Coffee roasters are responsible for the entire life cycle of coffee beans – from sourcing to roasting to packaging. This can be a challenging task but what makes this job so interesting is the fact that a good roaster understands the complex chemistry behind coffee, and apply the right knowledge to ensure that efficiency is maximized while quality is not compromised.
Coffee roasters are the very heart of the coffee business. They buy green coffee beans from suppliers and through careful roasting, turn them into the famed brown bean we all know and love. The process requires a lot of care and attention to get right, but coffee roasters are always looking for new ways of improving flavours to stand out from their competition.
Fun Fact: A coffee bean is a seed found inside the fruit of the Coffea plant. The fruit is often referred to as a cherry, although it is not related to cherries.
So how do they do it?
Growing Process
In order to know what the process of roasting coffee is, it’s important to understand the growing process. Coffee plants are evergreen perennials that bloom and bear fruit. After flowering, the plant begins to produce green fruits. These ripen to red and dark red as they mature—which usually takes several months. The fruit needs to be harvested when it is mature, but before it reaches its final colour.
Harvesting
Harvesting can be carried out by hand—a labour-intensive process—or machine harvested. There may be 3 picks a season as the cherries develop at different rates. Most regions harvest one crop a year, but some countries have two crops. The coffee harvested at the beginning and end of the season does not have flavours as well-developed flavours as the pick from the middle of the season. Thus, a good roaster will buy their coffee in mid-season.
Processing
To avoid the fruit spoiling, the cherries are processed quickly after harvesting. There are two methods of processing the cherries, depending on the location and the resources available.
- The Dry Method, also known as “natural” or “unwashed” is the ancient way of processing cherries and is carried out in locations where water is scarce. Typically, this is on smallholdings and the cherries are simply spread out on raised drying beds to let air circulate around them. They are left in the sun and left to dry for 15 to 20 days. Frequent turning and raking ensures they dry evenly and prevents fermentation. It may take several weeks for the drying process to complete—when the cherries moisture content is less than 11%. This method makes it reasonably easy to remove the outer skin and release the coffee bean.
- The Wet Method uses water to remove the skin from the cherries to extract the beans. A pulping machine squeezes out the skin. If the pulp is not removed, the cherries aren’t ripe enough and these are used to produce lower quality coffee. Pulping leaves a sticky residue on the beans (mucilage), which is dissolved by stirring the beans in large vats for 24 hours with enzymes to break down the mucilage. The beans are given a final rinse and dried for a day or so in the sun.
How are Coffee Beans Roasted?
Unroasted coffee is also referred to as green coffee and at this stage the beans have all the flavour locked in. Dried coffee beans are roasted in a rotating drum over an open flame. The green beans are heated to a constant temperature of around 200 degrees Celsius (370 Fahrenheit). During the roasting process the beans begin to lose moisture and absorb carbon dioxide. They begin to expand and the colour changes from green to brown.
This stage is called pyrolysis and gives the coffee its flavour and aroma. Roasting is light or medium roasted at this stage but to obtain a darker roast the process is continued. As the beans begin to turn from a medium to rich toast, they develop an oily sheen. Once the roasting is complete, the beans are immediately doused with cold water to instantly cool them off and stop the roasting process.
How Does Roasting Coffee Affect Flavour?
Coffee beans are rapidly brought to high temperatures by roasting them, resulting in chemical changes taking place that alters the flavour. Dark roasting coffee was carried out in the past on low-quality beans to mask a poor flavour. These days, with specialty coffee farms, dark roasting isn’t necessary with light or medium roasting enough to bring out complex flavour profiles.
However, slow roasting coffee beans does bring out more defined flavours. Mass produced coffee geta a fast roast to produce a result in about 90 seconds. This doesn’t leave enough time for deep flavours to develop and so, for example, deep roasting for 30 minutes can help to preserve the flavour of the coffee while lowering the acidic level of the beans. The level of roasting results in different flavours and aromas, which is why a good coffee roaster’s expertise is essential in producing the right cup of coffee.
Great Coffee Roasters Knows Their Beans
While the flavour of your coffee boils down to a number of factors, including the quality of the beans, the processes carried out and the equipment used, the overwhelming factor for how good your coffee is mainly due to the roaster. It takes years to be able to, for example, predict the internal temperatures of specific coffee beans when roasted to ensure they do not spoil. This is something learnt through years of experience and is as much an art as a science. A good coffee roaster can often be the difference between a good cup of coffee and a great cup of coffee.
The Bottom Line
Creating our favourite cup of Joe is an intense process that requires the know-how of a coffee roaster to develop blends with their own personality. Whether your preference is for light or dark roasts, the perfect roast is a personal choice. With so many options to choose from, it shouldn’t be long before you find your perfect match.
