Flesh color change

No change

Does not change — mushrooms with the trait «Does not change»

In a world where mushrooms turn blue, black and red at the slightest touch, keeping their original color when cut is an important diagnostic feature too. The absence of an oxidation reaction tells you that the mushroom's flesh lacks certain phenolic compounds (such as variegatic acid) or the enzymes that activate them.

24 species in the database.

The hallmark of true porcini

The best-known example of a mushroom whose flesh doesn't change color when cut is porcini (Boletus edulis) and its closest relatives (the pine, oak and summer porcini).

In the "Key to the Fungi of Ukraine," M.Ya. Zerova stresses that this very property gave porcini its Ukrainian name, "the white mushroom": its flesh stays perfectly white when cut, dried, pickled or simmered into broth.

David Arora describes this as the key way to tell true porcini from its many relatives:

- If you've found a large pored mushroom that looks like porcini but turns blue when cut, it's a lurid bolete, a cornflower bolete or a Xerocomus.

- If it turns pink or black, it may be a birch bolete or a bitter bolete.

- Porcini always stays white.

Other mushrooms with unchanging flesh

Roger Phillips lists many other genera for which a color change is atypical:

1. Brittlegills (Russula): Most edible brittlegills (the bare-toothed russula, the greencracked brittlegill) have perfectly white, brittle flesh that doesn't react to oxygen at all. Only a few specific species (for example, the blackening brittlegill) change color.

2. Chanterelle (Cantharellus cibarius): Chanterelle flesh is an even yellowish or pale color that doesn't dull or stain when broken.

3. Amanitas (Amanita): This is a very dangerous fact. Deadly poisonous mushrooms such as the death cap (Amanita phalloides) and the destroying angel (Amanita virosa) have perfectly white flesh that doesn't change at all when cut.

Questions and answers

Why doesn't porcini turn black when cooked, like a birch bolete does?

Birch boletes and orange boletes contain amino acids (tyrosine in particular) and enzymes that oxidize when heated and form a dark pigment, melanin. Porcini flesh has a different biochemical makeup and lacks this reaction, so porcini soup stays clear and light.

If a mushroom doesn't change color when cut, is it safe?

Absolutely not! As mentioned above, the most poisonous mushrooms in the world (the death cap) don't change color when cut. This rule (unchanging flesh) only works as a quality check for pored mushrooms (if you want to be sure you've found prized porcini and not an ordinary lurid bolete).

Are there exceptions in porcini?

Very rarely, in excessive humidity (during prolonged downpours), the thin layer of porcini flesh directly beneath the pores may take on a barely noticeable pale pink or yellowish tint from excess water, but the flesh of the stem and cap as a whole will stay white.

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