A SENSE of smell can be just as important as taste buds when it comes to enjoying food. But it is not just how food smells on the dinner plate that matters 鈥� chewing it and adding saliva 鈥� can release heady aromas into the nose through the back of the nasal passage, dramatically enhancing the flavour. To demonstrate how important these retronasal aromas really are, Deborah Roberts and her colleagues at Cornell University, New York, have devised an artificial mouth to simulate the action of chewing.
鈥淚t鈥檚 the aroma that really allows people to tell the difference between foods,鈥� says Roberts. 鈥淥ften with their noses closed people can鈥檛 tell the difference between, say, an onion and an apple.鈥�
The artificial mouth consists of a food mixer coupled to a gas chromatograph. Food and artificial saliva a water-based solution containing saliva salts and enzymes 鈥� are mixed and the released aromas fed to the chromatograph, which separates them into their individual chemical components. Each chemical is then cooled, moistened and fed to a human 鈥渟niffer鈥� who defines the odour according to a series of specific descriptions, such as 鈥渇ruity鈥� or 鈥渟moky鈥�.
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The human nose is more sensitive than the best analytical equipment when it comes to picking out the chemical that makes a particular flavour. To maximise receptiveness, the sniffer sits in a comfortable chair listening to pleasant music.
The 鈥渕outh-sniffer鈥� system has already picked out flavour compounds that were added in known quantities to food, and has identified the chemical that gives raspberries their 鈥渇loral鈥� flavour.
The next step in the research is to find out why low-fat foods often taste worse than their full-fat counterparts. The researchers speculate that the oil in full-fat food may trap some of the less desirable aroma compounds. Taking out the fat may release these compounds and spoil the flavour.
鈥淚t鈥檚 really a challenge to food product developers first to try to work out what flavour compounds are important in full-fat foods, and then to see what鈥檚 different in their reduced-fat counterparts,鈥� says Roberts. 鈥淥nce you know what it is that鈥檚 causing the 鈥榦ff鈥� note, you can look at what ingredient is responsible and do a reformulation to try to minimise that.鈥�
The artificial mouth is decidedly more dignified than the only known alternative technique for tracing tastes 鈥� getting a human subject to chew a particular food for a specified length of time and then sucking the aromas out through their nose for analysis.
Roberts reported the team鈥檚 work at the American Chemical Society鈥檚 meeting in Anaheim, California, this month.
