Phil’s Findings #1: A Matter of Taste

23 May 2011

Phil Howes, the Institute of Making’s post-doc researcher, shares his thoughts and findings as he delves into the sensoaesthetic world of materials. This is the first of a weekly installment: check this space every Monday for Phil's latest posting.

A Matter of Taste

It is generally believed that there are only a few basic taste sensations that humans experience. These are sweet, sour, salty and bitter, with the slightly mysterious ‘umami’ being a highly probable candidate to make the number up to five. This means that all of the food and drink you have tried in your life can be broken down into a simple combination of these five tastes. Now if you consider the wonderful variation in cuisine there is in the world, from the spicy curries of India to the pizzas and pastas of Italy, it seems inconceivable that this variation can be encompassed by just five basic tastes. Is this really possible?

Well, it is important to consider here the difference between taste and flavour. Taste is a sensation which arises from chemical stimulation of taste buds on the tongue, whereas the perception of flavour is built up from what the food smells like, and what it feels like in the mouth, its texture. We actually have two mechanisms by which we can smell. The first type just involves breathing in through the nostrils, as normal. The second type happens when you put the food or drink in your mouth. Vapours from the food make their way into the nasal cavity through the back of the throat, and the sensation this gives you is a really important part of our perception of flavour (just think of how food loses its flavour when your nose is blocked during a cold).

Eating really is a multisensory experience. For example, many people enjoy the flavour of hot chilli peppers. These contain a chemical called capsaicin which is responsible for the burn of the pepper. However, the capsaicin doesn’t stimulate taste receptors in the usual manner, it actually stimulates (and irritates) pain receptors on the tongue. So in this instance your perception of the flavour of say, a hot chilli con carne, is being augmented by a dose of pain. The same goes for strong mustard, which you can feel in the back of your throat and through your nose as it stimulates various pain receptors. Your sight can also have a strong influence of how you perceive the flavour of the food. I remember trying ‘green tomato ketchup’, but finding it disgusting because it was bright green. This stuff was not chemically different from normal red ketchup, and ‘tasted’ identical, but I found it unpalatable because it didn’t look right, which means that my perception of the flavour was actually being influenced by my visual impression of the food.

So, it would seem that armed with all your senses, along with your five basic tastes, you are able to enjoy a massive variety of flavours and foods. However, the basic tastes model does present some problems. For instance, where would you place metallic tastes in them? Some metals do elicit very distinctive tastes when put in the mouth, and actually there is evidence that some metallic sensations can be detected retronasally, just like other flavours. Well, it would seem some investigation is required. Watch this space…