Professor Laura López-Mascaraque held two workshops at Oxford, one on Monday 5th February 2018 for the Cortex Club and one for St John's College Research Centre on the following day.
Professor López-Mascaraque is President of the Spanish Olfactory Society, at Department of Molecular, Cellular and Developmental Neurobiology, within the Instituto Cajal-CSIC, in Madrid, Spain
She explained that our sense of smell is much more sensitive than any other of our senses, and that the olfactory response is immediate, since smell is the only sense where our neurons are directly exposed to the environment. In addition, when we eat our sense of smell and taste work together to detect the flavour, although 80% of what we perceive is really smell.
Professor López-Mascaraque went on to explain that odours/aromas have some effects that escape our conscious control. They are intimately linked to the world of emotions, in such a way that they can evoke sensations or even moods. In fact, the smell of our peers helps us to feel empathy and regulates our sexual and social behavior. And it is because each person has a characteristic smell that is genetically determined. The same perfume smells very differently on different person because of the individual characteristics of their skin. In fact, human beings can distinguish a billion odours, and Professor López-Mascaraque organised a practical workshop in which participants explored how many odours they could distinguish.
After a talk about the biological basis of smell and taste, the participants performed a series of individual tests. Amongst others, the participants explored whether they were super-tasters or not. The participants explored whether they had special ability to detect bitter flavors such as phenylthiocarbamide (PTC) much more intensely than the average person. The ability to taste PTC (or not) is conveyed by a single gene, TAS2R38, that encodes a specific PTC receptor. There are two alleles for this gene that determine sensitive or non-sensitive receptors. People with two copies of the "non-sensitive" allele are NT (non-tasters), while those with some copy of the "sensitive" allele are T (tasters) or ST (super-tasters) and are able to feel the bitter taste of this substance with great or extreme intensity, respectively.
Attendees had the opportunity to determine the number of their taste buds after staining the tip of their tongue with food colourant and then exploring the small fungiform papillae within a small selected area with magnifying glasses. Non-tasters have less then 8 buds, average tasters have 8-13 buds, whereas super-tasters have more than 18 buds in a unit area.
The participants also tested their olfactory threshold by exploring their sensitivity to capture the odours at different concentrations. Olfactory threshold of a given compound is the minimum odour concentration that is perceived by the human sense of smell. This allows the detection of the different sensitivity degree to capture the odours at different concentrations. Mirror image molecules (known as stereoisomers) have very different smells. The best-known stereoisomers that evoke very different aromas are D-carvone and L-carvone, which smell like caraway and spearmint, respectively.
The olfactory discrimination tests proved to be the most challenging tasks of the day. The participants were given 12 different small boxes with different natural aromas. Based on their previous experience they had to name these odours. Participants noted that they “knew what the aromas were” but that they just could not name them. Once the correct responses were announced, the participants could retrospectively identify the aromas of lemon, chocolate, rose etc.
The participants also tested their olfactory memory by recognising the hidden aromas in different small boxes, but this test was made easier using small images of three possibilities. This screening test of olfaction is reliable in recognising people with normal olfaction and can distinguish them from people with hyposmia or anosmia. A person with a score of 7 or 8 has a 99.74% probability of having a normal olfaction whereas patients with subjective hyposmia or anosmia score between 0 and 6.
The workshop at the Cortex Club was followed by demonstrations from Domen Prešern and Janice Wang, the current and previous Captains of the Oxford University Blind Tasting Society, and after the workshop at St John’s College, Professor Jan Obloj, Professor of Mathematics and Official Fellow and Wine Stewart at St John, College, gave various demonstrations on acidity, sweetness, combination of taste and smell experiences relevant to wine tasting. Janice Wang explained that even the shape of the glass, music, or illumination can influence our perception of the taste of the wine. The workshops were a tremendous success; it drew attention to the everyday importance of our sense of smell and taste, abilities that we use every day, but very much take it for granted.
The Department are very grateful to Professor Laura López-Mascaraque for her workshops, to Dr Lukas Krone President of Cortex Club and the St John’s College Research Centre for sponsoring these events, and to Professor Zoltán Molnár of DPAG, who proposed and coordinated these events.