It is commonly known that we have a small set of five sensations our tongue can detect: Salty, sour, bitter, sweet and unami, with increasing evidence we can also detect fat. But how do these work exactly?
How do we taste?
We have a number of receptors on our taste buds which allow us to detect these sensations, interestingly we only have two receptors for sweet, versus 25 for bitter sensations.
This is an evolutionary design to ensure survival. Most poisonous materials are bitter so we need a wide range of receptors to detect them, while we obtain calories from sweet foods and so our sweet receptors have evolved to be specific for those molecules which provide energy.
The interaction between molecules and receptors is not a simple ‘lock and key’ design. Different sweet molecules bind to different parts of the receptors and this is part of the reason why high intensity sweeteners are sweet but have a different sweetness profile to sugar.
What about flavour?
We also need to consider flavour - looking at the overall sensory experience, which, along with the sensations already mentioned, also includes an incredibly complex and varied dimension of aroma.
Olfaction forms our sense of smell, flavour is mainly a combination of taste and odour and these messages are processed in the same area of the brain as where emotions and memories are regulated. This is why a smell can transport you back to a memory where you feel powerful emotions.
Appearance, texture and sound also play a part in flavour perception - this effect is called cross modal correspondence and the link between smell and taste is called olfactory referral. Research into cross modal correspondence and neurological gastronomy continues to fascinate our research and development chemists. By exploiting the overlap in neurological processing, we can enhance perception of sweetness with odour components. For example - sugar enhances flavour impact, while strawberry flavour is shown to enhance sweet perception.