PART 2: What makes a great coffee?
In Part 1, we learnt about how climate, variety, harvest process affects coffee flavour. Today we discuss a few other determinants which determine the end result of your favourite coffee.
Roasting is where the flavour we are familiar with really begins to come through. Roasting the beans is so much more than just waiting for beans to change colour or hear the crack for you to know its ready to go. Coffee roasting is both an art and a science. It takes a great deal of passion, expertise, calculation and experience to master this art. Without the artisan skill, it’s very easy to mess up a batch of perfectly harvested and high quality beans. The roaster spends a great deal of time crafting a great roast profile which brings out the full potential of the beans. The roaster has to fine-tune variables like roasting time, charge temperature, air flow & cooling speed, drum speed, rate of rise, in response to certain data through sensory experience like cracks, smells and so on.
Light roasted coffee beans appear light brown colour, and have no oil on the surface of the beans. This coffee is usually light bodied and has toasted grain taste, pronounced acidity, and bright flavours.
Medium roast coffee beans have more body than the light roast. It also has no oil on the surface of the beans but it exhibits more balance in flavour, aroma and acidity. Many of the unique flavors of the coffee’s origin is preserved in this type of roast, but also has some of the sweet caramelised notes from a longer roast. Common names for this type of roast are Regular Roast, American Roast and City Roast. Medium-dark roasts are usually Full-City Roast, After Dinner Roast, and Vienna Roast.
Dark roast coffee beans has a dark brown colour in the cup. These are usually full bodied coffees, with low acidity and tends to dig deeper to extract the bean flavours. The surface of the beans is oily with the bean oils and thrives on its nutty, chocolate like and caramel flavors. Dark roasts go by many names which include French Roast, Italian Roast, Espresso Roast, Continental Roast, New Orleans Roast, and Spanish Roast. This of course inspired by different roasting profiles. Many dark roasts are used for espresso blends.
Brewing variables need to match the coffee your brewing as well as the brew method. This definitely affects the taste and flavour of your coffee.
The most important variables when brewing coffee are as follows:
Brew ratio (water to coffee) – Coffee grounds are usually around 20-22 % water soluble. So depending on the brewing method, they are stipulated and recommended times which ensure you to get a great quality delicious extraction. There is a very thin line between a great brew and a bad one. Too much extraction even by 4 seconds, can make the coffee bitter. An under extraction makes the coffee thin, weak, no body and even sour.
Grind size (and uniformity) – For the group espresso machine a fine grind (depending on blend and brewing time between, with water and coffee ratio) means more surface area of the bean is exposed to the water. Which gives us the ability experience all the flavours of the bean. For a brew method that uses a longer dwell time or less pressure such as French Press for instance, a coarser grind is necessary. Each brewing method has its own grind size and brewing time.
Extraction time – this is how long the coffee must take to brew according the brewing parameters of the specific method.
Water temperature (and quality) - water is an amazing solvent and the perfect brewing temperature is usually between 90 – 96 degrees Celsius. It should also be soft water which contains less minerals, rather than mineral rich hard water. The soft water with less soluble substance dissolved in is more capable to dissolve coffee nutrients. The hard water which already dissolved minerals within is less capable to dissolve substance in it. However there is another argument which sayings compounds in hard water tend to attach to the flavourful elements in roasted coffee beans during brewing. Water with higher levels of magnesium will likely extract more flavour from a coffee bean. Either way, both types of water give distinct delicious coffee profiles.
Another factors which affect the coffee bean taste is packaging. Beans must be packaged in a clean air tight bag in order to preserve its freshness and profile. And also kept in a dark area to avoid light. As well as the age of roasting depending on the coffee roaster. There are many more factors which play a role which we will go into in part 3.