Let's begin with a coffee bean lesson. When coffee fruit hangs on a coffee tree it is referred to as a coffee cherry. The coffee cherry typically contains two seeds. In a typical coffee bean both sides are fertilized and two coffee beans grow to a fruit, flat against each other like halves of a peanut. (See image above bottom right)
On a rare occasion, about 5% to 10% of the time, only one side of the coffee bean is fertilized and this is how you get a peaberry coffee bean. Basically, without the other coffee bean growing against it, the fertilized seed grows into a rounded bean (See image top right) These coffee beans are referred to as peaberry coffee beans, while the normal coffee beans are referred to as flat berry coffee beans.
Peaberry coffee is considered a natural mutation of the coffee bean inside its cherry. The peaberry coffee beans aresmaller, denser, and rounder than regular flat coffee beans. Although you may hear that Peaberry Coffeebeans are found in certain geographical locations, the truth is, peaberry coffee beans are found in every coffee growing region, so the distinction is solely on anatomy. This variation can happen in both robusta coffee beans and arabica coffee beans.
It is impossible to tell a coffee bean is a peaberry coffee bean until after it is picked and processed. Once picked and processed these lovely round peaberry coffee beans need to be hand-sorted. Often coffee farmers will have a screen that is sized to filter out the larger flat berries out and maybe a few smaller flat berries will make their way through. This added time to sort out the peaberry coffee bean is one of the reasons they are considered a reserve coffee.
Peaberry coffee beans also tend to roast differently. They are smaller and rounder than a flat berry coffee bean and some say they roll in the roaster easier which affects roasting. The higher coffee bean density may improve heat transfer in the roasting process and it may also require a slower roast.
Because of this difference in coffee bean density and the slower roast, the Peaberry Reserve Coffee bean tastes different than the flat berry coffee bean from the same crop. Many peaberry coffee fans note that the Peaberry Reserve Coffee has a sweeter and more flavorful taste profile.