Science Interviews


Tue, 16th Dec 2014

The perfect Christmas dinner

Dr Ophelia Deroy, Centre for the Study of the Senses

Listen Now    Download as mp3 from the show The Science of Christmas

Every year, there’s a huge amount of pressure on the chef of the family to Roast Dinnerproduce the perfect Christmas dinner. There’s the airiest, crispiest potatoes smothered in goose fat to worry about; the thick but not lumpy consistency of gravy and let’s not forget the piece-de-la-resistance – the Turkey! The continuous basting, the stuffing... It’s enough to make anyone go mad. However, Ophelia Deroy at Centre for the Study of the Senses has been examining all of the elements that contribute to the diner’s experience and how that can dramatically alter how nice (or terrible) you perceive the meal to be! She told Chris Smith how you can use psychology to alter how guests perceive your roast turkey to taste...

Ophelia -  Taste interacts with a lot of your olfactory system.

Chris -  ...your nose.  

Ophelia -  Your nose. Volatile components rise up and reach the piriform cortex, which is the olfactory receptors.  This retronasal smell gets bound with the taste you're experiencing.

Chris -  I see.  So, I put something in my mouth, yes, I get the sensation on my tongue around my mouth, but there are other chemicals coming out of the food that go up the back of my throat – for want of a better phrase – and they're activating my smell system.  But I don't regard them as a smell.  I am regarding them as a taste.  But actually, it’s the whole thing mixed together.

Ophelia -  Yeah.  We call this oral referrals.  So, the sensation is not experienced at the place where you actually receive the stimulation.

Chris -  How can one exploit this in order to maximise the enjoyment of food?

Ophelia -  So, because smell is involved in flavour experience then you can understand why some of the expectations that you will have come from your sense of smell.  So, when you enter a room and you have this delicious smells floating around then it’s already the same component you will experience when you actually taste the food.  So, the pleasure of anticipation is already at stake.  So, keep the doors of  the kitchen open.

Chris -  We were hearing just now from Elena about how children learn to integrate information to make jokes funny because they can hold several things in their mind at once.  Do you think the same applies then to flavours that when you're experiencing a flavour that actually, because a flavour doesn’t just come and go.  Actually, it evolves in your mouth and you experience different things at different times.  Do you think that actually is why adults are better at enjoying certain flavour experiences than things would be because they've got to hold those experiences in their mind all at once?

Ophelia -  So, there's probably less multisensory integration going on in the flavour system of children, but what is going on also when you're young is that you really want to keep track of what you're eating.  Most children will want to have the vegetables not touching the meat.  What is going on is a sort of clever way of learning to connect what you experience in the mouth and the shape and the colour of things so that later, you can actually know how to mix them.  But before that, you will keep them separate.

Chris -  What about other sorts of stimuli?  What about sound as well though?  If I place a music in a restaurant or if I eat an airline meal, do I experience the food differently on an airplane with all that noise going or the Indian restaurant playing that very Indian music?  Do I get a better flavour experience?

Ophelia -  So, this is part of a fascinating series of research projects we’ve been conducting and the fact that sounds actually affects your flavour experiences.

Chris -  So, it does.

Ophelia -  Yeah, absolutely.  In an aircraft, the sounds that you hear will actually lower your taste perception.  Many people will order tomato juice in a plane, I do.

Chris -  With vodka added.

Ophelia -  When you would never have it maybe on the ground.  The reason is that tomato juice is very rich in umami and whereas all your other tastes...

Chris -  This is this very meaty flavour compound, isn’t it?

Ophelia -  Yeah.  All the other tastes have sort of become dull because of the background sound, but umami resists.

Chris -  Then if I fly business class and I get my noise cancelling headphones on, is that going to mean the food taste better even though it might not be any different?

Ophelia -  The food will taste better because of these beautiful noise cancelling headphones.

Chris -  So, that's true.

