What Is Cas Fruit? Costa Rica's Tart Wild Guava

If you order just one fresh drink in Costa Rica, make it a fresco de cas. It comes from cas (pronounced KAHS), a small, round, green fruit that's one of the country's best-kept flavor secrets. Botanically it's Psidium friedrichsthalianum — a tart cousin of the guava, often called the "wild guava" or guayaba agria (sour guava). It's too sharp to eat like an apple, but blended into a drink it's absolutely magical. As your Jaco Beach Chef, I love sharing the flavors that say "Costa Rica" to every tico, so here's the story of cas, from www.jacobeachchef.com.

So, what exactly is cas?

Cas is a round, thin-skinned fruit about the size of a small apple or a large lime. It's picked firm and green, and as it ripens the skin softens to a pale yellow. Cut one open and you'll find soft, cream-colored flesh dotted with small seeds and packed with a bright, mouth-puckering acidity — think of the tartest, greenest guava you can imagine. That sourness is exactly why ticos love it: a little sugar and water turns cas into one of the most refreshing drinks on earth, perfect for Costa Rica's tropical heat.

Green cas fruits growing on the branch of a small tree — Cas grows on a small, hardy tree — the round green fruit is picked while still firm and tart.

Fresco de cas — the star drink

You'll find cas almost everywhere in Costa Rica as a fresco (also called a refresco or agua fresca). The fruit is blended with water, strained, and sweetened to taste — sometimes served en agua (with water) or en leche (with milk) for a creamier version. It's a staple at sodas (small local eateries), served ice-cold alongside a casado lunch. Beyond drinks, cas is also cooked down into jams, syrups, and sorbets.

A cas fruit tree growing under a blue Costa Rican sky — The cas tree grows readily in Costa Rica's climate — many ticos have one in the backyard.

Health benefits of cas

That intense tartness comes with real nutrition. Cas is a genuinely healthy little fruit:

Very high in vitamin C — like other guavas, cas is loaded with it, supporting your immune system and skin.
Rich in antioxidants — plant compounds that help the body fight free radicals.
Good source of fiber — supports healthy digestion.
Low in calories — naturally light, especially when you go easy on the added sugar.
Hydrating & refreshing — as a fresco, it's a delicious way to stay cool and hydrated in the tropics.

A quick note: these are general nutrition facts, shared for interest — not medical advice.

Where to try cas in Jacó

In and around Jacó, order a fresco de cas at almost any soda or restaurant — it's a menu regular. You can also find the fresh fruit (and frozen cas pulp) at the weekly feria and local supermarkets if you'd like to blend your own. It's the perfect cool-down after a morning of tours and adventures or a few hours on the beach.

Fresh tropical flavor, handled by your chef

When I cook for your group as your private chef in Jaco, I love pouring the authentic local drinks alongside the meal — fresco de cas, tamarindo, and fresh fruit batidos made from guanabana, mango, and pineapple, right through to tropical breakfasts and desserts.

Planning a bachelor party, wedding, or family getaway to Jacó? Message me on WhatsApp or visit www.jacobeachchef.com and I'll handle the food and drinks while you soak up everything the Pura Vida coast has to offer.