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!
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.
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 evidence that it is involved with our perception of taste and smell as well.
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 force 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 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 nutrients. For example, a fruity smell hints at vitamin C, sugar and energy, while meaty odours suggest iron and B group vitamins.
Research shows a decrease in the number of functional olfactory (smell) genes through primate evolution to humans. During the process of evolution, we moved from an arboreal (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 comes mostly from smell, and what we call flavour is usually a combination of taste, smell, temperature and texture of food.
Taste signals the nutritional qualities of the food we are about to eat. Our human ancestors evolved in an environment low in salt, fat and sugar, so our sensory systems were adapted to identify and acquire these scarce food types.
- Sour-tasting food signalled unripe fruit and vitamin C.
- Salty-tasting substances indicated salt and important minerals.
- Bitter suggested poisonous plants.
- Savoury umami taste – precious protein.
- Fatty tastes reveal valuable energy-rich foods.
Sweet or sugary tasting substances were valued as they increased body insulin levels that promote cell 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.
Visit the Biotechnology Learning Hub and watch this video clip to learn how sensory scientists at Plant & Food Research conduct sensory trials with apples.