Would you eat the forbidden fungi? Scientists have uncovered a mushroom-derived compound that seems to be the most bitter substance known on Earth.
Researchers in Germany made the not-so-tasty find in a species of mushroom called Amaropostia stiptica—also aptly known as the bitter bracket fungus. The compound is one of three new bitter molecules discovered by studying the mushroom. The findings may help scientists better understand how animals like us evolved to detect bitterness, among other unanswered questions, the researchers say.
Our taste buds can broadly pick out five distinctive types of taste, one of which is bitterness. Scientists have identified around 2,400 different molecules that elicit a bitter taste, with over 800 linked to at least one specific taste receptor. According to the study researchers, however, this list is only a small sample of the many bitter-inducing things truly out there.
Most of these compounds identified so far have come from flowering plants or are synthetically produced. And there’s simply a lot less we know about the bitter tastes that originate from the other branches of life, fungi included. So the researchers decided to take a closer look at the known but less studied bitter bracket fungus.
Though A. stiptica isn’t toxic like some species of mushroom, it is practically inedible due to its bitterness. The researchers found that some of its taste can be explained by the previously known compounds oligoporins A and B, which are examples of triterpene glycosides. But they also discovered three new similar compounds, which they’ve coined oligoporins D through F.
One of these compounds, oligoporin D, is so bitter that it can set off our bitter taste receptors (formally called TAS2Rs) at the incredibly low concentration of 63 millionths of a gram per liter, according to the researchers. To put it in plainer terms, this would be the equivalent of one gram dropped into roughly 100 bathtubs’ worth of water.
Scientists at the Leibniz Institute for Food Systems Biology at the Technical University of Munich in Freising and at the Leibniz Institute of Plant Biochemistry in Halle made the discovery together. Their findings were published earlier this February in the Journal of Agricultural and Food Chemistry.
The researchers say their study is the first to subject mushroom-derived compounds to functional bitter taste receptor screening. And what we learn from studying A. stiptica and similar mushrooms could help us better understand the nature of bitterness.
Bitterness is thought to be commonly used by living things to signal their toxicity to potential predators and avoid being eaten, for instance. But the bitter bracket fungus isn’t toxic to humans, and other very toxic fungal species like the deathcap mushroom taste quite fine. We also have bitter taste receptors in other parts of the body besides the mouth, but scientists still aren’t sure why. So discovering and studying these bitter compounds is an important part of the process needed to answer these and other burning questions, the researchers say.
“Our results contribute to expanding our knowledge of the molecular diversity and mode of action of natural bitter compounds,” said study researcher Maik Behrens in a statement from the Leibniz Institute for Food Systems Biology. ”In the long term, insights in this area could enable new applications in food and health research, for example in the development of sensorially appealing foods that positively influence digestion and satiety.”
Personally, I’m hoping scientists will one day explain why I hate olives so much.
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