Why do we have number ranging in the supermarkets from 1 to 5, dots increasing in a neat line or different shades of colour to identify what strength a bag of coffee is?
Surely strength is made up from the how much coffee is dissolved in the liquid. Take for example a nice gin and tonic, if you have a shot of gin in a pint of tonic it’s going to be weak? Now let’s take a shot of tonic and a pint of gin – strong eh! Every diluted beverage is the same whether it’s a cup of freshly brewed loose leaf tea, a refreshing orange squash or a pint of shandy – it’s all about the ratio to get the correct balance for the perfect drink.
When producing coffee (espresso or filter) not all the coffee bean itself can be dissolved into the liquid. In fact, only around 30% of the bean is dissolved hence being left with wet soggy coffee grounds once the liquid has been removed. Now within this 30% that will get dissolved, only around 20% approximately is what we want to go into the cup. This is your caffeine / strength.
No-matter how you brew the coffee, no matter how much liquid is used you can only ever get the same amount of extracted caffeine from the coffee bean. That’s just life and chemistry, no magic
What we can control are the other elements to get the best flavour. Water to coffee ratio as mentioned earlier with my G&T analogy, an excellent quality water and filtered where needed, the amount of time the ground coffee sits in the water, the correct water temperature and even down to the correct grind size for the chosen brew method ( Espresso, cafetiere, v60, chemex , or a pour over for example all should have different particle size) all these variables will have an impact on the extraction being either weak or strong.
The wonderful taste coffee gives us is dependent on its country of origin, the process used in its harvesting, the blending by the expert roasters and the physical process of roasting. Roasting brings out the flavour and aroma, and as a rule the darker the roast the more pronounced the bitterness will be with the least acidity in the finished drink.
If it’s a dark roast or a light roast it still has the same amount of caffeine which can be extracted so when our supermarkets are mentioning strength I feel this mostly referencing the roast profile i.e. a mild, a medium or a dark roast. The coffee descriptors will give you what you should expect in the cup.
As a guide to growing areas, South America’s (Costa Rica, Guatemala, Honduras, El Salvador and Nicaragua) tend to be described as having a clean and bright taste, natural acidity, well-balanced and with a mild to medium in body. Colombia, Brazil, Ecuador and Bolivia make up much of coffee growing countries in South America are often very mild-bodied, whilst being a light, clean cup, these coffees are also a bit creamier, often with a slight chocolaty aftertaste.
Brazilian coffee can vary in profile from spicy and rich to mild and fruity but great blended for filter coffee’s
The Africans – complex & bold that is generally described as sweet, fruity and floral. with the most popular roasts coming from Tanzania, Ethiopia, Kenya, Uganda, Rwanda and Burundi.
Asia – earthy, and full-bodied
Ultimately, it’s a personal choice, just like having a shot of tonic in a pint of gin. Strength guides on supermarket packaging can be a bit misleading.