Coffee is a natural product. And therefore the same coffee can taste different every year or every harvest. There are also many different types and varieties of coffee: which means that the size of the coffee beans also varies greatly. And this raises the question of whether the size of the coffee bean has anything to do with the quality of the coffee or not. We'll take a closer look at the beans and everything that has to do with size.
The Size of Coffee Beans – Genetics
There are many environmental conditions that affect the size of a coffee bean. But no environmental factors can override genetic makeup. What we mean by this is that the botanical variety of coffee plays a dominant role in the size of the coffee beans. For example, Maragogype beans are the largest in the world and Mocca beans are the smallest. And then there is also the difference between varieties: let's take the two most important varieties for the world market, Arabica and Robusta. Arabica varieties produce larger coffee beans than Robusta. The two types also differ in their appearance: Arabica beans are more elongated and oval than the often almost round Robusta beans. And the crack on the flat side is also clearly different. In Arabica coffee, it is curved and often takes the shape of an S, while in Robusta it is straighter.
The size of the coffee beans – climate
But of course the climate also has a big influence on the size of a coffee bean. Because coffee is - like apples, grapes and coconuts - a natural product. And to be precise, coffee beans are not beans, but the seeds of coffee cherries. And these can rarely be grown homogeneously. In other words, a coffee plant can have all stages of ripe fruit at the same time, as well as larger and smaller cherries and cherries that have absorbed more or fewer nutrients. That is why green coffee is pre-sorted by size before it is sold. The so-called screens and screen sizes are used for this. But more on that later.
The size of coffee beans – varieties
Let's briefly return to the varieties. Each variety has its own average size. The largest coffee bean mentioned above, the Maragogype or elephant bean, is 16 to 24 millimeters long and 12 to 16 millimeters wide. This makes it a good 40 percent larger than other Arabica beans. And the mocha bean from Yemen is the smallest commercially used one. The size says nothing about the quality of the bean - at least when you compare different varieties.
The size of the coffee beans – is it a quality indicator?
If you take beans from just one variety and want to determine the quality, the size of the beans can certainly say something about the quality. However, the size of the coffee beans alone is not the only quality characteristic. The Speciality Coffee Association, for example, classifies coffees based on a much wider range: such as size, color, density and also defects. So let's take one variety again and concentrate only on the size of the bean. In this case, the large beans are most likely better than the smaller ones. The main thing is that they have simply received more nutrients.
The size of the coffee beans – be careful when roasting
The size of the coffee bean also plays a role in roasting. Only beans of a similar or even the same size should be roasted together. If the difference in size is too significant, the small beans will already be burnt when the large ones are well roasted, or the other way around, the large ones will not be developed when the small ones are ready. This would lead to an unbalanced or even very bad coffee.
But we don't sit there and sort 60 kilograms of green coffee by hand and a ruler - green coffee is already pre-sorted according to screen size - i.e. bean size. For us as roasters, this only plays a role in blends, where we mix different green coffees. As an end consumer, you will rarely come into contact with beans of different sizes - in one package. Unless you buy your coffee from a roastery that does post-roast blending, where the individual varieties are roasted separately and then mixed. You can find out more about blends and why blending is used here.
The size of the coffee beans – screening
Sorting the green coffee beans by size is called screening. This comes from the screens that are used for this purpose. These sieves have holes through which the coffee beans can fall or not. The diameter of the holes is always given in 1/64 inch, i.e. just under 0.4 millimeters. Sieve sizes range from 8 to 20. The most common sizes on the market are 15 to 18. A sieve size of 8 corresponds to a coffee bean with a diameter of around 3.2 millimeters, and with sieve size 20 we already have just under 8 millimeters.
The size of the coffee beans – the measuring method
The harvested coffee is first sorted through the coarsest sieve and then through the next smallest until the beans no longer fall through the sieve. So if a coffee bean falls through a size 18 sieve but no longer through a size 16, it is assigned a size 18. This method of measurement is not perfect, however, so a certain degree of deviation is to be expected and also permitted. How accurate the sorting is depends, for example, on whether the beans are shaken through vibrating sieves or through sieves that only move back and forth, that rotate or that are cylindrical. There is also the manual method, which is more precise, but also much more time-consuming. The Speciality Coffee Association turns a blind eye to size deviations of up to +/- 5 percent.
The size of the coffee beans – the designations
Although almost everyone uses the same measuring method, the designation of size varies from country to country. In the coffee industry, there are terms such as shell, small, medium, large and very large. In Central America, the names are a little more creative, but you have to know what size the terms mean. Here the beans are called (from small to large): Caracolillo, Caracol, Terceras, Segundas and Superior. In Africa and India, the largest beans are called Elephant and the rest only have letters like AA, C or TT. And in Colombia it is similar to Central America, except that the sizes are called Supremo.
The size of the coffee beans – the Peaberry
Let's use an example to show why size can, but doesn't have to, say something about quality. The pearl bean, also known as a peaberry, is an example of this point. The pearl bean is a mutation of nature in which, instead of two coffee beans with flattened sides, only one round, pearl-like coffee bean is formed in the cherry. This can happen in up to 10 percent of cases with all varieties of all types.
Many coffee lovers see peaberries as a speciality, even though many coffee farmers don't bother to sort them out. This is often done by hand, which is a laborious process. This alone makes the peaberry special. But it is also true that all the nutrients - which are normally divided between two coffee beans - end up in just one. They are said to have fruitier aromas, which makes the coffee sweeter. And despite their intensity, they are said to produce a wonderfully smooth coffee.
The size of the coffee beans – Conclusion
Bigger does not always mean better! There are large and small coffee beans out there, and variety, roasting and preparation have a far greater influence on your cup profile than the bean size. If you compare beans from just one variety (or perhaps a batch), then the size may say something about the difference in quality - but it doesn't have to, because the pearl bean, for example, is also relatively small and still very good. When comparing different varieties, size plays absolutely no role: the small mocha bean is available in top quality, as is the large Maragogype. And your own taste is much more important anyway. And that's how you should choose your coffee, not based on the size of the beans.
