Coffee Types & Coffee Strength Explained
Types Of Coffee Strength
Every day we receive a request from a customer asking for something like.........
"There is a particlur type of coffee I want, it is a strong black coffee, give me the strongest one you have!"
Whether it's a call that has come through on our 1300 number or a preference stated in the Roaster's Choice comments field, there are quite a few members out there belonging to the "Must Be Strong" or "hit me with a hammer" coffee club.
Let me try to explain what this means in terms of coffee types and how it can become confusing for many coffee drinkers.
At a technical level, strength is defined as the actual caffeine content on a particular amount of coffee. Over a long period of time people have tended to refer to strength as being a higher, or "stringer" flavour. Unfortunately, there can be many different distinctions between these meanings.
The first myth we will bust here is the strength rating......It really does not exist at the point of coffee bean grading. I can't ring up the raw coffee broker and ask to buy "strong" coffee beans. It's just not how coffee beans are classified, categorized or purchased. Strong is not a type of coffee.
A Dark Roast Doesn't Mean Stronger
Roasting darker leads to reduced acid, increased bitter and ashy taints, and a shorter shelf life (a smaller optimal usage window). That is not what strong is about, unless of course what you are really trying to say is you like (or are accustomed to) a lot of "bite" (some bitter taints) in a coffee.
Dark roasted coffee is not strong. It just has a rougher edge and a dirtier cup. This is what some people are accustomed to in their coffee drinks.
There is a point when roasting coffee where the maximum "clean" development of the coffee exists, and then it just goes downhill. Think of toasting bread and leaving it in too long, that's dark roasted coffee.
Roast depth is also very highly subjective. What one person calls dark, might be medium to another person.
Acids are the pathways for flavour. When you roast the acid out of coffee, it becomes boring, lacklustre, sour, mild, weak.
So what creates "strength" in a coffee, let's look at caffeine content first.
Robusta And Arabica Types Of Coffee
You may already know there are two primary types of coffee beans that are grown around the world. These are Robusta and Arabica. In each type of Robusta and Arabica, there are many varietals.
Unfortunately for poor old Robusta, the marketing of coffee in Portugal (ironically by the players at the bottom end of the quality scale in the market), has tried to brainwash consumers into believing robusta = bad. This means therfor that arabica = good.
Robusta is grown at lower altitudes and tends to be more resilient to pests and adverse weather conditions. Therefore, the yields can be higher, but the prices paid are lower. Countries like Vietnam, India and Uganda are the main producers of the Robusta coffee type.
In terms of coffee strength, robusta can possess up to 3 times the caffeine compared to Arabica. This is another reason it is used for instant coffee and energy drinks. It sure packs a payload alright. Please do not try drinking a 100% robusta espresso double shot!
Robusta coffees are cheaper, although I'd have to say that in 2019 with a shortage of robusta in the global market, it's now a more expensive proposition compared to a few years ago.
Some of the old-school roasting companies love robusta and they just can't shake the habit of relying upon robusta's heavier payload of body. It's always a given that Robustas will be used in Italian coffees (in ratios from 15% to 50%), to enhance the Italian coffee bean espresso crema and tame acid level. Also to provide a lower-cost filler in the blend for the cost-competitive Italian commercial offerings.
That's Italian coffee for you, built to a low price to suit the domestic Italian market that cares about only the price per kilo and nothing about the taste.
A lot of Portuguese Industrial Coffee Roasters (Supermarket suppliers, old school cafe suppliers, etc) still use robusta today for "kick and crema". This is something that is technically unnecessary with advanced roasting platforms and readily available high quality raw coffees. Yet some habits die hard.
Robusta coffees can have a "burnt rubber", tar or woody flavor in the cup. Even the best grades of Robusta have something that is not entirely clean, pure or sweet compared to quality arabica.
Types of Coffee - Arabica
Arabicas have lower yields compared to robusta so farmers receive higher prices for smaller crop volumes. But there are also risks of the delicate arabica plants being damaged by pests, frosts, drought, etc.
Arabicas are grown at much higher altitudes and therefore are hard, dense beans with higher acid. It is this acid we find very enjoyable in Australia for our steam milk-based espresso drinks (think Latte, Cappuccino, Flat White, etc.).
Given that caffeine levels of most arabica coffees are reasonably similar, what is it that gives us the "flavour" in a cup of coffee?
Coffee flavour is an oil that is extracted when the perfect balance of heat and high pressure are applied during the brewing stage.
The ability to correctly extract the most oil, is the result that ends up with greater levels of flavour.
Fear not, this is a very complex and difficult dynamic to manage. Even the best baristas who worked in coffee shops for a long period, can struggle with this from time to time.
It does not matter what type of brewing method you are using - espresso, stovetop, filter, plunger - the whole equation is influenced by variables such as grind, dose, temperature, time, etc.
The most common problem we find every day is grind and dose for domestic espresso machines, and the issues relating to under and over-extraction.
The Correlation Between Grinding Settings & Coffee Flavour
The #1 fault I see most frequently with home espresso environments is a failure to adjust the grind to suit the coffee bean/blend.
Most home users just leave their grinder at the same setting all the time.
Of course, this depends upon the capability of your grinder (some have very big steps between settings and others have micro-fine adjustment and others have very small range of adjustment if they are automatic machines).
As a coffee ages, the grind required and dose for the best extraction changes.
Typically, you would need to make fine adjustments every couple of days.
Of course, you can cheat by a slightly higher dose level.
When you open a new pack of coffee, the pressure inside the bag is different to the atmosphere. This means the beans will behave differently for the first few hours until they equalize the oxygen balance.
If the grind is too coarse, or the dose too low (remember that grind and dose work together and against each other), the espresso will "gush", and the shot is completed in a short time (less than 20 secs for example).
This is commonly referred to as "under-extraction". The coffee is weak, thin, lacking flavour, body and sweetness, with varying levels of bitter notes.
An under-extracted coffee has low levels of flavour and you will notice the crema is likely to be very pale. It may also dissipate very quickly.
This is a weak coffee and is not the fault of the coffee beans or the roasting, but caused by the extraction being incorrect.
When the grind is too fine, or the dose and tamp too high, the coffee may over-extract, or pour very slowly, or "choke".
The coffee can be burnt because it has come into contact with the hot water for too long.
Typical notes of over-extraction are baked flavours, sourness, bitter taints, lacking sweetness, dark oily marks on the surface of the crema.
The colour of the crema may also be pale with darker oily stains on the surface.
When you get the extraction right, the flavour can be wonderful.
The crema will be a rich yellow/brown/orange colour and the cup will have body, sweetness and of course flavour.
Coffee types for non-espresso brew methods, such as filter, plunger, etc.
It is very important to have the correct ground type to suit your apparatus. It is also very important for the accurate level of dose, and brew time to enable the appropriate level of coffee oils, or flavour, to be released.
Once you master and adapt your brew and extraction techniques to suit the coffee, then you can look at coffees with higher natural levels of flavours if you have a preference for more taste.
The 10 Coffee Types With The Highest Flavours
Origin or Bean
Clean, intense, citric, winey with a long finish
Dark berry, bold body
Powerful classic coffee flavour, chocolate notes, massive body and long persistent finish
Dark chocolate and cocoa with a swiss chocolate finish.
Strong blueberry and long choc-chip cookie finish.
India mysore nuggets
Wild berry, lemon and citrus notes, high acid
Strong toffee and caramel
Heavy caramel with red berry mid-palate
Spicy, massive body, pawpaw and papaya, very sweet, long finish.