Why Do Bolete Mushrooms Turn Red When Cut?

You may have heard that many boletes change color when they are cut or damaged. Perhaps you’ve also heard that those staining blue or red should be avoided at all costs. But is this true across the board? Why do bolete mushrooms turn red when cut? Why do they turn blue? And does the color change really have anything to do with whether the mushroom is edible? Keep reading as we explore the answers to these and other questions!

Why Do Boletes Turn Red When Cut?

bolete mushroom turned red when cut

It is common for bolete mushrooms to change color when they are cut, and this color change isn’t necessarily an accurate indicator of whether a mushroom is edible. That said, as a general rule of thumb, bolete mushrooms that show red coloration should be avoided.

Very few boletes stain red or pink when cut. But if they do, it likely means they are a poisonous variety or are beginning to go bad.

Satan’s bolete, for example, will quickly turn pinkish when the pores are damaged before fading to a more blue color. This mushroom should be avoided, as it can cause extremely unpleasant digestive symptoms.

An exception to the rule would be the edible red-cracking bolete. This mushroom begins to crack as it ages, and these cracks (as well as any bug damage to the caps) turn red or pinkish when exposed to the air.

This is simply due to oxidation–when the damaged surface is exposed to air, it begins to change color, much like the cut surface of an apple might do.

If you were to cut open a red-cracking bolete, you would notice that it has a white cap with a reddish stem. Over time, the entire cut surface would begin to turn red.

Still, if you are not absolutely certain of your mushroom’s identity, it’s best to avoid eating any that stain red. While it’s possible the mushroom may simply be changing color due to oxidation, it’s just as likely that you’re dealing with a poisonous mushroom.

Why Do Boletes Turn Blue When Cut?

The vast majority of boletes turn some shade of blue when they are cut. This color change may happen within a few minutes, or it may take up to an hour.

This color change happens because of oxidation. Chemicals in the broken cells of the mushroom react with the air to cause the cut surface to change color.

Again, this color change doesn’t necessarily reflect the edibility of the mushroom. Both edible and inedible bolete species may turn blue when cut.

A good rule of thumb is to pay attention to what part of the mushroom turns blue. 

If you cut the mushroom open down the stem and only a small area around the pores turns dark blue, there’s a good chance you’re dealing with a poisonous mushroom. If the entire cut surface stains a lighter sky blue, then it’s more likely an edible species.

Check out this video to learn more about why bolete mushrooms stain blue:

Why Do Boletes Turn Yellow When Cut?

There are various bolete species that are naturally yellow, but none that turn yellow when they are cut.

Some have white caps or pore surfaces that will turn yellowish as the mushroom ages. This is a natural process however and has nothing to do with whether the mushroom is edible.

Yellow bolete species such as the gilled bolete or the lurid bolete may stain bluish when cut but, because they are naturally yellow, they don’t stain yellow.

A few yellow species of bolete that do not stain may become a darker yellow when cut or bruised. This is simply because of cell damage to the mushroom.

Some yellow bolete mushrooms are edible, while others are not. As with any mushroom, it’s important to correctly identify it before eating it, and you cannot use changing color alone to determine whether it’s safe to eat or not.

If anything, yellow is a far less accurate indicator even than red or blue because most boletes simply don’t turn this color–and those that do are either old or have simply been damaged.

Do Boletes Turn Any Other Colors?

Do Boletes Turn Any Other Colors?

Some boletes may turn a more greenish color when they are cut. This is especially true of yellow boletes that stain blue–the blue stain will appear more greenish against the yellow background of the mushroom’s flesh.

Some boletes may also stain a more brownish color. Again, this has a lot to do with the original color of the mushroom–if it is already reddish or orange in color, the surface may simply darken when cut, giving it a more brown appearance.

Many people use changing colors as a way of determining whether a mushroom is safe to eat, but again, this is not an accurate indicator. The basic fact is that many bolete mushrooms, both edible and poisonous species, may change color when they are cut or bruised.

If you’re uncertain of a mushroom’s identity, don’t rely on changes in color alone. Have the mushroom checked by a more experienced forager or someone trained in mycology. 


Bolete mushrooms may change color to red, pink, blue, blue-green, or even brown when they are cut. Some non-staining yellow mushrooms may turn a darker yellow at the cut surface.

All of these color changes have to do with cell damage and oxidation; they are not accurate indicators of whether a bolete mushroom is edible or toxic.

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