Inside a regular coffee cherry with no defects, you’re expected to find two seeds, with their flat fronts facing inwards, and their round backs facing outwards. The seeds of the coffee cherry are what is removed, processed, and roasted for consumers to enjoy i.e. coffee “beans”.
Peaberries are estimated to make up to around 5–10% of a harvest. They occur as a result of a natural mutation, or defect, inside a coffee cherry, where one ovule fails to pollinate. This results in extra space for the single developing seed. Within this space, a larger and rounder seed grows inside. This is a peaberry.
Not all one-seeded cherries can be defined as peaberries, as it’s possible for only one regular, flat-sided seed to develop inside a cherry.
It’s sometimes believed that because the single bean of a peaberry does not need to share nutrients between two separated beans, it has a superior flavour profile.
It’s commonly said that peaberries can offer bright acidity, sweetness, and concentrated and complex flavours in a cup. Roasters report higher levels of density in peaberries. But with very limited research having been done on peaberries, it’s hard to say if this evidence is the result of the peaberries’ unique growing conditions or simply that the lots in question are high-quality ones, perhaps grown at high altitudes or cool temperatures.
A peaberry’s quality is affected by the same variables, such as variety, processing method, and altitude, as regular coffee beans
The reported characteristics of peaberries such as bright acidity, sweetness, and complexity of flavours will, of course, be tasted in regular coffee beans
the round shape of peaberries make them roll better in the roasting machines, especially the drum roasters”
good beans to practise with during roasting.
However, there are a few things to watch out for. Birdie suggests that peaberries can “have a relatively earlier and lower volume (sometimes even unnoticeable) first crack”, which therefore requires acute attention during this time in roasting. Carlos emphasises that because of the peaberries’ shape, roasters need to be aware that the heat from the roaster may “take longer… getting to the centre” of the bean.