AIChE Webinar 26 October 2011 Peter Barham - Department of Physics, University of Bristol, UK

- Department of Food Science, University of Copenhagen, DK - Animal Demography Unit, University of Cape Town, RSA

Molecular Gastronomy The Science of Taste and Flavour

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Where did it all start

• Molecular Gastronomy has its origins in a series

of workshops for chefs and scientists held in Erice

in Sicily initially suggested by Elizabeth Thomas

and organised by Nicholas Kurti.

• The meetings were called “International

Workshops on Physical and Molecular Aspects of

Gastronomy”. Later abbreviated to Molecular

Gastronomy.

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The Erice meetings

Nicholas Kurti in 1969 Elizabeth Cawdry Thomas

4 What is Molecular Gastronomy?

Today, we want to understand what it is that

makes one dish delicious and another not;

whether it be the choice of ingredients and

how they were grown; the manner in which

the food was cooked and presented; or the

environment in which it was served.

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Example: Salt – why use it?

Most people, when they cook, add salt to nearly

everything.

Almost all recipes call for a “pinch of salt”.

But is it really necessary?

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Salt and green vegetables • Reasons given to add salt

• It raises the boiling point

• It decreases the boiling point

• It makes water boil more vigorously

• It „fixes‟ the color

• It adds seasoning

• What it actually does today • It raises the boiling point (by a fraction of a degree)

• It encourages nucleation and so gives the appearance of vigorous boiling

• What it may have done in the past • Divalent ions can replace any missing Mg in the chlorophyll – this

can lead to a color change from brown to green

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Taste sensations

•Salt

•Sweet

•Bitter

•Sour

•Umami

We each have five different types of taste buds distributed around the

tongue and the sides of the mouth.

•Salt an essential nutrient we would not get in a „natural‟ diet

•Sweet the taste of sugars needed to provide bursts of energy

•Bitter the taste of alkaloids – potentially toxic substances

•Sour the taste of acids – possibly dangerous

•Umami the taste of an essential nutrient – amino acids

Particularly the taste of the sodium salt of glutamic

acid

Also known as mono (sodium glutamate)

Or MSG

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Perception of Flavour

Flavour is the combination of taste in the mouth (from the

taste buds) and aroma in the nose.

Our noses are very much more sensitive than our tongues

– we have around 400 different types of aroma sensor

compared to just 5 types of taste sensors.

9 Perception of Flavour

An easy way to demonstrate the importance of aroma is

to try to identify the flavor of a food while holding your

nose – without the information about aroma you cannot

tell what you are eating.

This is why food tends to lose its flavor when you have a

cold and your nose is blocked.

Interestingly we detect different aromas depending on

whether we are breathing in (ortho-nasal) or out (retro-

nasal.

This explains why some really smelly foods taste so good.

– the best example is Durian fruit, but really ripe soft

cheeses also have the same effect.

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Adaptation

Our sense of smell evolved to help us

know what is in our environment.

We thus are more sensitive to changes in

the aromas around us.

This means that we quickly ”adapt” to

aromas – ignoring constant smells.

In food, constant flavours become “boring”

and are ignored.

Perception of Flavour

11 Perception of Flavour

In practice flavour is constructed in our minds.

We use all our senses to determine flavour.

What we see tells us what to expect.

A white wine coloured red will evoke red

wine memories and descriptions.

The colour of the plates on which we

serve food affects expectations and thus

appreciation. Food served on patterned

or blue plates often has a poorer rating

than food served from plain white plates.

12 Perception of Flavour

What we hear affects how we eat.

Try recording yourself eating a crunchy

food and then play the sound back while

trying to eat something soft.

Or take some chips and simply crush

them in your hands near the ears of a

„friend‟ who is trying to eat!

If you listen to music when eating, you

are liable to start to chew in time to the

beat.

13 Perception of Flavour

What we feel affects how we perceive

texture.

Try eating a creamy food (maybe a

yogurt) – note how creamy you think it

is.

Take a second spoonful while stroking

a smooth silky surface – it will

probably seem creamier.

Take a third spoonful while rubbing

your hand with sandpaper – the food

will probably seem a little gritty.

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Molecular Gastronomy: A New Emerging

Scientific Discipline

Peter Barham, Leif H. Skibsted, Wender L. P.

Bredie, Michael Bom Frøst, Per Møller, Jens

Risbo,Pia Snitkjær and Louise Mørch Mortensen

http://pubs.acs.org/doi/abs/10.1021/cr900105w

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