Smell is intimately related to how human beings taste food but has long remained the most enigmatic of our senses. The average human nose can detect nearly 10,000 distinct scents, a feat that requires about 1,000 olfactory genes, or roughly 3 per cent of the human genome.
In 1991 Americans Richard Axel and Linda Buck jointly published a fundamental paper in which they described this large family of 1,000 olfactory genes.
"The basic principles for recognising and remembering about 10,000 different odours were not understood. This year's Nobel Laureates in Physiology or Medicine have solved this problem and in a series of pioneering studies clarified how our olfactory system works," said the Nobel Assembly at Karolinska Institutet this week, awarding the prize.
When something tastes really good it is primarily activation of the olfactory system which helps us detect the qualities we regard as positive. A good wine or a sunripe wild strawberry activates a whole array of odorant receptors, helping us to perceive the different odorant molecules, continued the Nobel prize givers.
Axel and Buck discovered a large gene family, comprised of some 1,000 different genes (three per cent of our genes) that give rise to an equivalent number of olfactory receptor types. These receptors are located on the olfactory receptor cells, which occupy a small area in the upper part of the nasal epithelium and detect the inhaled odorant molecules.
Each olfactory receptor cell possesses only one type of odorant receptor, and each receptor can detect a limited number of odorant substances. The olfactory receptor cells are therefore highly specialised for a few odours.
The cells send thin nerve processes directly to distinct micro domains, glomeruli, in the olfactory bulb, the primary olfactory area of the brain. Receptor cells carrying the same type of receptor send their nerve processes to the same glomerulus. From these micro domains in the olfactory bulb the information is relayed further to other parts of the brain, where the information from several olfactory receptors is combined, forming a pattern.
The Karolinska Institutet writes: "Therefore, we can consciously experience the smell of a lilac flower in the spring and recall this olfactory memory at other times."
The food industry is gradually starting to use e-noses (electronic noses) as part of the quality supply chain to reduce costs. Earlier this year researchers at Cranfield University in the UK reported they had come up with an e-nose for the early detection of 'undesirable off-odours and microbial contaminants' in dairy and bakery products. The EU-funded project, led by Professor Naresh Magan, found the new technology can be used to quickly detect bacteria, yeasts, filamentous fungi and off-odours.
Based on conducting polymer sensor arrays or metal oxide sensor arrays the researchers claim the nose offers 'rapid and early cost effective' detection of undesirable, harmful contaminants, toxins and taints.
In his will the inventor of dynamite, Alfred Nobel who died in 1896, provided for the establishment of the Nobel prize. The prize is given for achievements in physics, chemistry, physiology or medicine, literature and peace. And in 1968, the Bank of Sweden instituted a prize in economic sciences in memory of Nobel. Each prize consists of a medal, personal diploma, and prize amount.