many times a day to dry naturally in the sun for about 3 weeks, after which the husks are removed and beans sorted. There are higher risks of defects due to handling, drying, and hand-sorting. Once the cherry is dried, it turns into a dark brown pod that is hard to the touch; the green seed is taken out, leaving the other layers behind. Because this process is so hands on and the defects can only visibly be accounted for, there is large room for error; greater chance of defects, taints, and a lack of uniformity in roasting in cupping occurrences. While there is more room for error, natural processed coffees tend to have more body and lower acidity than their washed counterparts and they tend to keep much of the body and earthy flavours as well as fruitiness, however this can tend to be dirty if not done properly.

Pulped Natural: During this process, the skin is removed from the coffee cherry, leaving the fruity mucilage intact during the drying process. The machinery used to eventually remove the mucilage is either pulped or taken off by forced demucilage equipment. Pulped natural coffee can have more body and lower acidity than the washed process, and a cleaner, more uniform cup than the natural process.

Honey Process: With this environmental friendly method, popular in Costa Rica, the skin and pulp are removed and then dried with the mucilage layer still left on the parchment. A lot of farmers prefer this, because it is like in between the natural and wet process in that the cherry dries with so e of it’s body naturally but you only use a little water to remove the mucilage at the end. It is called honey because when the cherry only has its mucilage on it, it has a honey like consistency. They tend to possess a lot of sweetness, balanced acidity with fruity undertones.

Which method is better ?

With washing or wet mill although the bean might be cleaner in taste, it might loose some of its more distinctive “earthy” tastes. In the end it comes down to a matter of taste and some experts prefer to mix clean washed coffees with natural dried coffees to get a blend of exotic and clean sweet tastes. 

In any case, whether the bean dries naturally or is wet processed, the beans have to be washed to get rid of any unwanted fruit – this eventually leads to the “green” bean which are then sorted and graded – bad beans are discarded and good beans tend to be uniformed in colour and shape.

Top exporting countries take the sorting and grading process very seriously as this is where you earn and maintain your reputation. The green beans are then packed into brown sacks and shipped across the world. On arrival the green beans are sent to specialist roasters and sometimes you might see some specialist shops just selling green beans or for decoration.

The Roasting and Blending Process

The next process is the most crucial as the coffee has to be made for consumption – this is the roasting process. The roaster or person who roasts the bean is a very specialized profession and a slight mistake can ruin a coffee roasting company. Master roasters have been doing this for many years and just know how each type of bean should be roasted to get the best flavour. Basically each green bean is different and can contain over 200 types of tastes – as the bean is roasted it goes through many transformations and chemical processes. An expert roaster will know how a particular bean should be roasted in order to get the best taste.

To make you more confused, there are many types of roasting methods and different types of roasts, each with its own advantage and disadvantage, but again it depends on the experts and the type of coffee you buy and on how you want to drink it. Naturally there is controversy.

In summary, the darker the roast, the more you lower acidity but the more you loose out on the best tastes in the coffee – now remember that high acidity in coffee is what experts like. Acidity in coffee doesn’t mean you get heartburn as these acids are the good ones. Darker roasts also tend to be more oily and not great as an espresso as they tend to be bitter.

In America, darker roasts seem to be in vogue, especially with the majors like Starbucks – darker roasts are complementary with milk based drinks, like caffe lattes. However, some experts believe that darker roasts make you loose the best tastes in coffee. From a marketing point of view, it has been suggested that darker roasts are easier and don’t require too much effort by a roaster, but also they conjure the image that the coffee is strong and only for the brave – now who doesn’t want to tell people that they only like strong coffee, despite it being filled with 60% to 70 % of hot milk. Outside America, darker roasts are favoured in southern Italy and France. You can tell a proper darker roasted coffee by the presence of oils on the beans. In any case, for some beans, you may be able to get a better taste when it is roasted more darkly.

 Some connoisseurs however prefer medium roasts as they maintain acidity and still let you taste all the wonderful tones in the coffee. For espresso lovers, you may not get that dark reddish crema, but you will still get crema with a a wonderful taste lining your mouth. Medium to dark roasts are popular in northern Italy and by followers of the now retired espresso expert, David Schomer of Espresso Vivace, Seattle.

 

We can even go further to what is called a cinnamon roast, favoured in some parts of America. This roast is much lighter and of course those who favour this type of roast stress that coffee roasted like this brings out the more delicate tones of the coffee. 

In the end, if you are lucky enough to live in a city where you can get different types of roasts of different types of beans from across the world then experiment and choose the best for your palate and type of coffee.

 When it comes to blending different types of coffee, there can be more confusion.

A traditional espresso blend usually has Brazilian as a base because it has a nutty taste, an Ethiopian coffee for its fruitless and a Costa Rican for its acidity. However, a good roaster or coffee source can get these taste profiles in just 2 coffee and sometimes a single origin.

Again, I encourage experimentation, which I tried once with Costa Rican Tarrazu and Brazilian Mogiana – lots of crema and a rich taste. If you do try blending, make sure you try and use equal proportions of the coffee you want to blend – this is best done by weighing the beans equally. Some other expert blenders now mix Arabica with robusta beans – the reason ? Robusta can produce more crema but of course it is bitter, however, it will look good.

 The Italians love to do this and often have a ratio of between 10-20 robusta added to arabica beans. Most specialist roasters and coffee shops have their own blends for sale, which are often used by the cafes they supply.

Also, some blends are good for espresso only drinks and some are better for milk based drinks.

Nowadays, although not that popular, there’s the concept of the OMNI roast – where a roaster will roast in a way that can be drank nicely for both espresso and filter/pour over coffee drinks.

I’ve only had two occasions where I enjoyed an OMNI roast – Brazilian Capao by Square Mile, London in 2010 and a coffee roasted by Emirati Coffee, UAE in 2018.

I encourage experimentation until you get what is best for you.

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