The Science of Taste
Posted on November 19th 2015 by Maddie
In last month’s Blog entry, I explained the cupping procedure we use to taste and assess our coffee. Careful preparation leads to a consistent evaluation utilizing all our senses.
When I first learned to cup, I realized the biggest challenge was learning to discern one taste from another: creating a vocabulary for the sensory experience.
Taste relies on multiple sensory stimuli. What we generally acknowledge as ‘taste’ extends beyond gustation and is much more complex.
How does the human brain receive and process multiple sensory input? Our experience of food and understanding taste and the sensory machinery is still being explored. Learning more on how the brain constructs flavour can only enhance our experience of food.
What is taste?
Very often people confuse flavour with taste. Taste is the sensation of flavour perceived by receptor cells in your taste buds.
Those raised bumps on the surface our tongues are called papillae. Each of those contain 250-270 tastes buds! On average, the human tongue has 2,000-8,000 taste buds.
They are also elsewhere in the oral cavity, including along the back of your throat.
Did you know that all of your taste buds are shed and regenerated every week? However, as people get older, their taste buds stop regenerating.
How do taste buds work?
Taste buds are our taste organ. Each has around 50 sensory cells referred to as the gustatory receptor cells.
Taste bud collects saliva. When we consume food or drink, the molecules mix in our taste pores (the opening of the taste bud) and are dissolved in the saliva. The gustatory receptor cells then send signals to the brain through cranial nerves. The brain then interprets the sensation as taste.
Basic Components of Taste
For many years, four basic tastes were recognized: sweet, salty, sour and bitter. A fifth, umami (“savoury” or “meaty”), was added more recently. Each of these tastes will trigger particular gustatory receptors. However, the myth that tastes occupy specific zones of the tongue has been debunked as the receptors throughout the mouth respond to multiple tastes.
Our olfactory sense can be accountable for roughly eighty percent of the impression of flavour.
Flashback to last time you were sick and stuffed up, remember how everything tasted bland and lacked flavour? Most of what you think you taste is actually smell.
The subtlety of flavour would be lost without smell. Try plugging your nose as you eat. You may acknowledge basic components of taste, but flavour characteristics are lost.
There are two pathways for smell.
- Orthonasal. When we inhale. Smelling directly through our noses. The aroma, which entices us to indulge.
- Retronasal. While we eat, volatiles flow up through the back of the throat and up the nasal cavity. Remember in cupping how important it was to slurp the coffee? This is to expel it across the palate and up the back of the throat.
Roasted coffee exposed to oxygen quickly goes stale and loses its aroma. Which is a definite contribution to the off taste!
Taste is also intrinsically linked to mouthfeel. Mouthfeel encompasses textural and chemical sensations, detected by the teeth and tactile nerve cells on the tongue and palate.
In coffee, the body of a cup is determined by mouthfeel. The tactile feeling of the liquid in the mouth. The sense organs are free nerve endings located on the tongue, gums, and palate. These nerve endings sense the beverage’s viscosity and oiliness.
Indonesians coffees like Kicking Horse® Coffee’s, 454 Horse Power®, have heavy body. Sipping them, you will notice a heavy oiliness coating your tongue.
Temperature also contributes to flavour. Our gustatory receptor cells have heightened intensity following temperature increases. This is why ice cream tastes sweeter as it melts.
When we cup coffee, it is important we smell the aroma and break the crust (the grounds that form at the top) within several minutes, not allowing the coffee to cool. The volatility of smell is related to temperature: only volatile molecules, in the form of gas carry odor, it is easier to smell hot foods than cold ones. Think about your last cold Kicking Horse® Coffee brew - not so luscious smelling as that steaming cup of Z-Wrangler you had this morning.
In understanding taste as a stimulation of our taste buds, it is apparent flavour is a much broader concept.
Flavour is the combined sense of all we just discussed. It combines taste, olfactory, touch and temperature.
A recent article in, The New Yorker, goes further to discuss how external packaging influences flavour (I feel another blog entry coming on!). Multiple studies done by Charles Spence, a professor of experimental psychology at Oxford University, demonstrate how people’s perceptions ultimately affect their concept of taste.
Taste, smell and touch all contribute to our experience of eating and drinking. They work in combination with cognitive factors of knowledge and expectation. We really do taste with our brains.
Next entry we will delve beyond sensory stimuli and examine external factors that can have an influential - and unconscious - impression on how our food and drink tastes.