Would you be willing to try the forbidden fungi? A team of scientists has discovered a compound derived from mushrooms that appears to be the most bitter substance known to exist on our planet.

In a fascinating discovery, researchers in Germany identified the unpleasant-tasting compound in a species of mushroom known as Amaropostia stiptica, also referred to as the bitter bracket fungus. This compound is one of three newly identified bitter molecules found in the mushroom, which may help scientists gain a better understanding of how humans and other animals have evolved to detect bitterness, among other unresolved questions.

Human taste buds are capable of recognizing five distinct types of taste, with bitterness being one of them. To date, scientists have identified approximately 2,400 molecules that trigger a bitter taste response, with over 800 linked to at least one specific taste receptor. However, according to the study’s researchers, this is only a small fraction of the numerous bitter-inducing substances that exist in nature.

The majority of the identified compounds have been derived from flowering plants or are synthetically produced. There is still much to be learned about the bitter tastes originating from other branches of life, including fungi. Therefore, the researchers decided to investigate the bitter bracket fungus, which, although not as well-studied, is known for its bitter taste.

Although A. stiptica is not toxic like some other mushroom species, it is nearly inedible due to its intense bitterness. The researchers found that some of its taste can be attributed to the previously known compounds oligoporins A and B, which belong to the triterpene glycoside family. However, they also discovered three new similar compounds, which they have termed oligoporins D through F.

One of these newly discovered compounds, oligoporin D, is exceptionally bitter, triggering bitter taste receptors (formally known as TAS2Rs) at a remarkably low concentration of 63 millionths of a gram per liter. To put this into perspective, this is equivalent to adding one gram of the compound to approximately 100 bathtubs’ worth of water.

The discovery was made by scientists from the Leibniz Institute for Food Systems Biology at the Technical University of Munich in Freising and the Leibniz Institute of Plant Biochemistry in Halle, who collaborated on the project. Their findings were published in the Journal of Agricultural and Food Chemistry earlier this February.

According to the researchers, their study is the first to subject mushroom-derived compounds to functional bitter taste receptor screening. The insights gained from studying A. stiptica and similar mushrooms may contribute to a deeper understanding of the nature of bitterness.

Bitterness is believed to serve as a signal for toxicity in living organisms, warning potential predators to avoid them. However, the bitter bracket fungus is not toxic to humans, while other highly toxic fungal species, such as the deathcap mushroom, have a relatively mild taste. Additionally, bitter taste receptors are found in other parts of the body beyond the mouth, but their purpose remains unclear. The discovery and study of these bitter compounds are essential for addressing these and other unanswered questions.

As study researcher Maik Behrens explained in a statement from the Leibniz Institute for Food Systems Biology, “Our results contribute to expanding our knowledge of the molecular diversity and mode of action of natural bitter compounds. In the long term, insights in this area could enable new applications in food and health research, such as the development of food products that positively influence digestion and satiety.”

On a personal note, I hope that scientists will eventually shed light on why some people, like myself, have a strong aversion to certain foods, such as olives.