The science of combining flavours

08 August 2014

Interview with

Sebastian Ahnert, The University of Cambridge

Lamb and mint sauce; cheese and wine; strawberries and cream. Some foods just go together better than others. But why is this? Sebastian Ahnert from the University of Cambridge has been analysing flavours across different food groups, and gave Ginny Smith a taste of what he found... 

Sebastian -   Every food has a unique combination of dozens or hundreds of flavour compounds and these are small molecules that we actually perceive in our nose rather than our mouth.  So in our nose, we have something called the olfactory epithelium and this tissue can differentiate between all of these hundreds of compounds whereas in our mouth, we can only distinguish 5 different tastes.

Ginny -   So, is that why when I've got a really bad cold, everything tastes rubbish?

Sebastian -   Exactly, that's why.

Ginny -   So, you need your nose to be able to actually taste those flavours.  So, if there are hundreds of these compounds, how do you find them and how do you find which ones are important for flavour?

Sebastian -   Well, you can put a food through a machine called GCMS and that will extract all these flavour compounds and tell you how much of each compound there is.  It will tell you the entire spectrum for that given food.

Ginny -   How many of these tend to make up a standard flavour, say a strawberry?  Is there just one strawberry compound or is it a combination of loads of different ones?

Sebastian -   It will be a combination of at least dozens which play an important role.  Actually, a strawberry is an interesting sample because in strawberry, there's no strawberry compound, but strawberry flavour is actually made up of a large number of very different flavours which in themselves don't smell of strawberry.

Ginny -   Fascinating!  It's all really interesting, but what can this kind of be used for?  Why do we need to know this?

Sebastian -   Flavour chemists and flavour scientists use this kind of information to generate artificial flavours.  But the work we were interested in was to actually look at the hypothesis that the chef, Heston Blumenthal put forward and he suggested that ingredients might taste well together if they share flavour compounds.  So, we actually collected a large amount of data on what foods contain what compounds and then drew a network of food ingredients where we linked two ingredients if they share compounds.

Ginny -   Were there any kind of classic combinations that we all know like pork and apple, that came out as actually sharing things on your database?

Sebastian -   Yeah, some of the classics came out and sort of if you look at the network as a whole, you do see that for instance, meat and vegetables are neighbours in the network and that makes sense from our every day experience.  Fruit and alcoholic drinks are neighbours which makes sense if you think about cocktails. But also, a few set of unusual combinations.

Ginny -   Yeah, so onto those unusual combinations.  Before the show, you gave us a few ideas for unusual combinations which we've actually brought along here.  Now Kat, in front of you, there are three little plates.  They're covered over.

Kat -   I'm so excited.

Ginny -   So, I want you to reveal the first one and tell us what you've got on there.

Kat -   This is olives and raspberries.  So, I've got some little slithers of the sort of the yellowy green olives and raspberry.  So, do I just eat them together?

Sebastian -   That would be the idea, yeah.

Kat -   Okay, right here it goes.  I've got raspberry, a bit of olive.

Ginny -   What's it taste like?

Kat -   It's really, really interesting.  It kind of - it doesn't have that really salty kind of flavour of the olive.  It's sort of offset by the sweetness of the raspberries.  It's like a chutney or something like that. It's very rick kind of flavour.

Ginny -   I definitely got raspberry first and then suddenly, the olive kind of kicked in. Why do those two work together?  Sorry, you've got your mouthful now.

Sebastian -   Well, they share a number of flavour compounds.  I mean, these predictions don't always work, one has to say because the data is not perfect.  But I think what this sort of automatic approach can give us is some suggestions for chefs or cooks to look at and try out maybe some new ideas.

Kat -   Yeah, I might put some raspberries in with my olives.  What have we got here?  what's this one?  This is - now, two of my favourite, favourite things in the world.  This is blue cheese and dark chocolate.  I'm going to get it stuck straight in here.

Ginny -   Cheese and chocolate.  I don't know.  It's a difficult one.  I've been reading more recipes recently thatare using dark chocolate as an ingredient, savoury things so often with venison and that sort of thing.

Sebastian -   That's right.  Chocolate has a lot flavour compounds.  It actually goes really well with a lot of things.  There's an American chocolate bar that has bacon in it.

Kat -   I've tried that.  I think it's horried.

Ginny -   I actually made cupcakes with bacon in them for a friend who was obsessed with bacon.  It added something.  I'm not sure if it was an improvement.

Kat -   There are some people who believe everything is improved with bacon.  That's interesting.  The blue cheese and chocolate is interesting.  I don't get any of the sweetness of the chocolate for me.

Sebastian -   It works well with dark chocolate rather than milk chocolate.

Kat -   It's a very savory combination.  Ginny is not looking convinced at all.

Ginny -   I'm not sure. 

Kat -   Papaya and parmesan.  Okay, here it goes.

Ginny -   Now, I can see this working because cheese and fruit is quite a kind of common combination you eat - cheddar with apple or with grapes - that sort of thing quite often.  What's it like, Kat?

Kat -   Mmm... I like that.  That's kind of the classic, sort of sweety, salty thing.

Ginny -   Yeah, that works.

Sebastian - Yes, I think if I remember correctly, actually, there was a dairy cluster in our network which was not far away from the fruit.  We put fruit ingredients.  So, we noticed really at that time that cheese and fruit sit well in the network as well.

Ginny -   Is this something that chefs are actually using to create new recipes?

Sebastian -   Yes.  I started to talk to restaurants and chefs.  They're really interested..

Kat -   This is one that maybe a little bit specialist here.  Ginny hates banana.  It's banana and parsley.  I have to say, I'm not very convinced by the look of this.  Let's go.

Ginny -   I'm afraid I'm not trying that.  I hate bananas.  I'm going to pass on that one.  There's no way I like it even with parsley on.  What do you think, Kat?

Kat -   I think that's quite nice actually.  I think they're quite complimentary.

Ginny -   So, we've had a couple of successes today but a few of you have tweeted us with your weird combinations.  We've got Chris, says, he likes fish fingers and custard.

Kat -   Weirdo!

Ginny -   Neil Brisco says he likes peanut butter and tomato sandwiches.

Kat -   Weird.

Ginny -   Yeah.  Although if you think of peanut butter as being like a satay sauce, you'd eat that with vegetables.  That's quite common.

Kat -   Not really with tomatoes though.

Ginny -   Yeah, maybe not tomatoes.

Sebastian -   The custard and fish fingers sounds very interesting.

Ginny -   We will have to try that one another time.

Kat -   Yeah, maybe not.

Ginny -   Thank you so much for that.  I'm not sure I'm going to thank you for the blue cheese and chocolate one, but olives and raspberries is a revelation.

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