SENSORY EVALUATION: THE SENSES
Diagram
Taste is one part of flavour
Taste
What the tongue senses: sweet, sour, salty, bitter and umami. Only five basic tastes, sensed by taste buds.
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Smell
What the nose senses: thousands of aromas carried up from the food, through the nose and from the mouth.
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Flavour
Taste plus smell plus mouthfeel: the whole experience of eating. Taste alone is only a small part of it.
Figure 1: Taste is the tongue alone; flavour is taste plus smell plus mouthfeel. Drawn in our own style from the taste and smell chapters of Lawless and Heymann, Sensory Evaluation of Food, chapters on the anatomy, physiology and functions of taste (p. 39) and of smell (p. 50).
Introduction
Taste and flavour are used as if they meant the same thing, but taste is only one part of flavour. Taste is what the tongue senses: sweet, sour, salty, bitter and umami, picked up by taste buds. Flavour is the whole experience of eating: taste plus smell plus mouthfeel. Lawless and Heymann give taste and smell their own chapters, on the anatomy, physiology and functions of taste (p. 39) and of smell (p. 50).
The core difference is scope: taste is a single sense on the tongue, and flavour is the sum of taste, smell, touch and temperature working together.
Quick comparison
Table 1: Taste compared with Flavour
| Aspect | Taste | Flavour |
|---|---|---|
| Sense used | Tongue only, through taste buds | Tongue plus nose plus mouth, and more |
| What is sensed | Five basic tastes: sweet, sour, salty, bitter, umami | Tastes plus aromas plus texture, temperature and mouthfeel |
| Number of qualities | Only five basic tastes | Thousands of flavours, because smells combine without limit |
| Role of the nose | None | Main: most of what we call flavour comes from smell |
| When the nose is blocked | Taste stays, so sweet and salty are still sensed | Flavour collapses, so food tastes flat and dull |
| Mouthfeel | Not part of taste | Part of flavour: crunch, creaminess, warmth, coolness |
| Where it happens | On the tongue | In the mouth and nose together, joined in the brain |
| Test method | Taste tests use single tastes in water | Flavour tests use whole foods, with smell free to work |
| Example | Sugar water tastes sweet, lemon juice tastes sour | A strawberry tastes of strawberry because of its smell as well as its sweetness and acidity |
| Loss | Losing taste dulls sweet, sour, salty, bitter and umami | Losing smell takes away flavour, so food tastes of almost nothing |
Scientific explanation
Definition
Taste is the sense of the tongue: the five basic tastes, sweet, sour, salty, bitter and umami, sensed by taste buds on the tongue. Lawless and Heymann cover the anatomy, physiology and functions of taste in their own chapter (p. 39).
Flavour is the full sensory experience of a food: taste plus smell plus mouthfeel, including texture, temperature and the trigeminal sense that gives warmth, coolness and pungency. Lawless and Heymann cover smell in its own chapter (p. 50), and Jelen covers odorants and tastants and the interaction of smell and taste in Food Flavors.
Working principle
Taste works through taste buds: chemicals in food dissolve in saliva and touch the buds, which send signals for the five basic tastes to the brain. Only five signals exist, so taste alone can never tell a strawberry from a raspberry.
Flavour works by joining signals: the tongue gives the five tastes, the nose gives thousands of aromas, carried up from the mouth as we chew, and the mouth gives texture and temperature. The brain joins them into one experience, which is why a blocked nose makes food taste flat: the smell half of flavour is gone, and only the five tastes are left.
Apparatus
Taste tests need little apparatus: small cups of taste solutions, water for rinsing, and a quiet room. Flavour tests need whole foods, served in coded cups or plates, with water and plain crackers to cleanse the palate between samples. The books used here describe the test rooms and serving, not one single instrument for this comparison.
Measurement procedure
To test taste alone, panellists taste solutions of one basic taste at a time, often with the nose clipped shut, and name the taste they sense. To test flavour, panellists taste whole foods with the nose free, and describe the full experience: the tastes, the aromas and the mouthfeel together.
There is no single standard measurement procedure for this comparison in the books used here: the distinction is a matter of which senses are allowed to work in the test.
Factors affecting readings
A cold dulls flavour more than taste, because it blocks the nose while the tongue still works. Temperature changes both: warm food gives off more aroma, so its flavour is stronger. Age, smoking and illness change smell more than taste, so flavour fades first.
Formulas and calculations
The books used for this article give no formula for this comparison, so none is given here. The comparison is qualitative: it rests on definitions, materials and method, not on a calculation.
Industrial applications
- Taste is tested in threshold tests, where the smallest amount of a taste that can be sensed is found.
- Taste is tested in product work where sweetness, saltiness or acidity must be set, such as drinks and sauces.
- Flavour is tested in descriptive analysis, where a trained panel profiles the full flavour of a food.
- Flavour is tested in consumer tests, where liking depends on the whole flavour, not on one taste.
- Both are used in quality control, where a change in taste or in flavour can show a fault in the product.
Advantages and limitations
- Taste, advantage: simple and clear, with only five qualities to measure, so tests are easy to run and to repeat.
- Taste, limitation: tells only a small part of the eating experience, so it cannot judge a whole food.
- Flavour, advantage: covers the whole experience of eating, which is what the buyer actually judges.
- Flavour, limitation: complex and harder to measure, because it joins several senses at once.
FAQ
Why does food taste dull when I have a cold?
Because your nose is blocked, and most of flavour comes from smell. Your tongue still senses the five tastes, but the aromas are gone, so the flavour collapses.
How many basic tastes are there?
Five: sweet, sour, salty, bitter and umami. Everything else we sense in food comes from smell, mouthfeel and temperature, not from taste.
Is umami really a taste?
Yes: umami is the savoury taste, sensed by the tongue like the other four. It is the taste of glutamate, found in cooked meat, cheese, tomatoes and soy sauce.
Can taste tell a strawberry from a raspberry?
No, not alone: both are sweet and sour, and taste gives only those two signals. The nose tells them apart, by their different aromas.
Is spicy heat a taste?
No: the heat of chilli is not a taste, it is a trigeminal sensation, a feeling of warmth and pain in the mouth. It is part of flavour, not part of taste.
References and further reading
- Harry T. Lawless and Hildegarde Heymann, Sensory Evaluation of Food: Principles and Practices, Springer, 1999 (Google Books page read)
- Henryk Jelen, Food Flavors: Chemical, Sensory and Technological Properties, CRC, 2011
