Hot-Water Extraction

Hot-water extraction is a method of making a mushroom extract by simmering dried mushrooms in water, often for hours, and then filtering and concentrating the liquid. It is the modern, industrial version of one of the oldest food preparations in the world: the long-brewed mushroom tea, known in herbal traditions as a decoction.

A traditional method

Long before extraction equipment existed, people in China, Japan, Korea, Russia and Scandinavia simmered tough mushrooms such as reishi, chaga and turkey tail in pots of water. These species are too woody to chew, so brewing them was the natural way to enjoy them. The result was a dark, earthy, sometimes bitter drink.

Why heat and time matter

Fungal cell walls are reinforced with chitin, a sturdy material that people cannot readily digest. Prolonged heat in water helps loosen that structure and release water-soluble polysaccharides, particularly beta-glucans. A quick steep, like a tea bag, extracts much less than a slow simmer.

How it is done commercially

1. Dried mushrooms are chopped or ground to increase surface area.
2. They are simmered in hot water, sometimes in several rounds.
3. The liquid is filtered to remove the spent fiber.
4. The extract is concentrated and usually spray-dried into a fine powder.

Strengths and limits

Hot-water extraction captures polysaccharides well but pulls out few alcohol-soluble compounds such as triterpenes. That is why some producers add an alcohol step, a process called dual extraction.

Try it at home, the culinary way

You can experience the idea with culinary mushrooms: simmer dried shiitake for a rich broth. It is the same principle, and a good reminder of why earthy mushroom notes pair so well with deep, roasted flavors like the cocoa in our Polkadot dark chocolate bars.