'Caramel receptor' identified
New insights from the world of chemical senses

Date:
October 12, 2021
Source:
Leibniz-Institut fu"r Lebensmittel-Systembiologie an der TU Mu"nchen
Summary:
Who doesn't like the smell of caramel? However, the olfactory
receptor that contributes decisively to this sensory impression
was unknown until now. Researchers have now solved the mystery
of its existence and identified the 'caramel receptor.' The new
knowledge contributes to a better understanding of the molecular
coding of food flavors.



FULL STORY ==========================================================================
Who doesn't like the smell of caramel? However, the olfactory receptor
that contributes decisively to this sensory impression was unknown
until now.

Researchers at the Leibniz Institute for Food Systems Biology at the
Technical University of Munich (LSB) have now solved the mystery of
its existence and identified the "caramel receptor." The new knowledge contributes to a better understanding of the molecular coding of food
flavors.


========================================================================== Furaneol is a natural odorant that gives numerous fruits such as
strawberries, but also coffee or bread, a caramel-like scent. Likewise,
the substance has long played an important role as a flavoring agent in
food production.

Nevertheless, until now it was unknown which of the approximately 400
different types of olfactory receptors humans use to perceive this
odorant.

Odorant receptors put to the test This is not an isolated case. Despite intensive research, it is still only known for about 20 percent of
human olfactory receptors which odorant spectrum they recognize. To help elucidate the recognition spectra, the team led by Dietmar Krautwurst
at LSB is using a collection of all human olfactory receptor genes and
their most common genetic variants to decipher their function using a
test cell system.

"The test system we developed is unique in the world. We have genetically modified the test cells so that they act like small biosensors for
odorants. In doing so, we specify exactly which type of odorant receptor
they present on their cell surface. In this way, we can specifically investigate which receptor reacts how strongly to which odorant," explains Dietmar Krautwurst. In the present study, the researchers examined a total
of 391 human odorant receptor types and 225 of their most common variants.

Only two odorants for one receptor "As our results show, furaneol
activated only the OR5M3 odorant receptor. Even one thousandth of a gram
of the odorant per liter is sufficient to generate a signal," says first
author of the study Franziska Haag. In addition, the team investigated
whether the receptor also reacts to other odorants. To this end, the
team examined 186 other substances that are key odorants and therefore
play a major role in shaping the aroma of food. Of these, however,
only homofuraneol was able to significantly activate the receptor.

This odorant is structurally closely related to furaneol. As shown by
previous LSB studies, it imparts a caramel-like aroma to fruits such
as durian. "We hypothesize that the receptor we identified, OR5M3,
has a very specific recognition spectrum for food ingredients that
smell caramel-like. In the future, this knowledge could be used to
develop new biotechnologies that can be used to quickly and easily
check the sensory quality of foods along the entire value chain,"
says Dietmar Krautwurst. Although there is still a long way to go to
understand the complex interplay between the approximately 230 key food- related odorants and human olfactory receptors, a start has been made,
the molecular biologist adds.

Veronika Somoza, Director of the Leibniz Institute adds: "In the future,
we will continue to use our extensive odorant and receptor collections
at the Institute to help elucidate the molecular basis of human olfactory perception.

After all, this significantly influences
our food choices and thus our health." ========================================================================== Story Source: Materials provided by Leibniz-Institut_fu"r_Lebensmittel-Systembiologie_an_der
TU_Mu"nchen. Note: Content may be edited for style and length.


========================================================================== Journal Reference:
1. Franziska Haag, Sandra Hoffmann, Dietmar Krautwurst. Key Food
Furanones
Furaneol and Sotolone Specifically Activate Distinct Odorant
Receptors.

Journal of Agricultural and Food Chemistry, 2021; 69 (37): 10999
DOI: 10.1021/acs.jafc.1c03314 ==========================================================================

Link to news story: https://www.sciencedaily.com/releases/2021/10/211012091844.htm

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