Scientists Uncover World’s Most Bitter Compound, Making Lemons Pale in Comparison
The World’s Most Bitter Substance Found in a Common Mushroom
When you think of bitter flavors, lemons, coffee, or Brussels sprouts might come to mind. But none compare to the intense bitterness of Amaropostia stiptica, a mushroom dubbed the “most bitter tasting thing ever.” Researchers at the Technical University of Munich identified this British tree-dwelling fungus, also called bitter bracket, as the source of three newly discovered bitter compounds. One, oligoporin D, is so potent that a single gram dissolved in 106 bathtubs of water remains detectable to human taste buds.
The bitter bracket fungus produces a compound so bitter it’s detectable even when massively diluted (stock image).
Why Bitterness Matters
Bitterness is one of the five basic tastes (alongside sweet, salty, sour, and umami) and often serves as a warning for potential toxins. However, the bitter bracket mushroom challenges this theory: despite its extreme bitterness, it’s non-toxic. Conversely, the lethally poisonous death cap mushroom (Amanita phalloides) reportedly tastes pleasant. This paradox suggests bitterness isn’t a reliable indicator of danger.
Scientists tested the mushroom’s compounds on lab-grown taste cells, finding oligoporin D activated the TAS2R46 bitter receptor at concentrations as low as 63 millionths of a gram per liter. This receptor also responds to strychnine, a deadly poison, yet the bitter bracket itself is harmless. Researchers speculate that bitter receptors—found not just in mouths but also in the gut and skin—may have evolved for purposes beyond poison detection, such as regulating digestion.
The death cap mushroom (pictured) is tasty but deadly, challenging the idea that bitterness signals toxicity.
Unlocking Bitter Mysteries
The discovery highlights gaps in our understanding of bitter compounds. The BitterDB database catalogs over 2,400 bitter molecules, but most derive from plants or synthetic sources. Fungi, animals, and bacteria are underrepresented, even though bitter receptors evolved ~500 million years ago—long before flowering plants (200 million years ago). Studying ancient fungi like Amaropostia stiptica could reveal why these receptors developed and how they function beyond taste.
Dr. Maik Behrens, lead researcher, notes: “Insights into natural bitter compounds could lead to applications in food and health, like creating foods that enhance satiety or digestion.”
A Bitter Evolutionary Puzzle
While bitterness may have initially helped ancestors avoid toxins, its role is clearly more complex. The bitter bracket’s extreme flavor—yet safety—suggests other factors, like deterring non-human predators, might drive its evolution. As Behrens’ team continues analyzing fungal compounds, their work could reshape our grasp of taste, evolution, and natural chemistry.
Oligoporin D’s structure (illustrated) makes it detectable at minuscule concentrations.
In short, this unassuming mushroom holds clues to one of biology’s oldest sensory mysteries—proving that sometimes, the most intense flavors hide in plain sight.
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