So what does light, medium or dark really mean when it comes to roasted coffee?
The process of roasting coffee goes back a couple of hundred years to the original discovery by Kaldi the goat shepherd in Yemen observing his flock becoming physically excited after eating the cherries from certain types of trees.
The cherries became seeds (beans) and the subsequent evolution in "cooking" the raw coffee from pan frying, wood or coal fuels to fire the drums/vessels and into today's advanced roasting plants with extremely precise computer controls.
It has really been in the last 40 years that a more rapid level of improvement in coffee bean quality and roasting technology has resulted in significantly better tasting coffee beverages.
These improvements are at the farming level, processing, storage and transport plus the operators of roasting equipment are now more skilled with better tools to manage the batch of raw coffee inside their roasting machine.
As an industry, we are still talking about roasted coffee beans in the wrong language when the primary descriptors of roasted coffees are the old fashioned light, medium and dark roast levels.
This terminology has carrying on for a long period and conditioned consumers (the coffee drinkers) to focus their coffee bean choices or selections upon this outdated method of describing differences in the finished result of roasted coffee.
Breaking concepts down into 3 simple outcomes for roasted coffee may seem like it is easier for the coffee drinker to zero in on their preferred style of roasting, but it also introduces a lazy and inaccurate way of categorizing roasted coffees.
Coffee drinkers that prefer a dark roast generally tend to link by default association a dark roast with it being a stronger coffee taste. Similarly, those same lovers of dark roasted coffee will also view a light or medium roast as being weaker than what they would tend to prefer.
When coffee was roasted using olfactory senses - sight, sound and smell, the roasting operator employed very simplistic methods to control the roast batch. At the time, the operator was not able to see graphs or curves of the roast batch performance against known good profiles.
It was a simple way of roasting coffee and it also called for a simple way to describe the end result - light, medium or dark. There was also a limited range of coffees available which were mostly if not all blends.
With the introduction of specialty coffee and the rise of single origin coffees, roasting operators needed more intelligent controls on their machine to "see" or monitor the progress of a roast batch. These monitoring tools were combinations of thermocouple probes to read temperatures, fan speeds and graphical plot curves to record the profile of the roasting.
The modern era of coffee includes many new and different brewing methods along with a wider range of raw coffee farming and processing techniques. This creates a broad set of variables in both raw ingredients and the brewing or extraction side where the roasted coffees are consumed.
In the middle you have the roasting operator who must possess all the skills and tools to carefully transform quality raw coffee into delicious tasting roasted beans.
Dark Roasted Coffee
Generally-speaking the dark roasting of coffee is an older method and is declining rapidly in popularity. Some markets outside of Australia still persist with dark roasted coffee.
However, in Australia dark roasted coffee is limited to lower-end qualities of cheaper grades and coffee roasters would deal with the problem of lower quality by roasting the bean darker in an attempt to "burn out" the majority of defects.
Dark roasted coffees are supposed to end up with a homogenous coffee bean product with the characteristics of coffee and some elements of bitterness and ashy flavors.
The longer and hotter you roast coffee, the darker the end "colour" result and the lower the acid.
Acid is perhaps one of the most important elements to manage when roasting coffee beans. Acid can be pleasant when it is in balance, or unpleasant when it is too high or tend towards sour when too low.
Darker roasted coffee beans do not automatically mean you end up with a stronger flavour - this is a big misconception (or mistake) when it comes to a consumers' individual understanding of coffee flavour.
Flavour is influenced more by dosage levels, perfectly matching the grind setting to the correct brew and extraction and of course the temperature and brew efficiency and effectiveness - ok, that's a mouthful, but basically when you have all this right and you nail it, then the flavour is abundant.
Dark roasted coffee beans have less fruit and will also lack original character as all the fruit complexity is roasted out of the bean.
Darker roasted coffee beans may have more caramel and chocolate notes but it is not guaranteed.
The outer color (or shade) of a roasted coffee bean may also not accurately indicate whether the coffee was roasted properly. For example, if the coffee was roasted fast and hot, there could be a major difference in colour between the outer surface of the bean and the inner core. Grinding roasted coffee beans will soon enough reveal these differences.
Coffee that is poorly roasted, e.g. too fast, too slow or was not controlled accurately in the key stages of roasting cycles, may exhibit inferior taste, sweetness, body, flavor, acidity or finish.
You cannot rely upon the outside color to assume the coffee is roasted well.
Some coffee bean work better with a darker roast than others.
Typically, hard and dense beans that are washed (fully) from Central America and African beans grown at high altitude such as Kenya, Ethiopia and Tanzania can handle darker roast depths.
