Why mushrooms taste bitter and how to get rid of it

You gathered a lovely basket, cooked it — and the dish is so bitter it's inedible. Mushroom bitterness has several causes, and some of them matter for safety. Let's look at why mushrooms taste bitter, how to remove the bitterness and when a bitter taste is a signal to leave the mushroom in the forest.

1. A bitter bolete got in among your mushrooms

The most common cause of a ruined dish is the bitter bolete (Tylopilus felleus), a lookalike of porcini. On the outside it looks almost like a porcino, but it's very bitter, and even a single one can ruin the whole pot.

The bitter bolete isn't deadly, but it's inedible precisely because of its unbearable bitterness, which only gets stronger with cooking. We explain in detail how to tell it apart from porcini in our article June lookalikes: the cornflower bolete and the bitter bolete.

2. Some mushrooms are bitter “by nature”

Some perfectly edible mushrooms are naturally bitter, and that's normal. Milk caps, woolly milk caps and other Lactarius species contain acrid milky latex. To remove the bitterness, they are:

• soaked in cold water for several days, changing the water;
• or boiled and the cooking water is poured off.

That's why these mushrooms are traditionally salted rather than fried. Without soaking they really are bitter.

3. The mushroom is overmature or improperly cooked

Sometimes even a familiar mushroom tastes bitter:

• overmature, old mushrooms often develop an unpleasant aftertaste;
• chanterelles can taste slightly bitter if overdried or fried over too high a heat;
• mushrooms picked near roads or in polluted places can also have an off taste — more on this in our article mushrooms near roads and cities.

4. When bitterness is a danger signal

Most important: a bitter or acrid taste is often a natural defense of poisonous mushrooms. That's why there's a simple safety rule — never taste unfamiliar mushrooms, not even raw, to “check whether they're bitter.”

Bitterness on its own doesn't prove toxicity, but an unfamiliar mushroom with a sharp taste is a reason to leave it in the forest. More on false “tests” in our article myths about identifying poisonous mushrooms.

Sources

• “Vyznachnyk hrybiv Ukrainy” (Field Guide to the Fungi of Ukraine; Kyiv, Naukova Dumka).
• Tylopilus felleus on GBIF, the global biodiversity database.
• Bitter bolete on Wikipedia.