An instant impression is made with the first bite of a new food or taste of drink.
Sensory analysis takes us past this first response, examining how the food’s properties stimulate each of our senses through:
- the appearance of food – using sight, hearing and touch
- the flavour of food – using smell and taste
- the odour of food – using smell.
All this before we’ve even swallowed a mouthful!
Sight
The human eye has an important role in the perception of colour, and this influences our idea of food flavour.
Research shows that we associate specific colour perception of food with certain flavours (although tastes like bitter and sweet are not associated with a particular colour). The stronger the flavour/colour link, the greater the impact of food colour. As colour levels increase our perception of taste and intensity of flavour do also.
We have difficulty correctly identifying foods that are either miscoloured or uncoloured, and people who are colour blind may be unable to tell the difference between certain foods. This may affect their ability to judge food based on its nutritional (or otherwise) qualities, and their enjoyment of certain foods could be impaired.
The human eye
The eye is our collector of light, giving us sight. Its delicate structures enable entering light energy to be converted to electrochemical energy. This stimulates the visual centres in the brain, giving us the sensation of seeing. Sight is one of five human senses that act as ‘gatekeepers’ of our bodies.
Hearing
Being able to hear the sounds of food contributes to the enjoyment of eating – not just the crackle and crunch as we eat but also the sizzle and spit of the cooking process.
Hearing sounds contributes to the experience of eating crisp and crunchy foods like potato chips and biscuits. There’s evidence1 that it is involved with our perception of taste and smell as well.
Touch
The sense of touch allows us to feel sensations caused by the external surfaces of objects (their texture). Food texture refers to qualities felt with the tongue, teeth and palate (also known as the ‘mouth feel’) and fingertips. Texture is what makes jelly feel slippery and slimy or a biscuit crunchy and chewy.
As food is chewed, it is being constantly evaluated. The teeth, tongue and jaw apply a force2 to the mouthful, calculating how easily it breaks down and flows in the mouth. We can then decide whether it is thick, chewy, brittle, runny, slippery, fizzy or prickly.
As consumers place greater demands on the food they eat, food texturisation is seen as an area of challenge and increasing opportunity for the food industry, and development of new, innovative textures are seen as a key area when considering new food developments.
Smell
Smell acts in tandem with taste to identify food flavours and helps us to appreciate the alluring flavours of food and drink. Scientists believe humans innately like smells signalling valuable nutrients3. For example, a fruity smell hints at vitamin C4, sugar and energy, while meaty odours suggest iron5 and B group vitamins.
Research shows a decrease in the number of functional olfactory6 (smell) genes7 through primate8 evolution9 to humans. During the process of evolution, we moved from an arboreal10 (tree-dwelling) way of life to a more erect-postured ground-dwelling mode with our noses moving away from the ground and all of its lovely smells! So, our noses became smaller, our jaws less prognathic (jutting forward) and our eyes moved towards the middle of the face, giving greater depth of vision.
Taste
Taste comes mostly from smell, and what we call flavour is usually a combination of taste, smell, temperature11 and texture of food.
Taste signals the nutritional qualities of the food we are about to eat. Our human ancestors evolved12 in an environment low in salt13, fat and sugar, so our sensory systems were adapted14 to identify and acquire these scarce food types.
- Sour-tasting food signalled unripe fruit and vitamin15 C.
- Salty-tasting substances indicated salt and important minerals.
- Bitter suggested poisonous16 plants.
- Savoury umami taste – precious protein17.
- Fatty tastes reveal valuable energy-rich foods.
Sweet or sugary tasting substances were valued as they increased body insulin18 levels that promote cell19 growth and were excellent sources of short-term energy, sparing our fat reserves.
Researchers have evidence that there is a further taste – that of calcium. This makes sense for our survival, as calcium is vital in cell operations and for skeleton building.
Watch this video clip below to learn how sensory scientists at Plant & Food Research conduct sensory trials with apples.
- evidence: Data, or information, used to prove or disprove something.
- force: A push or a pull that causes an object to change its shape, direction and/or motion.
- nutrient: A substance that provides nourishment for growth or metabolism.
- vitamin C: An antioxidant found in fruits and vegetables, such as oranges, kiwifruit, berries, tomatoes and leafy greens.
- iron: A chemical element with the symbol Fe.
- olfactory: Relating to the sense of smell.
- genes: A segment of a DNA molecule that carries the information needed to make a specific protein. Genes determine the traits (phenotype) of the individual.
- primate: A mammal of the order Primates that includes lemurs, marmosets, monkeys, apes and humans.
- evolution: In biology, the change in the genetic material and/or the behaviour of a population of organisms over time.
- arboreal: Living in trees.
- temperature: A measure of the degree of hotness or coldness of an object or substance. Temperature is measured with a thermometer calibrated in one or more temperature scales. Kelvin scale temperature is a measure of the average energy of the molecules of a body.
- evolve: To develop gradually. Changes in successive generations over long periods of time.
- salt: In chemistry, a salt is produced when a strong acid and strong base react. Strong acid + strong base = salt + water.
- adaptation: A change in the structure or function of something. In biology, a change in a species, as a result of natural selection. Individuals with a particular feature (adaptation) are more likely to survive and reproduce than individuals without this feature.
- vitamin: An organic compound required as a nutrient in tiny amounts by an organism.
- poisonous: Capable of harming or killing by or as if by poison. A poisonous organism only delivers its toxins when eaten, touched or inhaled.
- protein: Any of a large class of complex compounds that are essential for life. Proteins play a central role in biological processes and form the basis of living tissues. They have distinct and varied three-dimensional structures. Enzymes, antibodies and haemoglobin are examples of proteins.
- insulin: A hormone produced in the pancreas that controls blood sugar levels.
- cell: 1. Building block of the body. A human is made of millions of cells, which are adapted for different functions and can reproduce themselves exactly. 2. A simple electrolytic device that enables chemical energy to be transformed into electrical energy.
