Flesh color change

Reddening

Turns red — mushrooms with the trait «Turns red»

Reddening (or pinking) of white mushroom flesh on contact with air is a chemical process caused by the oxidation of specific phenols (such as tyrosine), which comes before the formation of darker pigments. For a mycologist this feature is critically important, because it lets you identify several well-known but highly controversial species.

24 species in the database.

Reddening saves lives: the blusher

The best-known example of a reddening mushroom is described by David Arora in "Mushrooms Demystified." It's the blusher (Amanita rubescens), which in Ukraine is popularly called "maremukha."

This amanita is a tasty edible mushroom (after cooking), but it has a deadly dangerous lookalike — the panther cap (Amanita pantherina). Both mushrooms have a brown cap with white scaly spots. The only reliable way to tell them apart:

- If you cut the base of the stem, damage the gills or simply look at spots nibbled by insects, the blusher's flesh takes on a coppery red, pink or wine-colored tint.

- The poisonous panther cap's flesh is perfectly white and never turns red.

Other mushrooms that redden when cut

Roger Phillips and M.Ya. Zerova give other striking examples of species with this reaction:

1. Shaggy parasol (Chlorophyllum rhacodes / Macrolepiota rhacodes): An excellent edible mushroom with a big "shaggy" cap. Unlike the parasol mushroom (whose flesh doesn't change), a cut on the shaggy parasol's stem turns an intense pink within a few seconds, then saffron red.

2. Blushing wood mushroom (Agaricus silvaticus): Many woodland Agaricus have flesh that noticeably reddens or turns pink when broken (unlike the poisonous yellow stainer, which turns sharply yellow).

3. Orange boletes (Leccinum aurantiacum): A vivid example of step-by-step oxidation. If you cut the thick stem of an orange bolete, its white flesh will first turn pink, then purplish red, and only after some time deep black.

Questions and answers

Why does an orange bolete first turn red and then black?

This is the classic work of the enzyme tyrosinase. First the enzyme converts the amino acid tyrosine into red-pink intermediate compounds (dopaquinone), which, as they oxidize further in the air, polymerize into a black pigment — melanin (the same one that colors human skin when you tan).

If a parasol turns red when cut, is it safe?

The shaggy parasol (Chlorophyllum rhacodes) is an excellent edible mushroom in Europe. In other regions, however (for example, North America), there is a poisonous lookalike — Chlorophyllum molybdites (the green-spored parasol), which can also redden slightly but has greenish spores. In Europe, the true shaggy parasol is safe and very tasty.

Are there death caps that turn red?

No! The absence of any change in flesh color (neither reddening nor yellowing) is one of the main characteristics of the deadly death cap (Amanita phalloides). If the flesh has clearly and quickly turned wine-red, it's definitely not a death cap.

Sources

1.Зерова М.Я. та ін. Визначник грибів України. 1979
2.Roger Phillips. Mushrooms (Roger Phillips)
3.David Arora. Mushrooms Demystified
4.Index Fungorum