Smell in every sense

Smell in every sense

The cold and flu often deprive us of the pleasure of smelling our favourite winter dishes at this time of year. Let’s pay tribute to the sense of smell and head out on a discovery of this often misunderstood airborne sense. Why do we lose the sense of taste when we have a cold?

In fact, the problem is not that we no longer perceive flavours (sweet, salty, sour, bitter and umami) but rather that we cannot smell them! What do you perceive if you pinch your nose or if you have a bad cold and you take a bite of, say, an apple or a piece of cheese? Not a lot, whether it be the tart sweetness of an apple or the salty or bitter taste of cheese. If you stop pinching your nose, you will soon enjoy the taste of that apple or cheese. This is because a food’s essential “taste” does not come from its flavour molecules; taste is derived from aromatic molecules. When the nose is unblocked, these volatile molecules travel up the throat and into the nasal cavity where they are detected by olfactory receptors. These two pieces of sensory information, flavour and smell, are unconsciously combined into one overall perception that is called the “taste” of food.
 

Cultivate your nose

A human being is capable of detecting hundreds of thousands of different smells. Note that I said detect, not identify! Most of us have no problem perceiving smells but naming them can be a real challenge. The ability to recognize and identify smells is a matter of experience and, happily, does improve with training. Think of the excellent olfactory memory of sommeliers (wine waiters) or perfumers.

Your olfactory performance does not need to remain limited. You can develop its tremendous potential. Do you want to improve it? Whenever you taste a dish, take the time to dissect the tastes: is that oregano, marjoram or thyme? Do you perceive cinnamon, cloves or allspice? Then confirm your smell impressions by taking a sniff of the herb or spice in its original container. The brain develops olfactory memory through repetition. Here’s a deliciously fun activity to do with your kids: take an assortment of Jelly Belly candy (yes, jelly beans come in more than 50 different flavours!). Try to recognize different smells with a plugged and unplugged nose. Children will learn how smell is essential to the appreciation of taste.
 

Did you know?

• Olfactory sensitivity decreases significantly with age, especially after age 70, and can reduce the pleasure of eating. To compensate, add herbs, spices or flavouring (such as vanilla, maple or almond) to your recipes.
• Some people completely lose their sense of smell and become “nose blind” or anosmic. People who suffer from anosmia can still perceive flavours tasted by their tongue (sweet, salty, sour, bitter and umami) as well as spicy foods but not the aroma. The most common cause of anosmia is untreated infections (acute rhinitis, sinusitis), head trauma and nasal polyps. Unfortunately, no effective treatment has been discovered to allow anosmics to regain their sense of smell.
• Each individual lives in their own olfactory world. If you experience a smell differently than your neighbour, it is because of your DNA! There is actually a condition called specific anosmia which is the inability to detect a certain smell. For example, some people are unable to perceive b-ionone (a molecule that gives violets their smell, also present in many fruits) or isovaleric acid (found in sweat) or cineole (a molecule that smells like camphor). So it’s true that taste is quite subjective!

Just like great chefs

Chefs have always added herbs and spices directly to their creations to add flavour. But how about adding them indirectly? Take a look at what these young and innovative top chefs are doing to add a new olfactory dimension to their dishes.

1. The young chef Grant Achatz, of Chicago's Alinea restaurant, uses a number of techniques to create an olfactory ambiance for his diners. He makes aromatic vapours by pouring hot water into a large bowl that also contains thin slices of ginger or lemon. The serving plate is placed in this large bowl and served to the customer. Ginger vapours accompany his Asian salmon dish, for example. Achatz also invented “air pillows” – plastic bags that are filled with scented air by a device that resembles a humidifier. When it comes time to serve the meal, the bag is punctured and put in a white cotton cloth that is then used as a place mat of sorts for the dish. Air is released from the pillow as the meal is being eaten. The subtle aroma of nutmeg, for example, is superimposed on the taste of a simple dish of white beans, without the inconvenience of this spice’s bitter or sometimes strong taste.

2. Heston Blumenthal, chef at Fat Duck restaurant in Bray, England, uses a small vaporizer filled with scented water to complement the dish being served. The diner is invited to spray the scent in the air before tasting the dish. For example, his Black Forest cake is served with a cherry spray, his truffle toast comes with an earthy, undergrowth-smelling spray.

3. Homaro Cantu, from Moto restaurant in Chicago, invented interactive utensils, knives, forks and spoons with spiral-shaped handles where herbs are inserted which perfume the air while the utensils are being used.

Hoe does the brain recognize thousands of different smells?

This big mystery was only solved in 2004. Research by Richard Axel and Linda Buck was so persuasive that it earned the pair the 2004 Nobel Prize in Physiology. They discovered that each type of olfactory receptor is encoded by a different gene. All in all, we possess no fewer than a thousand different genes dedicated to detecting odours – an impressive 3% of our genes! Researchers also found that each olfactory receptor cell only possesses one type of odorant receptor but that all olfactory receptor cells converge on the same place in the olfactory bulb. It is as if each smell triggers a different combination of light bulbs to shine on a large illuminated sign. Each smell has its own pattern of illuminated lights which allows the brain to distinguish between, for example, the smell of an apple and a banana.

By Christina Blais, nutritionist and professor of food sciences