Ophelia -  Yeah, but you will have also heavier cutlery.

Chris -  And that makes it different?

Ophelia -  Absolutely, to the perception of creaminess.  So, you just have a way in which – because it feels heavier on your hands then you will think, ahh! It’s because the stuff on the spoon is actually more dense.

Chris -  So, when people say, look, drinking tea just doesn’t taste right or wine does not taste right out of a plastic cup and put it in the glass or put it in the mug and it tastes totally different, same tea, that's purely a subjective biasing by the vessel you're drinking out of.

Ophelia -  Because we’re looking at the complex enjoyment of the food, it will actually change people’s overall perception.  They will think that it’s a more enjoyable experience and then they will refer it back to the wine and think it was a better wine.

Chris -  Okay, answer me this.  What can we do about Brussels sprouts, universally loathed by some, loved by others?  How do we turn them to everyone’s favourite vegetable?  Is it possible to play the same trick with Brussels?

Ophelia -  Yeah, some people might not like Brussels sprouts because they have more bitter receptors in the tongue.  So, for this part of the population, which we call supertasters, maybe there's nothing to be done.  But for other people, you might try changing the colour of the plate.  With a blue plate, it will taste saltier and with a red plate, you will bring the kind of sweeter flavours on the Brussels sprout.

Chris -  If I want to max-out on people’s enjoyment of my Christmas dinner, give us some tips then.  What should we actually be doing to give people the best Christmas experience with their dinner?

Ophelia -  Well, probably taking a cooking class before will help.

Chris -  That would help, that's true.

Ophelia -  The kind of research I've been involved in is looking at ways to improve your flavour experience without touching the food itself.  So, think about the visual appearance of the food.  So, if you add some colours, it will make you expect something more intense and it will make it taste more intense.

Chris -  Does that actually get borne out if you give people a more colourful meal than a more bland looking meal, but it’s the same stuff that tastes the same.  Do they say, “Wow!  That tastes great!” versus this that tastes bland?

Ophelia -  The colour intensity can improve the perceived intensity of flavour, absolutely.  Up to the point that if you give people just a little bit of red dye, lots of people will start saying, “It tasted raspberry” although there is nothing but colour in it.

Chris -  Is it true someone did an experiment where they got a glass of white wine and they stained it to look like red wine and they took some identical wine without the stain in it and said to people would sample these two and people thought they were drinking red wine and white wine, but in fact, they were the same thing?

Ophelia -  Yeah.  So, an experiment which has been conducted by a winologist.

Chris -  Wine specialist.

Ophelia -  Yeah and Frederic Brochet.  They were trying to show how important vision is in generating expectations.  Of course, what is tricky here with wine is that it’s a very social thing.  So, people didn’t want to look like fools and they probably reported kind of red fruit flavours  because they didn’t want to say something else.  So, it’s something that we know as a huge influence but there's something very complex going on with these wine examples.  

Something you might be looking at also is the candles you will light.  Scented candles make a difference to how much people will enjoy the food but also, how strongly they will remember the meal.  Probably, the perfect meal is the most memorable one.

Chris -  Indeed because you want people to come back.  So, what can I do then to make people want to come back?

Ophelia -  Give them good food, good company, good jokes.  But also, if you give them a smell that connects to their previous happy memories of Christmas like scented candles with pine tree or cinnamon.  They are likely to connect this episode with their previous happy memories of Christmas and it will improve their experience.

Chris -  Do restaurateurs do that?  Do they, by dishing up the peppermint at the end of the meal or something equivalent, is that their way of sending you home with a signature smell that reminds you of the wonderful occasion you've just enjoyed so you are likely to go back.

Ophelia -  Absolutely.  We have this example of Heston Blumenthal at the fat duck where it actually gives you a smell when you go out of the restaurant, which is the smell of a sweet shop, which connects you childhood memories and makes this final touch when you go – it extends the memory of the wonderful meal you had.


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