Peaberry, also known as caracoli, is a type of coffee bean. Normally the fruit ("cherry") of the coffee plant contains two seeds ("beans") that develop with flattened facing sides, but sometimes only one of the two seeds is fertilized, and the single seed develops with nothing to flatten it. This oval (or pea-shaped) bean is known as peaberry. Typically around 5% of all coffee beans harvested are of this form.
Normal coffee beans are less commonly called by contrast flat berry.
Peaberry beans roast differently from the corresponding flat berry beans; hence, to ensure an even roast in high-grade coffee peaberry beans are separated.
Peaberry beans are widely reputed to roast better than flat berries, being said to roast more evenly, because their rounder shape minimizes sharp edges and allows the berries to roll about the roasting chamber more easily, as well as because the alleged higher bean density may improve heat transfer in the roasting process. However, some sources claim that these effects are minor, and that the major benefit of peaberry beans is that they have been carefully selected, which is essential for optimal quality, regardless of bean shape.