A red or reddish-brown color inside your banana is almost certainly caused by a fungal infection called Nigrospora, sometimes known as “squirter disease.” Less commonly, it can be a bacterial infection. Neither poses a known threat to human health, but the fruit is unappetizing and best thrown out.
The Most Likely Cause: Nigrospora Fungus
The fungus Nigrospora sphaerica is the most common reason for a red or dark red center in an otherwise normal-looking banana. It causes what’s called “squirter disease” because the soft, discolored core can squeeze out when pressure is applied to the fruit. The infection typically shows up as a reddish to dark brown discoloration running through the center of the banana, sometimes spreading outward into the surrounding flesh.
Nigrospora spreads through wind, rain splash, and insects. The fungal spores produce a sticky substance that helps them cling to surfaces and to insect carriers like mites. The fungus tends to infect plants that are already weakened or wounded, so it often takes hold during growing or harvesting rather than in your kitchen. By the time you peel the banana, the infection has been developing for a while. The outside of the fruit can look perfectly fine.
Bacterial Infections That Discolor Banana Flesh
Two bacterial diseases can also turn banana flesh reddish-brown, though you’re less likely to encounter them in store-bought fruit from major suppliers.
Moko disease, caused by a soil bacterium, leads to premature ripening, vascular discoloration, and dry rot inside the fruit pulp. A related condition called Bugtok produces similar fruit-rotting symptoms, primarily in cooking banana varieties grown in Southeast Asia. Both cause brown to dark brown internal discoloration that can appear reddish in early stages.
A separate bacterial wilt caused by Xanthomonas bacteria turns the inside of the fruit brown to dark brown and rotten. Fruits from infected plants are considered unsuitable for consumption by humans or animals. These bacterial diseases are primarily a concern in tropical growing regions in Africa, Southeast Asia, and parts of Latin America, and major exporters screen for them. Still, occasional infected fruit can slip through.
It’s Probably Not Bruising
Bananas do brown from rough handling, and that discoloration can sometimes take on a reddish or amber tone. But bruising from impact typically appears as a soft, mushy patch in one area, not a streak or core of red running through the center. If the red color follows the central core of the banana or appears as distinct streaks through the flesh, that pattern points to infection rather than physical damage.
Peel discoloration is a separate issue entirely. The USDA notes that banana peels can turn reddish-bronze, rust, or brown from chilling, overheating, insect damage, or rough handling during transport. A discolored peel with normal white or cream flesh inside is not the same problem.
Could It Be a Red Banana Variety?
If you intentionally bought a red-skinned banana, the pinkish tint inside is normal. Red banana varieties (sometimes called Red Dacca) have a deep red or maroon peel and flesh that ranges from yellow-orange to ivory to light pink. The color is uniform and the fruit smells sweet and fruity. This is completely different from the dark, streaky, or concentrated redness caused by infection in a standard yellow Cavendish banana.
Is It Safe to Eat?
The Canadian Food Inspection Agency states that the fungal diseases causing red discoloration in bananas are not a threat to human health. That said, the texture and taste of infected fruit are unpleasant, and the agency’s practical advice is straightforward: when in doubt, throw it out or compost it.
For bacterial infections like Xanthomonas wilt, the guidance is firmer. Fruits that are brown, rotten, or discolored inside from bacterial disease are not considered fit for eating.
One reassuring detail: Panama disease, the infamous Fusarium wilt that threatens banana crops worldwide, does not affect the fruit itself. It causes reddish-brown discoloration in the plant’s vascular tissue, but symptoms do not develop in the fruit. So if your banana is red inside, Fusarium is not the cause.
How to Reduce Your Chances
You can’t prevent Nigrospora infection at home since it happens during growing and harvest. But proper storage helps you avoid conditions that accelerate fungal growth and other quality problems. Keep bananas at room temperature until ripe. Avoid refrigerating unripe bananas, as chilling injures the peel and can mask internal problems by altering how the fruit ripens. Once ripe, refrigeration slows further ripening, and while the peel will darken, the flesh inside stays better for a few extra days.
Inspect bananas before buying. Fruit with cracked or damaged peels is more vulnerable to secondary infections. And if you open one banana from a bunch and find red inside, check the others before eating them, as the infection may have reached multiple fruits from the same plant.