Coffee Science: What is a peaberry? The rare, round coffee bean explained
From coffee cherry to cup, Starbucks coffee master and educator Lincoln Bechard explains how rare peaberries form — and why they stand out in your bag.
Open a bag of coffee and you might notice something unexpected: a small, round bean that looks different from the rest. Known as a peaberry, this rare, naturally occurring variation forms inside the coffee cherry when only one seed develops instead of two. While it stands out in shape, it does not change the flavor in your cup and typically makes up around 5% of a roast.
“What are these tiny beans in your coffee bag? They’re called peaberries,” Bechard said. “They’re round, they’re a little quirky and they’re still delicious.”
To understand why they look different, it helps to start at the source. Coffee is a fruit, and each bean grows inside a bright red cherry on a coffee tree.
How peaberry coffee beans form inside the coffee cherry
Most coffee cherries develop two seeds. As they grow side by side, the seeds flatten against each other, creating the familiar flat-faced shape of a coffee bean. But not every cherry follows that pattern.
“Typically coffee cherries grow two seeds but, every once in a while, things happen and you get just one,” Bechard said.
When only one seed forms, it has more space to develop. Instead of flattening, it grows into a smaller, rounder bean — a peaberry.
“These adorable little guys are tiny and round and a little quirky and rare,” Bechard said. “And they taste just as good as their flatter counterparts.”
Why peaberries are rare — and how common they are in coffee
Peaberries make up a small portion of any harvest, typically about 5% of coffee beans. Their rounded shape makes them easy to spot, especially at the bottom of a bag where they settle differently from flatter beans.
Despite their appearance, peaberries are not a different species, roast level or quality grade. They are a natural variation in how coffee develops on the tree.
That variation reflects what makes coffee an agricultural product — shaped by plant biology, climate and growing conditions at every stage.
Do peaberries taste different?
One of the most common questions about peaberries is whether they taste different.
Answer? Not always. Sometimes they can add concentrated flavor, but generally, if just one or two are in a blend, you probably won’t notice it.
Peaberries come from the same cherries, trees and harvest as other coffee beans. The difference is structural, not sensory.
That means the flavors in your cup, whether chocolatey, citrusy or nutty, are driven by origin, processing and roast, not whether a bean is a peaberry. One advantage peaberries have, though, is that because of their symmetrical shape, when they are roasted, they can roll around and absorb heat uniformly, compared to flat, standard coffee beans. They add to the dense quality we look for in all arabica coffee.
How to spot a peaberry in your bag of coffee
Once you know what to look for, peaberries are easy to recognize.
Instead of having a flat side, they are small, smooth and fully rounded. You are most likely to find them clustered at the bottom of a bag, where their shape allows them to settle differently.
“So, the next time you open your bag, take a look,” Bechard said. “See if you find a peaberry.”
Arabica vs. robusta coffee: key differences in flavor and growth
If coffee cherries look similar on the outside, what happens inside can vary more than you might expect.
“There are more than 200 species of coffee, but arabica and robusta are the most common,” Bechard said. “They’re different trees and they taste different.”
Arabica coffee grows at higher altitudes, where cooler temperatures slow development and allow for greater complexity.
“That slower growth allows the seeds inside the cherry to become denser and develop more layered, nuanced flavors — one of the defining characteristics of arabica coffee,” Bechard explained. “And that’s why we use arabica here at Starbucks.”
Robusta coffee grows at lower altitudes and is a hardier plant with earthier, nuttier and more robust flavors.
“You’ll find arabica and robusta coffee all over the world in many forms,” Bechard said. “I encourage you to explore the world of coffee and find your favorite flavors.”
