A Day full of Flavor !

Friday, March 6th, 9 a.m. The scientists of the CSGA settle quietly into the conference room, coffee in hand. Silence falls… you could almost hear a fly buzzing. And sure enough, a fly appears on the screen. Here is Drosophila melanogaster, the vinegar fly, which loves sugar. Pierre-Yves Musso (GUSTABRAIN team) presents an “optogenetic” setup: when the fly extends its tongue to take a sip of sugary water, a red light switches on above its head. At that signal, researchers activate or deactivate the neurons involved in the perception of sweetness. We then discover with Yaël Grosjean (PERSING) that our little fly is put off by the addition of sugar in coffee: after all, you don’t catch flies with bitterness! Yaël then takes us on a journey into the insect’s brain to decode the mechanisms behind this aversion, which are far more complex than they seem at first.

“One receptor to rule them all!” could well be the motto of the single receptor responsible for detecting sweetness. Indeed, this receptor can detect a wide range of sweet molecules. Loïc Briand (SUPER) describes its different binding sites: imagine a large door fitted with many locks to which sweet “keys” can latch on… It’s far from a high-security vault, and that’s good news for researchers studying sweet molecules produced by plants. “Care for another receptor?” “No thanks, replies Sandrine Chometton (SUPER). I prefer glucose sensors!” For them, the motto is more like “all for one.” Whether located on the tongue, in the stomach, intestine, pancreas, or brain, their job is to detect glucose and prepare the body for its arrival. “What impact do diet and metabolic status have on the functioning of these sentinels?” This is a question that fascinates Sandrine, who recently joined the CSGA. We then head back to the mouth with Eric Neyraud (FFOPP) to explore our oral microbiota – a bustling community of bacteria, yeasts, and fungi firmly settled on our oral mucosa, and not shy about interfering with our ability to perceive flavours… sometimes with a bit of counterfeit: is the sugar in food perceived or consumed by the bacteria? Not always easy for the brain to tell the difference!

Without missing a beat, we move on to the brain. Alexandre Benani (NEUROFEED) explains how to “grease the wheels” of microglial cells to trigger a red alert. When the diet is high in fat, these tiny cells, which are scattered throughout the brain, increase the number of connections they have with neighbouring cells. In doing so, they help to limit food intake and maintain nutritional balance in the brain. Another research question, another alert system: Vincent Schneider (NEUROFEED) introduces the superpower of gustatory evoked potentials, which are the waves emitted by the brain in response to a taste stimulus. These signals can detect early alterations in the taste system, particularly in people with Parkinson’s disease.

Bread without salt is a bit like a bouquet without colour… And yet, reducing the salt in our diet means reducing the risk of hypertension. Thierry Thomas-Danguin and Charlotte Sinding (FFOPP) explored ways to reduce the salt content of our food without sacrificing the pleasure of eating. Thierry compared two methods of salting carrots: adding salt to the cooking water, or sprinkling it on the plate afterwards. The winner is... salt on the plate! This is counterintuitive, since most recipes recommend salting during cooking. However, when salt is added on the plate, its distribution becomes uneven: some bites deliver little bursts of saltiness, which makes it possible to reduce the overall salt content by about 30%. Charlotte looks at another strategy: aromas. Aroma can indeed enhance the perception of saltiness. For example, a lightly salted soup flavoured with beef broth tastes saltier than a lightly salted soup… but still less salty than a heavily salted one. Still with us? Charlotte then takes us deep into the twists and turns of our grey matter to understand how the brain creates this sensory illusion.

The final words go to Claire Sulmont-Rossé (MIAM). She approaches the issue from the opposite angle: should we add more taste compounds to foods to compensate for the decline in taste perception in older adults? Fortunately, this idea – very popular at the start of the century – has fallen out of favour due to a lack of convincing scientific evidence. A more effective strategy is to ask older adults about their sensory expectations and offer foods that match what they enjoy. After all, when it comes to tastes and colours, everyone has their own!

Sandrine Chometton: sandrine.chometton@inrae.fr

Pierre-Yves Musso: Pierre-Yves.Musso@u-bourgogne.fr

Monod R, Thomas-Danguin T, de Kock HL (2025). Exploring Culinary Methods to Reduce Sodium Intake: The Impact of Flavorings and Salt Addition Timing in Boiled Chicken. International Journal of Food Science, 1, 3703692. doi: 10.1155/ijfo/3703692

Mai L, Ramos AS, Jung AH, de Monteiro D, Vu I, Saputera T, Fan J, Adkins T, Dickerson D, Pittman DW, Chometton S, Schier LA (2026) Nutritional regulation of metabolism-dependent and-independent glucosensing in the mammalian taste system. Mol Metab. 103:102280. https://doi.org/10.1016/j.molmet.2025.102280

Montanari M., Manière G., Berthelot-Grosjean M., Dusabyinema Y., Gillet B., Grosjean Y., Kurz C.L. & Royet J. (2024) Larval microbiota primes the Drosophila adult gustatory response. Nat Commun, 15(1):1341. doi: 10.1038/s41467-024-45532-4.

Sulmont-Rossé C, Symoneaux R, Feyen V, Maître I (2018). Improving food sensory quality with and for elderly consumers. In Ares G, Varela Tomasco PA (eds), Methods in Consumer Research Volume 2: Alternative Approaches and Special Applications (pp 355-372). Elsevier. Cambridge, USA. doi: 10.1016/B978-0-08-101743-2.00014-5.

Taste, gustation, receptors, perception, sugar, salt, food

GUSTABRAIN, FFOPP, MIAM, NEUROFEED, PERSING, SUPER