Soft beans from the likes of Brazil, Colombia, Peru and some Sumatrans or natural (dry or sun processed) coffees do not work as well roasted darker.
Can you see the Light?
Over the last 10 years, the trend for roast depth in Australian cafes has progressively become lighter and lighter, driven mainly by Specialty Coffee cafes wanting to push the boundaries of quality and showcase the true attributes of a specific coffee bean.
The objectives have been to preserve fruit, enhancing the character and delivering more complexity in the cup.
Lighter roasting can also avoid some of the pitfalls of ashy/bitter taints - however, that in itself can be a function of extraction efficiency - a poor espresso shot of lightly roasted coffee beans will still taste terrible - perhaps worse than a medium or dark roasted coffee bean.
Sometimes it is a religious debate in the coffee industry - the light roast brigade (sometimes referred to as "hipsters") think anything roasted close to medium will destroy the coffee.
Light roasted coffee fanatics also tend to prefer non-espresso brew methods, such as siphon, filter, cold-drip, etc. that increase the fruity aspects without the taints caused by espresso extraction.
Light roasted coffee tends to have lower levels of body - this is best described as the "mouth feel" or texture you experience.
Light roasted coffee beans also have very high acid if not extracted correctly via espresso may taste sour, grassy, woody or even bitter.
At the extreme end of light roasted coffee, to prepare a traditional milk-based beverage such as a cappuccino, latte or flat white, you would not be alone in thinking the coffee was mild, light, sweet and not entirely what you were expecting.
For this reason, the light roasted coffee beans tend to end up being used for non-espresso brew methods.
Finding that sacred Middle ground - Medium
Identifying the appropriate roast depth for any particular coffee bean is challenging.
You start out by understanding the bean's screen size, moisture levels and relative density but it's only when the coffee bean is inside the roasting chamber and you observe what is happening that you develop the knowledge required to handle the coffee.
Sometimes, the theory you apply when roasting a coffee bean may not translate into the best result when the coffee is tasted (or cupped) after roasting.
As an example, we have 4 different Guatemala coffee beans in our roastery and I've found that they each prefer a slightly different roasting profile.
There are basically two approaches you could take when roasting coffee - is it for milk, or black ? (normally referred to as espresso, but could mean other brew types). The reason we think about this choice is because the act of adding milk to an espresso changes the acid balance of the coffee.
In Australia, around 90-93% of the espresso coffees are prepared for milk to be added. This means you need to think about having some type of "positive acid" balance for the coffee.
Most of the cafe coffees I sample in Melbourne cafes when I'm out and about from other coffee roasters do not work so well as a black espresso - ristretto, short-black or even a long-black.
Why ?
One explanation is because they have got caught up in the trends for lighter roasting and may not have adapted their raw/green bean purchasing to source cleaner and higher quality coffee beans. Their traditional approaches to "roast out" defects may not be precisely matched with the green beans.
Another reason is that coffee roasters are constantly seeking sweeter and fruitier cups whilst at the same moment they are obviously not taking the time and effort required to fully understood the acid levels in the raw coffee beans they are using.
Picking a spot in the middle is difficult. Whilst most other things in life are generally regarded as "mediocre" when referring to being in the middle, when it comes to the world of coffee bean roasting, preparing something that might appeal to a broad majority is actually very challenging.
Medium roasted coffee beans are rich, smooth, creamy and will have a "bit of everything" if they are roasted and blended correctly - little bit of fruit, chocolate, caramel, nut and sweet if you extract or brew it perfectly. 9 time out of 10 when people are describing a memorably coffee, this is what they want.
We roast a larger variety of coffee beans than almost any other coffee company in Australia. We can do 15 - 25 different coffees each night, 6 nights a week. Most other coffee roasters will run just a few blends and perhaps a couple of single origins and normally they will run just 1 or 2 types of coffees when they perform a roasting session.
Our regime is extremely tough and difficult and at times I wish it was simpler - but, it has developed and bred a high level of knowledge and experience for us in how coffees are best handled.
We also map the direct feedback from the Specialty Cafes we supply, enabling us to constantly optimize our roast profiles.
Based on all the input data, feedback and references we can analyse, we have formed quite solid ideas on how to roast our coffees in the right balance to appeal to the broader majority.
Coffee does not need to be "strong" in order to appeal. Customers need to keep in mind that strength is a function of how you grind, dose and brew or extract the coffee.
The most enjoyable moments with coffee are based around a "rich, smooth and creamy" experience.
We believe this description is where our coffees are focused with an emphasis on RICH - a long finish that is persistent well after you have finished the cup.
